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  • SemaChecking.cpp 436.85 KiB
    //===--- SemaChecking.cpp - Extra Semantic Checking -----------------------===//
    //
    //                     The LLVM Compiler Infrastructure
    //
    // This file is distributed under the University of Illinois Open Source
    // License. See LICENSE.TXT for details.
    //
    //===----------------------------------------------------------------------===//
    //
    //  This file implements extra semantic analysis beyond what is enforced
    //  by the C type system.
    //
    //===----------------------------------------------------------------------===//
    
    #include "clang/AST/ASTContext.h"
    #include "clang/AST/CharUnits.h"
    #include "clang/AST/DeclCXX.h"
    #include "clang/AST/DeclObjC.h"
    #include "clang/AST/EvaluatedExprVisitor.h"
    #include "clang/AST/Expr.h"
    #include "clang/AST/ExprCXX.h"
    #include "clang/AST/ExprObjC.h"
    #include "clang/AST/ExprOpenMP.h"
    #include "clang/AST/StmtCXX.h"
    #include "clang/AST/StmtObjC.h"
    #include "clang/Analysis/Analyses/FormatString.h"
    #include "clang/Basic/CharInfo.h"
    #include "clang/Basic/TargetBuiltins.h"
    #include "clang/Basic/TargetInfo.h"
    #include "clang/Lex/Lexer.h" // TODO: Extract static functions to fix layering.
    #include "clang/Sema/Initialization.h"
    #include "clang/Sema/Lookup.h"
    #include "clang/Sema/ScopeInfo.h"
    #include "clang/Sema/Sema.h"
    #include "clang/Sema/SemaInternal.h"
    #include "llvm/ADT/STLExtras.h"
    #include "llvm/ADT/SmallBitVector.h"
    #include "llvm/ADT/SmallString.h"
    #include "llvm/Support/ConvertUTF.h"
    #include "llvm/Support/Format.h"
    #include "llvm/Support/Locale.h"
    #include "llvm/Support/raw_ostream.h"
    
    using namespace clang;
    using namespace sema;
    
    SourceLocation Sema::getLocationOfStringLiteralByte(const StringLiteral *SL,
                                                        unsigned ByteNo) const {
      return SL->getLocationOfByte(ByteNo, getSourceManager(), LangOpts,
                                   Context.getTargetInfo());
    }
    
    /// Checks that a call expression's argument count is the desired number.
    /// This is useful when doing custom type-checking.  Returns true on error.
    static bool checkArgCount(Sema &S, CallExpr *call, unsigned desiredArgCount) {
      unsigned argCount = call->getNumArgs();
      if (argCount == desiredArgCount) return false;
    
      if (argCount < desiredArgCount)
        return S.Diag(call->getLocEnd(), diag::err_typecheck_call_too_few_args)
            << 0 /*function call*/ << desiredArgCount << argCount
            << call->getSourceRange();
    
      // Highlight all the excess arguments.
      SourceRange range(call->getArg(desiredArgCount)->getLocStart(),
                        call->getArg(argCount - 1)->getLocEnd());
        
      return S.Diag(range.getBegin(), diag::err_typecheck_call_too_many_args)
        << 0 /*function call*/ << desiredArgCount << argCount
        << call->getArg(1)->getSourceRange();
    }
    
    /// Check that the first argument to __builtin_annotation is an integer
    /// and the second argument is a non-wide string literal.
    static bool SemaBuiltinAnnotation(Sema &S, CallExpr *TheCall) {
      if (checkArgCount(S, TheCall, 2))
        return true;
    
      // First argument should be an integer.
      Expr *ValArg = TheCall->getArg(0);
      QualType Ty = ValArg->getType();
      if (!Ty->isIntegerType()) {
        S.Diag(ValArg->getLocStart(), diag::err_builtin_annotation_first_arg)
          << ValArg->getSourceRange();
        return true;
      }
    
      // Second argument should be a constant string.
      Expr *StrArg = TheCall->getArg(1)->IgnoreParenCasts();
      StringLiteral *Literal = dyn_cast<StringLiteral>(StrArg);
      if (!Literal || !Literal->isAscii()) {
        S.Diag(StrArg->getLocStart(), diag::err_builtin_annotation_second_arg)
          << StrArg->getSourceRange();
        return true;
      }
    
      TheCall->setType(Ty);
      return false;
    }
    
    /// Check that the argument to __builtin_addressof is a glvalue, and set the
    /// result type to the corresponding pointer type.
    static bool SemaBuiltinAddressof(Sema &S, CallExpr *TheCall) {
      if (checkArgCount(S, TheCall, 1))
        return true;
    
      ExprResult Arg(TheCall->getArg(0));
      QualType ResultType = S.CheckAddressOfOperand(Arg, TheCall->getLocStart());
      if (ResultType.isNull())
        return true;
    
      TheCall->setArg(0, Arg.get());
      TheCall->setType(ResultType);
      return false;
    }
    
    static bool SemaBuiltinOverflow(Sema &S, CallExpr *TheCall) {
      if (checkArgCount(S, TheCall, 3))
        return true;
    
      // First two arguments should be integers.
      for (unsigned I = 0; I < 2; ++I) {
        Expr *Arg = TheCall->getArg(I);
        QualType Ty = Arg->getType();
        if (!Ty->isIntegerType()) {
          S.Diag(Arg->getLocStart(), diag::err_overflow_builtin_must_be_int)
              << Ty << Arg->getSourceRange();
          return true;
        }
      }
    
      // Third argument should be a pointer to a non-const integer.
      // IRGen correctly handles volatile, restrict, and address spaces, and
      // the other qualifiers aren't possible.
      {
        Expr *Arg = TheCall->getArg(2);
        QualType Ty = Arg->getType();
        const auto *PtrTy = Ty->getAs<PointerType>();
        if (!(PtrTy && PtrTy->getPointeeType()->isIntegerType() &&
              !PtrTy->getPointeeType().isConstQualified())) {
          S.Diag(Arg->getLocStart(), diag::err_overflow_builtin_must_be_ptr_int)
              << Ty << Arg->getSourceRange();
          return true;
        }
      }
    
      return false;
    }
    
    static void SemaBuiltinMemChkCall(Sema &S, FunctionDecl *FDecl,
    		                  CallExpr *TheCall, unsigned SizeIdx,
                                      unsigned DstSizeIdx) {
      if (TheCall->getNumArgs() <= SizeIdx ||
          TheCall->getNumArgs() <= DstSizeIdx)
        return;
    
      const Expr *SizeArg = TheCall->getArg(SizeIdx);
      const Expr *DstSizeArg = TheCall->getArg(DstSizeIdx);
    
      llvm::APSInt Size, DstSize;
    
      // find out if both sizes are known at compile time
      if (!SizeArg->EvaluateAsInt(Size, S.Context) ||
          !DstSizeArg->EvaluateAsInt(DstSize, S.Context))
        return;
    
      if (Size.ule(DstSize))
        return;
    
      // confirmed overflow so generate the diagnostic.
      IdentifierInfo *FnName = FDecl->getIdentifier();
      SourceLocation SL = TheCall->getLocStart();
      SourceRange SR = TheCall->getSourceRange();
    
      S.Diag(SL, diag::warn_memcpy_chk_overflow) << SR << FnName;
    }
    
    static bool SemaBuiltinCallWithStaticChain(Sema &S, CallExpr *BuiltinCall) {
      if (checkArgCount(S, BuiltinCall, 2))
        return true;
    
      SourceLocation BuiltinLoc = BuiltinCall->getLocStart();
      Expr *Builtin = BuiltinCall->getCallee()->IgnoreImpCasts();
      Expr *Call = BuiltinCall->getArg(0);
      Expr *Chain = BuiltinCall->getArg(1);
    
      if (Call->getStmtClass() != Stmt::CallExprClass) {
        S.Diag(BuiltinLoc, diag::err_first_argument_to_cwsc_not_call)
            << Call->getSourceRange();
        return true;
      }
    
      auto CE = cast<CallExpr>(Call);
      if (CE->getCallee()->getType()->isBlockPointerType()) {
        S.Diag(BuiltinLoc, diag::err_first_argument_to_cwsc_block_call)
            << Call->getSourceRange();
        return true;
      }
    
      const Decl *TargetDecl = CE->getCalleeDecl();
      if (const FunctionDecl *FD = dyn_cast_or_null<FunctionDecl>(TargetDecl))
        if (FD->getBuiltinID()) {
          S.Diag(BuiltinLoc, diag::err_first_argument_to_cwsc_builtin_call)
              << Call->getSourceRange();
          return true;
        }
    
      if (isa<CXXPseudoDestructorExpr>(CE->getCallee()->IgnoreParens())) {
        S.Diag(BuiltinLoc, diag::err_first_argument_to_cwsc_pdtor_call)
            << Call->getSourceRange();
        return true;
      }
    
      ExprResult ChainResult = S.UsualUnaryConversions(Chain);
      if (ChainResult.isInvalid())
        return true;
      if (!ChainResult.get()->getType()->isPointerType()) {
        S.Diag(BuiltinLoc, diag::err_second_argument_to_cwsc_not_pointer)
            << Chain->getSourceRange();
        return true;
      }
    
      QualType ReturnTy = CE->getCallReturnType(S.Context);
      QualType ArgTys[2] = { ReturnTy, ChainResult.get()->getType() };
      QualType BuiltinTy = S.Context.getFunctionType(
          ReturnTy, ArgTys, FunctionProtoType::ExtProtoInfo());
      QualType BuiltinPtrTy = S.Context.getPointerType(BuiltinTy);
    
      Builtin =
          S.ImpCastExprToType(Builtin, BuiltinPtrTy, CK_BuiltinFnToFnPtr).get();
    
      BuiltinCall->setType(CE->getType());
      BuiltinCall->setValueKind(CE->getValueKind());
      BuiltinCall->setObjectKind(CE->getObjectKind());
      BuiltinCall->setCallee(Builtin);
      BuiltinCall->setArg(1, ChainResult.get());
    
      return false;
    }
    
    static bool SemaBuiltinSEHScopeCheck(Sema &SemaRef, CallExpr *TheCall,
                                         Scope::ScopeFlags NeededScopeFlags,
                                         unsigned DiagID) {
      // Scopes aren't available during instantiation. Fortunately, builtin
      // functions cannot be template args so they cannot be formed through template
      // instantiation. Therefore checking once during the parse is sufficient.
      if (!SemaRef.ActiveTemplateInstantiations.empty())
        return false;
    
      Scope *S = SemaRef.getCurScope();
      while (S && !S->isSEHExceptScope())
        S = S->getParent();
      if (!S || !(S->getFlags() & NeededScopeFlags)) {
        auto *DRE = cast<DeclRefExpr>(TheCall->getCallee()->IgnoreParenCasts());
        SemaRef.Diag(TheCall->getExprLoc(), DiagID)
            << DRE->getDecl()->getIdentifier();
        return true;
      }
    
      return false;
    }
    
    static inline bool isBlockPointer(Expr *Arg) {
      return Arg->getType()->isBlockPointerType();
    }
    
    /// OpenCL C v2.0, s6.13.17.2 - Checks that the block parameters are all local
    /// void*, which is a requirement of device side enqueue.
    static bool checkOpenCLBlockArgs(Sema &S, Expr *BlockArg) {
      const BlockPointerType *BPT =
          cast<BlockPointerType>(BlockArg->getType().getCanonicalType());
      ArrayRef<QualType> Params =
          BPT->getPointeeType()->getAs<FunctionProtoType>()->getParamTypes();
      unsigned ArgCounter = 0;
      bool IllegalParams = false;
      // Iterate through the block parameters until either one is found that is not
      // a local void*, or the block is valid.
      for (ArrayRef<QualType>::iterator I = Params.begin(), E = Params.end();
           I != E; ++I, ++ArgCounter) {
        if (!(*I)->isPointerType() || !(*I)->getPointeeType()->isVoidType() ||
            (*I)->getPointeeType().getQualifiers().getAddressSpace() !=
                LangAS::opencl_local) {
          // Get the location of the error. If a block literal has been passed
          // (BlockExpr) then we can point straight to the offending argument,
          // else we just point to the variable reference.
          SourceLocation ErrorLoc;
          if (isa<BlockExpr>(BlockArg)) {
            BlockDecl *BD = cast<BlockExpr>(BlockArg)->getBlockDecl();
            ErrorLoc = BD->getParamDecl(ArgCounter)->getLocStart();
          } else if (isa<DeclRefExpr>(BlockArg)) {
            ErrorLoc = cast<DeclRefExpr>(BlockArg)->getLocStart();
          }
          S.Diag(ErrorLoc,
                 diag::err_opencl_enqueue_kernel_blocks_non_local_void_args);
          IllegalParams = true;
        }
      }
    
      return IllegalParams;
    }
    
    /// OpenCL C v2.0, s6.13.17.6 - Check the argument to the
    /// get_kernel_work_group_size
    /// and get_kernel_preferred_work_group_size_multiple builtin functions.
    static bool SemaOpenCLBuiltinKernelWorkGroupSize(Sema &S, CallExpr *TheCall) {
      if (checkArgCount(S, TheCall, 1))
        return true;
    
      Expr *BlockArg = TheCall->getArg(0);
      if (!isBlockPointer(BlockArg)) {
        S.Diag(BlockArg->getLocStart(),
               diag::err_opencl_enqueue_kernel_expected_type) << "block";
        return true;
      }
      return checkOpenCLBlockArgs(S, BlockArg);
    }
    
    /// Diagnose integer type and any valid implicit convertion to it.
    static bool checkOpenCLEnqueueIntType(Sema &S, Expr *E,
                                          const QualType &IntType);
    
    static bool checkOpenCLEnqueueLocalSizeArgs(Sema &S, CallExpr *TheCall,
                                                unsigned Start, unsigned End) {
      bool IllegalParams = false;
      for (unsigned I = Start; I <= End; ++I)
        IllegalParams |= checkOpenCLEnqueueIntType(S, TheCall->getArg(I),
                                                  S.Context.getSizeType());
      return IllegalParams;
    }
    
    /// OpenCL v2.0, s6.13.17.1 - Check that sizes are provided for all
    /// 'local void*' parameter of passed block.
    static bool checkOpenCLEnqueueVariadicArgs(Sema &S, CallExpr *TheCall,
                                               Expr *BlockArg,
                                               unsigned NumNonVarArgs) {
      const BlockPointerType *BPT =
          cast<BlockPointerType>(BlockArg->getType().getCanonicalType());
      unsigned NumBlockParams =
          BPT->getPointeeType()->getAs<FunctionProtoType>()->getNumParams();
      unsigned TotalNumArgs = TheCall->getNumArgs();
    
      // For each argument passed to the block, a corresponding uint needs to
      // be passed to describe the size of the local memory.
      if (TotalNumArgs != NumBlockParams + NumNonVarArgs) {
        S.Diag(TheCall->getLocStart(),
               diag::err_opencl_enqueue_kernel_local_size_args);
        return true;
      }
    
      // Check that the sizes of the local memory are specified by integers.
      return checkOpenCLEnqueueLocalSizeArgs(S, TheCall, NumNonVarArgs,
                                             TotalNumArgs - 1);
    }
    
    /// OpenCL C v2.0, s6.13.17 - Enqueue kernel function contains four different
    /// overload formats specified in Table 6.13.17.1.
    /// int enqueue_kernel(queue_t queue,
    ///                    kernel_enqueue_flags_t flags,
    ///                    const ndrange_t ndrange,
    ///                    void (^block)(void))
    /// int enqueue_kernel(queue_t queue,
    ///                    kernel_enqueue_flags_t flags,
    ///                    const ndrange_t ndrange,
    ///                    uint num_events_in_wait_list,
    ///                    clk_event_t *event_wait_list,
    ///                    clk_event_t *event_ret,
    ///                    void (^block)(void))
    /// int enqueue_kernel(queue_t queue,
    ///                    kernel_enqueue_flags_t flags,
    ///                    const ndrange_t ndrange,
    ///                    void (^block)(local void*, ...),
    ///                    uint size0, ...)
    /// int enqueue_kernel(queue_t queue,
    ///                    kernel_enqueue_flags_t flags,
    ///                    const ndrange_t ndrange,
    ///                    uint num_events_in_wait_list,
    ///                    clk_event_t *event_wait_list,
    ///                    clk_event_t *event_ret,
    ///                    void (^block)(local void*, ...),
    ///                    uint size0, ...)
    static bool SemaOpenCLBuiltinEnqueueKernel(Sema &S, CallExpr *TheCall) {
      unsigned NumArgs = TheCall->getNumArgs();
    
      if (NumArgs < 4) {
        S.Diag(TheCall->getLocStart(), diag::err_typecheck_call_too_few_args);
        return true;
      }
    
      Expr *Arg0 = TheCall->getArg(0);
      Expr *Arg1 = TheCall->getArg(1);
      Expr *Arg2 = TheCall->getArg(2);
      Expr *Arg3 = TheCall->getArg(3);
    
      // First argument always needs to be a queue_t type.
      if (!Arg0->getType()->isQueueT()) {
        S.Diag(TheCall->getArg(0)->getLocStart(),
               diag::err_opencl_enqueue_kernel_expected_type)
            << S.Context.OCLQueueTy;
        return true;
      }
    
      // Second argument always needs to be a kernel_enqueue_flags_t enum value.
      if (!Arg1->getType()->isIntegerType()) {
        S.Diag(TheCall->getArg(1)->getLocStart(),
               diag::err_opencl_enqueue_kernel_expected_type)
            << "'kernel_enqueue_flags_t' (i.e. uint)";
        return true;
      }
    
      // Third argument is always an ndrange_t type.
      if (!Arg2->getType()->isNDRangeT()) {
        S.Diag(TheCall->getArg(2)->getLocStart(),
               diag::err_opencl_enqueue_kernel_expected_type)
            << S.Context.OCLNDRangeTy;
        return true;
      }
    
      // With four arguments, there is only one form that the function could be
      // called in: no events and no variable arguments.
      if (NumArgs == 4) {
        // check that the last argument is the right block type.
        if (!isBlockPointer(Arg3)) {
          S.Diag(Arg3->getLocStart(), diag::err_opencl_enqueue_kernel_expected_type)
              << "block";
          return true;
        }
        // we have a block type, check the prototype
        const BlockPointerType *BPT =
            cast<BlockPointerType>(Arg3->getType().getCanonicalType());
        if (BPT->getPointeeType()->getAs<FunctionProtoType>()->getNumParams() > 0) {
          S.Diag(Arg3->getLocStart(),
                 diag::err_opencl_enqueue_kernel_blocks_no_args);
          return true;
        }
        return false;
      }
      // we can have block + varargs.
      if (isBlockPointer(Arg3))
        return (checkOpenCLBlockArgs(S, Arg3) ||
                checkOpenCLEnqueueVariadicArgs(S, TheCall, Arg3, 4));
      // last two cases with either exactly 7 args or 7 args and varargs.
      if (NumArgs >= 7) {
        // check common block argument.
        Expr *Arg6 = TheCall->getArg(6);
        if (!isBlockPointer(Arg6)) {
          S.Diag(Arg6->getLocStart(), diag::err_opencl_enqueue_kernel_expected_type)
              << "block";
          return true;
        }
        if (checkOpenCLBlockArgs(S, Arg6))
          return true;
    
        // Forth argument has to be any integer type.
        if (!Arg3->getType()->isIntegerType()) {
          S.Diag(TheCall->getArg(3)->getLocStart(),
                 diag::err_opencl_enqueue_kernel_expected_type)
              << "integer";
          return true;
        }
        // check remaining common arguments.
        Expr *Arg4 = TheCall->getArg(4);
        Expr *Arg5 = TheCall->getArg(5);
    
        // Fifth argument is always passed as a pointer to clk_event_t.
        if (!Arg4->isNullPointerConstant(S.Context,
                                         Expr::NPC_ValueDependentIsNotNull) &&
            !Arg4->getType()->getPointeeOrArrayElementType()->isClkEventT()) {
          S.Diag(TheCall->getArg(4)->getLocStart(),
                 diag::err_opencl_enqueue_kernel_expected_type)
              << S.Context.getPointerType(S.Context.OCLClkEventTy);
          return true;
        }
    
        // Sixth argument is always passed as a pointer to clk_event_t.
        if (!Arg5->isNullPointerConstant(S.Context,
                                         Expr::NPC_ValueDependentIsNotNull) &&
            !(Arg5->getType()->isPointerType() &&
              Arg5->getType()->getPointeeType()->isClkEventT())) {
          S.Diag(TheCall->getArg(5)->getLocStart(),
                 diag::err_opencl_enqueue_kernel_expected_type)
              << S.Context.getPointerType(S.Context.OCLClkEventTy);
          return true;
        }
    
        if (NumArgs == 7)
          return false;
    
        return checkOpenCLEnqueueVariadicArgs(S, TheCall, Arg6, 7);
      }
    
      // None of the specific case has been detected, give generic error
      S.Diag(TheCall->getLocStart(),
             diag::err_opencl_enqueue_kernel_incorrect_args);
      return true;
    }
    
    /// Returns OpenCL access qual.
    static OpenCLAccessAttr *getOpenCLArgAccess(const Decl *D) {
        return D->getAttr<OpenCLAccessAttr>();
    }
    
    /// Returns true if pipe element type is different from the pointer.
    static bool checkOpenCLPipeArg(Sema &S, CallExpr *Call) {
      const Expr *Arg0 = Call->getArg(0);
      // First argument type should always be pipe.
      if (!Arg0->getType()->isPipeType()) {
        S.Diag(Call->getLocStart(), diag::err_opencl_builtin_pipe_first_arg)
            << Call->getDirectCallee() << Arg0->getSourceRange();
        return true;
      }
      OpenCLAccessAttr *AccessQual =
          getOpenCLArgAccess(cast<DeclRefExpr>(Arg0)->getDecl());
      // Validates the access qualifier is compatible with the call.
      // OpenCL v2.0 s6.13.16 - The access qualifiers for pipe should only be
      // read_only and write_only, and assumed to be read_only if no qualifier is
      // specified.
      switch (Call->getDirectCallee()->getBuiltinID()) {
      case Builtin::BIread_pipe:
      case Builtin::BIreserve_read_pipe:
      case Builtin::BIcommit_read_pipe:
      case Builtin::BIwork_group_reserve_read_pipe:
      case Builtin::BIsub_group_reserve_read_pipe:
      case Builtin::BIwork_group_commit_read_pipe:
      case Builtin::BIsub_group_commit_read_pipe:
        if (!(!AccessQual || AccessQual->isReadOnly())) {
          S.Diag(Arg0->getLocStart(),
                 diag::err_opencl_builtin_pipe_invalid_access_modifier)
              << "read_only" << Arg0->getSourceRange();
          return true;
        }
        break;
      case Builtin::BIwrite_pipe:
      case Builtin::BIreserve_write_pipe:
      case Builtin::BIcommit_write_pipe:
      case Builtin::BIwork_group_reserve_write_pipe:
      case Builtin::BIsub_group_reserve_write_pipe:
      case Builtin::BIwork_group_commit_write_pipe:
      case Builtin::BIsub_group_commit_write_pipe:
        if (!(AccessQual && AccessQual->isWriteOnly())) {
          S.Diag(Arg0->getLocStart(),
                 diag::err_opencl_builtin_pipe_invalid_access_modifier)
              << "write_only" << Arg0->getSourceRange();
          return true;
        }
        break;
      default:
        break;
      }
      return false;
    }
    
    /// Returns true if pipe element type is different from the pointer.
    static bool checkOpenCLPipePacketType(Sema &S, CallExpr *Call, unsigned Idx) {
      const Expr *Arg0 = Call->getArg(0);
      const Expr *ArgIdx = Call->getArg(Idx);
      const PipeType *PipeTy = cast<PipeType>(Arg0->getType());
      const QualType EltTy = PipeTy->getElementType();
      const PointerType *ArgTy = ArgIdx->getType()->getAs<PointerType>();
      // The Idx argument should be a pointer and the type of the pointer and
      // the type of pipe element should also be the same.
      if (!ArgTy ||
          !S.Context.hasSameType(
              EltTy, ArgTy->getPointeeType()->getCanonicalTypeInternal())) {
        S.Diag(Call->getLocStart(), diag::err_opencl_builtin_pipe_invalid_arg)
            << Call->getDirectCallee() << S.Context.getPointerType(EltTy)
            << ArgIdx->getType() << ArgIdx->getSourceRange();
        return true;
      }
      return false;
    }
    
    // \brief Performs semantic analysis for the read/write_pipe call.
    // \param S Reference to the semantic analyzer.
    // \param Call A pointer to the builtin call.
    // \return True if a semantic error has been found, false otherwise.
    static bool SemaBuiltinRWPipe(Sema &S, CallExpr *Call) {
      // OpenCL v2.0 s6.13.16.2 - The built-in read/write
      // functions have two forms.
      switch (Call->getNumArgs()) {
      case 2: {
        if (checkOpenCLPipeArg(S, Call))
          return true;
        // The call with 2 arguments should be
        // read/write_pipe(pipe T, T*).
        // Check packet type T.
        if (checkOpenCLPipePacketType(S, Call, 1))
          return true;
      } break;
    
      case 4: {
        if (checkOpenCLPipeArg(S, Call))
          return true;
        // The call with 4 arguments should be
        // read/write_pipe(pipe T, reserve_id_t, uint, T*).
        // Check reserve_id_t.
        if (!Call->getArg(1)->getType()->isReserveIDT()) {
          S.Diag(Call->getLocStart(), diag::err_opencl_builtin_pipe_invalid_arg)
              << Call->getDirectCallee() << S.Context.OCLReserveIDTy
              << Call->getArg(1)->getType() << Call->getArg(1)->getSourceRange();
          return true;
        }
    
        // Check the index.
        const Expr *Arg2 = Call->getArg(2);
        if (!Arg2->getType()->isIntegerType() &&
            !Arg2->getType()->isUnsignedIntegerType()) {
          S.Diag(Call->getLocStart(), diag::err_opencl_builtin_pipe_invalid_arg)
              << Call->getDirectCallee() << S.Context.UnsignedIntTy
              << Arg2->getType() << Arg2->getSourceRange();
          return true;
        }
    
        // Check packet type T.
        if (checkOpenCLPipePacketType(S, Call, 3))
          return true;
      } break;
      default:
        S.Diag(Call->getLocStart(), diag::err_opencl_builtin_pipe_arg_num)
            << Call->getDirectCallee() << Call->getSourceRange();
        return true;
      }
    
      return false;
    }
    
    // \brief Performs a semantic analysis on the {work_group_/sub_group_
    //        /_}reserve_{read/write}_pipe
    // \param S Reference to the semantic analyzer.
    // \param Call The call to the builtin function to be analyzed.
    // \return True if a semantic error was found, false otherwise.
    static bool SemaBuiltinReserveRWPipe(Sema &S, CallExpr *Call) {
      if (checkArgCount(S, Call, 2))
        return true;
    
      if (checkOpenCLPipeArg(S, Call))
        return true;
    
      // Check the reserve size.
      if (!Call->getArg(1)->getType()->isIntegerType() &&
          !Call->getArg(1)->getType()->isUnsignedIntegerType()) {
        S.Diag(Call->getLocStart(), diag::err_opencl_builtin_pipe_invalid_arg)
            << Call->getDirectCallee() << S.Context.UnsignedIntTy
            << Call->getArg(1)->getType() << Call->getArg(1)->getSourceRange();
        return true;
      }
    
      return false;
    }
    
    // \brief Performs a semantic analysis on {work_group_/sub_group_
    //        /_}commit_{read/write}_pipe
    // \param S Reference to the semantic analyzer.
    // \param Call The call to the builtin function to be analyzed.
    // \return True if a semantic error was found, false otherwise.
    static bool SemaBuiltinCommitRWPipe(Sema &S, CallExpr *Call) {
      if (checkArgCount(S, Call, 2))
        return true;
    
      if (checkOpenCLPipeArg(S, Call))
        return true;
    
      // Check reserve_id_t.
      if (!Call->getArg(1)->getType()->isReserveIDT()) {
        S.Diag(Call->getLocStart(), diag::err_opencl_builtin_pipe_invalid_arg)
            << Call->getDirectCallee() << S.Context.OCLReserveIDTy
            << Call->getArg(1)->getType() << Call->getArg(1)->getSourceRange();
        return true;
      }
    
      return false;
    }
    
    // \brief Performs a semantic analysis on the call to built-in Pipe
    //        Query Functions.
    // \param S Reference to the semantic analyzer.
    // \param Call The call to the builtin function to be analyzed.
    // \return True if a semantic error was found, false otherwise.
    static bool SemaBuiltinPipePackets(Sema &S, CallExpr *Call) {
      if (checkArgCount(S, Call, 1))
        return true;
    
      if (!Call->getArg(0)->getType()->isPipeType()) {
        S.Diag(Call->getLocStart(), diag::err_opencl_builtin_pipe_first_arg)
            << Call->getDirectCallee() << Call->getArg(0)->getSourceRange();
        return true;
      }
    
      return false;
    }
    // \brief OpenCL v2.0 s6.13.9 - Address space qualifier functions.
    // \brief Performs semantic analysis for the to_global/local/private call.
    // \param S Reference to the semantic analyzer.
    // \param BuiltinID ID of the builtin function.
    // \param Call A pointer to the builtin call.
    // \return True if a semantic error has been found, false otherwise.
    static bool SemaOpenCLBuiltinToAddr(Sema &S, unsigned BuiltinID,
                                        CallExpr *Call) {
      if (Call->getNumArgs() != 1) {
        S.Diag(Call->getLocStart(), diag::err_opencl_builtin_to_addr_arg_num)
            << Call->getDirectCallee() << Call->getSourceRange();
        return true;
      }
    
      auto RT = Call->getArg(0)->getType();
      if (!RT->isPointerType() || RT->getPointeeType()
          .getAddressSpace() == LangAS::opencl_constant) {
        S.Diag(Call->getLocStart(), diag::err_opencl_builtin_to_addr_invalid_arg)
            << Call->getArg(0) << Call->getDirectCallee() << Call->getSourceRange();
        return true;
      }
    
      RT = RT->getPointeeType();
      auto Qual = RT.getQualifiers();
      switch (BuiltinID) {
      case Builtin::BIto_global:
        Qual.setAddressSpace(LangAS::opencl_global);
        break;
      case Builtin::BIto_local:
        Qual.setAddressSpace(LangAS::opencl_local);
        break;
      default:
        Qual.removeAddressSpace();
      }
      Call->setType(S.Context.getPointerType(S.Context.getQualifiedType(
          RT.getUnqualifiedType(), Qual)));
    
      return false;
    }
    
    ExprResult
    Sema::CheckBuiltinFunctionCall(FunctionDecl *FDecl, unsigned BuiltinID,
                                   CallExpr *TheCall) {
      ExprResult TheCallResult(TheCall);
    
      // Find out if any arguments are required to be integer constant expressions.
      unsigned ICEArguments = 0;
      ASTContext::GetBuiltinTypeError Error;
      Context.GetBuiltinType(BuiltinID, Error, &ICEArguments);
      if (Error != ASTContext::GE_None)
        ICEArguments = 0;  // Don't diagnose previously diagnosed errors.
      
      // If any arguments are required to be ICE's, check and diagnose.
      for (unsigned ArgNo = 0; ICEArguments != 0; ++ArgNo) {
        // Skip arguments not required to be ICE's.
        if ((ICEArguments & (1 << ArgNo)) == 0) continue;
        
        llvm::APSInt Result;
        if (SemaBuiltinConstantArg(TheCall, ArgNo, Result))
          return true;
        ICEArguments &= ~(1 << ArgNo);
      }
      
      switch (BuiltinID) {
      case Builtin::BI__builtin___CFStringMakeConstantString:
        assert(TheCall->getNumArgs() == 1 &&
               "Wrong # arguments to builtin CFStringMakeConstantString");
        if (CheckObjCString(TheCall->getArg(0)))
          return ExprError();
        break;
      case Builtin::BI__builtin_stdarg_start:
      case Builtin::BI__builtin_va_start:
        if (SemaBuiltinVAStart(TheCall))
          return ExprError();
        break;
      case Builtin::BI__va_start: {
        switch (Context.getTargetInfo().getTriple().getArch()) {
        case llvm::Triple::arm:
        case llvm::Triple::thumb:
          if (SemaBuiltinVAStartARM(TheCall))
            return ExprError();
          break;
        default:
          if (SemaBuiltinVAStart(TheCall))
            return ExprError();
          break;
        }
        break;
      }
      case Builtin::BI__builtin_isgreater:
      case Builtin::BI__builtin_isgreaterequal:
      case Builtin::BI__builtin_isless:
      case Builtin::BI__builtin_islessequal:
      case Builtin::BI__builtin_islessgreater:
      case Builtin::BI__builtin_isunordered:
        if (SemaBuiltinUnorderedCompare(TheCall))
          return ExprError();
        break;
      case Builtin::BI__builtin_fpclassify:
        if (SemaBuiltinFPClassification(TheCall, 6))
          return ExprError();
        break;
      case Builtin::BI__builtin_isfinite:
      case Builtin::BI__builtin_isinf:
      case Builtin::BI__builtin_isinf_sign:
      case Builtin::BI__builtin_isnan:
      case Builtin::BI__builtin_isnormal:
        if (SemaBuiltinFPClassification(TheCall, 1))
          return ExprError();
        break;
      case Builtin::BI__builtin_shufflevector:
        return SemaBuiltinShuffleVector(TheCall);
        // TheCall will be freed by the smart pointer here, but that's fine, since
        // SemaBuiltinShuffleVector guts it, but then doesn't release it.
      case Builtin::BI__builtin_prefetch:
        if (SemaBuiltinPrefetch(TheCall))
          return ExprError();
        break;
      case Builtin::BI__builtin_alloca_with_align:
        if (SemaBuiltinAllocaWithAlign(TheCall))
          return ExprError();
        break;
      case Builtin::BI__assume:
      case Builtin::BI__builtin_assume:
        if (SemaBuiltinAssume(TheCall))
          return ExprError();
        break;
      case Builtin::BI__builtin_assume_aligned:
        if (SemaBuiltinAssumeAligned(TheCall))
          return ExprError();
        break;
      case Builtin::BI__builtin_object_size:
        if (SemaBuiltinConstantArgRange(TheCall, 1, 0, 3))
          return ExprError();
        break;
      case Builtin::BI__builtin_longjmp:
        if (SemaBuiltinLongjmp(TheCall))
          return ExprError();
        break;
      case Builtin::BI__builtin_setjmp:
        if (SemaBuiltinSetjmp(TheCall))
          return ExprError();
        break;
      case Builtin::BI_setjmp:
      case Builtin::BI_setjmpex:
        if (checkArgCount(*this, TheCall, 1))
          return true;
        break;
    
      case Builtin::BI__builtin_classify_type:
        if (checkArgCount(*this, TheCall, 1)) return true;
        TheCall->setType(Context.IntTy);
        break;
      case Builtin::BI__builtin_constant_p:
        if (checkArgCount(*this, TheCall, 1)) return true;
        TheCall->setType(Context.IntTy);
        break;
      case Builtin::BI__sync_fetch_and_add:
      case Builtin::BI__sync_fetch_and_add_1:
      case Builtin::BI__sync_fetch_and_add_2:
      case Builtin::BI__sync_fetch_and_add_4:
      case Builtin::BI__sync_fetch_and_add_8:
      case Builtin::BI__sync_fetch_and_add_16:
      case Builtin::BI__sync_fetch_and_sub:
      case Builtin::BI__sync_fetch_and_sub_1:
      case Builtin::BI__sync_fetch_and_sub_2:
      case Builtin::BI__sync_fetch_and_sub_4:
      case Builtin::BI__sync_fetch_and_sub_8:
      case Builtin::BI__sync_fetch_and_sub_16:
      case Builtin::BI__sync_fetch_and_or:
      case Builtin::BI__sync_fetch_and_or_1:
      case Builtin::BI__sync_fetch_and_or_2:
      case Builtin::BI__sync_fetch_and_or_4:
      case Builtin::BI__sync_fetch_and_or_8:
      case Builtin::BI__sync_fetch_and_or_16:
      case Builtin::BI__sync_fetch_and_and:
      case Builtin::BI__sync_fetch_and_and_1:
      case Builtin::BI__sync_fetch_and_and_2:
      case Builtin::BI__sync_fetch_and_and_4:
      case Builtin::BI__sync_fetch_and_and_8:
      case Builtin::BI__sync_fetch_and_and_16:
      case Builtin::BI__sync_fetch_and_xor:
      case Builtin::BI__sync_fetch_and_xor_1:
      case Builtin::BI__sync_fetch_and_xor_2:
      case Builtin::BI__sync_fetch_and_xor_4:
      case Builtin::BI__sync_fetch_and_xor_8:
      case Builtin::BI__sync_fetch_and_xor_16:
      case Builtin::BI__sync_fetch_and_nand:
      case Builtin::BI__sync_fetch_and_nand_1:
      case Builtin::BI__sync_fetch_and_nand_2:
      case Builtin::BI__sync_fetch_and_nand_4:
      case Builtin::BI__sync_fetch_and_nand_8:
      case Builtin::BI__sync_fetch_and_nand_16:
      case Builtin::BI__sync_add_and_fetch:
      case Builtin::BI__sync_add_and_fetch_1:
      case Builtin::BI__sync_add_and_fetch_2:
      case Builtin::BI__sync_add_and_fetch_4:
      case Builtin::BI__sync_add_and_fetch_8:
      case Builtin::BI__sync_add_and_fetch_16:
      case Builtin::BI__sync_sub_and_fetch:
      case Builtin::BI__sync_sub_and_fetch_1:
      case Builtin::BI__sync_sub_and_fetch_2:
      case Builtin::BI__sync_sub_and_fetch_4:
      case Builtin::BI__sync_sub_and_fetch_8:
      case Builtin::BI__sync_sub_and_fetch_16:
      case Builtin::BI__sync_and_and_fetch:
      case Builtin::BI__sync_and_and_fetch_1:
      case Builtin::BI__sync_and_and_fetch_2:
      case Builtin::BI__sync_and_and_fetch_4:
      case Builtin::BI__sync_and_and_fetch_8:
      case Builtin::BI__sync_and_and_fetch_16:
      case Builtin::BI__sync_or_and_fetch:
      case Builtin::BI__sync_or_and_fetch_1:
      case Builtin::BI__sync_or_and_fetch_2:
      case Builtin::BI__sync_or_and_fetch_4:
      case Builtin::BI__sync_or_and_fetch_8:
      case Builtin::BI__sync_or_and_fetch_16:
      case Builtin::BI__sync_xor_and_fetch:
      case Builtin::BI__sync_xor_and_fetch_1:
      case Builtin::BI__sync_xor_and_fetch_2:
      case Builtin::BI__sync_xor_and_fetch_4:
      case Builtin::BI__sync_xor_and_fetch_8:
      case Builtin::BI__sync_xor_and_fetch_16:
      case Builtin::BI__sync_nand_and_fetch:
      case Builtin::BI__sync_nand_and_fetch_1:
      case Builtin::BI__sync_nand_and_fetch_2:
      case Builtin::BI__sync_nand_and_fetch_4:
      case Builtin::BI__sync_nand_and_fetch_8:
      case Builtin::BI__sync_nand_and_fetch_16:
      case Builtin::BI__sync_val_compare_and_swap:
      case Builtin::BI__sync_val_compare_and_swap_1:
      case Builtin::BI__sync_val_compare_and_swap_2:
      case Builtin::BI__sync_val_compare_and_swap_4:
      case Builtin::BI__sync_val_compare_and_swap_8:
      case Builtin::BI__sync_val_compare_and_swap_16:
      case Builtin::BI__sync_bool_compare_and_swap:
      case Builtin::BI__sync_bool_compare_and_swap_1:
      case Builtin::BI__sync_bool_compare_and_swap_2:
      case Builtin::BI__sync_bool_compare_and_swap_4:
      case Builtin::BI__sync_bool_compare_and_swap_8:
      case Builtin::BI__sync_bool_compare_and_swap_16:
      case Builtin::BI__sync_lock_test_and_set:
      case Builtin::BI__sync_lock_test_and_set_1:
      case Builtin::BI__sync_lock_test_and_set_2:
      case Builtin::BI__sync_lock_test_and_set_4:
      case Builtin::BI__sync_lock_test_and_set_8:
      case Builtin::BI__sync_lock_test_and_set_16:
      case Builtin::BI__sync_lock_release:
      case Builtin::BI__sync_lock_release_1:
      case Builtin::BI__sync_lock_release_2:
      case Builtin::BI__sync_lock_release_4:
      case Builtin::BI__sync_lock_release_8:
      case Builtin::BI__sync_lock_release_16:
      case Builtin::BI__sync_swap:
      case Builtin::BI__sync_swap_1:
      case Builtin::BI__sync_swap_2:
      case Builtin::BI__sync_swap_4:
      case Builtin::BI__sync_swap_8:
      case Builtin::BI__sync_swap_16:
        return SemaBuiltinAtomicOverloaded(TheCallResult);
      case Builtin::BI__builtin_nontemporal_load:
      case Builtin::BI__builtin_nontemporal_store:
        return SemaBuiltinNontemporalOverloaded(TheCallResult);
    #define BUILTIN(ID, TYPE, ATTRS)
    #define ATOMIC_BUILTIN(ID, TYPE, ATTRS) \
      case Builtin::BI##ID: \
        return SemaAtomicOpsOverloaded(TheCallResult, AtomicExpr::AO##ID);
    #include "clang/Basic/Builtins.def"
      case Builtin::BI__builtin_annotation:
        if (SemaBuiltinAnnotation(*this, TheCall))
          return ExprError();
        break;
      case Builtin::BI__builtin_addressof:
        if (SemaBuiltinAddressof(*this, TheCall))
          return ExprError();
        break;
      case Builtin::BI__builtin_add_overflow:
      case Builtin::BI__builtin_sub_overflow:
      case Builtin::BI__builtin_mul_overflow:
        if (SemaBuiltinOverflow(*this, TheCall))
          return ExprError();
        break;
      case Builtin::BI__builtin_operator_new:
      case Builtin::BI__builtin_operator_delete:
        if (!getLangOpts().CPlusPlus) {
          Diag(TheCall->getExprLoc(), diag::err_builtin_requires_language)
            << (BuiltinID == Builtin::BI__builtin_operator_new
                    ? "__builtin_operator_new"
                    : "__builtin_operator_delete")
            << "C++";
          return ExprError();
        }
        // CodeGen assumes it can find the global new and delete to call,
        // so ensure that they are declared.
        DeclareGlobalNewDelete();
        break;
    
      // check secure string manipulation functions where overflows
      // are detectable at compile time
      case Builtin::BI__builtin___memcpy_chk:
      case Builtin::BI__builtin___memmove_chk:
      case Builtin::BI__builtin___memset_chk:
      case Builtin::BI__builtin___strlcat_chk:
      case Builtin::BI__builtin___strlcpy_chk:
      case Builtin::BI__builtin___strncat_chk:
      case Builtin::BI__builtin___strncpy_chk:
      case Builtin::BI__builtin___stpncpy_chk:
        SemaBuiltinMemChkCall(*this, FDecl, TheCall, 2, 3);
        break;
      case Builtin::BI__builtin___memccpy_chk:
        SemaBuiltinMemChkCall(*this, FDecl, TheCall, 3, 4);
        break;
      case Builtin::BI__builtin___snprintf_chk:
      case Builtin::BI__builtin___vsnprintf_chk:
        SemaBuiltinMemChkCall(*this, FDecl, TheCall, 1, 3);
        break;
      case Builtin::BI__builtin_call_with_static_chain:
        if (SemaBuiltinCallWithStaticChain(*this, TheCall))
          return ExprError();
        break;
      case Builtin::BI__exception_code:
      case Builtin::BI_exception_code:
        if (SemaBuiltinSEHScopeCheck(*this, TheCall, Scope::SEHExceptScope,
                                     diag::err_seh___except_block))
          return ExprError();
        break;
      case Builtin::BI__exception_info:
      case Builtin::BI_exception_info:
        if (SemaBuiltinSEHScopeCheck(*this, TheCall, Scope::SEHFilterScope,
                                     diag::err_seh___except_filter))
          return ExprError();
        break;
      case Builtin::BI__GetExceptionInfo:
        if (checkArgCount(*this, TheCall, 1))
          return ExprError();
    
        if (CheckCXXThrowOperand(
                TheCall->getLocStart(),
                Context.getExceptionObjectType(FDecl->getParamDecl(0)->getType()),
                TheCall))
          return ExprError();
    
        TheCall->setType(Context.VoidPtrTy);
        break;
      // OpenCL v2.0, s6.13.16 - Pipe functions
      case Builtin::BIread_pipe:
      case Builtin::BIwrite_pipe:
        // Since those two functions are declared with var args, we need a semantic
        // check for the argument.
        if (SemaBuiltinRWPipe(*this, TheCall))
          return ExprError();
        TheCall->setType(Context.IntTy);
        break;
      case Builtin::BIreserve_read_pipe:
      case Builtin::BIreserve_write_pipe:
      case Builtin::BIwork_group_reserve_read_pipe:
      case Builtin::BIwork_group_reserve_write_pipe:
      case Builtin::BIsub_group_reserve_read_pipe:
      case Builtin::BIsub_group_reserve_write_pipe:
        if (SemaBuiltinReserveRWPipe(*this, TheCall))
          return ExprError();
        // Since return type of reserve_read/write_pipe built-in function is
        // reserve_id_t, which is not defined in the builtin def file , we used int
        // as return type and need to override the return type of these functions.
        TheCall->setType(Context.OCLReserveIDTy);
        break;
      case Builtin::BIcommit_read_pipe:
      case Builtin::BIcommit_write_pipe:
      case Builtin::BIwork_group_commit_read_pipe:
      case Builtin::BIwork_group_commit_write_pipe:
      case Builtin::BIsub_group_commit_read_pipe:
      case Builtin::BIsub_group_commit_write_pipe:
        if (SemaBuiltinCommitRWPipe(*this, TheCall))
          return ExprError();
        break;
      case Builtin::BIget_pipe_num_packets:
      case Builtin::BIget_pipe_max_packets:
        if (SemaBuiltinPipePackets(*this, TheCall))
          return ExprError();
        TheCall->setType(Context.UnsignedIntTy);
        break;
      case Builtin::BIto_global:
      case Builtin::BIto_local:
      case Builtin::BIto_private:
        if (SemaOpenCLBuiltinToAddr(*this, BuiltinID, TheCall))
          return ExprError();
        break;
      // OpenCL v2.0, s6.13.17 - Enqueue kernel functions.
      case Builtin::BIenqueue_kernel:
        if (SemaOpenCLBuiltinEnqueueKernel(*this, TheCall))
          return ExprError();
        break;
      case Builtin::BIget_kernel_work_group_size:
      case Builtin::BIget_kernel_preferred_work_group_size_multiple:
        if (SemaOpenCLBuiltinKernelWorkGroupSize(*this, TheCall))
          return ExprError();
        break;
      case Builtin::BI__builtin_os_log_format:
      case Builtin::BI__builtin_os_log_format_buffer_size:
        if (SemaBuiltinOSLogFormat(TheCall)) {
          return ExprError();
        }
        break;
      }
    
      // Since the target specific builtins for each arch overlap, only check those
      // of the arch we are compiling for.
      if (Context.BuiltinInfo.isTSBuiltin(BuiltinID)) {
        switch (Context.getTargetInfo().getTriple().getArch()) {
          case llvm::Triple::arm:
          case llvm::Triple::armeb:
          case llvm::Triple::thumb:
          case llvm::Triple::thumbeb:
            if (CheckARMBuiltinFunctionCall(BuiltinID, TheCall))
              return ExprError();
            break;
          case llvm::Triple::aarch64:
          case llvm::Triple::aarch64_be:
            if (CheckAArch64BuiltinFunctionCall(BuiltinID, TheCall))
              return ExprError();
            break;
          case llvm::Triple::mips:
          case llvm::Triple::mipsel:
          case llvm::Triple::mips64:
          case llvm::Triple::mips64el:
            if (CheckMipsBuiltinFunctionCall(BuiltinID, TheCall))
              return ExprError();
            break;
          case llvm::Triple::systemz:
            if (CheckSystemZBuiltinFunctionCall(BuiltinID, TheCall))
              return ExprError();
            break;
          case llvm::Triple::x86:
          case llvm::Triple::x86_64:
            if (CheckX86BuiltinFunctionCall(BuiltinID, TheCall))
              return ExprError();
            break;
          case llvm::Triple::ppc:
          case llvm::Triple::ppc64:
          case llvm::Triple::ppc64le:
            if (CheckPPCBuiltinFunctionCall(BuiltinID, TheCall))
              return ExprError();
            break;
          default:
            break;
        }
      }
    
      return TheCallResult;
    }
    
    // Get the valid immediate range for the specified NEON type code.
    static unsigned RFT(unsigned t, bool shift = false, bool ForceQuad = false) {
      NeonTypeFlags Type(t);
      int IsQuad = ForceQuad ? true : Type.isQuad();
      switch (Type.getEltType()) {
      case NeonTypeFlags::Int8:
      case NeonTypeFlags::Poly8:
        return shift ? 7 : (8 << IsQuad) - 1;
      case NeonTypeFlags::Int16:
      case NeonTypeFlags::Poly16:
        return shift ? 15 : (4 << IsQuad) - 1;
      case NeonTypeFlags::Int32:
        return shift ? 31 : (2 << IsQuad) - 1;
      case NeonTypeFlags::Int64:
      case NeonTypeFlags::Poly64:
        return shift ? 63 : (1 << IsQuad) - 1;
      case NeonTypeFlags::Poly128:
        return shift ? 127 : (1 << IsQuad) - 1;
      case NeonTypeFlags::Float16:
        assert(!shift && "cannot shift float types!");
        return (4 << IsQuad) - 1;
      case NeonTypeFlags::Float32:
        assert(!shift && "cannot shift float types!");
        return (2 << IsQuad) - 1;
      case NeonTypeFlags::Float64:
        assert(!shift && "cannot shift float types!");
        return (1 << IsQuad) - 1;
      }
      llvm_unreachable("Invalid NeonTypeFlag!");
    }
    
    /// getNeonEltType - Return the QualType corresponding to the elements of
    /// the vector type specified by the NeonTypeFlags.  This is used to check
    /// the pointer arguments for Neon load/store intrinsics.
    static QualType getNeonEltType(NeonTypeFlags Flags, ASTContext &Context,
                                   bool IsPolyUnsigned, bool IsInt64Long) {
      switch (Flags.getEltType()) {
      case NeonTypeFlags::Int8:
        return Flags.isUnsigned() ? Context.UnsignedCharTy : Context.SignedCharTy;
      case NeonTypeFlags::Int16:
        return Flags.isUnsigned() ? Context.UnsignedShortTy : Context.ShortTy;
      case NeonTypeFlags::Int32:
        return Flags.isUnsigned() ? Context.UnsignedIntTy : Context.IntTy;
      case NeonTypeFlags::Int64:
        if (IsInt64Long)
          return Flags.isUnsigned() ? Context.UnsignedLongTy : Context.LongTy;
        else
          return Flags.isUnsigned() ? Context.UnsignedLongLongTy
                                    : Context.LongLongTy;
      case NeonTypeFlags::Poly8:
        return IsPolyUnsigned ? Context.UnsignedCharTy : Context.SignedCharTy;
      case NeonTypeFlags::Poly16:
        return IsPolyUnsigned ? Context.UnsignedShortTy : Context.ShortTy;
      case NeonTypeFlags::Poly64:
        if (IsInt64Long)
          return Context.UnsignedLongTy;
        else
          return Context.UnsignedLongLongTy;
      case NeonTypeFlags::Poly128:
        break;
      case NeonTypeFlags::Float16:
        return Context.HalfTy;
      case NeonTypeFlags::Float32:
        return Context.FloatTy;
      case NeonTypeFlags::Float64:
        return Context.DoubleTy;
      }
      llvm_unreachable("Invalid NeonTypeFlag!");
    }
    
    bool Sema::CheckNeonBuiltinFunctionCall(unsigned BuiltinID, CallExpr *TheCall) {
      llvm::APSInt Result;
      uint64_t mask = 0;
      unsigned TV = 0;
      int PtrArgNum = -1;
      bool HasConstPtr = false;
      switch (BuiltinID) {
    #define GET_NEON_OVERLOAD_CHECK
    #include "clang/Basic/arm_neon.inc"
    #undef GET_NEON_OVERLOAD_CHECK
      }
    
      // For NEON intrinsics which are overloaded on vector element type, validate
      // the immediate which specifies which variant to emit.
      unsigned ImmArg = TheCall->getNumArgs()-1;
      if (mask) {
        if (SemaBuiltinConstantArg(TheCall, ImmArg, Result))
          return true;
    
        TV = Result.getLimitedValue(64);
        if ((TV > 63) || (mask & (1ULL << TV)) == 0)
          return Diag(TheCall->getLocStart(), diag::err_invalid_neon_type_code)
            << TheCall->getArg(ImmArg)->getSourceRange();
      }
    
      if (PtrArgNum >= 0) {
        // Check that pointer arguments have the specified type.
        Expr *Arg = TheCall->getArg(PtrArgNum);
        if (ImplicitCastExpr *ICE = dyn_cast<ImplicitCastExpr>(Arg))
          Arg = ICE->getSubExpr();
        ExprResult RHS = DefaultFunctionArrayLvalueConversion(Arg);
        QualType RHSTy = RHS.get()->getType();
    
        llvm::Triple::ArchType Arch = Context.getTargetInfo().getTriple().getArch();
        bool IsPolyUnsigned = Arch == llvm::Triple::aarch64;
        bool IsInt64Long =
            Context.getTargetInfo().getInt64Type() == TargetInfo::SignedLong;
        QualType EltTy =
            getNeonEltType(NeonTypeFlags(TV), Context, IsPolyUnsigned, IsInt64Long);
        if (HasConstPtr)
          EltTy = EltTy.withConst();
        QualType LHSTy = Context.getPointerType(EltTy);
        AssignConvertType ConvTy;
        ConvTy = CheckSingleAssignmentConstraints(LHSTy, RHS);
        if (RHS.isInvalid())
          return true;
        if (DiagnoseAssignmentResult(ConvTy, Arg->getLocStart(), LHSTy, RHSTy,
                                     RHS.get(), AA_Assigning))
          return true;
      }
    
      // For NEON intrinsics which take an immediate value as part of the
      // instruction, range check them here.
      unsigned i = 0, l = 0, u = 0;
      switch (BuiltinID) {
      default:
        return false;
    #define GET_NEON_IMMEDIATE_CHECK
    #include "clang/Basic/arm_neon.inc"
    #undef GET_NEON_IMMEDIATE_CHECK
      }
    
      return SemaBuiltinConstantArgRange(TheCall, i, l, u + l);
    }
    
    bool Sema::CheckARMBuiltinExclusiveCall(unsigned BuiltinID, CallExpr *TheCall,
                                            unsigned MaxWidth) {
      assert((BuiltinID == ARM::BI__builtin_arm_ldrex ||
              BuiltinID == ARM::BI__builtin_arm_ldaex ||
              BuiltinID == ARM::BI__builtin_arm_strex ||
              BuiltinID == ARM::BI__builtin_arm_stlex ||
              BuiltinID == AArch64::BI__builtin_arm_ldrex ||
              BuiltinID == AArch64::BI__builtin_arm_ldaex ||
              BuiltinID == AArch64::BI__builtin_arm_strex ||
              BuiltinID == AArch64::BI__builtin_arm_stlex) &&
             "unexpected ARM builtin");
      bool IsLdrex = BuiltinID == ARM::BI__builtin_arm_ldrex ||
                     BuiltinID == ARM::BI__builtin_arm_ldaex ||
                     BuiltinID == AArch64::BI__builtin_arm_ldrex ||
                     BuiltinID == AArch64::BI__builtin_arm_ldaex;
    
      DeclRefExpr *DRE =cast<DeclRefExpr>(TheCall->getCallee()->IgnoreParenCasts());
    
      // Ensure that we have the proper number of arguments.
      if (checkArgCount(*this, TheCall, IsLdrex ? 1 : 2))
        return true;
    
      // Inspect the pointer argument of the atomic builtin.  This should always be
      // a pointer type, whose element is an integral scalar or pointer type.
      // Because it is a pointer type, we don't have to worry about any implicit
      // casts here.
      Expr *PointerArg = TheCall->getArg(IsLdrex ? 0 : 1);
      ExprResult PointerArgRes = DefaultFunctionArrayLvalueConversion(PointerArg);
      if (PointerArgRes.isInvalid())
        return true;
      PointerArg = PointerArgRes.get();
    
      const PointerType *pointerType = PointerArg->getType()->getAs<PointerType>();
      if (!pointerType) {
        Diag(DRE->getLocStart(), diag::err_atomic_builtin_must_be_pointer)
          << PointerArg->getType() << PointerArg->getSourceRange();
        return true;
      }
    
      // ldrex takes a "const volatile T*" and strex takes a "volatile T*". Our next
      // task is to insert the appropriate casts into the AST. First work out just
      // what the appropriate type is.
      QualType ValType = pointerType->getPointeeType();
      QualType AddrType = ValType.getUnqualifiedType().withVolatile();
      if (IsLdrex)
        AddrType.addConst();
    
      // Issue a warning if the cast is dodgy.
      CastKind CastNeeded = CK_NoOp;
      if (!AddrType.isAtLeastAsQualifiedAs(ValType)) {
        CastNeeded = CK_BitCast;
        Diag(DRE->getLocStart(), diag::ext_typecheck_convert_discards_qualifiers)
          << PointerArg->getType()
          << Context.getPointerType(AddrType)
          << AA_Passing << PointerArg->getSourceRange();
      }
    
      // Finally, do the cast and replace the argument with the corrected version.
      AddrType = Context.getPointerType(AddrType);
      PointerArgRes = ImpCastExprToType(PointerArg, AddrType, CastNeeded);
      if (PointerArgRes.isInvalid())
        return true;
      PointerArg = PointerArgRes.get();
    
      TheCall->setArg(IsLdrex ? 0 : 1, PointerArg);
    
      // In general, we allow ints, floats and pointers to be loaded and stored.
      if (!ValType->isIntegerType() && !ValType->isAnyPointerType() &&
          !ValType->isBlockPointerType() && !ValType->isFloatingType()) {
        Diag(DRE->getLocStart(), diag::err_atomic_builtin_must_be_pointer_intfltptr)
          << PointerArg->getType() << PointerArg->getSourceRange();
        return true;
      }
    
      // But ARM doesn't have instructions to deal with 128-bit versions.
      if (Context.getTypeSize(ValType) > MaxWidth) {
        assert(MaxWidth == 64 && "Diagnostic unexpectedly inaccurate");
        Diag(DRE->getLocStart(), diag::err_atomic_exclusive_builtin_pointer_size)
          << PointerArg->getType() << PointerArg->getSourceRange();
        return true;
      }
    
      switch (ValType.getObjCLifetime()) {
      case Qualifiers::OCL_None:
      case Qualifiers::OCL_ExplicitNone:
        // okay
        break;
    
      case Qualifiers::OCL_Weak:
      case Qualifiers::OCL_Strong:
      case Qualifiers::OCL_Autoreleasing:
        Diag(DRE->getLocStart(), diag::err_arc_atomic_ownership)
          << ValType << PointerArg->getSourceRange();
        return true;
      }
    
      if (IsLdrex) {
        TheCall->setType(ValType);
        return false;
      }
    
      // Initialize the argument to be stored.
      ExprResult ValArg = TheCall->getArg(0);
      InitializedEntity Entity = InitializedEntity::InitializeParameter(
          Context, ValType, /*consume*/ false);
      ValArg = PerformCopyInitialization(Entity, SourceLocation(), ValArg);
      if (ValArg.isInvalid())
        return true;
      TheCall->setArg(0, ValArg.get());
    
      // __builtin_arm_strex always returns an int. It's marked as such in the .def,
      // but the custom checker bypasses all default analysis.
      TheCall->setType(Context.IntTy);
      return false;
    }
    
    bool Sema::CheckARMBuiltinFunctionCall(unsigned BuiltinID, CallExpr *TheCall) {
      llvm::APSInt Result;
    
      if (BuiltinID == ARM::BI__builtin_arm_ldrex ||
          BuiltinID == ARM::BI__builtin_arm_ldaex ||
          BuiltinID == ARM::BI__builtin_arm_strex ||
          BuiltinID == ARM::BI__builtin_arm_stlex) {
        return CheckARMBuiltinExclusiveCall(BuiltinID, TheCall, 64);
      }
    
      if (BuiltinID == ARM::BI__builtin_arm_prefetch) {
        return SemaBuiltinConstantArgRange(TheCall, 1, 0, 1) ||
          SemaBuiltinConstantArgRange(TheCall, 2, 0, 1);
      }
    
      if (BuiltinID == ARM::BI__builtin_arm_rsr64 ||
          BuiltinID == ARM::BI__builtin_arm_wsr64)
        return SemaBuiltinARMSpecialReg(BuiltinID, TheCall, 0, 3, false);
    
      if (BuiltinID == ARM::BI__builtin_arm_rsr ||
          BuiltinID == ARM::BI__builtin_arm_rsrp ||
          BuiltinID == ARM::BI__builtin_arm_wsr ||
          BuiltinID == ARM::BI__builtin_arm_wsrp)
        return SemaBuiltinARMSpecialReg(BuiltinID, TheCall, 0, 5, true);
    
      if (CheckNeonBuiltinFunctionCall(BuiltinID, TheCall))
        return true;
    
      // For intrinsics which take an immediate value as part of the instruction,
      // range check them here.
      unsigned i = 0, l = 0, u = 0;
      switch (BuiltinID) {
      default: return false;
      case ARM::BI__builtin_arm_ssat: i = 1; l = 1; u = 31; break;
      case ARM::BI__builtin_arm_usat: i = 1; u = 31; break;
      case ARM::BI__builtin_arm_vcvtr_f:
      case ARM::BI__builtin_arm_vcvtr_d: i = 1; u = 1; break;
      case ARM::BI__builtin_arm_dmb:
      case ARM::BI__builtin_arm_dsb:
      case ARM::BI__builtin_arm_isb:
      case ARM::BI__builtin_arm_dbg: l = 0; u = 15; break;
      }
    
      // FIXME: VFP Intrinsics should error if VFP not present.
      return SemaBuiltinConstantArgRange(TheCall, i, l, u + l);
    }
    
    bool Sema::CheckAArch64BuiltinFunctionCall(unsigned BuiltinID,
                                             CallExpr *TheCall) {
      llvm::APSInt Result;
    
      if (BuiltinID == AArch64::BI__builtin_arm_ldrex ||
          BuiltinID == AArch64::BI__builtin_arm_ldaex ||
          BuiltinID == AArch64::BI__builtin_arm_strex ||
          BuiltinID == AArch64::BI__builtin_arm_stlex) {
        return CheckARMBuiltinExclusiveCall(BuiltinID, TheCall, 128);
      }
    
      if (BuiltinID == AArch64::BI__builtin_arm_prefetch) {
        return SemaBuiltinConstantArgRange(TheCall, 1, 0, 1) ||
          SemaBuiltinConstantArgRange(TheCall, 2, 0, 2) ||
          SemaBuiltinConstantArgRange(TheCall, 3, 0, 1) ||
          SemaBuiltinConstantArgRange(TheCall, 4, 0, 1);
      }
    
      if (BuiltinID == AArch64::BI__builtin_arm_rsr64 ||
          BuiltinID == AArch64::BI__builtin_arm_wsr64)
        return SemaBuiltinARMSpecialReg(BuiltinID, TheCall, 0, 5, true);
    
      if (BuiltinID == AArch64::BI__builtin_arm_rsr ||
          BuiltinID == AArch64::BI__builtin_arm_rsrp ||
          BuiltinID == AArch64::BI__builtin_arm_wsr ||
          BuiltinID == AArch64::BI__builtin_arm_wsrp)
        return SemaBuiltinARMSpecialReg(BuiltinID, TheCall, 0, 5, true);
    
      if (CheckNeonBuiltinFunctionCall(BuiltinID, TheCall))
        return true;
    
      // For intrinsics which take an immediate value as part of the instruction,
      // range check them here.
      unsigned i = 0, l = 0, u = 0;
      switch (BuiltinID) {
      default: return false;
      case AArch64::BI__builtin_arm_dmb:
      case AArch64::BI__builtin_arm_dsb:
      case AArch64::BI__builtin_arm_isb: l = 0; u = 15; break;
      }
    
      return SemaBuiltinConstantArgRange(TheCall, i, l, u + l);
    }
    
    // CheckMipsBuiltinFunctionCall - Checks the constant value passed to the
    // intrinsic is correct. The switch statement is ordered by DSP, MSA. The
    // ordering for DSP is unspecified. MSA is ordered by the data format used
    // by the underlying instruction i.e., df/m, df/n and then by size.
    //
    // FIXME: The size tests here should instead be tablegen'd along with the
    //        definitions from include/clang/Basic/BuiltinsMips.def.
    // FIXME: GCC is strict on signedness for some of these intrinsics, we should
    //        be too.
    bool Sema::CheckMipsBuiltinFunctionCall(unsigned BuiltinID, CallExpr *TheCall) {
      unsigned i = 0, l = 0, u = 0, m = 0;
      switch (BuiltinID) {
      default: return false;
      case Mips::BI__builtin_mips_wrdsp: i = 1; l = 0; u = 63; break;
      case Mips::BI__builtin_mips_rddsp: i = 0; l = 0; u = 63; break;
      case Mips::BI__builtin_mips_append: i = 2; l = 0; u = 31; break;
      case Mips::BI__builtin_mips_balign: i = 2; l = 0; u = 3; break;
      case Mips::BI__builtin_mips_precr_sra_ph_w: i = 2; l = 0; u = 31; break;
      case Mips::BI__builtin_mips_precr_sra_r_ph_w: i = 2; l = 0; u = 31; break;
      case Mips::BI__builtin_mips_prepend: i = 2; l = 0; u = 31; break;
      // MSA instrinsics. Instructions (which the intrinsics maps to) which use the
      // df/m field.
      // These intrinsics take an unsigned 3 bit immediate.
      case Mips::BI__builtin_msa_bclri_b:
      case Mips::BI__builtin_msa_bnegi_b:
      case Mips::BI__builtin_msa_bseti_b:
      case Mips::BI__builtin_msa_sat_s_b:
      case Mips::BI__builtin_msa_sat_u_b:
      case Mips::BI__builtin_msa_slli_b:
      case Mips::BI__builtin_msa_srai_b:
      case Mips::BI__builtin_msa_srari_b:
      case Mips::BI__builtin_msa_srli_b:
      case Mips::BI__builtin_msa_srlri_b: i = 1; l = 0; u = 7; break;
      case Mips::BI__builtin_msa_binsli_b:
      case Mips::BI__builtin_msa_binsri_b: i = 2; l = 0; u = 7; break;
      // These intrinsics take an unsigned 4 bit immediate.
      case Mips::BI__builtin_msa_bclri_h:
      case Mips::BI__builtin_msa_bnegi_h:
      case Mips::BI__builtin_msa_bseti_h:
      case Mips::BI__builtin_msa_sat_s_h:
      case Mips::BI__builtin_msa_sat_u_h:
      case Mips::BI__builtin_msa_slli_h:
      case Mips::BI__builtin_msa_srai_h:
      case Mips::BI__builtin_msa_srari_h:
      case Mips::BI__builtin_msa_srli_h:
      case Mips::BI__builtin_msa_srlri_h: i = 1; l = 0; u = 15; break;
      case Mips::BI__builtin_msa_binsli_h:
      case Mips::BI__builtin_msa_binsri_h: i = 2; l = 0; u = 15; break;
      // These intrinsics take an unsigned 5 bit immedate.
      // The first block of intrinsics actually have an unsigned 5 bit field,
      // not a df/n field.
      case Mips::BI__builtin_msa_clei_u_b:
      case Mips::BI__builtin_msa_clei_u_h:
      case Mips::BI__builtin_msa_clei_u_w:
      case Mips::BI__builtin_msa_clei_u_d:
      case Mips::BI__builtin_msa_clti_u_b:
      case Mips::BI__builtin_msa_clti_u_h:
      case Mips::BI__builtin_msa_clti_u_w:
      case Mips::BI__builtin_msa_clti_u_d:
      case Mips::BI__builtin_msa_maxi_u_b:
      case Mips::BI__builtin_msa_maxi_u_h:
      case Mips::BI__builtin_msa_maxi_u_w:
      case Mips::BI__builtin_msa_maxi_u_d:
      case Mips::BI__builtin_msa_mini_u_b:
      case Mips::BI__builtin_msa_mini_u_h:
      case Mips::BI__builtin_msa_mini_u_w:
      case Mips::BI__builtin_msa_mini_u_d:
      case Mips::BI__builtin_msa_addvi_b:
      case Mips::BI__builtin_msa_addvi_h:
      case Mips::BI__builtin_msa_addvi_w:
      case Mips::BI__builtin_msa_addvi_d:
      case Mips::BI__builtin_msa_bclri_w:
      case Mips::BI__builtin_msa_bnegi_w:
      case Mips::BI__builtin_msa_bseti_w:
      case Mips::BI__builtin_msa_sat_s_w:
      case Mips::BI__builtin_msa_sat_u_w:
      case Mips::BI__builtin_msa_slli_w:
      case Mips::BI__builtin_msa_srai_w:
      case Mips::BI__builtin_msa_srari_w:
      case Mips::BI__builtin_msa_srli_w:
      case Mips::BI__builtin_msa_srlri_w:
      case Mips::BI__builtin_msa_subvi_b:
      case Mips::BI__builtin_msa_subvi_h:
      case Mips::BI__builtin_msa_subvi_w:
      case Mips::BI__builtin_msa_subvi_d: i = 1; l = 0; u = 31; break;
      case Mips::BI__builtin_msa_binsli_w:
      case Mips::BI__builtin_msa_binsri_w: i = 2; l = 0; u = 31; break;
      // These intrinsics take an unsigned 6 bit immediate.
      case Mips::BI__builtin_msa_bclri_d:
      case Mips::BI__builtin_msa_bnegi_d:
      case Mips::BI__builtin_msa_bseti_d:
      case Mips::BI__builtin_msa_sat_s_d:
      case Mips::BI__builtin_msa_sat_u_d:
      case Mips::BI__builtin_msa_slli_d:
      case Mips::BI__builtin_msa_srai_d:
      case Mips::BI__builtin_msa_srari_d:
      case Mips::BI__builtin_msa_srli_d:
      case Mips::BI__builtin_msa_srlri_d: i = 1; l = 0; u = 63; break;
      case Mips::BI__builtin_msa_binsli_d:
      case Mips::BI__builtin_msa_binsri_d: i = 2; l = 0; u = 63; break;
      // These intrinsics take a signed 5 bit immediate.
      case Mips::BI__builtin_msa_ceqi_b:
      case Mips::BI__builtin_msa_ceqi_h:
      case Mips::BI__builtin_msa_ceqi_w:
      case Mips::BI__builtin_msa_ceqi_d:
      case Mips::BI__builtin_msa_clti_s_b:
      case Mips::BI__builtin_msa_clti_s_h:
      case Mips::BI__builtin_msa_clti_s_w:
      case Mips::BI__builtin_msa_clti_s_d:
      case Mips::BI__builtin_msa_clei_s_b:
      case Mips::BI__builtin_msa_clei_s_h:
      case Mips::BI__builtin_msa_clei_s_w:
      case Mips::BI__builtin_msa_clei_s_d:
      case Mips::BI__builtin_msa_maxi_s_b:
      case Mips::BI__builtin_msa_maxi_s_h:
      case Mips::BI__builtin_msa_maxi_s_w:
      case Mips::BI__builtin_msa_maxi_s_d:
      case Mips::BI__builtin_msa_mini_s_b:
      case Mips::BI__builtin_msa_mini_s_h:
      case Mips::BI__builtin_msa_mini_s_w:
      case Mips::BI__builtin_msa_mini_s_d: i = 1; l = -16; u = 15; break;
      // These intrinsics take an unsigned 8 bit immediate.
      case Mips::BI__builtin_msa_andi_b:
      case Mips::BI__builtin_msa_nori_b:
      case Mips::BI__builtin_msa_ori_b:
      case Mips::BI__builtin_msa_shf_b:
      case Mips::BI__builtin_msa_shf_h:
      case Mips::BI__builtin_msa_shf_w:
      case Mips::BI__builtin_msa_xori_b: i = 1; l = 0; u = 255; break;
      case Mips::BI__builtin_msa_bseli_b:
      case Mips::BI__builtin_msa_bmnzi_b:
      case Mips::BI__builtin_msa_bmzi_b: i = 2; l = 0; u = 255; break;
      // df/n format
      // These intrinsics take an unsigned 4 bit immediate.
      case Mips::BI__builtin_msa_copy_s_b:
      case Mips::BI__builtin_msa_copy_u_b:
      case Mips::BI__builtin_msa_insve_b:
      case Mips::BI__builtin_msa_splati_b: i = 1; l = 0; u = 15; break;
      case Mips::BI__builtin_msa_sld_b:
      case Mips::BI__builtin_msa_sldi_b: i = 2; l = 0; u = 15; break;
      // These intrinsics take an unsigned 3 bit immediate.
      case Mips::BI__builtin_msa_copy_s_h:
      case Mips::BI__builtin_msa_copy_u_h:
      case Mips::BI__builtin_msa_insve_h:
      case Mips::BI__builtin_msa_splati_h: i = 1; l = 0; u = 7; break;
      case Mips::BI__builtin_msa_sld_h:
      case Mips::BI__builtin_msa_sldi_h: i = 2; l = 0; u = 7; break;
      // These intrinsics take an unsigned 2 bit immediate.
      case Mips::BI__builtin_msa_copy_s_w:
      case Mips::BI__builtin_msa_copy_u_w:
      case Mips::BI__builtin_msa_insve_w:
      case Mips::BI__builtin_msa_splati_w: i = 1; l = 0; u = 3; break;
      case Mips::BI__builtin_msa_sld_w:
      case Mips::BI__builtin_msa_sldi_w: i = 2; l = 0; u = 3; break;
      // These intrinsics take an unsigned 1 bit immediate.
      case Mips::BI__builtin_msa_copy_s_d:
      case Mips::BI__builtin_msa_copy_u_d:
      case Mips::BI__builtin_msa_insve_d:
      case Mips::BI__builtin_msa_splati_d: i = 1; l = 0; u = 1; break;
      case Mips::BI__builtin_msa_sld_d:
      case Mips::BI__builtin_msa_sldi_d: i = 2; l = 0; u = 1; break;
      // Memory offsets and immediate loads.
      // These intrinsics take a signed 10 bit immediate.
      case Mips::BI__builtin_msa_ldi_b: i = 0; l = -128; u = 127; break;
      case Mips::BI__builtin_msa_ldi_h:
      case Mips::BI__builtin_msa_ldi_w:
      case Mips::BI__builtin_msa_ldi_d: i = 0; l = -512; u = 511; break;
      case Mips::BI__builtin_msa_ld_b: i = 1; l = -512; u = 511; m = 16; break;
      case Mips::BI__builtin_msa_ld_h: i = 1; l = -1024; u = 1022; m = 16; break;
      case Mips::BI__builtin_msa_ld_w: i = 1; l = -2048; u = 2044; m = 16; break;
      case Mips::BI__builtin_msa_ld_d: i = 1; l = -4096; u = 4088; m = 16; break;
      case Mips::BI__builtin_msa_st_b: i = 2; l = -512; u = 511; m = 16; break;
      case Mips::BI__builtin_msa_st_h: i = 2; l = -1024; u = 1022; m = 16; break;
      case Mips::BI__builtin_msa_st_w: i = 2; l = -2048; u = 2044; m = 16; break;
      case Mips::BI__builtin_msa_st_d: i = 2; l = -4096; u = 4088; m = 16; break;
      }
    
      if (!m)
        return SemaBuiltinConstantArgRange(TheCall, i, l, u);
    
      return SemaBuiltinConstantArgRange(TheCall, i, l, u) ||
             SemaBuiltinConstantArgMultiple(TheCall, i, m);
    }
    
    bool Sema::CheckPPCBuiltinFunctionCall(unsigned BuiltinID, CallExpr *TheCall) {
      unsigned i = 0, l = 0, u = 0;
      bool Is64BitBltin = BuiltinID == PPC::BI__builtin_divde ||
                          BuiltinID == PPC::BI__builtin_divdeu ||
                          BuiltinID == PPC::BI__builtin_bpermd;
      bool IsTarget64Bit = Context.getTargetInfo()
                                  .getTypeWidth(Context
                                                .getTargetInfo()
                                                .getIntPtrType()) == 64;
      bool IsBltinExtDiv = BuiltinID == PPC::BI__builtin_divwe ||
                           BuiltinID == PPC::BI__builtin_divweu ||
                           BuiltinID == PPC::BI__builtin_divde ||
                           BuiltinID == PPC::BI__builtin_divdeu;
    
      if (Is64BitBltin && !IsTarget64Bit)
          return Diag(TheCall->getLocStart(), diag::err_64_bit_builtin_32_bit_tgt)
                 << TheCall->getSourceRange();
    
      if ((IsBltinExtDiv && !Context.getTargetInfo().hasFeature("extdiv")) ||
          (BuiltinID == PPC::BI__builtin_bpermd &&
           !Context.getTargetInfo().hasFeature("bpermd")))
        return Diag(TheCall->getLocStart(), diag::err_ppc_builtin_only_on_pwr7)
               << TheCall->getSourceRange();
    
      switch (BuiltinID) {
      default: return false;
      case PPC::BI__builtin_altivec_crypto_vshasigmaw:
      case PPC::BI__builtin_altivec_crypto_vshasigmad:
        return SemaBuiltinConstantArgRange(TheCall, 1, 0, 1) ||
               SemaBuiltinConstantArgRange(TheCall, 2, 0, 15);
      case PPC::BI__builtin_tbegin:
      case PPC::BI__builtin_tend: i = 0; l = 0; u = 1; break;
      case PPC::BI__builtin_tsr: i = 0; l = 0; u = 7; break;
      case PPC::BI__builtin_tabortwc:
      case PPC::BI__builtin_tabortdc: i = 0; l = 0; u = 31; break;
      case PPC::BI__builtin_tabortwci:
      case PPC::BI__builtin_tabortdci:
        return SemaBuiltinConstantArgRange(TheCall, 0, 0, 31) ||
               SemaBuiltinConstantArgRange(TheCall, 2, 0, 31);
      }
      return SemaBuiltinConstantArgRange(TheCall, i, l, u);
    }
    
    bool Sema::CheckSystemZBuiltinFunctionCall(unsigned BuiltinID,
                                               CallExpr *TheCall) {
      if (BuiltinID == SystemZ::BI__builtin_tabort) {
        Expr *Arg = TheCall->getArg(0);
        llvm::APSInt AbortCode(32);
        if (Arg->isIntegerConstantExpr(AbortCode, Context) &&
            AbortCode.getSExtValue() >= 0 && AbortCode.getSExtValue() < 256)
          return Diag(Arg->getLocStart(), diag::err_systemz_invalid_tabort_code)
                 << Arg->getSourceRange();
      }
    
      // For intrinsics which take an immediate value as part of the instruction,
      // range check them here.
      unsigned i = 0, l = 0, u = 0;
      switch (BuiltinID) {
      default: return false;
      case SystemZ::BI__builtin_s390_lcbb: i = 1; l = 0; u = 15; break;
      case SystemZ::BI__builtin_s390_verimb:
      case SystemZ::BI__builtin_s390_verimh:
      case SystemZ::BI__builtin_s390_verimf:
      case SystemZ::BI__builtin_s390_verimg: i = 3; l = 0; u = 255; break;
      case SystemZ::BI__builtin_s390_vfaeb:
      case SystemZ::BI__builtin_s390_vfaeh:
      case SystemZ::BI__builtin_s390_vfaef:
      case SystemZ::BI__builtin_s390_vfaebs:
      case SystemZ::BI__builtin_s390_vfaehs:
      case SystemZ::BI__builtin_s390_vfaefs:
      case SystemZ::BI__builtin_s390_vfaezb:
      case SystemZ::BI__builtin_s390_vfaezh:
      case SystemZ::BI__builtin_s390_vfaezf:
      case SystemZ::BI__builtin_s390_vfaezbs:
      case SystemZ::BI__builtin_s390_vfaezhs:
      case SystemZ::BI__builtin_s390_vfaezfs: i = 2; l = 0; u = 15; break;
      case SystemZ::BI__builtin_s390_vfidb:
        return SemaBuiltinConstantArgRange(TheCall, 1, 0, 15) ||
               SemaBuiltinConstantArgRange(TheCall, 2, 0, 15);
      case SystemZ::BI__builtin_s390_vftcidb: i = 1; l = 0; u = 4095; break;
      case SystemZ::BI__builtin_s390_vlbb: i = 1; l = 0; u = 15; break;
      case SystemZ::BI__builtin_s390_vpdi: i = 2; l = 0; u = 15; break;
      case SystemZ::BI__builtin_s390_vsldb: i = 2; l = 0; u = 15; break;
      case SystemZ::BI__builtin_s390_vstrcb:
      case SystemZ::BI__builtin_s390_vstrch:
      case SystemZ::BI__builtin_s390_vstrcf:
      case SystemZ::BI__builtin_s390_vstrczb:
      case SystemZ::BI__builtin_s390_vstrczh:
      case SystemZ::BI__builtin_s390_vstrczf:
      case SystemZ::BI__builtin_s390_vstrcbs:
      case SystemZ::BI__builtin_s390_vstrchs:
      case SystemZ::BI__builtin_s390_vstrcfs:
      case SystemZ::BI__builtin_s390_vstrczbs:
      case SystemZ::BI__builtin_s390_vstrczhs:
      case SystemZ::BI__builtin_s390_vstrczfs: i = 3; l = 0; u = 15; break;
      }
      return SemaBuiltinConstantArgRange(TheCall, i, l, u);
    }
    
    /// SemaBuiltinCpuSupports - Handle __builtin_cpu_supports(char *).
    /// This checks that the target supports __builtin_cpu_supports and
    /// that the string argument is constant and valid.
    static bool SemaBuiltinCpuSupports(Sema &S, CallExpr *TheCall) {
      Expr *Arg = TheCall->getArg(0);
    
      // Check if the argument is a string literal.
      if (!isa<StringLiteral>(Arg->IgnoreParenImpCasts()))
        return S.Diag(TheCall->getLocStart(), diag::err_expr_not_string_literal)
               << Arg->getSourceRange();
    
      // Check the contents of the string.
      StringRef Feature =
          cast<StringLiteral>(Arg->IgnoreParenImpCasts())->getString();
      if (!S.Context.getTargetInfo().validateCpuSupports(Feature))
        return S.Diag(TheCall->getLocStart(), diag::err_invalid_cpu_supports)
               << Arg->getSourceRange();
      return false;
    }
    
    // Check if the rounding mode is legal.
    bool Sema::CheckX86BuiltinRoundingOrSAE(unsigned BuiltinID, CallExpr *TheCall) {
      // Indicates if this instruction has rounding control or just SAE.
      bool HasRC = false;
    
      unsigned ArgNum = 0;
      switch (BuiltinID) {
      default:
        return false;
      case X86::BI__builtin_ia32_vcvttsd2si32:
      case X86::BI__builtin_ia32_vcvttsd2si64:
      case X86::BI__builtin_ia32_vcvttsd2usi32:
      case X86::BI__builtin_ia32_vcvttsd2usi64:
      case X86::BI__builtin_ia32_vcvttss2si32:
      case X86::BI__builtin_ia32_vcvttss2si64:
      case X86::BI__builtin_ia32_vcvttss2usi32:
      case X86::BI__builtin_ia32_vcvttss2usi64:
        ArgNum = 1;
        break;
      case X86::BI__builtin_ia32_cvtps2pd512_mask:
      case X86::BI__builtin_ia32_cvttpd2dq512_mask:
      case X86::BI__builtin_ia32_cvttpd2qq512_mask:
      case X86::BI__builtin_ia32_cvttpd2udq512_mask:
      case X86::BI__builtin_ia32_cvttpd2uqq512_mask:
      case X86::BI__builtin_ia32_cvttps2dq512_mask:
      case X86::BI__builtin_ia32_cvttps2qq512_mask:
      case X86::BI__builtin_ia32_cvttps2udq512_mask:
      case X86::BI__builtin_ia32_cvttps2uqq512_mask:
      case X86::BI__builtin_ia32_exp2pd_mask:
      case X86::BI__builtin_ia32_exp2ps_mask:
      case X86::BI__builtin_ia32_getexppd512_mask:
      case X86::BI__builtin_ia32_getexpps512_mask:
      case X86::BI__builtin_ia32_rcp28pd_mask:
      case X86::BI__builtin_ia32_rcp28ps_mask:
      case X86::BI__builtin_ia32_rsqrt28pd_mask:
      case X86::BI__builtin_ia32_rsqrt28ps_mask:
      case X86::BI__builtin_ia32_vcomisd:
      case X86::BI__builtin_ia32_vcomiss:
      case X86::BI__builtin_ia32_vcvtph2ps512_mask:
        ArgNum = 3;
        break;
      case X86::BI__builtin_ia32_cmppd512_mask:
      case X86::BI__builtin_ia32_cmpps512_mask:
      case X86::BI__builtin_ia32_cmpsd_mask:
      case X86::BI__builtin_ia32_cmpss_mask:
      case X86::BI__builtin_ia32_cvtss2sd_round_mask:
      case X86::BI__builtin_ia32_getexpsd128_round_mask:
      case X86::BI__builtin_ia32_getexpss128_round_mask:
      case X86::BI__builtin_ia32_maxpd512_mask:
      case X86::BI__builtin_ia32_maxps512_mask:
      case X86::BI__builtin_ia32_maxsd_round_mask:
      case X86::BI__builtin_ia32_maxss_round_mask:
      case X86::BI__builtin_ia32_minpd512_mask:
      case X86::BI__builtin_ia32_minps512_mask:
      case X86::BI__builtin_ia32_minsd_round_mask:
      case X86::BI__builtin_ia32_minss_round_mask:
      case X86::BI__builtin_ia32_rcp28sd_round_mask:
      case X86::BI__builtin_ia32_rcp28ss_round_mask:
      case X86::BI__builtin_ia32_reducepd512_mask:
      case X86::BI__builtin_ia32_reduceps512_mask:
      case X86::BI__builtin_ia32_rndscalepd_mask:
      case X86::BI__builtin_ia32_rndscaleps_mask:
      case X86::BI__builtin_ia32_rsqrt28sd_round_mask:
      case X86::BI__builtin_ia32_rsqrt28ss_round_mask:
        ArgNum = 4;
        break;
      case X86::BI__builtin_ia32_fixupimmpd512_mask:
      case X86::BI__builtin_ia32_fixupimmpd512_maskz:
      case X86::BI__builtin_ia32_fixupimmps512_mask:
      case X86::BI__builtin_ia32_fixupimmps512_maskz:
      case X86::BI__builtin_ia32_fixupimmsd_mask:
      case X86::BI__builtin_ia32_fixupimmsd_maskz:
      case X86::BI__builtin_ia32_fixupimmss_mask:
      case X86::BI__builtin_ia32_fixupimmss_maskz:
      case X86::BI__builtin_ia32_rangepd512_mask:
      case X86::BI__builtin_ia32_rangeps512_mask:
      case X86::BI__builtin_ia32_rangesd128_round_mask:
      case X86::BI__builtin_ia32_rangess128_round_mask:
      case X86::BI__builtin_ia32_reducesd_mask:
      case X86::BI__builtin_ia32_reducess_mask:
      case X86::BI__builtin_ia32_rndscalesd_round_mask:
      case X86::BI__builtin_ia32_rndscaless_round_mask:
        ArgNum = 5;
        break;
      case X86::BI__builtin_ia32_vcvtsd2si64:
      case X86::BI__builtin_ia32_vcvtsd2si32:
      case X86::BI__builtin_ia32_vcvtsd2usi32:
      case X86::BI__builtin_ia32_vcvtsd2usi64:
      case X86::BI__builtin_ia32_vcvtss2si32:
      case X86::BI__builtin_ia32_vcvtss2si64:
      case X86::BI__builtin_ia32_vcvtss2usi32:
      case X86::BI__builtin_ia32_vcvtss2usi64:
        ArgNum = 1;
        HasRC = true;
        break;
      case X86::BI__builtin_ia32_cvtsi2sd64:
      case X86::BI__builtin_ia32_cvtsi2ss32:
      case X86::BI__builtin_ia32_cvtsi2ss64:
      case X86::BI__builtin_ia32_cvtusi2sd64:
      case X86::BI__builtin_ia32_cvtusi2ss32:
      case X86::BI__builtin_ia32_cvtusi2ss64:
        ArgNum = 2;
        HasRC = true;
        break;
      case X86::BI__builtin_ia32_cvtdq2ps512_mask:
      case X86::BI__builtin_ia32_cvtudq2ps512_mask:
      case X86::BI__builtin_ia32_cvtpd2ps512_mask:
      case X86::BI__builtin_ia32_cvtpd2qq512_mask:
      case X86::BI__builtin_ia32_cvtpd2uqq512_mask:
      case X86::BI__builtin_ia32_cvtps2qq512_mask:
      case X86::BI__builtin_ia32_cvtps2uqq512_mask:
      case X86::BI__builtin_ia32_cvtqq2pd512_mask:
      case X86::BI__builtin_ia32_cvtqq2ps512_mask:
      case X86::BI__builtin_ia32_cvtuqq2pd512_mask:
      case X86::BI__builtin_ia32_cvtuqq2ps512_mask:
      case X86::BI__builtin_ia32_sqrtpd512_mask:
      case X86::BI__builtin_ia32_sqrtps512_mask:
        ArgNum = 3;
        HasRC = true;
        break;
      case X86::BI__builtin_ia32_addpd512_mask:
      case X86::BI__builtin_ia32_addps512_mask:
      case X86::BI__builtin_ia32_divpd512_mask:
      case X86::BI__builtin_ia32_divps512_mask:
      case X86::BI__builtin_ia32_mulpd512_mask:
      case X86::BI__builtin_ia32_mulps512_mask:
      case X86::BI__builtin_ia32_subpd512_mask:
      case X86::BI__builtin_ia32_subps512_mask:
      case X86::BI__builtin_ia32_addss_round_mask:
      case X86::BI__builtin_ia32_addsd_round_mask:
      case X86::BI__builtin_ia32_divss_round_mask:
      case X86::BI__builtin_ia32_divsd_round_mask:
      case X86::BI__builtin_ia32_mulss_round_mask:
      case X86::BI__builtin_ia32_mulsd_round_mask:
      case X86::BI__builtin_ia32_subss_round_mask:
      case X86::BI__builtin_ia32_subsd_round_mask:
      case X86::BI__builtin_ia32_scalefpd512_mask:
      case X86::BI__builtin_ia32_scalefps512_mask:
      case X86::BI__builtin_ia32_scalefsd_round_mask:
      case X86::BI__builtin_ia32_scalefss_round_mask:
      case X86::BI__builtin_ia32_getmantpd512_mask:
      case X86::BI__builtin_ia32_getmantps512_mask:
      case X86::BI__builtin_ia32_cvtsd2ss_round_mask:
      case X86::BI__builtin_ia32_sqrtsd_round_mask:
      case X86::BI__builtin_ia32_sqrtss_round_mask:
      case X86::BI__builtin_ia32_vfmaddpd512_mask:
      case X86::BI__builtin_ia32_vfmaddpd512_mask3:
      case X86::BI__builtin_ia32_vfmaddpd512_maskz:
      case X86::BI__builtin_ia32_vfmaddps512_mask:
      case X86::BI__builtin_ia32_vfmaddps512_mask3:
      case X86::BI__builtin_ia32_vfmaddps512_maskz:
      case X86::BI__builtin_ia32_vfmaddsubpd512_mask:
      case X86::BI__builtin_ia32_vfmaddsubpd512_mask3:
      case X86::BI__builtin_ia32_vfmaddsubpd512_maskz:
      case X86::BI__builtin_ia32_vfmaddsubps512_mask:
      case X86::BI__builtin_ia32_vfmaddsubps512_mask3:
      case X86::BI__builtin_ia32_vfmaddsubps512_maskz:
      case X86::BI__builtin_ia32_vfmsubpd512_mask3:
      case X86::BI__builtin_ia32_vfmsubps512_mask3:
      case X86::BI__builtin_ia32_vfmsubaddpd512_mask3:
      case X86::BI__builtin_ia32_vfmsubaddps512_mask3:
      case X86::BI__builtin_ia32_vfnmaddpd512_mask:
      case X86::BI__builtin_ia32_vfnmaddps512_mask:
      case X86::BI__builtin_ia32_vfnmsubpd512_mask:
      case X86::BI__builtin_ia32_vfnmsubpd512_mask3:
      case X86::BI__builtin_ia32_vfnmsubps512_mask:
      case X86::BI__builtin_ia32_vfnmsubps512_mask3:
      case X86::BI__builtin_ia32_vfmaddsd3_mask:
      case X86::BI__builtin_ia32_vfmaddsd3_maskz:
      case X86::BI__builtin_ia32_vfmaddsd3_mask3:
      case X86::BI__builtin_ia32_vfmaddss3_mask:
      case X86::BI__builtin_ia32_vfmaddss3_maskz:
      case X86::BI__builtin_ia32_vfmaddss3_mask3:
        ArgNum = 4;
        HasRC = true;
        break;
      case X86::BI__builtin_ia32_getmantsd_round_mask:
      case X86::BI__builtin_ia32_getmantss_round_mask:
        ArgNum = 5;
        HasRC = true;
        break;
      }
    
      llvm::APSInt Result;
    
      // We can't check the value of a dependent argument.
      Expr *Arg = TheCall->getArg(ArgNum);
      if (Arg->isTypeDependent() || Arg->isValueDependent())
        return false;
    
      // Check constant-ness first.
      if (SemaBuiltinConstantArg(TheCall, ArgNum, Result))
        return true;
    
      // Make sure rounding mode is either ROUND_CUR_DIRECTION or ROUND_NO_EXC bit
      // is set. If the intrinsic has rounding control(bits 1:0), make sure its only
      // combined with ROUND_NO_EXC.
      if (Result == 4/*ROUND_CUR_DIRECTION*/ ||
          Result == 8/*ROUND_NO_EXC*/ ||
          (HasRC && Result.getZExtValue() >= 8 && Result.getZExtValue() <= 11))
        return false;
    
      return Diag(TheCall->getLocStart(), diag::err_x86_builtin_invalid_rounding)
        << Arg->getSourceRange();
    }
    
    bool Sema::CheckX86BuiltinFunctionCall(unsigned BuiltinID, CallExpr *TheCall) {
      if (BuiltinID == X86::BI__builtin_cpu_supports)
        return SemaBuiltinCpuSupports(*this, TheCall);
    
      if (BuiltinID == X86::BI__builtin_ms_va_start)
        return SemaBuiltinMSVAStart(TheCall);
    
      // If the intrinsic has rounding or SAE make sure its valid.
      if (CheckX86BuiltinRoundingOrSAE(BuiltinID, TheCall))
        return true;
    
      // For intrinsics which take an immediate value as part of the instruction,
      // range check them here.
      int i = 0, l = 0, u = 0;
      switch (BuiltinID) {
      default:
        return false;
      case X86::BI_mm_prefetch:
        i = 1; l = 0; u = 3;
        break;
      case X86::BI__builtin_ia32_sha1rnds4:
      case X86::BI__builtin_ia32_shuf_f32x4_256_mask:
      case X86::BI__builtin_ia32_shuf_f64x2_256_mask:
      case X86::BI__builtin_ia32_shuf_i32x4_256_mask:
      case X86::BI__builtin_ia32_shuf_i64x2_256_mask:
        i = 2; l = 0; u = 3;
        break;
      case X86::BI__builtin_ia32_vpermil2pd:
      case X86::BI__builtin_ia32_vpermil2pd256:
      case X86::BI__builtin_ia32_vpermil2ps:
      case X86::BI__builtin_ia32_vpermil2ps256:
        i = 3; l = 0; u = 3;
        break;
      case X86::BI__builtin_ia32_cmpb128_mask:
      case X86::BI__builtin_ia32_cmpw128_mask:
      case X86::BI__builtin_ia32_cmpd128_mask:
      case X86::BI__builtin_ia32_cmpq128_mask:
      case X86::BI__builtin_ia32_cmpb256_mask:
      case X86::BI__builtin_ia32_cmpw256_mask:
      case X86::BI__builtin_ia32_cmpd256_mask:
      case X86::BI__builtin_ia32_cmpq256_mask:
      case X86::BI__builtin_ia32_cmpb512_mask:
      case X86::BI__builtin_ia32_cmpw512_mask:
      case X86::BI__builtin_ia32_cmpd512_mask:
      case X86::BI__builtin_ia32_cmpq512_mask:
      case X86::BI__builtin_ia32_ucmpb128_mask:
      case X86::BI__builtin_ia32_ucmpw128_mask:
      case X86::BI__builtin_ia32_ucmpd128_mask:
      case X86::BI__builtin_ia32_ucmpq128_mask:
      case X86::BI__builtin_ia32_ucmpb256_mask:
      case X86::BI__builtin_ia32_ucmpw256_mask:
      case X86::BI__builtin_ia32_ucmpd256_mask:
      case X86::BI__builtin_ia32_ucmpq256_mask:
      case X86::BI__builtin_ia32_ucmpb512_mask:
      case X86::BI__builtin_ia32_ucmpw512_mask:
      case X86::BI__builtin_ia32_ucmpd512_mask:
      case X86::BI__builtin_ia32_ucmpq512_mask:
      case X86::BI__builtin_ia32_vpcomub:
      case X86::BI__builtin_ia32_vpcomuw:
      case X86::BI__builtin_ia32_vpcomud:
      case X86::BI__builtin_ia32_vpcomuq:
      case X86::BI__builtin_ia32_vpcomb:
      case X86::BI__builtin_ia32_vpcomw:
      case X86::BI__builtin_ia32_vpcomd:
      case X86::BI__builtin_ia32_vpcomq:
        i = 2; l = 0; u = 7;
        break;
      case X86::BI__builtin_ia32_roundps:
      case X86::BI__builtin_ia32_roundpd:
      case X86::BI__builtin_ia32_roundps256:
      case X86::BI__builtin_ia32_roundpd256:
        i = 1; l = 0; u = 15;
        break;
      case X86::BI__builtin_ia32_roundss:
      case X86::BI__builtin_ia32_roundsd:
      case X86::BI__builtin_ia32_rangepd128_mask:
      case X86::BI__builtin_ia32_rangepd256_mask:
      case X86::BI__builtin_ia32_rangepd512_mask:
      case X86::BI__builtin_ia32_rangeps128_mask:
      case X86::BI__builtin_ia32_rangeps256_mask:
      case X86::BI__builtin_ia32_rangeps512_mask:
      case X86::BI__builtin_ia32_getmantsd_round_mask:
      case X86::BI__builtin_ia32_getmantss_round_mask:
        i = 2; l = 0; u = 15;
        break;
      case X86::BI__builtin_ia32_cmpps:
      case X86::BI__builtin_ia32_cmpss:
      case X86::BI__builtin_ia32_cmppd:
      case X86::BI__builtin_ia32_cmpsd:
      case X86::BI__builtin_ia32_cmpps256:
      case X86::BI__builtin_ia32_cmppd256:
      case X86::BI__builtin_ia32_cmpps128_mask:
      case X86::BI__builtin_ia32_cmppd128_mask:
      case X86::BI__builtin_ia32_cmpps256_mask:
      case X86::BI__builtin_ia32_cmppd256_mask:
      case X86::BI__builtin_ia32_cmpps512_mask:
      case X86::BI__builtin_ia32_cmppd512_mask:
      case X86::BI__builtin_ia32_cmpsd_mask:
      case X86::BI__builtin_ia32_cmpss_mask:
        i = 2; l = 0; u = 31;
        break;
      case X86::BI__builtin_ia32_xabort:
        i = 0; l = -128; u = 255;
        break;
      case X86::BI__builtin_ia32_pshufw:
      case X86::BI__builtin_ia32_aeskeygenassist128:
        i = 1; l = -128; u = 255;
        break;
      case X86::BI__builtin_ia32_vcvtps2ph:
      case X86::BI__builtin_ia32_vcvtps2ph256:
      case X86::BI__builtin_ia32_rndscaleps_128_mask:
      case X86::BI__builtin_ia32_rndscalepd_128_mask:
      case X86::BI__builtin_ia32_rndscaleps_256_mask:
      case X86::BI__builtin_ia32_rndscalepd_256_mask:
      case X86::BI__builtin_ia32_rndscaleps_mask:
      case X86::BI__builtin_ia32_rndscalepd_mask:
      case X86::BI__builtin_ia32_reducepd128_mask:
      case X86::BI__builtin_ia32_reducepd256_mask:
      case X86::BI__builtin_ia32_reducepd512_mask:
      case X86::BI__builtin_ia32_reduceps128_mask:
      case X86::BI__builtin_ia32_reduceps256_mask:
      case X86::BI__builtin_ia32_reduceps512_mask:
      case X86::BI__builtin_ia32_prold512_mask:
      case X86::BI__builtin_ia32_prolq512_mask:
      case X86::BI__builtin_ia32_prold128_mask:
      case X86::BI__builtin_ia32_prold256_mask:
      case X86::BI__builtin_ia32_prolq128_mask:
      case X86::BI__builtin_ia32_prolq256_mask:
      case X86::BI__builtin_ia32_prord128_mask:
      case X86::BI__builtin_ia32_prord256_mask:
      case X86::BI__builtin_ia32_prorq128_mask:
      case X86::BI__builtin_ia32_prorq256_mask:
      case X86::BI__builtin_ia32_fpclasspd128_mask:
      case X86::BI__builtin_ia32_fpclasspd256_mask:
      case X86::BI__builtin_ia32_fpclassps128_mask:
      case X86::BI__builtin_ia32_fpclassps256_mask:
      case X86::BI__builtin_ia32_fpclassps512_mask:
      case X86::BI__builtin_ia32_fpclasspd512_mask:
      case X86::BI__builtin_ia32_fpclasssd_mask:
      case X86::BI__builtin_ia32_fpclassss_mask:
        i = 1; l = 0; u = 255;
        break;
      case X86::BI__builtin_ia32_palignr:
      case X86::BI__builtin_ia32_insertps128:
      case X86::BI__builtin_ia32_dpps:
      case X86::BI__builtin_ia32_dppd:
      case X86::BI__builtin_ia32_dpps256:
      case X86::BI__builtin_ia32_mpsadbw128:
      case X86::BI__builtin_ia32_mpsadbw256:
      case X86::BI__builtin_ia32_pcmpistrm128:
      case X86::BI__builtin_ia32_pcmpistri128:
      case X86::BI__builtin_ia32_pcmpistria128:
      case X86::BI__builtin_ia32_pcmpistric128:
      case X86::BI__builtin_ia32_pcmpistrio128:
      case X86::BI__builtin_ia32_pcmpistris128:
      case X86::BI__builtin_ia32_pcmpistriz128:
      case X86::BI__builtin_ia32_pclmulqdq128:
      case X86::BI__builtin_ia32_vperm2f128_pd256:
      case X86::BI__builtin_ia32_vperm2f128_ps256:
      case X86::BI__builtin_ia32_vperm2f128_si256:
      case X86::BI__builtin_ia32_permti256:
        i = 2; l = -128; u = 255;
        break;
      case X86::BI__builtin_ia32_palignr128:
      case X86::BI__builtin_ia32_palignr256:
      case X86::BI__builtin_ia32_palignr512_mask:
      case X86::BI__builtin_ia32_vcomisd:
      case X86::BI__builtin_ia32_vcomiss:
      case X86::BI__builtin_ia32_shuf_f32x4_mask:
      case X86::BI__builtin_ia32_shuf_f64x2_mask:
      case X86::BI__builtin_ia32_shuf_i32x4_mask:
      case X86::BI__builtin_ia32_shuf_i64x2_mask:
      case X86::BI__builtin_ia32_dbpsadbw128_mask:
      case X86::BI__builtin_ia32_dbpsadbw256_mask:
      case X86::BI__builtin_ia32_dbpsadbw512_mask:
        i = 2; l = 0; u = 255;
        break;
      case X86::BI__builtin_ia32_fixupimmpd512_mask:
      case X86::BI__builtin_ia32_fixupimmpd512_maskz:
      case X86::BI__builtin_ia32_fixupimmps512_mask:
      case X86::BI__builtin_ia32_fixupimmps512_maskz:
      case X86::BI__builtin_ia32_fixupimmsd_mask:
      case X86::BI__builtin_ia32_fixupimmsd_maskz:
      case X86::BI__builtin_ia32_fixupimmss_mask:
      case X86::BI__builtin_ia32_fixupimmss_maskz:
      case X86::BI__builtin_ia32_fixupimmpd128_mask:
      case X86::BI__builtin_ia32_fixupimmpd128_maskz:
      case X86::BI__builtin_ia32_fixupimmpd256_mask:
      case X86::BI__builtin_ia32_fixupimmpd256_maskz:
      case X86::BI__builtin_ia32_fixupimmps128_mask:
      case X86::BI__builtin_ia32_fixupimmps128_maskz:
      case X86::BI__builtin_ia32_fixupimmps256_mask:
      case X86::BI__builtin_ia32_fixupimmps256_maskz:
      case X86::BI__builtin_ia32_pternlogd512_mask:
      case X86::BI__builtin_ia32_pternlogd512_maskz:
      case X86::BI__builtin_ia32_pternlogq512_mask:
      case X86::BI__builtin_ia32_pternlogq512_maskz:
      case X86::BI__builtin_ia32_pternlogd128_mask:
      case X86::BI__builtin_ia32_pternlogd128_maskz:
      case X86::BI__builtin_ia32_pternlogd256_mask:
      case X86::BI__builtin_ia32_pternlogd256_maskz:
      case X86::BI__builtin_ia32_pternlogq128_mask:
      case X86::BI__builtin_ia32_pternlogq128_maskz:
      case X86::BI__builtin_ia32_pternlogq256_mask:
      case X86::BI__builtin_ia32_pternlogq256_maskz:
        i = 3; l = 0; u = 255;
        break;
      case X86::BI__builtin_ia32_pcmpestrm128:
      case X86::BI__builtin_ia32_pcmpestri128:
      case X86::BI__builtin_ia32_pcmpestria128:
      case X86::BI__builtin_ia32_pcmpestric128:
      case X86::BI__builtin_ia32_pcmpestrio128:
      case X86::BI__builtin_ia32_pcmpestris128:
      case X86::BI__builtin_ia32_pcmpestriz128:
        i = 4; l = -128; u = 255;
        break;
      case X86::BI__builtin_ia32_rndscalesd_round_mask:
      case X86::BI__builtin_ia32_rndscaless_round_mask:
        i = 4; l = 0; u = 255;
        break;
      }
      return SemaBuiltinConstantArgRange(TheCall, i, l, u);
    }
    
    /// Given a FunctionDecl's FormatAttr, attempts to populate the FomatStringInfo
    /// parameter with the FormatAttr's correct format_idx and firstDataArg.
    /// Returns true when the format fits the function and the FormatStringInfo has
    /// been populated.
    bool Sema::getFormatStringInfo(const FormatAttr *Format, bool IsCXXMember,
                                   FormatStringInfo *FSI) {
      FSI->HasVAListArg = Format->getFirstArg() == 0;
      FSI->FormatIdx = Format->getFormatIdx() - 1;
      FSI->FirstDataArg = FSI->HasVAListArg ? 0 : Format->getFirstArg() - 1;
    
      // The way the format attribute works in GCC, the implicit this argument
      // of member functions is counted. However, it doesn't appear in our own
      // lists, so decrement format_idx in that case.
      if (IsCXXMember) {
        if(FSI->FormatIdx == 0)
          return false;
        --FSI->FormatIdx;
        if (FSI->FirstDataArg != 0)
          --FSI->FirstDataArg;
      }
      return true;
    }
    
    /// Checks if a the given expression evaluates to null.
    ///
    /// \brief Returns true if the value evaluates to null.
    static bool CheckNonNullExpr(Sema &S, const Expr *Expr) {
      // If the expression has non-null type, it doesn't evaluate to null.
      if (auto nullability
            = Expr->IgnoreImplicit()->getType()->getNullability(S.Context)) {
        if (*nullability == NullabilityKind::NonNull)
          return false;
      }
    
      // As a special case, transparent unions initialized with zero are
      // considered null for the purposes of the nonnull attribute.
      if (const RecordType *UT = Expr->getType()->getAsUnionType()) {
        if (UT->getDecl()->hasAttr<TransparentUnionAttr>())
          if (const CompoundLiteralExpr *CLE =
              dyn_cast<CompoundLiteralExpr>(Expr))
            if (const InitListExpr *ILE =
                dyn_cast<InitListExpr>(CLE->getInitializer()))
              Expr = ILE->getInit(0);
      }
    
      bool Result;
      return (!Expr->isValueDependent() &&
              Expr->EvaluateAsBooleanCondition(Result, S.Context) &&
              !Result);
    }
    
    static void CheckNonNullArgument(Sema &S,
                                     const Expr *ArgExpr,
                                     SourceLocation CallSiteLoc) {
      if (CheckNonNullExpr(S, ArgExpr))
        S.DiagRuntimeBehavior(CallSiteLoc, ArgExpr,
               S.PDiag(diag::warn_null_arg) << ArgExpr->getSourceRange());
    }
    
    bool Sema::GetFormatNSStringIdx(const FormatAttr *Format, unsigned &Idx) {
      FormatStringInfo FSI;
      if ((GetFormatStringType(Format) == FST_NSString) &&
          getFormatStringInfo(Format, false, &FSI)) {
        Idx = FSI.FormatIdx;
        return true;
      }
      return false;
    }
    /// \brief Diagnose use of %s directive in an NSString which is being passed
    /// as formatting string to formatting method.
    static void
    DiagnoseCStringFormatDirectiveInCFAPI(Sema &S,
                                            const NamedDecl *FDecl,
                                            Expr **Args,
                                            unsigned NumArgs) {
      unsigned Idx = 0;
      bool Format = false;
      ObjCStringFormatFamily SFFamily = FDecl->getObjCFStringFormattingFamily();
      if (SFFamily == ObjCStringFormatFamily::SFF_CFString) {
        Idx = 2;
        Format = true;
      }
      else
        for (const auto *I : FDecl->specific_attrs<FormatAttr>()) {
          if (S.GetFormatNSStringIdx(I, Idx)) {
            Format = true;
            break;
          }
        }
      if (!Format || NumArgs <= Idx)
        return;
      const Expr *FormatExpr = Args[Idx];
      if (const CStyleCastExpr *CSCE = dyn_cast<CStyleCastExpr>(FormatExpr))
        FormatExpr = CSCE->getSubExpr();
      const StringLiteral *FormatString;
      if (const ObjCStringLiteral *OSL =
          dyn_cast<ObjCStringLiteral>(FormatExpr->IgnoreParenImpCasts()))
        FormatString = OSL->getString();
      else
        FormatString = dyn_cast<StringLiteral>(FormatExpr->IgnoreParenImpCasts());
      if (!FormatString)
        return;
      if (S.FormatStringHasSArg(FormatString)) {
        S.Diag(FormatExpr->getExprLoc(), diag::warn_objc_cdirective_format_string)
          << "%s" << 1 << 1;
        S.Diag(FDecl->getLocation(), diag::note_entity_declared_at)
          << FDecl->getDeclName();
      }
    }
    
    /// Determine whether the given type has a non-null nullability annotation.
    static bool isNonNullType(ASTContext &ctx, QualType type) {
      if (auto nullability = type->getNullability(ctx))
        return *nullability == NullabilityKind::NonNull;
         
      return false;
    }
    
    static void CheckNonNullArguments(Sema &S,
                                      const NamedDecl *FDecl,
                                      const FunctionProtoType *Proto,
                                      ArrayRef<const Expr *> Args,
                                      SourceLocation CallSiteLoc) {
      assert((FDecl || Proto) && "Need a function declaration or prototype");
    
      // Check the attributes attached to the method/function itself.
      llvm::SmallBitVector NonNullArgs;
      if (FDecl) {
        // Handle the nonnull attribute on the function/method declaration itself.
        for (const auto *NonNull : FDecl->specific_attrs<NonNullAttr>()) {
          if (!NonNull->args_size()) {
            // Easy case: all pointer arguments are nonnull.
            for (const auto *Arg : Args)
              if (S.isValidPointerAttrType(Arg->getType()))
                CheckNonNullArgument(S, Arg, CallSiteLoc);
            return;
          }
    
          for (unsigned Val : NonNull->args()) {
            if (Val >= Args.size())
              continue;
            if (NonNullArgs.empty())
              NonNullArgs.resize(Args.size());
            NonNullArgs.set(Val);
          }
        }
      }
    
      if (FDecl && (isa<FunctionDecl>(FDecl) || isa<ObjCMethodDecl>(FDecl))) {
        // Handle the nonnull attribute on the parameters of the
        // function/method.
        ArrayRef<ParmVarDecl*> parms;
        if (const FunctionDecl *FD = dyn_cast<FunctionDecl>(FDecl))
          parms = FD->parameters();
        else
          parms = cast<ObjCMethodDecl>(FDecl)->parameters();
        
        unsigned ParamIndex = 0;
        for (ArrayRef<ParmVarDecl*>::iterator I = parms.begin(), E = parms.end();
             I != E; ++I, ++ParamIndex) {
          const ParmVarDecl *PVD = *I;
          if (PVD->hasAttr<NonNullAttr>() || 
              isNonNullType(S.Context, PVD->getType())) {
            if (NonNullArgs.empty())
              NonNullArgs.resize(Args.size());
    
            NonNullArgs.set(ParamIndex);
          }
        }
      } else {
        // If we have a non-function, non-method declaration but no
        // function prototype, try to dig out the function prototype.
        if (!Proto) {
          if (const ValueDecl *VD = dyn_cast<ValueDecl>(FDecl)) {
            QualType type = VD->getType().getNonReferenceType();
            if (auto pointerType = type->getAs<PointerType>())
              type = pointerType->getPointeeType();
            else if (auto blockType = type->getAs<BlockPointerType>())
              type = blockType->getPointeeType();
            // FIXME: data member pointers?
    
            // Dig out the function prototype, if there is one.
            Proto = type->getAs<FunctionProtoType>();
          } 
        }
    
        // Fill in non-null argument information from the nullability
        // information on the parameter types (if we have them).
        if (Proto) {
          unsigned Index = 0;
          for (auto paramType : Proto->getParamTypes()) {
            if (isNonNullType(S.Context, paramType)) {
              if (NonNullArgs.empty())
                NonNullArgs.resize(Args.size());
              
              NonNullArgs.set(Index);
            }
            
            ++Index;
          }
        }
      }
    
      // Check for non-null arguments.
      for (unsigned ArgIndex = 0, ArgIndexEnd = NonNullArgs.size(); 
           ArgIndex != ArgIndexEnd; ++ArgIndex) {
        if (NonNullArgs[ArgIndex])
          CheckNonNullArgument(S, Args[ArgIndex], CallSiteLoc);
      }
    }
    
    /// Handles the checks for format strings, non-POD arguments to vararg
    /// functions, and NULL arguments passed to non-NULL parameters.
    void Sema::checkCall(NamedDecl *FDecl, const FunctionProtoType *Proto,
                         ArrayRef<const Expr *> Args, bool IsMemberFunction,
                         SourceLocation Loc, SourceRange Range,
                         VariadicCallType CallType) {
      // FIXME: We should check as much as we can in the template definition.
      if (CurContext->isDependentContext())
        return;
    
      // Printf and scanf checking.
      llvm::SmallBitVector CheckedVarArgs;
      if (FDecl) {
        for (const auto *I : FDecl->specific_attrs<FormatAttr>()) {
          // Only create vector if there are format attributes.
          CheckedVarArgs.resize(Args.size());
    
          CheckFormatArguments(I, Args, IsMemberFunction, CallType, Loc, Range,
                               CheckedVarArgs);
        }
      }
    
      // Refuse POD arguments that weren't caught by the format string
      // checks above.
      auto *FD = dyn_cast_or_null<FunctionDecl>(FDecl);
      if (CallType != VariadicDoesNotApply &&
          (!FD || FD->getBuiltinID() != Builtin::BI__noop)) {
        unsigned NumParams = Proto ? Proto->getNumParams()
                           : FDecl && isa<FunctionDecl>(FDecl)
                               ? cast<FunctionDecl>(FDecl)->getNumParams()
                           : FDecl && isa<ObjCMethodDecl>(FDecl)
                               ? cast<ObjCMethodDecl>(FDecl)->param_size()
                           : 0;
    
        for (unsigned ArgIdx = NumParams; ArgIdx < Args.size(); ++ArgIdx) {
          // Args[ArgIdx] can be null in malformed code.
          if (const Expr *Arg = Args[ArgIdx]) {
            if (CheckedVarArgs.empty() || !CheckedVarArgs[ArgIdx])
              checkVariadicArgument(Arg, CallType);
          }
        }
      }
    
      if (FDecl || Proto) {
        CheckNonNullArguments(*this, FDecl, Proto, Args, Loc);
    
        // Type safety checking.
        if (FDecl) {
          for (const auto *I : FDecl->specific_attrs<ArgumentWithTypeTagAttr>())
            CheckArgumentWithTypeTag(I, Args.data());
        }
      }
    }
    
    /// CheckConstructorCall - Check a constructor call for correctness and safety
    /// properties not enforced by the C type system.
    void Sema::CheckConstructorCall(FunctionDecl *FDecl,
                                    ArrayRef<const Expr *> Args,
                                    const FunctionProtoType *Proto,
                                    SourceLocation Loc) {
      VariadicCallType CallType =
        Proto->isVariadic() ? VariadicConstructor : VariadicDoesNotApply;
      checkCall(FDecl, Proto, Args, /*IsMemberFunction=*/true, Loc, SourceRange(), 
                CallType);
    }
    
    /// CheckFunctionCall - Check a direct function call for various correctness
    /// and safety properties not strictly enforced by the C type system.
    bool Sema::CheckFunctionCall(FunctionDecl *FDecl, CallExpr *TheCall,
                                 const FunctionProtoType *Proto) {
      bool IsMemberOperatorCall = isa<CXXOperatorCallExpr>(TheCall) &&
                                  isa<CXXMethodDecl>(FDecl);
      bool IsMemberFunction = isa<CXXMemberCallExpr>(TheCall) ||
                              IsMemberOperatorCall;
      VariadicCallType CallType = getVariadicCallType(FDecl, Proto,
                                                      TheCall->getCallee());
      Expr** Args = TheCall->getArgs();
      unsigned NumArgs = TheCall->getNumArgs();
      if (IsMemberOperatorCall) {
        // If this is a call to a member operator, hide the first argument
        // from checkCall.
        // FIXME: Our choice of AST representation here is less than ideal.
        ++Args;
        --NumArgs;
      }
      checkCall(FDecl, Proto, llvm::makeArrayRef(Args, NumArgs), 
                IsMemberFunction, TheCall->getRParenLoc(),
                TheCall->getCallee()->getSourceRange(), CallType);
    
      IdentifierInfo *FnInfo = FDecl->getIdentifier();
      // None of the checks below are needed for functions that don't have
      // simple names (e.g., C++ conversion functions).
      if (!FnInfo)
        return false;
    
      CheckAbsoluteValueFunction(TheCall, FDecl);
      CheckMaxUnsignedZero(TheCall, FDecl);
    
      if (getLangOpts().ObjC1)
        DiagnoseCStringFormatDirectiveInCFAPI(*this, FDecl, Args, NumArgs);
    
      unsigned CMId = FDecl->getMemoryFunctionKind();
      if (CMId == 0)
        return false;
    
      // Handle memory setting and copying functions.
      if (CMId == Builtin::BIstrlcpy || CMId == Builtin::BIstrlcat)
        CheckStrlcpycatArguments(TheCall, FnInfo);
      else if (CMId == Builtin::BIstrncat)
        CheckStrncatArguments(TheCall, FnInfo);
      else
        CheckMemaccessArguments(TheCall, CMId, FnInfo);
    
      return false;
    }
    
    bool Sema::CheckObjCMethodCall(ObjCMethodDecl *Method, SourceLocation lbrac, 
                                   ArrayRef<const Expr *> Args) {
      VariadicCallType CallType =
          Method->isVariadic() ? VariadicMethod : VariadicDoesNotApply;
    
      checkCall(Method, nullptr, Args,
                /*IsMemberFunction=*/false, lbrac, Method->getSourceRange(), 
                CallType);
    
      return false;
    }
    
    bool Sema::CheckPointerCall(NamedDecl *NDecl, CallExpr *TheCall,
                                const FunctionProtoType *Proto) {
      QualType Ty;
      if (const auto *V = dyn_cast<VarDecl>(NDecl))
        Ty = V->getType().getNonReferenceType();
      else if (const auto *F = dyn_cast<FieldDecl>(NDecl))
        Ty = F->getType().getNonReferenceType();
      else
        return false;
    
      if (!Ty->isBlockPointerType() && !Ty->isFunctionPointerType() &&
          !Ty->isFunctionProtoType())
        return false;
    
      VariadicCallType CallType;
      if (!Proto || !Proto->isVariadic()) {
        CallType = VariadicDoesNotApply;
      } else if (Ty->isBlockPointerType()) {
        CallType = VariadicBlock;
      } else { // Ty->isFunctionPointerType()
        CallType = VariadicFunction;
      }
    
      checkCall(NDecl, Proto,
                llvm::makeArrayRef(TheCall->getArgs(), TheCall->getNumArgs()),
                /*IsMemberFunction=*/false, TheCall->getRParenLoc(),
                TheCall->getCallee()->getSourceRange(), CallType);
    
      return false;
    }
    
    /// Checks function calls when a FunctionDecl or a NamedDecl is not available,
    /// such as function pointers returned from functions.
    bool Sema::CheckOtherCall(CallExpr *TheCall, const FunctionProtoType *Proto) {
      VariadicCallType CallType = getVariadicCallType(/*FDecl=*/nullptr, Proto,
                                                      TheCall->getCallee());
      checkCall(/*FDecl=*/nullptr, Proto,
                llvm::makeArrayRef(TheCall->getArgs(), TheCall->getNumArgs()),
                /*IsMemberFunction=*/false, TheCall->getRParenLoc(),
                TheCall->getCallee()->getSourceRange(), CallType);
    
      return false;
    }
    
    static bool isValidOrderingForOp(int64_t Ordering, AtomicExpr::AtomicOp Op) {
      if (!llvm::isValidAtomicOrderingCABI(Ordering))
        return false;
    
      auto OrderingCABI = (llvm::AtomicOrderingCABI)Ordering;
      switch (Op) {
      case AtomicExpr::AO__c11_atomic_init:
        llvm_unreachable("There is no ordering argument for an init");
    
      case AtomicExpr::AO__c11_atomic_load:
      case AtomicExpr::AO__atomic_load_n:
      case AtomicExpr::AO__atomic_load:
        return OrderingCABI != llvm::AtomicOrderingCABI::release &&
               OrderingCABI != llvm::AtomicOrderingCABI::acq_rel;
    
      case AtomicExpr::AO__c11_atomic_store:
      case AtomicExpr::AO__atomic_store:
      case AtomicExpr::AO__atomic_store_n:
        return OrderingCABI != llvm::AtomicOrderingCABI::consume &&
               OrderingCABI != llvm::AtomicOrderingCABI::acquire &&
               OrderingCABI != llvm::AtomicOrderingCABI::acq_rel;
    
      default:
        return true;
      }
    }
    
    ExprResult Sema::SemaAtomicOpsOverloaded(ExprResult TheCallResult,
                                             AtomicExpr::AtomicOp Op) {
      CallExpr *TheCall = cast<CallExpr>(TheCallResult.get());
      DeclRefExpr *DRE =cast<DeclRefExpr>(TheCall->getCallee()->IgnoreParenCasts());
    
      // All these operations take one of the following forms:
      enum {
        // C    __c11_atomic_init(A *, C)
        Init,
        // C    __c11_atomic_load(A *, int)
        Load,
        // void __atomic_load(A *, CP, int)
        LoadCopy,
        // void __atomic_store(A *, CP, int)
        Copy,
        // C    __c11_atomic_add(A *, M, int)
        Arithmetic,
        // C    __atomic_exchange_n(A *, CP, int)
        Xchg,
        // void __atomic_exchange(A *, C *, CP, int)
        GNUXchg,
        // bool __c11_atomic_compare_exchange_strong(A *, C *, CP, int, int)
        C11CmpXchg,
        // bool __atomic_compare_exchange(A *, C *, CP, bool, int, int)
        GNUCmpXchg
      } Form = Init;
      const unsigned NumArgs[] = { 2, 2, 3, 3, 3, 3, 4, 5, 6 };
      const unsigned NumVals[] = { 1, 0, 1, 1, 1, 1, 2, 2, 3 };
      // where:
      //   C is an appropriate type,
      //   A is volatile _Atomic(C) for __c11 builtins and is C for GNU builtins,
      //   CP is C for __c11 builtins and GNU _n builtins and is C * otherwise,
      //   M is C if C is an integer, and ptrdiff_t if C is a pointer, and
      //   the int parameters are for orderings.
    
      static_assert(AtomicExpr::AO__c11_atomic_init == 0 &&
                        AtomicExpr::AO__c11_atomic_fetch_xor + 1 ==
                            AtomicExpr::AO__atomic_load,
                    "need to update code for modified C11 atomics");
      bool IsC11 = Op >= AtomicExpr::AO__c11_atomic_init &&
                   Op <= AtomicExpr::AO__c11_atomic_fetch_xor;
      bool IsN = Op == AtomicExpr::AO__atomic_load_n ||
                 Op == AtomicExpr::AO__atomic_store_n ||
                 Op == AtomicExpr::AO__atomic_exchange_n ||
                 Op == AtomicExpr::AO__atomic_compare_exchange_n;
      bool IsAddSub = false;
    
      switch (Op) {
      case AtomicExpr::AO__c11_atomic_init:
        Form = Init;
        break;
    
      case AtomicExpr::AO__c11_atomic_load:
      case AtomicExpr::AO__atomic_load_n:
        Form = Load;
        break;
    
      case AtomicExpr::AO__atomic_load:
        Form = LoadCopy;
        break;
    
      case AtomicExpr::AO__c11_atomic_store:
      case AtomicExpr::AO__atomic_store:
      case AtomicExpr::AO__atomic_store_n:
        Form = Copy;
        break;
    
      case AtomicExpr::AO__c11_atomic_fetch_add:
      case AtomicExpr::AO__c11_atomic_fetch_sub:
      case AtomicExpr::AO__atomic_fetch_add:
      case AtomicExpr::AO__atomic_fetch_sub:
      case AtomicExpr::AO__atomic_add_fetch:
      case AtomicExpr::AO__atomic_sub_fetch:
        IsAddSub = true;
        // Fall through.
      case AtomicExpr::AO__c11_atomic_fetch_and:
      case AtomicExpr::AO__c11_atomic_fetch_or:
      case AtomicExpr::AO__c11_atomic_fetch_xor:
      case AtomicExpr::AO__atomic_fetch_and:
      case AtomicExpr::AO__atomic_fetch_or:
      case AtomicExpr::AO__atomic_fetch_xor:
      case AtomicExpr::AO__atomic_fetch_nand:
      case AtomicExpr::AO__atomic_and_fetch:
      case AtomicExpr::AO__atomic_or_fetch:
      case AtomicExpr::AO__atomic_xor_fetch:
      case AtomicExpr::AO__atomic_nand_fetch:
        Form = Arithmetic;
        break;
    
      case AtomicExpr::AO__c11_atomic_exchange:
      case AtomicExpr::AO__atomic_exchange_n:
        Form = Xchg;
        break;
    
      case AtomicExpr::AO__atomic_exchange:
        Form = GNUXchg;
        break;
    
      case AtomicExpr::AO__c11_atomic_compare_exchange_strong:
      case AtomicExpr::AO__c11_atomic_compare_exchange_weak:
        Form = C11CmpXchg;
        break;
    
      case AtomicExpr::AO__atomic_compare_exchange:
      case AtomicExpr::AO__atomic_compare_exchange_n:
        Form = GNUCmpXchg;
        break;
      }
    
      // Check we have the right number of arguments.
      if (TheCall->getNumArgs() < NumArgs[Form]) {
        Diag(TheCall->getLocEnd(), diag::err_typecheck_call_too_few_args)
          << 0 << NumArgs[Form] << TheCall->getNumArgs()
          << TheCall->getCallee()->getSourceRange();
        return ExprError();
      } else if (TheCall->getNumArgs() > NumArgs[Form]) {
        Diag(TheCall->getArg(NumArgs[Form])->getLocStart(),
             diag::err_typecheck_call_too_many_args)
          << 0 << NumArgs[Form] << TheCall->getNumArgs()
          << TheCall->getCallee()->getSourceRange();
        return ExprError();
      }
    
      // Inspect the first argument of the atomic operation.
      Expr *Ptr = TheCall->getArg(0);
      ExprResult ConvertedPtr = DefaultFunctionArrayLvalueConversion(Ptr);
      if (ConvertedPtr.isInvalid())
        return ExprError();
    
      Ptr = ConvertedPtr.get();
      const PointerType *pointerType = Ptr->getType()->getAs<PointerType>();
      if (!pointerType) {
        Diag(DRE->getLocStart(), diag::err_atomic_builtin_must_be_pointer)
          << Ptr->getType() << Ptr->getSourceRange();
        return ExprError();
      }
    
      // For a __c11 builtin, this should be a pointer to an _Atomic type.
      QualType AtomTy = pointerType->getPointeeType(); // 'A'
      QualType ValType = AtomTy; // 'C'
      if (IsC11) {
        if (!AtomTy->isAtomicType()) {
          Diag(DRE->getLocStart(), diag::err_atomic_op_needs_atomic)
            << Ptr->getType() << Ptr->getSourceRange();
          return ExprError();
        }
        if (AtomTy.isConstQualified()) {
          Diag(DRE->getLocStart(), diag::err_atomic_op_needs_non_const_atomic)
            << Ptr->getType() << Ptr->getSourceRange();
          return ExprError();
        }
        ValType = AtomTy->getAs<AtomicType>()->getValueType();
      } else if (Form != Load && Form != LoadCopy) {
        if (ValType.isConstQualified()) {
          Diag(DRE->getLocStart(), diag::err_atomic_op_needs_non_const_pointer)
            << Ptr->getType() << Ptr->getSourceRange();
          return ExprError();
        }
      }
    
      // For an arithmetic operation, the implied arithmetic must be well-formed.
      if (Form == Arithmetic) {
        // gcc does not enforce these rules for GNU atomics, but we do so for sanity.
        if (IsAddSub && !ValType->isIntegerType() && !ValType->isPointerType()) {
          Diag(DRE->getLocStart(), diag::err_atomic_op_needs_atomic_int_or_ptr)
            << IsC11 << Ptr->getType() << Ptr->getSourceRange();
          return ExprError();
        }
        if (!IsAddSub && !ValType->isIntegerType()) {
          Diag(DRE->getLocStart(), diag::err_atomic_op_bitwise_needs_atomic_int)
            << IsC11 << Ptr->getType() << Ptr->getSourceRange();
          return ExprError();
        }
        if (IsC11 && ValType->isPointerType() &&
            RequireCompleteType(Ptr->getLocStart(), ValType->getPointeeType(),
                                diag::err_incomplete_type)) {
          return ExprError();
        }
      } else if (IsN && !ValType->isIntegerType() && !ValType->isPointerType()) {
        // For __atomic_*_n operations, the value type must be a scalar integral or
        // pointer type which is 1, 2, 4, 8 or 16 bytes in length.
        Diag(DRE->getLocStart(), diag::err_atomic_op_needs_atomic_int_or_ptr)
          << IsC11 << Ptr->getType() << Ptr->getSourceRange();
        return ExprError();
      }
    
      if (!IsC11 && !AtomTy.isTriviallyCopyableType(Context) &&
          !AtomTy->isScalarType()) {
        // For GNU atomics, require a trivially-copyable type. This is not part of
        // the GNU atomics specification, but we enforce it for sanity.
        Diag(DRE->getLocStart(), diag::err_atomic_op_needs_trivial_copy)
          << Ptr->getType() << Ptr->getSourceRange();
        return ExprError();
      }
    
      switch (ValType.getObjCLifetime()) {
      case Qualifiers::OCL_None:
      case Qualifiers::OCL_ExplicitNone:
        // okay
        break;
    
      case Qualifiers::OCL_Weak:
      case Qualifiers::OCL_Strong:
      case Qualifiers::OCL_Autoreleasing:
        // FIXME: Can this happen? By this point, ValType should be known
        // to be trivially copyable.
        Diag(DRE->getLocStart(), diag::err_arc_atomic_ownership)
          << ValType << Ptr->getSourceRange();
        return ExprError();
      }
    
      // atomic_fetch_or takes a pointer to a volatile 'A'.  We shouldn't let the
      // volatile-ness of the pointee-type inject itself into the result or the
      // other operands. Similarly atomic_load can take a pointer to a const 'A'.
      ValType.removeLocalVolatile();
      ValType.removeLocalConst();
      QualType ResultType = ValType;
      if (Form == Copy || Form == LoadCopy || Form == GNUXchg || Form == Init)
        ResultType = Context.VoidTy;
      else if (Form == C11CmpXchg || Form == GNUCmpXchg)
        ResultType = Context.BoolTy;
    
      // The type of a parameter passed 'by value'. In the GNU atomics, such
      // arguments are actually passed as pointers.
      QualType ByValType = ValType; // 'CP'
      if (!IsC11 && !IsN)
        ByValType = Ptr->getType();
    
      // The first argument --- the pointer --- has a fixed type; we
      // deduce the types of the rest of the arguments accordingly.  Walk
      // the remaining arguments, converting them to the deduced value type.
      for (unsigned i = 1; i != NumArgs[Form]; ++i) {
        QualType Ty;
        if (i < NumVals[Form] + 1) {
          switch (i) {
          case 1:
            // The second argument is the non-atomic operand. For arithmetic, this
            // is always passed by value, and for a compare_exchange it is always
            // passed by address. For the rest, GNU uses by-address and C11 uses
            // by-value.
            assert(Form != Load);
            if (Form == Init || (Form == Arithmetic && ValType->isIntegerType()))
              Ty = ValType;
            else if (Form == Copy || Form == Xchg)
              Ty = ByValType;
            else if (Form == Arithmetic)
              Ty = Context.getPointerDiffType();
            else {
              Expr *ValArg = TheCall->getArg(i);
              // Treat this argument as _Nonnull as we want to show a warning if
              // NULL is passed into it.
              CheckNonNullArgument(*this, ValArg, DRE->getLocStart());
              unsigned AS = 0;
              // Keep address space of non-atomic pointer type.
              if (const PointerType *PtrTy =
                      ValArg->getType()->getAs<PointerType>()) {
                AS = PtrTy->getPointeeType().getAddressSpace();
              }
              Ty = Context.getPointerType(
                  Context.getAddrSpaceQualType(ValType.getUnqualifiedType(), AS));
            }
            break;
          case 2:
            // The third argument to compare_exchange / GNU exchange is a
            // (pointer to a) desired value.
            Ty = ByValType;
            break;
          case 3:
            // The fourth argument to GNU compare_exchange is a 'weak' flag.
            Ty = Context.BoolTy;
            break;
          }
        } else {
          // The order(s) are always converted to int.
          Ty = Context.IntTy;
        }
    
        InitializedEntity Entity =
            InitializedEntity::InitializeParameter(Context, Ty, false);
        ExprResult Arg = TheCall->getArg(i);
        Arg = PerformCopyInitialization(Entity, SourceLocation(), Arg);
        if (Arg.isInvalid())
          return true;
        TheCall->setArg(i, Arg.get());
      }
    
      // Permute the arguments into a 'consistent' order.
      SmallVector<Expr*, 5> SubExprs;
      SubExprs.push_back(Ptr);
      switch (Form) {
      case Init:
        // Note, AtomicExpr::getVal1() has a special case for this atomic.
        SubExprs.push_back(TheCall->getArg(1)); // Val1
        break;
      case Load:
        SubExprs.push_back(TheCall->getArg(1)); // Order
        break;
      case LoadCopy:
      case Copy:
      case Arithmetic:
      case Xchg:
        SubExprs.push_back(TheCall->getArg(2)); // Order
        SubExprs.push_back(TheCall->getArg(1)); // Val1
        break;
      case GNUXchg:
        // Note, AtomicExpr::getVal2() has a special case for this atomic.
        SubExprs.push_back(TheCall->getArg(3)); // Order
        SubExprs.push_back(TheCall->getArg(1)); // Val1
        SubExprs.push_back(TheCall->getArg(2)); // Val2
        break;
      case C11CmpXchg:
        SubExprs.push_back(TheCall->getArg(3)); // Order
        SubExprs.push_back(TheCall->getArg(1)); // Val1
        SubExprs.push_back(TheCall->getArg(4)); // OrderFail
        SubExprs.push_back(TheCall->getArg(2)); // Val2
        break;
      case GNUCmpXchg:
        SubExprs.push_back(TheCall->getArg(4)); // Order
        SubExprs.push_back(TheCall->getArg(1)); // Val1
        SubExprs.push_back(TheCall->getArg(5)); // OrderFail
        SubExprs.push_back(TheCall->getArg(2)); // Val2
        SubExprs.push_back(TheCall->getArg(3)); // Weak
        break;
      }
    
      if (SubExprs.size() >= 2 && Form != Init) {
        llvm::APSInt Result(32);
        if (SubExprs[1]->isIntegerConstantExpr(Result, Context) &&
            !isValidOrderingForOp(Result.getSExtValue(), Op))
          Diag(SubExprs[1]->getLocStart(),
               diag::warn_atomic_op_has_invalid_memory_order)
              << SubExprs[1]->getSourceRange();
      }
    
      AtomicExpr *AE = new (Context) AtomicExpr(TheCall->getCallee()->getLocStart(),
                                                SubExprs, ResultType, Op,
                                                TheCall->getRParenLoc());
      
      if ((Op == AtomicExpr::AO__c11_atomic_load ||
           (Op == AtomicExpr::AO__c11_atomic_store)) &&
          Context.AtomicUsesUnsupportedLibcall(AE))
        Diag(AE->getLocStart(), diag::err_atomic_load_store_uses_lib) <<
        ((Op == AtomicExpr::AO__c11_atomic_load) ? 0 : 1);
    
      return AE;
    }
    
    /// checkBuiltinArgument - Given a call to a builtin function, perform
    /// normal type-checking on the given argument, updating the call in
    /// place.  This is useful when a builtin function requires custom
    /// type-checking for some of its arguments but not necessarily all of
    /// them.
    ///
    /// Returns true on error.
    static bool checkBuiltinArgument(Sema &S, CallExpr *E, unsigned ArgIndex) {
      FunctionDecl *Fn = E->getDirectCallee();
      assert(Fn && "builtin call without direct callee!");
    
      ParmVarDecl *Param = Fn->getParamDecl(ArgIndex);
      InitializedEntity Entity =
        InitializedEntity::InitializeParameter(S.Context, Param);
    
      ExprResult Arg = E->getArg(0);
      Arg = S.PerformCopyInitialization(Entity, SourceLocation(), Arg);
      if (Arg.isInvalid())
        return true;
    
      E->setArg(ArgIndex, Arg.get());
      return false;
    }
    
    /// SemaBuiltinAtomicOverloaded - We have a call to a function like
    /// __sync_fetch_and_add, which is an overloaded function based on the pointer
    /// type of its first argument.  The main ActOnCallExpr routines have already
    /// promoted the types of arguments because all of these calls are prototyped as
    /// void(...).
    ///
    /// This function goes through and does final semantic checking for these
    /// builtins,
    ExprResult
    Sema::SemaBuiltinAtomicOverloaded(ExprResult TheCallResult) {
      CallExpr *TheCall = (CallExpr *)TheCallResult.get();
      DeclRefExpr *DRE =cast<DeclRefExpr>(TheCall->getCallee()->IgnoreParenCasts());
      FunctionDecl *FDecl = cast<FunctionDecl>(DRE->getDecl());
    
      // Ensure that we have at least one argument to do type inference from.
      if (TheCall->getNumArgs() < 1) {
        Diag(TheCall->getLocEnd(), diag::err_typecheck_call_too_few_args_at_least)
          << 0 << 1 << TheCall->getNumArgs()
          << TheCall->getCallee()->getSourceRange();
        return ExprError();
      }
    
      // Inspect the first argument of the atomic builtin.  This should always be
      // a pointer type, whose element is an integral scalar or pointer type.
      // Because it is a pointer type, we don't have to worry about any implicit
      // casts here.
      // FIXME: We don't allow floating point scalars as input.
      Expr *FirstArg = TheCall->getArg(0);
      ExprResult FirstArgResult = DefaultFunctionArrayLvalueConversion(FirstArg);
      if (FirstArgResult.isInvalid())
        return ExprError();
      FirstArg = FirstArgResult.get();
      TheCall->setArg(0, FirstArg);
    
      const PointerType *pointerType = FirstArg->getType()->getAs<PointerType>();
      if (!pointerType) {
        Diag(DRE->getLocStart(), diag::err_atomic_builtin_must_be_pointer)
          << FirstArg->getType() << FirstArg->getSourceRange();
        return ExprError();
      }
    
      QualType ValType = pointerType->getPointeeType();
      if (!ValType->isIntegerType() && !ValType->isAnyPointerType() &&
          !ValType->isBlockPointerType()) {
        Diag(DRE->getLocStart(), diag::err_atomic_builtin_must_be_pointer_intptr)
          << FirstArg->getType() << FirstArg->getSourceRange();
        return ExprError();
      }
    
      switch (ValType.getObjCLifetime()) {
      case Qualifiers::OCL_None:
      case Qualifiers::OCL_ExplicitNone:
        // okay
        break;
    
      case Qualifiers::OCL_Weak:
      case Qualifiers::OCL_Strong:
      case Qualifiers::OCL_Autoreleasing:
        Diag(DRE->getLocStart(), diag::err_arc_atomic_ownership)
          << ValType << FirstArg->getSourceRange();
        return ExprError();
      }
    
      // Strip any qualifiers off ValType.
      ValType = ValType.getUnqualifiedType();
    
      // The majority of builtins return a value, but a few have special return
      // types, so allow them to override appropriately below.
      QualType ResultType = ValType;
    
      // We need to figure out which concrete builtin this maps onto.  For example,
      // __sync_fetch_and_add with a 2 byte object turns into
      // __sync_fetch_and_add_2.
    #define BUILTIN_ROW(x) \
      { Builtin::BI##x##_1, Builtin::BI##x##_2, Builtin::BI##x##_4, \
        Builtin::BI##x##_8, Builtin::BI##x##_16 }
    
      static const unsigned BuiltinIndices[][5] = {
        BUILTIN_ROW(__sync_fetch_and_add),
        BUILTIN_ROW(__sync_fetch_and_sub),
        BUILTIN_ROW(__sync_fetch_and_or),
        BUILTIN_ROW(__sync_fetch_and_and),
        BUILTIN_ROW(__sync_fetch_and_xor),
        BUILTIN_ROW(__sync_fetch_and_nand),
    
        BUILTIN_ROW(__sync_add_and_fetch),
        BUILTIN_ROW(__sync_sub_and_fetch),
        BUILTIN_ROW(__sync_and_and_fetch),
        BUILTIN_ROW(__sync_or_and_fetch),
        BUILTIN_ROW(__sync_xor_and_fetch),
        BUILTIN_ROW(__sync_nand_and_fetch),
    
        BUILTIN_ROW(__sync_val_compare_and_swap),
        BUILTIN_ROW(__sync_bool_compare_and_swap),
        BUILTIN_ROW(__sync_lock_test_and_set),
        BUILTIN_ROW(__sync_lock_release),
        BUILTIN_ROW(__sync_swap)
      };
    #undef BUILTIN_ROW
    
      // Determine the index of the size.
      unsigned SizeIndex;
      switch (Context.getTypeSizeInChars(ValType).getQuantity()) {
      case 1: SizeIndex = 0; break;
      case 2: SizeIndex = 1; break;
      case 4: SizeIndex = 2; break;
      case 8: SizeIndex = 3; break;
      case 16: SizeIndex = 4; break;
      default:
        Diag(DRE->getLocStart(), diag::err_atomic_builtin_pointer_size)
          << FirstArg->getType() << FirstArg->getSourceRange();
        return ExprError();
      }
    
      // Each of these builtins has one pointer argument, followed by some number of
      // values (0, 1 or 2) followed by a potentially empty varags list of stuff
      // that we ignore.  Find out which row of BuiltinIndices to read from as well
      // as the number of fixed args.
      unsigned BuiltinID = FDecl->getBuiltinID();
      unsigned BuiltinIndex, NumFixed = 1;
      bool WarnAboutSemanticsChange = false;
      switch (BuiltinID) {
      default: llvm_unreachable("Unknown overloaded atomic builtin!");
      case Builtin::BI__sync_fetch_and_add: 
      case Builtin::BI__sync_fetch_and_add_1:
      case Builtin::BI__sync_fetch_and_add_2:
      case Builtin::BI__sync_fetch_and_add_4:
      case Builtin::BI__sync_fetch_and_add_8:
      case Builtin::BI__sync_fetch_and_add_16:
        BuiltinIndex = 0; 
        break;
          
      case Builtin::BI__sync_fetch_and_sub: 
      case Builtin::BI__sync_fetch_and_sub_1:
      case Builtin::BI__sync_fetch_and_sub_2:
      case Builtin::BI__sync_fetch_and_sub_4:
      case Builtin::BI__sync_fetch_and_sub_8:
      case Builtin::BI__sync_fetch_and_sub_16:
        BuiltinIndex = 1; 
        break;
          
      case Builtin::BI__sync_fetch_and_or:  
      case Builtin::BI__sync_fetch_and_or_1:
      case Builtin::BI__sync_fetch_and_or_2:
      case Builtin::BI__sync_fetch_and_or_4:
      case Builtin::BI__sync_fetch_and_or_8:
      case Builtin::BI__sync_fetch_and_or_16:
        BuiltinIndex = 2; 
        break;
          
      case Builtin::BI__sync_fetch_and_and: 
      case Builtin::BI__sync_fetch_and_and_1:
      case Builtin::BI__sync_fetch_and_and_2:
      case Builtin::BI__sync_fetch_and_and_4:
      case Builtin::BI__sync_fetch_and_and_8:
      case Builtin::BI__sync_fetch_and_and_16:
        BuiltinIndex = 3; 
        break;
    
      case Builtin::BI__sync_fetch_and_xor: 
      case Builtin::BI__sync_fetch_and_xor_1:
      case Builtin::BI__sync_fetch_and_xor_2:
      case Builtin::BI__sync_fetch_and_xor_4:
      case Builtin::BI__sync_fetch_and_xor_8:
      case Builtin::BI__sync_fetch_and_xor_16:
        BuiltinIndex = 4; 
        break;
    
      case Builtin::BI__sync_fetch_and_nand: 
      case Builtin::BI__sync_fetch_and_nand_1:
      case Builtin::BI__sync_fetch_and_nand_2:
      case Builtin::BI__sync_fetch_and_nand_4:
      case Builtin::BI__sync_fetch_and_nand_8:
      case Builtin::BI__sync_fetch_and_nand_16:
        BuiltinIndex = 5;
        WarnAboutSemanticsChange = true;
        break;
    
      case Builtin::BI__sync_add_and_fetch: 
      case Builtin::BI__sync_add_and_fetch_1:
      case Builtin::BI__sync_add_and_fetch_2:
      case Builtin::BI__sync_add_and_fetch_4:
      case Builtin::BI__sync_add_and_fetch_8:
      case Builtin::BI__sync_add_and_fetch_16:
        BuiltinIndex = 6; 
        break;
          
      case Builtin::BI__sync_sub_and_fetch: 
      case Builtin::BI__sync_sub_and_fetch_1:
      case Builtin::BI__sync_sub_and_fetch_2:
      case Builtin::BI__sync_sub_and_fetch_4:
      case Builtin::BI__sync_sub_and_fetch_8:
      case Builtin::BI__sync_sub_and_fetch_16:
        BuiltinIndex = 7; 
        break;
          
      case Builtin::BI__sync_and_and_fetch: 
      case Builtin::BI__sync_and_and_fetch_1:
      case Builtin::BI__sync_and_and_fetch_2:
      case Builtin::BI__sync_and_and_fetch_4:
      case Builtin::BI__sync_and_and_fetch_8:
      case Builtin::BI__sync_and_and_fetch_16:
        BuiltinIndex = 8; 
        break;
          
      case Builtin::BI__sync_or_and_fetch:  
      case Builtin::BI__sync_or_and_fetch_1:
      case Builtin::BI__sync_or_and_fetch_2:
      case Builtin::BI__sync_or_and_fetch_4:
      case Builtin::BI__sync_or_and_fetch_8:
      case Builtin::BI__sync_or_and_fetch_16:
        BuiltinIndex = 9; 
        break;
          
      case Builtin::BI__sync_xor_and_fetch: 
      case Builtin::BI__sync_xor_and_fetch_1:
      case Builtin::BI__sync_xor_and_fetch_2:
      case Builtin::BI__sync_xor_and_fetch_4:
      case Builtin::BI__sync_xor_and_fetch_8:
      case Builtin::BI__sync_xor_and_fetch_16:
        BuiltinIndex = 10;
        break;
    
      case Builtin::BI__sync_nand_and_fetch: 
      case Builtin::BI__sync_nand_and_fetch_1:
      case Builtin::BI__sync_nand_and_fetch_2:
      case Builtin::BI__sync_nand_and_fetch_4:
      case Builtin::BI__sync_nand_and_fetch_8:
      case Builtin::BI__sync_nand_and_fetch_16:
        BuiltinIndex = 11;
        WarnAboutSemanticsChange = true;
        break;
    
      case Builtin::BI__sync_val_compare_and_swap:
      case Builtin::BI__sync_val_compare_and_swap_1:
      case Builtin::BI__sync_val_compare_and_swap_2:
      case Builtin::BI__sync_val_compare_and_swap_4:
      case Builtin::BI__sync_val_compare_and_swap_8:
      case Builtin::BI__sync_val_compare_and_swap_16:
        BuiltinIndex = 12;
        NumFixed = 2;
        break;
          
      case Builtin::BI__sync_bool_compare_and_swap:
      case Builtin::BI__sync_bool_compare_and_swap_1:
      case Builtin::BI__sync_bool_compare_and_swap_2:
      case Builtin::BI__sync_bool_compare_and_swap_4:
      case Builtin::BI__sync_bool_compare_and_swap_8:
      case Builtin::BI__sync_bool_compare_and_swap_16:
        BuiltinIndex = 13;
        NumFixed = 2;
        ResultType = Context.BoolTy;
        break;
          
      case Builtin::BI__sync_lock_test_and_set: 
      case Builtin::BI__sync_lock_test_and_set_1:
      case Builtin::BI__sync_lock_test_and_set_2:
      case Builtin::BI__sync_lock_test_and_set_4:
      case Builtin::BI__sync_lock_test_and_set_8:
      case Builtin::BI__sync_lock_test_and_set_16:
        BuiltinIndex = 14; 
        break;
          
      case Builtin::BI__sync_lock_release:
      case Builtin::BI__sync_lock_release_1:
      case Builtin::BI__sync_lock_release_2:
      case Builtin::BI__sync_lock_release_4:
      case Builtin::BI__sync_lock_release_8:
      case Builtin::BI__sync_lock_release_16:
        BuiltinIndex = 15;
        NumFixed = 0;
        ResultType = Context.VoidTy;
        break;
          
      case Builtin::BI__sync_swap: 
      case Builtin::BI__sync_swap_1:
      case Builtin::BI__sync_swap_2:
      case Builtin::BI__sync_swap_4:
      case Builtin::BI__sync_swap_8:
      case Builtin::BI__sync_swap_16:
        BuiltinIndex = 16; 
        break;
      }
    
      // Now that we know how many fixed arguments we expect, first check that we
      // have at least that many.
      if (TheCall->getNumArgs() < 1+NumFixed) {
        Diag(TheCall->getLocEnd(), diag::err_typecheck_call_too_few_args_at_least)
          << 0 << 1+NumFixed << TheCall->getNumArgs()
          << TheCall->getCallee()->getSourceRange();
        return ExprError();
      }
    
      if (WarnAboutSemanticsChange) {
        Diag(TheCall->getLocEnd(), diag::warn_sync_fetch_and_nand_semantics_change)
          << TheCall->getCallee()->getSourceRange();
      }
    
      // Get the decl for the concrete builtin from this, we can tell what the
      // concrete integer type we should convert to is.
      unsigned NewBuiltinID = BuiltinIndices[BuiltinIndex][SizeIndex];
      const char *NewBuiltinName = Context.BuiltinInfo.getName(NewBuiltinID);
      FunctionDecl *NewBuiltinDecl;
      if (NewBuiltinID == BuiltinID)
        NewBuiltinDecl = FDecl;
      else {
        // Perform builtin lookup to avoid redeclaring it.
        DeclarationName DN(&Context.Idents.get(NewBuiltinName));
        LookupResult Res(*this, DN, DRE->getLocStart(), LookupOrdinaryName);
        LookupName(Res, TUScope, /*AllowBuiltinCreation=*/true);
        assert(Res.getFoundDecl());
        NewBuiltinDecl = dyn_cast<FunctionDecl>(Res.getFoundDecl());
        if (!NewBuiltinDecl)
          return ExprError();
      }
    
      // The first argument --- the pointer --- has a fixed type; we
      // deduce the types of the rest of the arguments accordingly.  Walk
      // the remaining arguments, converting them to the deduced value type.
      for (unsigned i = 0; i != NumFixed; ++i) {
        ExprResult Arg = TheCall->getArg(i+1);
    
        // GCC does an implicit conversion to the pointer or integer ValType.  This
        // can fail in some cases (1i -> int**), check for this error case now.
        // Initialize the argument.
        InitializedEntity Entity = InitializedEntity::InitializeParameter(Context,
                                                       ValType, /*consume*/ false);
        Arg = PerformCopyInitialization(Entity, SourceLocation(), Arg);
        if (Arg.isInvalid())
          return ExprError();
    
        // Okay, we have something that *can* be converted to the right type.  Check
        // to see if there is a potentially weird extension going on here.  This can
        // happen when you do an atomic operation on something like an char* and
        // pass in 42.  The 42 gets converted to char.  This is even more strange
        // for things like 45.123 -> char, etc.
        // FIXME: Do this check.
        TheCall->setArg(i+1, Arg.get());
      }
    
      ASTContext& Context = this->getASTContext();
    
      // Create a new DeclRefExpr to refer to the new decl.
      DeclRefExpr* NewDRE = DeclRefExpr::Create(
          Context,
          DRE->getQualifierLoc(),
          SourceLocation(),
          NewBuiltinDecl,
          /*enclosing*/ false,
          DRE->getLocation(),
          Context.BuiltinFnTy,
          DRE->getValueKind());
    
      // Set the callee in the CallExpr.
      // FIXME: This loses syntactic information.
      QualType CalleePtrTy = Context.getPointerType(NewBuiltinDecl->getType());
      ExprResult PromotedCall = ImpCastExprToType(NewDRE, CalleePtrTy,
                                                  CK_BuiltinFnToFnPtr);
      TheCall->setCallee(PromotedCall.get());
    
      // Change the result type of the call to match the original value type. This
      // is arbitrary, but the codegen for these builtins ins design to handle it
      // gracefully.
      TheCall->setType(ResultType);
    
      return TheCallResult;
    }
    
    /// SemaBuiltinNontemporalOverloaded - We have a call to
    /// __builtin_nontemporal_store or __builtin_nontemporal_load, which is an
    /// overloaded function based on the pointer type of its last argument.
    ///
    /// This function goes through and does final semantic checking for these
    /// builtins.
    ExprResult Sema::SemaBuiltinNontemporalOverloaded(ExprResult TheCallResult) {
      CallExpr *TheCall = (CallExpr *)TheCallResult.get();
      DeclRefExpr *DRE =
          cast<DeclRefExpr>(TheCall->getCallee()->IgnoreParenCasts());
      FunctionDecl *FDecl = cast<FunctionDecl>(DRE->getDecl());
      unsigned BuiltinID = FDecl->getBuiltinID();
      assert((BuiltinID == Builtin::BI__builtin_nontemporal_store ||
              BuiltinID == Builtin::BI__builtin_nontemporal_load) &&
             "Unexpected nontemporal load/store builtin!");
      bool isStore = BuiltinID == Builtin::BI__builtin_nontemporal_store;
      unsigned numArgs = isStore ? 2 : 1;
    
      // Ensure that we have the proper number of arguments.
      if (checkArgCount(*this, TheCall, numArgs))
        return ExprError();
    
      // Inspect the last argument of the nontemporal builtin.  This should always
      // be a pointer type, from which we imply the type of the memory access.
      // Because it is a pointer type, we don't have to worry about any implicit
      // casts here.
      Expr *PointerArg = TheCall->getArg(numArgs - 1);
      ExprResult PointerArgResult =
          DefaultFunctionArrayLvalueConversion(PointerArg);
    
      if (PointerArgResult.isInvalid())
        return ExprError();
      PointerArg = PointerArgResult.get();
      TheCall->setArg(numArgs - 1, PointerArg);
    
      const PointerType *pointerType = PointerArg->getType()->getAs<PointerType>();
      if (!pointerType) {
        Diag(DRE->getLocStart(), diag::err_nontemporal_builtin_must_be_pointer)
            << PointerArg->getType() << PointerArg->getSourceRange();
        return ExprError();
      }
    
      QualType ValType = pointerType->getPointeeType();
    
      // Strip any qualifiers off ValType.
      ValType = ValType.getUnqualifiedType();
      if (!ValType->isIntegerType() && !ValType->isAnyPointerType() &&
          !ValType->isBlockPointerType() && !ValType->isFloatingType() &&
          !ValType->isVectorType()) {
        Diag(DRE->getLocStart(),
             diag::err_nontemporal_builtin_must_be_pointer_intfltptr_or_vector)
            << PointerArg->getType() << PointerArg->getSourceRange();
        return ExprError();
      }
    
      if (!isStore) {
        TheCall->setType(ValType);
        return TheCallResult;
      }
    
      ExprResult ValArg = TheCall->getArg(0);
      InitializedEntity Entity = InitializedEntity::InitializeParameter(
          Context, ValType, /*consume*/ false);
      ValArg = PerformCopyInitialization(Entity, SourceLocation(), ValArg);
      if (ValArg.isInvalid())
        return ExprError();
    
      TheCall->setArg(0, ValArg.get());
      TheCall->setType(Context.VoidTy);
      return TheCallResult;
    }
    
    /// CheckObjCString - Checks that the argument to the builtin
    /// CFString constructor is correct
    /// Note: It might also make sense to do the UTF-16 conversion here (would
    /// simplify the backend).
    bool Sema::CheckObjCString(Expr *Arg) {
      Arg = Arg->IgnoreParenCasts();
      StringLiteral *Literal = dyn_cast<StringLiteral>(Arg);
    
      if (!Literal || !Literal->isAscii()) {
        Diag(Arg->getLocStart(), diag::err_cfstring_literal_not_string_constant)
          << Arg->getSourceRange();
        return true;
      }
    
      if (Literal->containsNonAsciiOrNull()) {
        StringRef String = Literal->getString();
        unsigned NumBytes = String.size();
        SmallVector<llvm::UTF16, 128> ToBuf(NumBytes);
        const llvm::UTF8 *FromPtr = (const llvm::UTF8 *)String.data();
        llvm::UTF16 *ToPtr = &ToBuf[0];
    
        llvm::ConversionResult Result =
            llvm::ConvertUTF8toUTF16(&FromPtr, FromPtr + NumBytes, &ToPtr,
                                     ToPtr + NumBytes, llvm::strictConversion);
        // Check for conversion failure.
        if (Result != llvm::conversionOK)
          Diag(Arg->getLocStart(),
               diag::warn_cfstring_truncated) << Arg->getSourceRange();
      }
      return false;
    }
    
    /// CheckObjCString - Checks that the format string argument to the os_log()
    /// and os_trace() functions is correct, and converts it to const char *.
    ExprResult Sema::CheckOSLogFormatStringArg(Expr *Arg) {
      Arg = Arg->IgnoreParenCasts();
      auto *Literal = dyn_cast<StringLiteral>(Arg);
      if (!Literal) {
        if (auto *ObjcLiteral = dyn_cast<ObjCStringLiteral>(Arg)) {
          Literal = ObjcLiteral->getString();
        }
      }
    
      if (!Literal || (!Literal->isAscii() && !Literal->isUTF8())) {
        return ExprError(
            Diag(Arg->getLocStart(), diag::err_os_log_format_not_string_constant)
            << Arg->getSourceRange());
      }
    
      ExprResult Result(Literal);
      QualType ResultTy = Context.getPointerType(Context.CharTy.withConst());
      InitializedEntity Entity =
          InitializedEntity::InitializeParameter(Context, ResultTy, false);
      Result = PerformCopyInitialization(Entity, SourceLocation(), Result);
      return Result;
    }
    
    /// Check the arguments to '__builtin_va_start' or '__builtin_ms_va_start'
    /// for validity.  Emit an error and return true on failure; return false
    /// on success.
    bool Sema::SemaBuiltinVAStartImpl(CallExpr *TheCall) {
      Expr *Fn = TheCall->getCallee();
      if (TheCall->getNumArgs() > 2) {
        Diag(TheCall->getArg(2)->getLocStart(),
             diag::err_typecheck_call_too_many_args)
          << 0 /*function call*/ << 2 << TheCall->getNumArgs()
          << Fn->getSourceRange()
          << SourceRange(TheCall->getArg(2)->getLocStart(),
                         (*(TheCall->arg_end()-1))->getLocEnd());
        return true;
      }
    
      if (TheCall->getNumArgs() < 2) {
        return Diag(TheCall->getLocEnd(),
          diag::err_typecheck_call_too_few_args_at_least)
          << 0 /*function call*/ << 2 << TheCall->getNumArgs();
      }
    
      // Type-check the first argument normally.
      if (checkBuiltinArgument(*this, TheCall, 0))
        return true;
    
      // Determine whether the current function is variadic or not.
      BlockScopeInfo *CurBlock = getCurBlock();
      bool isVariadic;
      if (CurBlock)
        isVariadic = CurBlock->TheDecl->isVariadic();
      else if (FunctionDecl *FD = getCurFunctionDecl())
        isVariadic = FD->isVariadic();
      else
        isVariadic = getCurMethodDecl()->isVariadic();
    
      if (!isVariadic) {
        Diag(Fn->getLocStart(), diag::err_va_start_used_in_non_variadic_function);
        return true;
      }
    
      // Verify that the second argument to the builtin is the last argument of the
      // current function or method.
      bool SecondArgIsLastNamedArgument = false;
      const Expr *Arg = TheCall->getArg(1)->IgnoreParenCasts();
    
      // These are valid if SecondArgIsLastNamedArgument is false after the next
      // block.
      QualType Type;
      SourceLocation ParamLoc;
      bool IsCRegister = false;
    
      if (const DeclRefExpr *DR = dyn_cast<DeclRefExpr>(Arg)) {
        if (const ParmVarDecl *PV = dyn_cast<ParmVarDecl>(DR->getDecl())) {
          // FIXME: This isn't correct for methods (results in bogus warning).
          // Get the last formal in the current function.
          const ParmVarDecl *LastArg;
          if (CurBlock)
            LastArg = CurBlock->TheDecl->parameters().back();
          else if (FunctionDecl *FD = getCurFunctionDecl())
            LastArg = FD->parameters().back();
          else
            LastArg = getCurMethodDecl()->parameters().back();
          SecondArgIsLastNamedArgument = PV == LastArg;
    
          Type = PV->getType();
          ParamLoc = PV->getLocation();
          IsCRegister =
              PV->getStorageClass() == SC_Register && !getLangOpts().CPlusPlus;
        }
      }
    
      if (!SecondArgIsLastNamedArgument)
        Diag(TheCall->getArg(1)->getLocStart(),
             diag::warn_second_arg_of_va_start_not_last_named_param);
      else if (IsCRegister || Type->isReferenceType() ||
               Type->isSpecificBuiltinType(BuiltinType::Float) || [=] {
                 // Promotable integers are UB, but enumerations need a bit of
                 // extra checking to see what their promotable type actually is.
                 if (!Type->isPromotableIntegerType())
                   return false;
                 if (!Type->isEnumeralType())
                   return true;
                 const EnumDecl *ED = Type->getAs<EnumType>()->getDecl();
                 return !(ED &&
                          Context.typesAreCompatible(ED->getPromotionType(), Type));
               }()) {
        unsigned Reason = 0;
        if (Type->isReferenceType())  Reason = 1;
        else if (IsCRegister)         Reason = 2;
        Diag(Arg->getLocStart(), diag::warn_va_start_type_is_undefined) << Reason;
        Diag(ParamLoc, diag::note_parameter_type) << Type;
      }
    
      TheCall->setType(Context.VoidTy);
      return false;
    }
    
    /// Check the arguments to '__builtin_va_start' for validity, and that
    /// it was called from a function of the native ABI.
    /// Emit an error and return true on failure; return false on success.
    bool Sema::SemaBuiltinVAStart(CallExpr *TheCall) {
      // On x86-64 Unix, don't allow this in Win64 ABI functions.
      // On x64 Windows, don't allow this in System V ABI functions.
      // (Yes, that means there's no corresponding way to support variadic
      // System V ABI functions on Windows.)
      if (Context.getTargetInfo().getTriple().getArch() == llvm::Triple::x86_64) {
        unsigned OS = Context.getTargetInfo().getTriple().getOS();
        clang::CallingConv CC = CC_C;
        if (const FunctionDecl *FD = getCurFunctionDecl())
          CC = FD->getType()->getAs<FunctionType>()->getCallConv();
        if ((OS == llvm::Triple::Win32 && CC == CC_X86_64SysV) ||
            (OS != llvm::Triple::Win32 && CC == CC_X86_64Win64))
          return Diag(TheCall->getCallee()->getLocStart(),
                      diag::err_va_start_used_in_wrong_abi_function)
                 << (OS != llvm::Triple::Win32);
      }
      return SemaBuiltinVAStartImpl(TheCall);
    }
    
    /// Check the arguments to '__builtin_ms_va_start' for validity, and that
    /// it was called from a Win64 ABI function.
    /// Emit an error and return true on failure; return false on success.
    bool Sema::SemaBuiltinMSVAStart(CallExpr *TheCall) {
      // This only makes sense for x86-64.
      const llvm::Triple &TT = Context.getTargetInfo().getTriple();
      Expr *Callee = TheCall->getCallee();
      if (TT.getArch() != llvm::Triple::x86_64)
        return Diag(Callee->getLocStart(), diag::err_x86_builtin_32_bit_tgt);
      // Don't allow this in System V ABI functions.
      clang::CallingConv CC = CC_C;
      if (const FunctionDecl *FD = getCurFunctionDecl())
        CC = FD->getType()->getAs<FunctionType>()->getCallConv();
      if (CC == CC_X86_64SysV ||
          (TT.getOS() != llvm::Triple::Win32 && CC != CC_X86_64Win64))
        return Diag(Callee->getLocStart(),
                    diag::err_ms_va_start_used_in_sysv_function);
      return SemaBuiltinVAStartImpl(TheCall);
    }
    
    bool Sema::SemaBuiltinVAStartARM(CallExpr *Call) {
      // void __va_start(va_list *ap, const char *named_addr, size_t slot_size,
      //                 const char *named_addr);
    
      Expr *Func = Call->getCallee();
    
      if (Call->getNumArgs() < 3)
        return Diag(Call->getLocEnd(),
                    diag::err_typecheck_call_too_few_args_at_least)
               << 0 /*function call*/ << 3 << Call->getNumArgs();
    
      // Determine whether the current function is variadic or not.
      bool IsVariadic;
      if (BlockScopeInfo *CurBlock = getCurBlock())
        IsVariadic = CurBlock->TheDecl->isVariadic();
      else if (FunctionDecl *FD = getCurFunctionDecl())
        IsVariadic = FD->isVariadic();
      else if (ObjCMethodDecl *MD = getCurMethodDecl())
        IsVariadic = MD->isVariadic();
      else
        llvm_unreachable("unexpected statement type");
    
      if (!IsVariadic) {
        Diag(Func->getLocStart(), diag::err_va_start_used_in_non_variadic_function);
        return true;
      }
    
      // Type-check the first argument normally.
      if (checkBuiltinArgument(*this, Call, 0))
        return true;
    
      const struct {
        unsigned ArgNo;
        QualType Type;
      } ArgumentTypes[] = {
        { 1, Context.getPointerType(Context.CharTy.withConst()) },
        { 2, Context.getSizeType() },
      };
    
      for (const auto &AT : ArgumentTypes) {
        const Expr *Arg = Call->getArg(AT.ArgNo)->IgnoreParens();
        if (Arg->getType().getCanonicalType() == AT.Type.getCanonicalType())
          continue;
        Diag(Arg->getLocStart(), diag::err_typecheck_convert_incompatible)
          << Arg->getType() << AT.Type << 1 /* different class */
          << 0 /* qualifier difference */ << 3 /* parameter mismatch */
          << AT.ArgNo + 1 << Arg->getType() << AT.Type;
      }
    
      return false;
    }
    
    /// SemaBuiltinUnorderedCompare - Handle functions like __builtin_isgreater and
    /// friends.  This is declared to take (...), so we have to check everything.
    bool Sema::SemaBuiltinUnorderedCompare(CallExpr *TheCall) {
      if (TheCall->getNumArgs() < 2)
        return Diag(TheCall->getLocEnd(), diag::err_typecheck_call_too_few_args)
          << 0 << 2 << TheCall->getNumArgs()/*function call*/;
      if (TheCall->getNumArgs() > 2)
        return Diag(TheCall->getArg(2)->getLocStart(),
                    diag::err_typecheck_call_too_many_args)
          << 0 /*function call*/ << 2 << TheCall->getNumArgs()
          << SourceRange(TheCall->getArg(2)->getLocStart(),
                         (*(TheCall->arg_end()-1))->getLocEnd());
    
      ExprResult OrigArg0 = TheCall->getArg(0);
      ExprResult OrigArg1 = TheCall->getArg(1);
    
      // Do standard promotions between the two arguments, returning their common
      // type.
      QualType Res = UsualArithmeticConversions(OrigArg0, OrigArg1, false);
      if (OrigArg0.isInvalid() || OrigArg1.isInvalid())
        return true;
    
      // Make sure any conversions are pushed back into the call; this is
      // type safe since unordered compare builtins are declared as "_Bool
      // foo(...)".
      TheCall->setArg(0, OrigArg0.get());
      TheCall->setArg(1, OrigArg1.get());
    
      if (OrigArg0.get()->isTypeDependent() || OrigArg1.get()->isTypeDependent())
        return false;
    
      // If the common type isn't a real floating type, then the arguments were
      // invalid for this operation.
      if (Res.isNull() || !Res->isRealFloatingType())
        return Diag(OrigArg0.get()->getLocStart(),
                    diag::err_typecheck_call_invalid_ordered_compare)
          << OrigArg0.get()->getType() << OrigArg1.get()->getType()
          << SourceRange(OrigArg0.get()->getLocStart(), OrigArg1.get()->getLocEnd());
    
      return false;
    }
    
    /// SemaBuiltinSemaBuiltinFPClassification - Handle functions like
    /// __builtin_isnan and friends.  This is declared to take (...), so we have
    /// to check everything. We expect the last argument to be a floating point
    /// value.
    bool Sema::SemaBuiltinFPClassification(CallExpr *TheCall, unsigned NumArgs) {
      if (TheCall->getNumArgs() < NumArgs)
        return Diag(TheCall->getLocEnd(), diag::err_typecheck_call_too_few_args)
          << 0 << NumArgs << TheCall->getNumArgs()/*function call*/;
      if (TheCall->getNumArgs() > NumArgs)
        return Diag(TheCall->getArg(NumArgs)->getLocStart(),
                    diag::err_typecheck_call_too_many_args)
          << 0 /*function call*/ << NumArgs << TheCall->getNumArgs()
          << SourceRange(TheCall->getArg(NumArgs)->getLocStart(),
                         (*(TheCall->arg_end()-1))->getLocEnd());
    
      Expr *OrigArg = TheCall->getArg(NumArgs-1);
    
      if (OrigArg->isTypeDependent())
        return false;
    
      // This operation requires a non-_Complex floating-point number.
      if (!OrigArg->getType()->isRealFloatingType())
        return Diag(OrigArg->getLocStart(),
                    diag::err_typecheck_call_invalid_unary_fp)
          << OrigArg->getType() << OrigArg->getSourceRange();
    
      // If this is an implicit conversion from float -> float or double, remove it.
      if (ImplicitCastExpr *Cast = dyn_cast<ImplicitCastExpr>(OrigArg)) {
        // Only remove standard FloatCasts, leaving other casts inplace
        if (Cast->getCastKind() == CK_FloatingCast) {
          Expr *CastArg = Cast->getSubExpr();
          if (CastArg->getType()->isSpecificBuiltinType(BuiltinType::Float)) {
              assert((Cast->getType()->isSpecificBuiltinType(BuiltinType::Double) ||
                      Cast->getType()->isSpecificBuiltinType(BuiltinType::Float)) &&
                   "promotion from float to either float or double is the only expected cast here");
            Cast->setSubExpr(nullptr);
            TheCall->setArg(NumArgs-1, CastArg);
          }
        }
      }
      
      return false;
    }
    
    /// SemaBuiltinShuffleVector - Handle __builtin_shufflevector.
    // This is declared to take (...), so we have to check everything.
    ExprResult Sema::SemaBuiltinShuffleVector(CallExpr *TheCall) {
      if (TheCall->getNumArgs() < 2)
        return ExprError(Diag(TheCall->getLocEnd(),
                              diag::err_typecheck_call_too_few_args_at_least)
                         << 0 /*function call*/ << 2 << TheCall->getNumArgs()
                         << TheCall->getSourceRange());
    
      // Determine which of the following types of shufflevector we're checking:
      // 1) unary, vector mask: (lhs, mask)
      // 2) binary, scalar mask: (lhs, rhs, index, ..., index)
      QualType resType = TheCall->getArg(0)->getType();
      unsigned numElements = 0;
    
      if (!TheCall->getArg(0)->isTypeDependent() &&
          !TheCall->getArg(1)->isTypeDependent()) {
        QualType LHSType = TheCall->getArg(0)->getType();
        QualType RHSType = TheCall->getArg(1)->getType();
    
        if (!LHSType->isVectorType() || !RHSType->isVectorType())
          return ExprError(Diag(TheCall->getLocStart(),
                                diag::err_shufflevector_non_vector)
                           << SourceRange(TheCall->getArg(0)->getLocStart(),
                                          TheCall->getArg(1)->getLocEnd()));
    
        numElements = LHSType->getAs<VectorType>()->getNumElements();
        unsigned numResElements = TheCall->getNumArgs() - 2;
    
        // Check to see if we have a call with 2 vector arguments, the unary shuffle
        // with mask.  If so, verify that RHS is an integer vector type with the
        // same number of elts as lhs.
        if (TheCall->getNumArgs() == 2) {
          if (!RHSType->hasIntegerRepresentation() ||
              RHSType->getAs<VectorType>()->getNumElements() != numElements)
            return ExprError(Diag(TheCall->getLocStart(),
                                  diag::err_shufflevector_incompatible_vector)
                             << SourceRange(TheCall->getArg(1)->getLocStart(),
                                            TheCall->getArg(1)->getLocEnd()));
        } else if (!Context.hasSameUnqualifiedType(LHSType, RHSType)) {
          return ExprError(Diag(TheCall->getLocStart(),
                                diag::err_shufflevector_incompatible_vector)
                           << SourceRange(TheCall->getArg(0)->getLocStart(),
                                          TheCall->getArg(1)->getLocEnd()));
        } else if (numElements != numResElements) {
          QualType eltType = LHSType->getAs<VectorType>()->getElementType();
          resType = Context.getVectorType(eltType, numResElements,
                                          VectorType::GenericVector);
        }
      }
    
      for (unsigned i = 2; i < TheCall->getNumArgs(); i++) {
        if (TheCall->getArg(i)->isTypeDependent() ||
            TheCall->getArg(i)->isValueDependent())
          continue;
    
        llvm::APSInt Result(32);
        if (!TheCall->getArg(i)->isIntegerConstantExpr(Result, Context))
          return ExprError(Diag(TheCall->getLocStart(),
                                diag::err_shufflevector_nonconstant_argument)
                           << TheCall->getArg(i)->getSourceRange());
    
        // Allow -1 which will be translated to undef in the IR.
        if (Result.isSigned() && Result.isAllOnesValue())
          continue;
    
        if (Result.getActiveBits() > 64 || Result.getZExtValue() >= numElements*2)
          return ExprError(Diag(TheCall->getLocStart(),
                                diag::err_shufflevector_argument_too_large)
                           << TheCall->getArg(i)->getSourceRange());
      }
    
      SmallVector<Expr*, 32> exprs;
    
      for (unsigned i = 0, e = TheCall->getNumArgs(); i != e; i++) {
        exprs.push_back(TheCall->getArg(i));
        TheCall->setArg(i, nullptr);
      }
    
      return new (Context) ShuffleVectorExpr(Context, exprs, resType,
                                             TheCall->getCallee()->getLocStart(),
                                             TheCall->getRParenLoc());
    }
    
    /// SemaConvertVectorExpr - Handle __builtin_convertvector
    ExprResult Sema::SemaConvertVectorExpr(Expr *E, TypeSourceInfo *TInfo,
                                           SourceLocation BuiltinLoc,
                                           SourceLocation RParenLoc) {
      ExprValueKind VK = VK_RValue;
      ExprObjectKind OK = OK_Ordinary;
      QualType DstTy = TInfo->getType();
      QualType SrcTy = E->getType();
    
      if (!SrcTy->isVectorType() && !SrcTy->isDependentType())
        return ExprError(Diag(BuiltinLoc,
                              diag::err_convertvector_non_vector)
                         << E->getSourceRange());
      if (!DstTy->isVectorType() && !DstTy->isDependentType())
        return ExprError(Diag(BuiltinLoc,
                              diag::err_convertvector_non_vector_type));
    
      if (!SrcTy->isDependentType() && !DstTy->isDependentType()) {
        unsigned SrcElts = SrcTy->getAs<VectorType>()->getNumElements();
        unsigned DstElts = DstTy->getAs<VectorType>()->getNumElements();
        if (SrcElts != DstElts)
          return ExprError(Diag(BuiltinLoc,
                                diag::err_convertvector_incompatible_vector)
                           << E->getSourceRange());
      }
    
      return new (Context)
          ConvertVectorExpr(E, TInfo, DstTy, VK, OK, BuiltinLoc, RParenLoc);
    }
    
    /// SemaBuiltinPrefetch - Handle __builtin_prefetch.
    // This is declared to take (const void*, ...) and can take two
    // optional constant int args.
    bool Sema::SemaBuiltinPrefetch(CallExpr *TheCall) {
      unsigned NumArgs = TheCall->getNumArgs();
    
      if (NumArgs > 3)
        return Diag(TheCall->getLocEnd(),
                 diag::err_typecheck_call_too_many_args_at_most)
                 << 0 /*function call*/ << 3 << NumArgs
                 << TheCall->getSourceRange();
    
      // Argument 0 is checked for us and the remaining arguments must be
      // constant integers.
      for (unsigned i = 1; i != NumArgs; ++i)
        if (SemaBuiltinConstantArgRange(TheCall, i, 0, i == 1 ? 1 : 3))
          return true;
    
      return false;
    }
    
    /// SemaBuiltinAssume - Handle __assume (MS Extension).
    // __assume does not evaluate its arguments, and should warn if its argument
    // has side effects.
    bool Sema::SemaBuiltinAssume(CallExpr *TheCall) {
      Expr *Arg = TheCall->getArg(0);
      if (Arg->isInstantiationDependent()) return false;
    
      if (Arg->HasSideEffects(Context))
        Diag(Arg->getLocStart(), diag::warn_assume_side_effects)
          << Arg->getSourceRange()
          << cast<FunctionDecl>(TheCall->getCalleeDecl())->getIdentifier();
    
      return false;
    }
    
    /// Handle __builtin_alloca_with_align. This is declared
    /// as (size_t, size_t) where the second size_t must be a power of 2 greater
    /// than 8.
    bool Sema::SemaBuiltinAllocaWithAlign(CallExpr *TheCall) {
      // The alignment must be a constant integer.
      Expr *Arg = TheCall->getArg(1);
    
      // We can't check the value of a dependent argument.
      if (!Arg->isTypeDependent() && !Arg->isValueDependent()) {
        if (const auto *UE =
                dyn_cast<UnaryExprOrTypeTraitExpr>(Arg->IgnoreParenImpCasts()))
          if (UE->getKind() == UETT_AlignOf)
            Diag(TheCall->getLocStart(), diag::warn_alloca_align_alignof)
              << Arg->getSourceRange();
    
        llvm::APSInt Result = Arg->EvaluateKnownConstInt(Context);
    
        if (!Result.isPowerOf2())
          return Diag(TheCall->getLocStart(),
                      diag::err_alignment_not_power_of_two)
               << Arg->getSourceRange();
    
        if (Result < Context.getCharWidth())
          return Diag(TheCall->getLocStart(), diag::err_alignment_too_small)
               << (unsigned)Context.getCharWidth()
               << Arg->getSourceRange();
    
        if (Result > INT32_MAX)
          return Diag(TheCall->getLocStart(), diag::err_alignment_too_big)
               << INT32_MAX
               << Arg->getSourceRange();
      }
    
      return false;
    }
    
    /// Handle __builtin_assume_aligned. This is declared
    /// as (const void*, size_t, ...) and can take one optional constant int arg.
    bool Sema::SemaBuiltinAssumeAligned(CallExpr *TheCall) {
      unsigned NumArgs = TheCall->getNumArgs();
    
      if (NumArgs > 3)
        return Diag(TheCall->getLocEnd(),
                 diag::err_typecheck_call_too_many_args_at_most)
                 << 0 /*function call*/ << 3 << NumArgs
                 << TheCall->getSourceRange();
    
      // The alignment must be a constant integer.
      Expr *Arg = TheCall->getArg(1);
    
      // We can't check the value of a dependent argument.
      if (!Arg->isTypeDependent() && !Arg->isValueDependent()) {
        llvm::APSInt Result;
        if (SemaBuiltinConstantArg(TheCall, 1, Result))
          return true;
    
        if (!Result.isPowerOf2())
          return Diag(TheCall->getLocStart(),
                      diag::err_alignment_not_power_of_two)
               << Arg->getSourceRange();
      }
    
      if (NumArgs > 2) {
        ExprResult Arg(TheCall->getArg(2));
        InitializedEntity Entity = InitializedEntity::InitializeParameter(Context,
          Context.getSizeType(), false);
        Arg = PerformCopyInitialization(Entity, SourceLocation(), Arg);
        if (Arg.isInvalid()) return true;
        TheCall->setArg(2, Arg.get());
      }
    
      return false;
    }
    
    bool Sema::SemaBuiltinOSLogFormat(CallExpr *TheCall) {
      unsigned BuiltinID =
          cast<FunctionDecl>(TheCall->getCalleeDecl())->getBuiltinID();
      bool IsSizeCall = BuiltinID == Builtin::BI__builtin_os_log_format_buffer_size;
    
      unsigned NumArgs = TheCall->getNumArgs();
      unsigned NumRequiredArgs = IsSizeCall ? 1 : 2;
      if (NumArgs < NumRequiredArgs) {
        return Diag(TheCall->getLocEnd(), diag::err_typecheck_call_too_few_args)
               << 0 /* function call */ << NumRequiredArgs << NumArgs
               << TheCall->getSourceRange();
      }
      if (NumArgs >= NumRequiredArgs + 0x100) {
        return Diag(TheCall->getLocEnd(),
                    diag::err_typecheck_call_too_many_args_at_most)
               << 0 /* function call */ << (NumRequiredArgs + 0xff) << NumArgs
               << TheCall->getSourceRange();
      }
      unsigned i = 0;
    
      // For formatting call, check buffer arg.
      if (!IsSizeCall) {
        ExprResult Arg(TheCall->getArg(i));
        InitializedEntity Entity = InitializedEntity::InitializeParameter(
            Context, Context.VoidPtrTy, false);
        Arg = PerformCopyInitialization(Entity, SourceLocation(), Arg);
        if (Arg.isInvalid())
          return true;
        TheCall->setArg(i, Arg.get());
        i++;
      }
    
      // Check string literal arg.
      unsigned FormatIdx = i;
      {
        ExprResult Arg = CheckOSLogFormatStringArg(TheCall->getArg(i));
        if (Arg.isInvalid())
          return true;
        TheCall->setArg(i, Arg.get());
        i++;
      }
    
      // Make sure variadic args are scalar.
      unsigned FirstDataArg = i;
      while (i < NumArgs) {
        ExprResult Arg = DefaultVariadicArgumentPromotion(
            TheCall->getArg(i), VariadicFunction, nullptr);
        if (Arg.isInvalid())
          return true;
        CharUnits ArgSize = Context.getTypeSizeInChars(Arg.get()->getType());
        if (ArgSize.getQuantity() >= 0x100) {
          return Diag(Arg.get()->getLocEnd(), diag::err_os_log_argument_too_big)
                 << i << (int)ArgSize.getQuantity() << 0xff
                 << TheCall->getSourceRange();
        }
        TheCall->setArg(i, Arg.get());
        i++;
      }
    
      // Check formatting specifiers. NOTE: We're only doing this for the non-size
      // call to avoid duplicate diagnostics.
      if (!IsSizeCall) {
        llvm::SmallBitVector CheckedVarArgs(NumArgs, false);
        ArrayRef<const Expr *> Args(TheCall->getArgs(), TheCall->getNumArgs());
        bool Success = CheckFormatArguments(
            Args, /*HasVAListArg*/ false, FormatIdx, FirstDataArg, FST_OSLog,
            VariadicFunction, TheCall->getLocStart(), SourceRange(),
            CheckedVarArgs);
        if (!Success)
          return true;
      }
    
      if (IsSizeCall) {
        TheCall->setType(Context.getSizeType());
      } else {
        TheCall->setType(Context.VoidPtrTy);
      }
      return false;
    }
    
    /// SemaBuiltinConstantArg - Handle a check if argument ArgNum of CallExpr
    /// TheCall is a constant expression.
    bool Sema::SemaBuiltinConstantArg(CallExpr *TheCall, int ArgNum,
                                      llvm::APSInt &Result) {
      Expr *Arg = TheCall->getArg(ArgNum);
      DeclRefExpr *DRE =cast<DeclRefExpr>(TheCall->getCallee()->IgnoreParenCasts());
      FunctionDecl *FDecl = cast<FunctionDecl>(DRE->getDecl());
      
      if (Arg->isTypeDependent() || Arg->isValueDependent()) return false;
      
      if (!Arg->isIntegerConstantExpr(Result, Context))
        return Diag(TheCall->getLocStart(), diag::err_constant_integer_arg_type)
                    << FDecl->getDeclName() <<  Arg->getSourceRange();
      
      return false;
    }
    
    /// SemaBuiltinConstantArgRange - Handle a check if argument ArgNum of CallExpr
    /// TheCall is a constant expression in the range [Low, High].
    bool Sema::SemaBuiltinConstantArgRange(CallExpr *TheCall, int ArgNum,
                                           int Low, int High) {
      llvm::APSInt Result;
    
      // We can't check the value of a dependent argument.
      Expr *Arg = TheCall->getArg(ArgNum);
      if (Arg->isTypeDependent() || Arg->isValueDependent())
        return false;
    
      // Check constant-ness first.
      if (SemaBuiltinConstantArg(TheCall, ArgNum, Result))
        return true;
    
      if (Result.getSExtValue() < Low || Result.getSExtValue() > High)
        return Diag(TheCall->getLocStart(), diag::err_argument_invalid_range)
          << Low << High << Arg->getSourceRange();
    
      return false;
    }
    
    /// SemaBuiltinConstantArgMultiple - Handle a check if argument ArgNum of CallExpr
    /// TheCall is a constant expression is a multiple of Num..
    bool Sema::SemaBuiltinConstantArgMultiple(CallExpr *TheCall, int ArgNum,
                                              unsigned Num) {
      llvm::APSInt Result;
    
      // We can't check the value of a dependent argument.
      Expr *Arg = TheCall->getArg(ArgNum);
      if (Arg->isTypeDependent() || Arg->isValueDependent())
        return false;
    
      // Check constant-ness first.
      if (SemaBuiltinConstantArg(TheCall, ArgNum, Result))
        return true;
    
      if (Result.getSExtValue() % Num != 0)
        return Diag(TheCall->getLocStart(), diag::err_argument_not_multiple)
          << Num << Arg->getSourceRange();
    
      return false;
    }
    
    /// SemaBuiltinARMSpecialReg - Handle a check if argument ArgNum of CallExpr
    /// TheCall is an ARM/AArch64 special register string literal.
    bool Sema::SemaBuiltinARMSpecialReg(unsigned BuiltinID, CallExpr *TheCall,
                                        int ArgNum, unsigned ExpectedFieldNum,
                                        bool AllowName) {
      bool IsARMBuiltin = BuiltinID == ARM::BI__builtin_arm_rsr64 ||
                          BuiltinID == ARM::BI__builtin_arm_wsr64 ||
                          BuiltinID == ARM::BI__builtin_arm_rsr ||
                          BuiltinID == ARM::BI__builtin_arm_rsrp ||
                          BuiltinID == ARM::BI__builtin_arm_wsr ||
                          BuiltinID == ARM::BI__builtin_arm_wsrp;
      bool IsAArch64Builtin = BuiltinID == AArch64::BI__builtin_arm_rsr64 ||
                              BuiltinID == AArch64::BI__builtin_arm_wsr64 ||
                              BuiltinID == AArch64::BI__builtin_arm_rsr ||
                              BuiltinID == AArch64::BI__builtin_arm_rsrp ||
                              BuiltinID == AArch64::BI__builtin_arm_wsr ||
                              BuiltinID == AArch64::BI__builtin_arm_wsrp;
      assert((IsARMBuiltin || IsAArch64Builtin) && "Unexpected ARM builtin.");
    
      // We can't check the value of a dependent argument.
      Expr *Arg = TheCall->getArg(ArgNum);
      if (Arg->isTypeDependent() || Arg->isValueDependent())
        return false;
    
      // Check if the argument is a string literal.
      if (!isa<StringLiteral>(Arg->IgnoreParenImpCasts()))
        return Diag(TheCall->getLocStart(), diag::err_expr_not_string_literal)
               << Arg->getSourceRange();
    
      // Check the type of special register given.
      StringRef Reg = cast<StringLiteral>(Arg->IgnoreParenImpCasts())->getString();
      SmallVector<StringRef, 6> Fields;
      Reg.split(Fields, ":");
    
      if (Fields.size() != ExpectedFieldNum && !(AllowName && Fields.size() == 1))
        return Diag(TheCall->getLocStart(), diag::err_arm_invalid_specialreg)
               << Arg->getSourceRange();
    
      // If the string is the name of a register then we cannot check that it is
      // valid here but if the string is of one the forms described in ACLE then we
      // can check that the supplied fields are integers and within the valid
      // ranges.
      if (Fields.size() > 1) {
        bool FiveFields = Fields.size() == 5;
    
        bool ValidString = true;
        if (IsARMBuiltin) {
          ValidString &= Fields[0].startswith_lower("cp") ||
                         Fields[0].startswith_lower("p");
          if (ValidString)
            Fields[0] =
              Fields[0].drop_front(Fields[0].startswith_lower("cp") ? 2 : 1);
    
          ValidString &= Fields[2].startswith_lower("c");
          if (ValidString)
            Fields[2] = Fields[2].drop_front(1);
    
          if (FiveFields) {
            ValidString &= Fields[3].startswith_lower("c");
            if (ValidString)
              Fields[3] = Fields[3].drop_front(1);
          }
        }
    
        SmallVector<int, 5> Ranges;
        if (FiveFields)
          Ranges.append({IsAArch64Builtin ? 1 : 15, 7, 15, 15, 7});
        else
          Ranges.append({15, 7, 15});
    
        for (unsigned i=0; i<Fields.size(); ++i) {
          int IntField;
          ValidString &= !Fields[i].getAsInteger(10, IntField);
          ValidString &= (IntField >= 0 && IntField <= Ranges[i]);
        }
    
        if (!ValidString)
          return Diag(TheCall->getLocStart(), diag::err_arm_invalid_specialreg)
                 << Arg->getSourceRange();
    
      } else if (IsAArch64Builtin && Fields.size() == 1) {
        // If the register name is one of those that appear in the condition below
        // and the special register builtin being used is one of the write builtins,
        // then we require that the argument provided for writing to the register
        // is an integer constant expression. This is because it will be lowered to
        // an MSR (immediate) instruction, so we need to know the immediate at
        // compile time.
        if (TheCall->getNumArgs() != 2)
          return false;
    
        std::string RegLower = Reg.lower();
        if (RegLower != "spsel" && RegLower != "daifset" && RegLower != "daifclr" &&
            RegLower != "pan" && RegLower != "uao")
          return false;
    
        return SemaBuiltinConstantArgRange(TheCall, 1, 0, 15);
      }
    
      return false;
    }
    
    /// SemaBuiltinLongjmp - Handle __builtin_longjmp(void *env[5], int val).
    /// This checks that the target supports __builtin_longjmp and
    /// that val is a constant 1.
    bool Sema::SemaBuiltinLongjmp(CallExpr *TheCall) {
      if (!Context.getTargetInfo().hasSjLjLowering())
        return Diag(TheCall->getLocStart(), diag::err_builtin_longjmp_unsupported)
                 << SourceRange(TheCall->getLocStart(), TheCall->getLocEnd());
    
      Expr *Arg = TheCall->getArg(1);
      llvm::APSInt Result;
    
      // TODO: This is less than ideal. Overload this to take a value.
      if (SemaBuiltinConstantArg(TheCall, 1, Result))
        return true;
      
      if (Result != 1)
        return Diag(TheCall->getLocStart(), diag::err_builtin_longjmp_invalid_val)
                 << SourceRange(Arg->getLocStart(), Arg->getLocEnd());
    
      return false;
    }
    
    /// SemaBuiltinSetjmp - Handle __builtin_setjmp(void *env[5]).
    /// This checks that the target supports __builtin_setjmp.
    bool Sema::SemaBuiltinSetjmp(CallExpr *TheCall) {
      if (!Context.getTargetInfo().hasSjLjLowering())
        return Diag(TheCall->getLocStart(), diag::err_builtin_setjmp_unsupported)
                 << SourceRange(TheCall->getLocStart(), TheCall->getLocEnd());
      return false;
    }
    
    namespace {
    class UncoveredArgHandler {
      enum { Unknown = -1, AllCovered = -2 };
      signed FirstUncoveredArg;
      SmallVector<const Expr *, 4> DiagnosticExprs;
    
    public:
      UncoveredArgHandler() : FirstUncoveredArg(Unknown) { }
    
      bool hasUncoveredArg() const {
        return (FirstUncoveredArg >= 0);
      }
    
      unsigned getUncoveredArg() const {
        assert(hasUncoveredArg() && "no uncovered argument");
        return FirstUncoveredArg;
      }
    
      void setAllCovered() {
        // A string has been found with all arguments covered, so clear out
        // the diagnostics.
        DiagnosticExprs.clear();
        FirstUncoveredArg = AllCovered;
      }
    
      void Update(signed NewFirstUncoveredArg, const Expr *StrExpr) {
        assert(NewFirstUncoveredArg >= 0 && "Outside range");
    
        // Don't update if a previous string covers all arguments.
        if (FirstUncoveredArg == AllCovered)
          return;
    
        // UncoveredArgHandler tracks the highest uncovered argument index
        // and with it all the strings that match this index.
        if (NewFirstUncoveredArg == FirstUncoveredArg)
          DiagnosticExprs.push_back(StrExpr);
        else if (NewFirstUncoveredArg > FirstUncoveredArg) {
          DiagnosticExprs.clear();
          DiagnosticExprs.push_back(StrExpr);
          FirstUncoveredArg = NewFirstUncoveredArg;
        }
      }
    
      void Diagnose(Sema &S, bool IsFunctionCall, const Expr *ArgExpr);
    };
    
    enum StringLiteralCheckType {
      SLCT_NotALiteral,
      SLCT_UncheckedLiteral,
      SLCT_CheckedLiteral
    };
    } // end anonymous namespace
    
    static void sumOffsets(llvm::APSInt &Offset, llvm::APSInt Addend,
                                         BinaryOperatorKind BinOpKind,
                                         bool AddendIsRight) {
      unsigned BitWidth = Offset.getBitWidth();
      unsigned AddendBitWidth = Addend.getBitWidth();
      // There might be negative interim results.
      if (Addend.isUnsigned()) {
        Addend = Addend.zext(++AddendBitWidth);
        Addend.setIsSigned(true);
      }
      // Adjust the bit width of the APSInts.
      if (AddendBitWidth > BitWidth) {
        Offset = Offset.sext(AddendBitWidth);
        BitWidth = AddendBitWidth;
      } else if (BitWidth > AddendBitWidth) {
        Addend = Addend.sext(BitWidth);
      }
    
      bool Ov = false;
      llvm::APSInt ResOffset = Offset;
      if (BinOpKind == BO_Add)
        ResOffset = Offset.sadd_ov(Addend, Ov);
      else {
        assert(AddendIsRight && BinOpKind == BO_Sub &&
               "operator must be add or sub with addend on the right");
        ResOffset = Offset.ssub_ov(Addend, Ov);
      }
    
      // We add an offset to a pointer here so we should support an offset as big as
      // possible.
      if (Ov) {
        assert(BitWidth <= UINT_MAX / 2 && "index (intermediate) result too big");
        Offset = Offset.sext(2 * BitWidth);
        sumOffsets(Offset, Addend, BinOpKind, AddendIsRight);
        return;
      }
    
      Offset = ResOffset;
    }
    
    namespace {
    // This is a wrapper class around StringLiteral to support offsetted string
    // literals as format strings. It takes the offset into account when returning
    // the string and its length or the source locations to display notes correctly.
    class FormatStringLiteral {
      const StringLiteral *FExpr;
      int64_t Offset;
    
     public:
      FormatStringLiteral(const StringLiteral *fexpr, int64_t Offset = 0)
          : FExpr(fexpr), Offset(Offset) {}
    
      StringRef getString() const {
        return FExpr->getString().drop_front(Offset);
      }
    
      unsigned getByteLength() const {
        return FExpr->getByteLength() - getCharByteWidth() * Offset;
      }
      unsigned getLength() const { return FExpr->getLength() - Offset; }
      unsigned getCharByteWidth() const { return FExpr->getCharByteWidth(); }
    
      StringLiteral::StringKind getKind() const { return FExpr->getKind(); }
    
      QualType getType() const { return FExpr->getType(); }
    
      bool isAscii() const { return FExpr->isAscii(); }
      bool isWide() const { return FExpr->isWide(); }
      bool isUTF8() const { return FExpr->isUTF8(); }
      bool isUTF16() const { return FExpr->isUTF16(); }
      bool isUTF32() const { return FExpr->isUTF32(); }
      bool isPascal() const { return FExpr->isPascal(); }
    
      SourceLocation getLocationOfByte(
          unsigned ByteNo, const SourceManager &SM, const LangOptions &Features,
          const TargetInfo &Target, unsigned *StartToken = nullptr,
          unsigned *StartTokenByteOffset = nullptr) const {
        return FExpr->getLocationOfByte(ByteNo + Offset, SM, Features, Target,
                                        StartToken, StartTokenByteOffset);
      }
    
      SourceLocation getLocStart() const LLVM_READONLY {
        return FExpr->getLocStart().getLocWithOffset(Offset);
      }
      SourceLocation getLocEnd() const LLVM_READONLY { return FExpr->getLocEnd(); }
    };
    }  // end anonymous namespace
    
    static void CheckFormatString(Sema &S, const FormatStringLiteral *FExpr,
                                  const Expr *OrigFormatExpr,
                                  ArrayRef<const Expr *> Args,
                                  bool HasVAListArg, unsigned format_idx,
                                  unsigned firstDataArg,
                                  Sema::FormatStringType Type,
                                  bool inFunctionCall,
                                  Sema::VariadicCallType CallType,
                                  llvm::SmallBitVector &CheckedVarArgs,
                                  UncoveredArgHandler &UncoveredArg);
    
    // Determine if an expression is a string literal or constant string.
    // If this function returns false on the arguments to a function expecting a
    // format string, we will usually need to emit a warning.
    // True string literals are then checked by CheckFormatString.
    static StringLiteralCheckType
    checkFormatStringExpr(Sema &S, const Expr *E, ArrayRef<const Expr *> Args,
                          bool HasVAListArg, unsigned format_idx,
                          unsigned firstDataArg, Sema::FormatStringType Type,
                          Sema::VariadicCallType CallType, bool InFunctionCall,
                          llvm::SmallBitVector &CheckedVarArgs,
                          UncoveredArgHandler &UncoveredArg,
                          llvm::APSInt Offset) {
     tryAgain:
      assert(Offset.isSigned() && "invalid offset");
    
      if (E->isTypeDependent() || E->isValueDependent())
        return SLCT_NotALiteral;
    
      E = E->IgnoreParenCasts();
    
      if (E->isNullPointerConstant(S.Context, Expr::NPC_ValueDependentIsNotNull))
        // Technically -Wformat-nonliteral does not warn about this case.
        // The behavior of printf and friends in this case is implementation
        // dependent.  Ideally if the format string cannot be null then
        // it should have a 'nonnull' attribute in the function prototype.
        return SLCT_UncheckedLiteral;
    
      switch (E->getStmtClass()) {
      case Stmt::BinaryConditionalOperatorClass:
      case Stmt::ConditionalOperatorClass: {
        // The expression is a literal if both sub-expressions were, and it was
        // completely checked only if both sub-expressions were checked.
        const AbstractConditionalOperator *C =
            cast<AbstractConditionalOperator>(E);
    
        // Determine whether it is necessary to check both sub-expressions, for
        // example, because the condition expression is a constant that can be
        // evaluated at compile time.
        bool CheckLeft = true, CheckRight = true;
    
        bool Cond;
        if (C->getCond()->EvaluateAsBooleanCondition(Cond, S.getASTContext())) {
          if (Cond)
            CheckRight = false;
          else
            CheckLeft = false;
        }
    
        // We need to maintain the offsets for the right and the left hand side
        // separately to check if every possible indexed expression is a valid
        // string literal. They might have different offsets for different string
        // literals in the end.
        StringLiteralCheckType Left;
        if (!CheckLeft)
          Left = SLCT_UncheckedLiteral;
        else {
          Left = checkFormatStringExpr(S, C->getTrueExpr(), Args,
                                       HasVAListArg, format_idx, firstDataArg,
                                       Type, CallType, InFunctionCall,
                                       CheckedVarArgs, UncoveredArg, Offset);
          if (Left == SLCT_NotALiteral || !CheckRight) {
            return Left;
          }
        }
    
        StringLiteralCheckType Right =
            checkFormatStringExpr(S, C->getFalseExpr(), Args,
                                  HasVAListArg, format_idx, firstDataArg,
                                  Type, CallType, InFunctionCall, CheckedVarArgs,
                                  UncoveredArg, Offset);
    
        return (CheckLeft && Left < Right) ? Left : Right;
      }
    
      case Stmt::ImplicitCastExprClass: {
        E = cast<ImplicitCastExpr>(E)->getSubExpr();
        goto tryAgain;
      }
    
      case Stmt::OpaqueValueExprClass:
        if (const Expr *src = cast<OpaqueValueExpr>(E)->getSourceExpr()) {
          E = src;
          goto tryAgain;
        }
        return SLCT_NotALiteral;
    
      case Stmt::PredefinedExprClass:
        // While __func__, etc., are technically not string literals, they
        // cannot contain format specifiers and thus are not a security
        // liability.
        return SLCT_UncheckedLiteral;
          
      case Stmt::DeclRefExprClass: {
        const DeclRefExpr *DR = cast<DeclRefExpr>(E);
    
        // As an exception, do not flag errors for variables binding to
        // const string literals.
        if (const VarDecl *VD = dyn_cast<VarDecl>(DR->getDecl())) {
          bool isConstant = false;
          QualType T = DR->getType();
    
          if (const ArrayType *AT = S.Context.getAsArrayType(T)) {
            isConstant = AT->getElementType().isConstant(S.Context);
          } else if (const PointerType *PT = T->getAs<PointerType>()) {
            isConstant = T.isConstant(S.Context) &&
                         PT->getPointeeType().isConstant(S.Context);
          } else if (T->isObjCObjectPointerType()) {
            // In ObjC, there is usually no "const ObjectPointer" type,
            // so don't check if the pointee type is constant.
            isConstant = T.isConstant(S.Context);
          }
    
          if (isConstant) {
            if (const Expr *Init = VD->getAnyInitializer()) {
              // Look through initializers like const char c[] = { "foo" }
              if (const InitListExpr *InitList = dyn_cast<InitListExpr>(Init)) {
                if (InitList->isStringLiteralInit())
                  Init = InitList->getInit(0)->IgnoreParenImpCasts();
              }
              return checkFormatStringExpr(S, Init, Args,
                                           HasVAListArg, format_idx,
                                           firstDataArg, Type, CallType,
                                           /*InFunctionCall*/ false, CheckedVarArgs,
                                           UncoveredArg, Offset);
            }
          }
    
          // For vprintf* functions (i.e., HasVAListArg==true), we add a
          // special check to see if the format string is a function parameter
          // of the function calling the printf function.  If the function
          // has an attribute indicating it is a printf-like function, then we
          // should suppress warnings concerning non-literals being used in a call
          // to a vprintf function.  For example:
          //
          // void
          // logmessage(char const *fmt __attribute__ (format (printf, 1, 2)), ...){
          //      va_list ap;
          //      va_start(ap, fmt);
          //      vprintf(fmt, ap);  // Do NOT emit a warning about "fmt".
          //      ...
          // }
          if (HasVAListArg) {
            if (const ParmVarDecl *PV = dyn_cast<ParmVarDecl>(VD)) {
              if (const NamedDecl *ND = dyn_cast<NamedDecl>(PV->getDeclContext())) {
                int PVIndex = PV->getFunctionScopeIndex() + 1;
                for (const auto *PVFormat : ND->specific_attrs<FormatAttr>()) {
                  // adjust for implicit parameter
                  if (const CXXMethodDecl *MD = dyn_cast<CXXMethodDecl>(ND))
                    if (MD->isInstance())
                      ++PVIndex;
                  // We also check if the formats are compatible.
                  // We can't pass a 'scanf' string to a 'printf' function.
                  if (PVIndex == PVFormat->getFormatIdx() &&
                      Type == S.GetFormatStringType(PVFormat))
                    return SLCT_UncheckedLiteral;
                }
              }
            }
          }
        }
    
        return SLCT_NotALiteral;
      }
    
      case Stmt::CallExprClass:
      case Stmt::CXXMemberCallExprClass: {
        const CallExpr *CE = cast<CallExpr>(E);
        if (const NamedDecl *ND = dyn_cast_or_null<NamedDecl>(CE->getCalleeDecl())) {
          if (const FormatArgAttr *FA = ND->getAttr<FormatArgAttr>()) {
            unsigned ArgIndex = FA->getFormatIdx();
            if (const CXXMethodDecl *MD = dyn_cast<CXXMethodDecl>(ND))
              if (MD->isInstance())
                --ArgIndex;
            const Expr *Arg = CE->getArg(ArgIndex - 1);
    
            return checkFormatStringExpr(S, Arg, Args,
                                         HasVAListArg, format_idx, firstDataArg,
                                         Type, CallType, InFunctionCall,
                                         CheckedVarArgs, UncoveredArg, Offset);
          } else if (const FunctionDecl *FD = dyn_cast<FunctionDecl>(ND)) {
            unsigned BuiltinID = FD->getBuiltinID();
            if (BuiltinID == Builtin::BI__builtin___CFStringMakeConstantString ||
                BuiltinID == Builtin::BI__builtin___NSStringMakeConstantString) {
              const Expr *Arg = CE->getArg(0);
              return checkFormatStringExpr(S, Arg, Args,
                                           HasVAListArg, format_idx,
                                           firstDataArg, Type, CallType,
                                           InFunctionCall, CheckedVarArgs,
                                           UncoveredArg, Offset);
            }
          }
        }
    
        return SLCT_NotALiteral;
      }
      case Stmt::ObjCMessageExprClass: {
        const auto *ME = cast<ObjCMessageExpr>(E);
        if (const auto *ND = ME->getMethodDecl()) {
          if (const auto *FA = ND->getAttr<FormatArgAttr>()) {
            unsigned ArgIndex = FA->getFormatIdx();
            const Expr *Arg = ME->getArg(ArgIndex - 1);
            return checkFormatStringExpr(
                S, Arg, Args, HasVAListArg, format_idx, firstDataArg, Type,
                CallType, InFunctionCall, CheckedVarArgs, UncoveredArg, Offset);
          }
        }
    
        return SLCT_NotALiteral;
      }
      case Stmt::ObjCStringLiteralClass:
      case Stmt::StringLiteralClass: {
        const StringLiteral *StrE = nullptr;
    
        if (const ObjCStringLiteral *ObjCFExpr = dyn_cast<ObjCStringLiteral>(E))
          StrE = ObjCFExpr->getString();
        else
          StrE = cast<StringLiteral>(E);
    
        if (StrE) {
          if (Offset.isNegative() || Offset > StrE->getLength()) {
            // TODO: It would be better to have an explicit warning for out of
            // bounds literals.
            return SLCT_NotALiteral;
          }
          FormatStringLiteral FStr(StrE, Offset.sextOrTrunc(64).getSExtValue());
          CheckFormatString(S, &FStr, E, Args, HasVAListArg, format_idx,
                            firstDataArg, Type, InFunctionCall, CallType,
                            CheckedVarArgs, UncoveredArg);
          return SLCT_CheckedLiteral;
        }
    
        return SLCT_NotALiteral;
      }
      case Stmt::BinaryOperatorClass: {
        llvm::APSInt LResult;
        llvm::APSInt RResult;
    
        const BinaryOperator *BinOp = cast<BinaryOperator>(E);
    
        // A string literal + an int offset is still a string literal.
        if (BinOp->isAdditiveOp()) {
          bool LIsInt = BinOp->getLHS()->EvaluateAsInt(LResult, S.Context);
          bool RIsInt = BinOp->getRHS()->EvaluateAsInt(RResult, S.Context);
    
          if (LIsInt != RIsInt) {
            BinaryOperatorKind BinOpKind = BinOp->getOpcode();
    
            if (LIsInt) {
              if (BinOpKind == BO_Add) {
                sumOffsets(Offset, LResult, BinOpKind, RIsInt);
                E = BinOp->getRHS();
                goto tryAgain;
              }
            } else {
              sumOffsets(Offset, RResult, BinOpKind, RIsInt);
              E = BinOp->getLHS();
              goto tryAgain;
            }
          }
        }
    
        return SLCT_NotALiteral;
      }
      case Stmt::UnaryOperatorClass: {
        const UnaryOperator *UnaOp = cast<UnaryOperator>(E);
        auto ASE = dyn_cast<ArraySubscriptExpr>(UnaOp->getSubExpr());
        if (UnaOp->getOpcode() == clang::UO_AddrOf && ASE) {
          llvm::APSInt IndexResult;
          if (ASE->getRHS()->EvaluateAsInt(IndexResult, S.Context)) {
            sumOffsets(Offset, IndexResult, BO_Add, /*RHS is int*/ true);
            E = ASE->getBase();
            goto tryAgain;
          }
        }
    
        return SLCT_NotALiteral;
      }
    
      default:
        return SLCT_NotALiteral;
      }
    }
    
    Sema::FormatStringType Sema::GetFormatStringType(const FormatAttr *Format) {
      return llvm::StringSwitch<FormatStringType>(Format->getType()->getName())
          .Case("scanf", FST_Scanf)
          .Cases("printf", "printf0", FST_Printf)
          .Cases("NSString", "CFString", FST_NSString)
          .Case("strftime", FST_Strftime)
          .Case("strfmon", FST_Strfmon)
          .Cases("kprintf", "cmn_err", "vcmn_err", "zcmn_err", FST_Kprintf)
          .Case("freebsd_kprintf", FST_FreeBSDKPrintf)
          .Case("os_trace", FST_OSLog)
          .Case("os_log", FST_OSLog)
          .Default(FST_Unknown);
    }
    
    /// CheckFormatArguments - Check calls to printf and scanf (and similar
    /// functions) for correct use of format strings.
    /// Returns true if a format string has been fully checked.
    bool Sema::CheckFormatArguments(const FormatAttr *Format,
                                    ArrayRef<const Expr *> Args,
                                    bool IsCXXMember,
                                    VariadicCallType CallType,
                                    SourceLocation Loc, SourceRange Range,
                                    llvm::SmallBitVector &CheckedVarArgs) {
      FormatStringInfo FSI;
      if (getFormatStringInfo(Format, IsCXXMember, &FSI))
        return CheckFormatArguments(Args, FSI.HasVAListArg, FSI.FormatIdx,
                                    FSI.FirstDataArg, GetFormatStringType(Format),
                                    CallType, Loc, Range, CheckedVarArgs);
      return false;
    }
    
    bool Sema::CheckFormatArguments(ArrayRef<const Expr *> Args,
                                    bool HasVAListArg, unsigned format_idx,
                                    unsigned firstDataArg, FormatStringType Type,
                                    VariadicCallType CallType,
                                    SourceLocation Loc, SourceRange Range,
                                    llvm::SmallBitVector &CheckedVarArgs) {
      // CHECK: printf/scanf-like function is called with no format string.
      if (format_idx >= Args.size()) {
        Diag(Loc, diag::warn_missing_format_string) << Range;
        return false;
      }
    
      const Expr *OrigFormatExpr = Args[format_idx]->IgnoreParenCasts();
    
      // CHECK: format string is not a string literal.
      //
      // Dynamically generated format strings are difficult to
      // automatically vet at compile time.  Requiring that format strings
      // are string literals: (1) permits the checking of format strings by
      // the compiler and thereby (2) can practically remove the source of
      // many format string exploits.
    
      // Format string can be either ObjC string (e.g. @"%d") or
      // C string (e.g. "%d")
      // ObjC string uses the same format specifiers as C string, so we can use
      // the same format string checking logic for both ObjC and C strings.
      UncoveredArgHandler UncoveredArg;
      StringLiteralCheckType CT =
          checkFormatStringExpr(*this, OrigFormatExpr, Args, HasVAListArg,
                                format_idx, firstDataArg, Type, CallType,
                                /*IsFunctionCall*/ true, CheckedVarArgs,
                                UncoveredArg,
                                /*no string offset*/ llvm::APSInt(64, false) = 0);
    
      // Generate a diagnostic where an uncovered argument is detected.
      if (UncoveredArg.hasUncoveredArg()) {
        unsigned ArgIdx = UncoveredArg.getUncoveredArg() + firstDataArg;
        assert(ArgIdx < Args.size() && "ArgIdx outside bounds");
        UncoveredArg.Diagnose(*this, /*IsFunctionCall*/true, Args[ArgIdx]);
      }
    
      if (CT != SLCT_NotALiteral)
        // Literal format string found, check done!
        return CT == SLCT_CheckedLiteral;
    
      // Strftime is particular as it always uses a single 'time' argument,
      // so it is safe to pass a non-literal string.
      if (Type == FST_Strftime)
        return false;
    
      // Do not emit diag when the string param is a macro expansion and the
      // format is either NSString or CFString. This is a hack to prevent
      // diag when using the NSLocalizedString and CFCopyLocalizedString macros
      // which are usually used in place of NS and CF string literals.
      SourceLocation FormatLoc = Args[format_idx]->getLocStart();
      if (Type == FST_NSString && SourceMgr.isInSystemMacro(FormatLoc))
        return false;
    
      // If there are no arguments specified, warn with -Wformat-security, otherwise
      // warn only with -Wformat-nonliteral.
      if (Args.size() == firstDataArg) {
        Diag(FormatLoc, diag::warn_format_nonliteral_noargs)
          << OrigFormatExpr->getSourceRange();
        switch (Type) {
        default:
          break;
        case FST_Kprintf:
        case FST_FreeBSDKPrintf:
        case FST_Printf:
          Diag(FormatLoc, diag::note_format_security_fixit)
            << FixItHint::CreateInsertion(FormatLoc, "\"%s\", ");
          break;
        case FST_NSString:
          Diag(FormatLoc, diag::note_format_security_fixit)
            << FixItHint::CreateInsertion(FormatLoc, "@\"%@\", ");
          break;
        }
      } else {
        Diag(FormatLoc, diag::warn_format_nonliteral)
          << OrigFormatExpr->getSourceRange();
      }
      return false;
    }
    
    namespace {
    class CheckFormatHandler : public analyze_format_string::FormatStringHandler {
    protected:
      Sema &S;
      const FormatStringLiteral *FExpr;
      const Expr *OrigFormatExpr;
      const Sema::FormatStringType FSType;
      const unsigned FirstDataArg;
      const unsigned NumDataArgs;
      const char *Beg; // Start of format string.
      const bool HasVAListArg;
      ArrayRef<const Expr *> Args;
      unsigned FormatIdx;
      llvm::SmallBitVector CoveredArgs;
      bool usesPositionalArgs;
      bool atFirstArg;
      bool inFunctionCall;
      Sema::VariadicCallType CallType;
      llvm::SmallBitVector &CheckedVarArgs;
      UncoveredArgHandler &UncoveredArg;
    
    public:
      CheckFormatHandler(Sema &s, const FormatStringLiteral *fexpr,
                         const Expr *origFormatExpr,
                         const Sema::FormatStringType type, unsigned firstDataArg,
                         unsigned numDataArgs, const char *beg, bool hasVAListArg,
                         ArrayRef<const Expr *> Args, unsigned formatIdx,
                         bool inFunctionCall, Sema::VariadicCallType callType,
                         llvm::SmallBitVector &CheckedVarArgs,
                         UncoveredArgHandler &UncoveredArg)
          : S(s), FExpr(fexpr), OrigFormatExpr(origFormatExpr), FSType(type),
            FirstDataArg(firstDataArg), NumDataArgs(numDataArgs), Beg(beg),
            HasVAListArg(hasVAListArg), Args(Args), FormatIdx(formatIdx),
            usesPositionalArgs(false), atFirstArg(true),
            inFunctionCall(inFunctionCall), CallType(callType),
            CheckedVarArgs(CheckedVarArgs), UncoveredArg(UncoveredArg) {
        CoveredArgs.resize(numDataArgs);
        CoveredArgs.reset();
      }
    
      void DoneProcessing();
    
      void HandleIncompleteSpecifier(const char *startSpecifier,
                                     unsigned specifierLen) override;
    
      void HandleInvalidLengthModifier(
                               const analyze_format_string::FormatSpecifier &FS,
                               const analyze_format_string::ConversionSpecifier &CS,
                               const char *startSpecifier, unsigned specifierLen,
                               unsigned DiagID);
    
      void HandleNonStandardLengthModifier(
                        const analyze_format_string::FormatSpecifier &FS,
                        const char *startSpecifier, unsigned specifierLen);
    
      void HandleNonStandardConversionSpecifier(
                        const analyze_format_string::ConversionSpecifier &CS,
                        const char *startSpecifier, unsigned specifierLen);
    
      void HandlePosition(const char *startPos, unsigned posLen) override;
    
      void HandleInvalidPosition(const char *startSpecifier,
                                 unsigned specifierLen,
                                 analyze_format_string::PositionContext p) override;
    
      void HandleZeroPosition(const char *startPos, unsigned posLen) override;
    
      void HandleNullChar(const char *nullCharacter) override;
    
      template <typename Range>
      static void
      EmitFormatDiagnostic(Sema &S, bool inFunctionCall, const Expr *ArgumentExpr,
                           const PartialDiagnostic &PDiag, SourceLocation StringLoc,
                           bool IsStringLocation, Range StringRange,
                           ArrayRef<FixItHint> Fixit = None);
    
    protected:
      bool HandleInvalidConversionSpecifier(unsigned argIndex, SourceLocation Loc,
                                            const char *startSpec,
                                            unsigned specifierLen,
                                            const char *csStart, unsigned csLen);
    
      void HandlePositionalNonpositionalArgs(SourceLocation Loc,
                                             const char *startSpec,
                                             unsigned specifierLen);
      
      SourceRange getFormatStringRange();
      CharSourceRange getSpecifierRange(const char *startSpecifier,
                                        unsigned specifierLen);
      SourceLocation getLocationOfByte(const char *x);
    
      const Expr *getDataArg(unsigned i) const;
      
      bool CheckNumArgs(const analyze_format_string::FormatSpecifier &FS,
                        const analyze_format_string::ConversionSpecifier &CS,
                        const char *startSpecifier, unsigned specifierLen,
                        unsigned argIndex);
    
      template <typename Range>
      void EmitFormatDiagnostic(PartialDiagnostic PDiag, SourceLocation StringLoc,
                                bool IsStringLocation, Range StringRange,
                                ArrayRef<FixItHint> Fixit = None);
    };
    } // end anonymous namespace
    
    SourceRange CheckFormatHandler::getFormatStringRange() {
      return OrigFormatExpr->getSourceRange();
    }
    
    CharSourceRange CheckFormatHandler::
    getSpecifierRange(const char *startSpecifier, unsigned specifierLen) {
      SourceLocation Start = getLocationOfByte(startSpecifier);
      SourceLocation End   = getLocationOfByte(startSpecifier + specifierLen - 1);
    
      // Advance the end SourceLocation by one due to half-open ranges.
      End = End.getLocWithOffset(1);
    
      return CharSourceRange::getCharRange(Start, End);
    }
    
    SourceLocation CheckFormatHandler::getLocationOfByte(const char *x) {
      return FExpr->getLocationOfByte(x - Beg, S.getSourceManager(),
                                      S.getLangOpts(), S.Context.getTargetInfo());
    }
    
    void CheckFormatHandler::HandleIncompleteSpecifier(const char *startSpecifier,
                                                       unsigned specifierLen){
      EmitFormatDiagnostic(S.PDiag(diag::warn_printf_incomplete_specifier),
                           getLocationOfByte(startSpecifier),
                           /*IsStringLocation*/true,
                           getSpecifierRange(startSpecifier, specifierLen));
    }
    
    void CheckFormatHandler::HandleInvalidLengthModifier(
        const analyze_format_string::FormatSpecifier &FS,
        const analyze_format_string::ConversionSpecifier &CS,
        const char *startSpecifier, unsigned specifierLen, unsigned DiagID) {
      using namespace analyze_format_string;
    
      const LengthModifier &LM = FS.getLengthModifier();
      CharSourceRange LMRange = getSpecifierRange(LM.getStart(), LM.getLength());
    
      // See if we know how to fix this length modifier.
      Optional<LengthModifier> FixedLM = FS.getCorrectedLengthModifier();
      if (FixedLM) {
        EmitFormatDiagnostic(S.PDiag(DiagID) << LM.toString() << CS.toString(),
                             getLocationOfByte(LM.getStart()),
                             /*IsStringLocation*/true,
                             getSpecifierRange(startSpecifier, specifierLen));
    
        S.Diag(getLocationOfByte(LM.getStart()), diag::note_format_fix_specifier)
          << FixedLM->toString()
          << FixItHint::CreateReplacement(LMRange, FixedLM->toString());
    
      } else {
        FixItHint Hint;
        if (DiagID == diag::warn_format_nonsensical_length)
          Hint = FixItHint::CreateRemoval(LMRange);
    
        EmitFormatDiagnostic(S.PDiag(DiagID) << LM.toString() << CS.toString(),
                             getLocationOfByte(LM.getStart()),
                             /*IsStringLocation*/true,
                             getSpecifierRange(startSpecifier, specifierLen),
                             Hint);
      }
    }
    
    void CheckFormatHandler::HandleNonStandardLengthModifier(
        const analyze_format_string::FormatSpecifier &FS,
        const char *startSpecifier, unsigned specifierLen) {
      using namespace analyze_format_string;
    
      const LengthModifier &LM = FS.getLengthModifier();
      CharSourceRange LMRange = getSpecifierRange(LM.getStart(), LM.getLength());
    
      // See if we know how to fix this length modifier.
      Optional<LengthModifier> FixedLM = FS.getCorrectedLengthModifier();
      if (FixedLM) {
        EmitFormatDiagnostic(S.PDiag(diag::warn_format_non_standard)
                               << LM.toString() << 0,
                             getLocationOfByte(LM.getStart()),
                             /*IsStringLocation*/true,
                             getSpecifierRange(startSpecifier, specifierLen));
    
        S.Diag(getLocationOfByte(LM.getStart()), diag::note_format_fix_specifier)
          << FixedLM->toString()
          << FixItHint::CreateReplacement(LMRange, FixedLM->toString());
    
      } else {
        EmitFormatDiagnostic(S.PDiag(diag::warn_format_non_standard)
                               << LM.toString() << 0,
                             getLocationOfByte(LM.getStart()),
                             /*IsStringLocation*/true,
                             getSpecifierRange(startSpecifier, specifierLen));
      }
    }
    
    void CheckFormatHandler::HandleNonStandardConversionSpecifier(
        const analyze_format_string::ConversionSpecifier &CS,
        const char *startSpecifier, unsigned specifierLen) {
      using namespace analyze_format_string;
    
      // See if we know how to fix this conversion specifier.
      Optional<ConversionSpecifier> FixedCS = CS.getStandardSpecifier();
      if (FixedCS) {
        EmitFormatDiagnostic(S.PDiag(diag::warn_format_non_standard)
                              << CS.toString() << /*conversion specifier*/1,
                             getLocationOfByte(CS.getStart()),
                             /*IsStringLocation*/true,
                             getSpecifierRange(startSpecifier, specifierLen));
    
        CharSourceRange CSRange = getSpecifierRange(CS.getStart(), CS.getLength());
        S.Diag(getLocationOfByte(CS.getStart()), diag::note_format_fix_specifier)
          << FixedCS->toString()
          << FixItHint::CreateReplacement(CSRange, FixedCS->toString());
      } else {
        EmitFormatDiagnostic(S.PDiag(diag::warn_format_non_standard)
                              << CS.toString() << /*conversion specifier*/1,
                             getLocationOfByte(CS.getStart()),
                             /*IsStringLocation*/true,
                             getSpecifierRange(startSpecifier, specifierLen));
      }
    }
    
    void CheckFormatHandler::HandlePosition(const char *startPos,
                                            unsigned posLen) {
      EmitFormatDiagnostic(S.PDiag(diag::warn_format_non_standard_positional_arg),
                                   getLocationOfByte(startPos),
                                   /*IsStringLocation*/true,
                                   getSpecifierRange(startPos, posLen));
    }
    
    void
    CheckFormatHandler::HandleInvalidPosition(const char *startPos, unsigned posLen,
                                         analyze_format_string::PositionContext p) {
      EmitFormatDiagnostic(S.PDiag(diag::warn_format_invalid_positional_specifier)
                             << (unsigned) p,
                           getLocationOfByte(startPos), /*IsStringLocation*/true,
                           getSpecifierRange(startPos, posLen));
    }
    
    void CheckFormatHandler::HandleZeroPosition(const char *startPos,
                                                unsigned posLen) {
      EmitFormatDiagnostic(S.PDiag(diag::warn_format_zero_positional_specifier),
                                   getLocationOfByte(startPos),
                                   /*IsStringLocation*/true,
                                   getSpecifierRange(startPos, posLen));
    }
    
    void CheckFormatHandler::HandleNullChar(const char *nullCharacter) {
      if (!isa<ObjCStringLiteral>(OrigFormatExpr)) {
        // The presence of a null character is likely an error.
        EmitFormatDiagnostic(
          S.PDiag(diag::warn_printf_format_string_contains_null_char),
          getLocationOfByte(nullCharacter), /*IsStringLocation*/true,
          getFormatStringRange());
      }
    }
    
    // Note that this may return NULL if there was an error parsing or building
    // one of the argument expressions.
    const Expr *CheckFormatHandler::getDataArg(unsigned i) const {
      return Args[FirstDataArg + i];
    }
    
    void CheckFormatHandler::DoneProcessing() {
      // Does the number of data arguments exceed the number of
      // format conversions in the format string?
      if (!HasVAListArg) {
          // Find any arguments that weren't covered.
        CoveredArgs.flip();
        signed notCoveredArg = CoveredArgs.find_first();
        if (notCoveredArg >= 0) {
          assert((unsigned)notCoveredArg < NumDataArgs);
          UncoveredArg.Update(notCoveredArg, OrigFormatExpr);
        } else {
          UncoveredArg.setAllCovered();
        }
      }
    }
    
    void UncoveredArgHandler::Diagnose(Sema &S, bool IsFunctionCall,
                                       const Expr *ArgExpr) {
      assert(hasUncoveredArg() && DiagnosticExprs.size() > 0 &&
             "Invalid state");
    
      if (!ArgExpr)
        return;
    
      SourceLocation Loc = ArgExpr->getLocStart();
    
      if (S.getSourceManager().isInSystemMacro(Loc))
        return;
    
      PartialDiagnostic PDiag = S.PDiag(diag::warn_printf_data_arg_not_used);
      for (auto E : DiagnosticExprs)
        PDiag << E->getSourceRange();
    
      CheckFormatHandler::EmitFormatDiagnostic(
                                      S, IsFunctionCall, DiagnosticExprs[0],
                                      PDiag, Loc, /*IsStringLocation*/false,
                                      DiagnosticExprs[0]->getSourceRange());
    }
    
    bool
    CheckFormatHandler::HandleInvalidConversionSpecifier(unsigned argIndex,
                                                         SourceLocation Loc,
                                                         const char *startSpec,
                                                         unsigned specifierLen,
                                                         const char *csStart,
                                                         unsigned csLen) {
      bool keepGoing = true;
      if (argIndex < NumDataArgs) {
        // Consider the argument coverered, even though the specifier doesn't
        // make sense.
        CoveredArgs.set(argIndex);
      }
      else {
        // If argIndex exceeds the number of data arguments we
        // don't issue a warning because that is just a cascade of warnings (and
        // they may have intended '%%' anyway). We don't want to continue processing
        // the format string after this point, however, as we will like just get
        // gibberish when trying to match arguments.
        keepGoing = false;
      }
    
      StringRef Specifier(csStart, csLen);
    
      // If the specifier in non-printable, it could be the first byte of a UTF-8
      // sequence. In that case, print the UTF-8 code point. If not, print the byte
      // hex value.
      std::string CodePointStr;
      if (!llvm::sys::locale::isPrint(*csStart)) {
        llvm::UTF32 CodePoint;
        const llvm::UTF8 **B = reinterpret_cast<const llvm::UTF8 **>(&csStart);
        const llvm::UTF8 *E =
            reinterpret_cast<const llvm::UTF8 *>(csStart + csLen);
        llvm::ConversionResult Result =
            llvm::convertUTF8Sequence(B, E, &CodePoint, llvm::strictConversion);
    
        if (Result != llvm::conversionOK) {
          unsigned char FirstChar = *csStart;
          CodePoint = (llvm::UTF32)FirstChar;
        }
    
        llvm::raw_string_ostream OS(CodePointStr);
        if (CodePoint < 256)
          OS << "\\x" << llvm::format("%02x", CodePoint);
        else if (CodePoint <= 0xFFFF)
          OS << "\\u" << llvm::format("%04x", CodePoint);
        else
          OS << "\\U" << llvm::format("%08x", CodePoint);
        OS.flush();
        Specifier = CodePointStr;
      }
    
      EmitFormatDiagnostic(
          S.PDiag(diag::warn_format_invalid_conversion) << Specifier, Loc,
          /*IsStringLocation*/ true, getSpecifierRange(startSpec, specifierLen));
    
      return keepGoing;
    }
    
    void
    CheckFormatHandler::HandlePositionalNonpositionalArgs(SourceLocation Loc,
                                                          const char *startSpec,
                                                          unsigned specifierLen) {
      EmitFormatDiagnostic(
        S.PDiag(diag::warn_format_mix_positional_nonpositional_args),
        Loc, /*isStringLoc*/true, getSpecifierRange(startSpec, specifierLen));
    }
    
    bool
    CheckFormatHandler::CheckNumArgs(
      const analyze_format_string::FormatSpecifier &FS,
      const analyze_format_string::ConversionSpecifier &CS,
      const char *startSpecifier, unsigned specifierLen, unsigned argIndex) {
    
      if (argIndex >= NumDataArgs) {
        PartialDiagnostic PDiag = FS.usesPositionalArg()
          ? (S.PDiag(diag::warn_printf_positional_arg_exceeds_data_args)
               << (argIndex+1) << NumDataArgs)
          : S.PDiag(diag::warn_printf_insufficient_data_args);
        EmitFormatDiagnostic(
          PDiag, getLocationOfByte(CS.getStart()), /*IsStringLocation*/true,
          getSpecifierRange(startSpecifier, specifierLen));
    
        // Since more arguments than conversion tokens are given, by extension
        // all arguments are covered, so mark this as so.
        UncoveredArg.setAllCovered();
        return false;
      }
      return true;
    }
    
    template<typename Range>
    void CheckFormatHandler::EmitFormatDiagnostic(PartialDiagnostic PDiag,
                                                  SourceLocation Loc,
                                                  bool IsStringLocation,
                                                  Range StringRange,
                                                  ArrayRef<FixItHint> FixIt) {
      EmitFormatDiagnostic(S, inFunctionCall, Args[FormatIdx], PDiag,
                           Loc, IsStringLocation, StringRange, FixIt);
    }
    
    /// \brief If the format string is not within the funcion call, emit a note
    /// so that the function call and string are in diagnostic messages.
    ///
    /// \param InFunctionCall if true, the format string is within the function
    /// call and only one diagnostic message will be produced.  Otherwise, an
    /// extra note will be emitted pointing to location of the format string.
    ///
    /// \param ArgumentExpr the expression that is passed as the format string
    /// argument in the function call.  Used for getting locations when two
    /// diagnostics are emitted.
    ///
    /// \param PDiag the callee should already have provided any strings for the
    /// diagnostic message.  This function only adds locations and fixits
    /// to diagnostics.
    ///
    /// \param Loc primary location for diagnostic.  If two diagnostics are
    /// required, one will be at Loc and a new SourceLocation will be created for
    /// the other one.
    ///
    /// \param IsStringLocation if true, Loc points to the format string should be
    /// used for the note.  Otherwise, Loc points to the argument list and will
    /// be used with PDiag.
    ///
    /// \param StringRange some or all of the string to highlight.  This is
    /// templated so it can accept either a CharSourceRange or a SourceRange.
    ///
    /// \param FixIt optional fix it hint for the format string.
    template <typename Range>
    void CheckFormatHandler::EmitFormatDiagnostic(
        Sema &S, bool InFunctionCall, const Expr *ArgumentExpr,
        const PartialDiagnostic &PDiag, SourceLocation Loc, bool IsStringLocation,
        Range StringRange, ArrayRef<FixItHint> FixIt) {
      if (InFunctionCall) {
        const Sema::SemaDiagnosticBuilder &D = S.Diag(Loc, PDiag);
        D << StringRange;
        D << FixIt;
      } else {
        S.Diag(IsStringLocation ? ArgumentExpr->getExprLoc() : Loc, PDiag)
          << ArgumentExpr->getSourceRange();
    
        const Sema::SemaDiagnosticBuilder &Note =
          S.Diag(IsStringLocation ? Loc : StringRange.getBegin(),
                 diag::note_format_string_defined);
    
        Note << StringRange;
        Note << FixIt;
      }
    }
    
    //===--- CHECK: Printf format string checking ------------------------------===//
    
    namespace {
    class CheckPrintfHandler : public CheckFormatHandler {
    public:
      CheckPrintfHandler(Sema &s, const FormatStringLiteral *fexpr,
                         const Expr *origFormatExpr,
                         const Sema::FormatStringType type, unsigned firstDataArg,
                         unsigned numDataArgs, bool isObjC, const char *beg,
                         bool hasVAListArg, ArrayRef<const Expr *> Args,
                         unsigned formatIdx, bool inFunctionCall,
                         Sema::VariadicCallType CallType,
                         llvm::SmallBitVector &CheckedVarArgs,
                         UncoveredArgHandler &UncoveredArg)
          : CheckFormatHandler(s, fexpr, origFormatExpr, type, firstDataArg,
                               numDataArgs, beg, hasVAListArg, Args, formatIdx,
                               inFunctionCall, CallType, CheckedVarArgs,
                               UncoveredArg) {}
    
      bool isObjCContext() const { return FSType == Sema::FST_NSString; }
    
      /// Returns true if '%@' specifiers are allowed in the format string.
      bool allowsObjCArg() const {
        return FSType == Sema::FST_NSString || FSType == Sema::FST_OSLog ||
               FSType == Sema::FST_OSTrace;
      }
    
      bool HandleInvalidPrintfConversionSpecifier(
                                          const analyze_printf::PrintfSpecifier &FS,
                                          const char *startSpecifier,
                                          unsigned specifierLen) override;
    
      bool HandlePrintfSpecifier(const analyze_printf::PrintfSpecifier &FS,
                                 const char *startSpecifier,
                                 unsigned specifierLen) override;
      bool checkFormatExpr(const analyze_printf::PrintfSpecifier &FS,
                           const char *StartSpecifier,
                           unsigned SpecifierLen,
                           const Expr *E);
    
      bool HandleAmount(const analyze_format_string::OptionalAmount &Amt, unsigned k,
                        const char *startSpecifier, unsigned specifierLen);
      void HandleInvalidAmount(const analyze_printf::PrintfSpecifier &FS,
                               const analyze_printf::OptionalAmount &Amt,
                               unsigned type,
                               const char *startSpecifier, unsigned specifierLen);
      void HandleFlag(const analyze_printf::PrintfSpecifier &FS,
                      const analyze_printf::OptionalFlag &flag,
                      const char *startSpecifier, unsigned specifierLen);
      void HandleIgnoredFlag(const analyze_printf::PrintfSpecifier &FS,
                             const analyze_printf::OptionalFlag &ignoredFlag,
                             const analyze_printf::OptionalFlag &flag,
                             const char *startSpecifier, unsigned specifierLen);
      bool checkForCStrMembers(const analyze_printf::ArgType &AT,
                               const Expr *E);
                               
      void HandleEmptyObjCModifierFlag(const char *startFlag,
                                       unsigned flagLen) override;
    
      void HandleInvalidObjCModifierFlag(const char *startFlag,
                                                unsigned flagLen) override;
    
      void HandleObjCFlagsWithNonObjCConversion(const char *flagsStart,
                                               const char *flagsEnd,
                                               const char *conversionPosition) 
                                                 override;
    };
    } // end anonymous namespace
    
    bool CheckPrintfHandler::HandleInvalidPrintfConversionSpecifier(
                                          const analyze_printf::PrintfSpecifier &FS,
                                          const char *startSpecifier,
                                          unsigned specifierLen) {
      const analyze_printf::PrintfConversionSpecifier &CS =
        FS.getConversionSpecifier();
      
      return HandleInvalidConversionSpecifier(FS.getArgIndex(),
                                              getLocationOfByte(CS.getStart()),
                                              startSpecifier, specifierLen,
                                              CS.getStart(), CS.getLength());
    }
    
    bool CheckPrintfHandler::HandleAmount(
                                   const analyze_format_string::OptionalAmount &Amt,
                                   unsigned k, const char *startSpecifier,
                                   unsigned specifierLen) {
      if (Amt.hasDataArgument()) {
        if (!HasVAListArg) {
          unsigned argIndex = Amt.getArgIndex();
          if (argIndex >= NumDataArgs) {
            EmitFormatDiagnostic(S.PDiag(diag::warn_printf_asterisk_missing_arg)
                                   << k,
                                 getLocationOfByte(Amt.getStart()),
                                 /*IsStringLocation*/true,
                                 getSpecifierRange(startSpecifier, specifierLen));
            // Don't do any more checking.  We will just emit
            // spurious errors.
            return false;
          }
    
          // Type check the data argument.  It should be an 'int'.
          // Although not in conformance with C99, we also allow the argument to be
          // an 'unsigned int' as that is a reasonably safe case.  GCC also
          // doesn't emit a warning for that case.
          CoveredArgs.set(argIndex);
          const Expr *Arg = getDataArg(argIndex);
          if (!Arg)
            return false;
    
          QualType T = Arg->getType();
    
          const analyze_printf::ArgType &AT = Amt.getArgType(S.Context);
          assert(AT.isValid());
    
          if (!AT.matchesType(S.Context, T)) {
            EmitFormatDiagnostic(S.PDiag(diag::warn_printf_asterisk_wrong_type)
                                   << k << AT.getRepresentativeTypeName(S.Context)
                                   << T << Arg->getSourceRange(),
                                 getLocationOfByte(Amt.getStart()),
                                 /*IsStringLocation*/true,
                                 getSpecifierRange(startSpecifier, specifierLen));
            // Don't do any more checking.  We will just emit
            // spurious errors.
            return false;
          }
        }
      }
      return true;
    }
    
    void CheckPrintfHandler::HandleInvalidAmount(
                                          const analyze_printf::PrintfSpecifier &FS,
                                          const analyze_printf::OptionalAmount &Amt,
                                          unsigned type,
                                          const char *startSpecifier,
                                          unsigned specifierLen) {
      const analyze_printf::PrintfConversionSpecifier &CS =
        FS.getConversionSpecifier();
    
      FixItHint fixit =
        Amt.getHowSpecified() == analyze_printf::OptionalAmount::Constant
          ? FixItHint::CreateRemoval(getSpecifierRange(Amt.getStart(),
                                     Amt.getConstantLength()))
          : FixItHint();
    
      EmitFormatDiagnostic(S.PDiag(diag::warn_printf_nonsensical_optional_amount)
                             << type << CS.toString(),
                           getLocationOfByte(Amt.getStart()),
                           /*IsStringLocation*/true,
                           getSpecifierRange(startSpecifier, specifierLen),
                           fixit);
    }
    
    void CheckPrintfHandler::HandleFlag(const analyze_printf::PrintfSpecifier &FS,
                                        const analyze_printf::OptionalFlag &flag,
                                        const char *startSpecifier,
                                        unsigned specifierLen) {
      // Warn about pointless flag with a fixit removal.
      const analyze_printf::PrintfConversionSpecifier &CS =
        FS.getConversionSpecifier();
      EmitFormatDiagnostic(S.PDiag(diag::warn_printf_nonsensical_flag)
                             << flag.toString() << CS.toString(),
                           getLocationOfByte(flag.getPosition()),
                           /*IsStringLocation*/true,
                           getSpecifierRange(startSpecifier, specifierLen),
                           FixItHint::CreateRemoval(
                             getSpecifierRange(flag.getPosition(), 1)));
    }
    
    void CheckPrintfHandler::HandleIgnoredFlag(
                                    const analyze_printf::PrintfSpecifier &FS,
                                    const analyze_printf::OptionalFlag &ignoredFlag,
                                    const analyze_printf::OptionalFlag &flag,
                                    const char *startSpecifier,
                                    unsigned specifierLen) {
      // Warn about ignored flag with a fixit removal.
      EmitFormatDiagnostic(S.PDiag(diag::warn_printf_ignored_flag)
                             << ignoredFlag.toString() << flag.toString(),
                           getLocationOfByte(ignoredFlag.getPosition()),
                           /*IsStringLocation*/true,
                           getSpecifierRange(startSpecifier, specifierLen),
                           FixItHint::CreateRemoval(
                             getSpecifierRange(ignoredFlag.getPosition(), 1)));
    }
    
    //  void EmitFormatDiagnostic(PartialDiagnostic PDiag, SourceLocation StringLoc,
    //                            bool IsStringLocation, Range StringRange,
    //                            ArrayRef<FixItHint> Fixit = None);
                                
    void CheckPrintfHandler::HandleEmptyObjCModifierFlag(const char *startFlag,
                                                         unsigned flagLen) {
      // Warn about an empty flag.
      EmitFormatDiagnostic(S.PDiag(diag::warn_printf_empty_objc_flag),
                           getLocationOfByte(startFlag),
                           /*IsStringLocation*/true,
                           getSpecifierRange(startFlag, flagLen));
    }
    
    void CheckPrintfHandler::HandleInvalidObjCModifierFlag(const char *startFlag,
                                                           unsigned flagLen) {
      // Warn about an invalid flag.
      auto Range = getSpecifierRange(startFlag, flagLen);
      StringRef flag(startFlag, flagLen);
      EmitFormatDiagnostic(S.PDiag(diag::warn_printf_invalid_objc_flag) << flag,
                          getLocationOfByte(startFlag),
                          /*IsStringLocation*/true,
                          Range, FixItHint::CreateRemoval(Range));
    }
    
    void CheckPrintfHandler::HandleObjCFlagsWithNonObjCConversion(
        const char *flagsStart, const char *flagsEnd, const char *conversionPosition) {
        // Warn about using '[...]' without a '@' conversion.
        auto Range = getSpecifierRange(flagsStart, flagsEnd - flagsStart + 1);
        auto diag = diag::warn_printf_ObjCflags_without_ObjCConversion;
        EmitFormatDiagnostic(S.PDiag(diag) << StringRef(conversionPosition, 1),
                             getLocationOfByte(conversionPosition),
                             /*IsStringLocation*/true,
                             Range, FixItHint::CreateRemoval(Range));
    }
    
    // Determines if the specified is a C++ class or struct containing
    // a member with the specified name and kind (e.g. a CXXMethodDecl named
    // "c_str()").
    template<typename MemberKind>
    static llvm::SmallPtrSet<MemberKind*, 1>
    CXXRecordMembersNamed(StringRef Name, Sema &S, QualType Ty) {
      const RecordType *RT = Ty->getAs<RecordType>();
      llvm::SmallPtrSet<MemberKind*, 1> Results;
    
      if (!RT)
        return Results;
      const CXXRecordDecl *RD = dyn_cast<CXXRecordDecl>(RT->getDecl());
      if (!RD || !RD->getDefinition())
        return Results;
    
      LookupResult R(S, &S.Context.Idents.get(Name), SourceLocation(),
                     Sema::LookupMemberName);
      R.suppressDiagnostics();
    
      // We just need to include all members of the right kind turned up by the
      // filter, at this point.
      if (S.LookupQualifiedName(R, RT->getDecl()))
        for (LookupResult::iterator I = R.begin(), E = R.end(); I != E; ++I) {
          NamedDecl *decl = (*I)->getUnderlyingDecl();
          if (MemberKind *FK = dyn_cast<MemberKind>(decl))
            Results.insert(FK);
        }
      return Results;
    }
    
    /// Check if we could call '.c_str()' on an object.
    ///
    /// FIXME: This returns the wrong results in some cases (if cv-qualifiers don't
    /// allow the call, or if it would be ambiguous).
    bool Sema::hasCStrMethod(const Expr *E) {
      typedef llvm::SmallPtrSet<CXXMethodDecl*, 1> MethodSet;
      MethodSet Results =
          CXXRecordMembersNamed<CXXMethodDecl>("c_str", *this, E->getType());
      for (MethodSet::iterator MI = Results.begin(), ME = Results.end();
           MI != ME; ++MI)
        if ((*MI)->getMinRequiredArguments() == 0)
          return true;
      return false;
    }
    
    // Check if a (w)string was passed when a (w)char* was needed, and offer a
    // better diagnostic if so. AT is assumed to be valid.
    // Returns true when a c_str() conversion method is found.
    bool CheckPrintfHandler::checkForCStrMembers(
        const analyze_printf::ArgType &AT, const Expr *E) {
      typedef llvm::SmallPtrSet<CXXMethodDecl*, 1> MethodSet;
    
      MethodSet Results =
          CXXRecordMembersNamed<CXXMethodDecl>("c_str", S, E->getType());
    
      for (MethodSet::iterator MI = Results.begin(), ME = Results.end();
           MI != ME; ++MI) {
        const CXXMethodDecl *Method = *MI;
        if (Method->getMinRequiredArguments() == 0 &&
            AT.matchesType(S.Context, Method->getReturnType())) {
          // FIXME: Suggest parens if the expression needs them.
          SourceLocation EndLoc = S.getLocForEndOfToken(E->getLocEnd());
          S.Diag(E->getLocStart(), diag::note_printf_c_str)
              << "c_str()"
              << FixItHint::CreateInsertion(EndLoc, ".c_str()");
          return true;
        }
      }
    
      return false;
    }
    
    bool
    CheckPrintfHandler::HandlePrintfSpecifier(const analyze_printf::PrintfSpecifier
                                                &FS,
                                              const char *startSpecifier,
                                              unsigned specifierLen) {
      using namespace analyze_format_string;
      using namespace analyze_printf;  
      const PrintfConversionSpecifier &CS = FS.getConversionSpecifier();
    
      if (FS.consumesDataArgument()) {
        if (atFirstArg) {
            atFirstArg = false;
            usesPositionalArgs = FS.usesPositionalArg();
        }
        else if (usesPositionalArgs != FS.usesPositionalArg()) {
          HandlePositionalNonpositionalArgs(getLocationOfByte(CS.getStart()),
                                            startSpecifier, specifierLen);
          return false;
        }
      }
    
      // First check if the field width, precision, and conversion specifier
      // have matching data arguments.
      if (!HandleAmount(FS.getFieldWidth(), /* field width */ 0,
                        startSpecifier, specifierLen)) {
        return false;
      }
    
      if (!HandleAmount(FS.getPrecision(), /* precision */ 1,
                        startSpecifier, specifierLen)) {
        return false;
      }
    
      if (!CS.consumesDataArgument()) {
        // FIXME: Technically specifying a precision or field width here
        // makes no sense.  Worth issuing a warning at some point.
        return true;
      }
    
      // Consume the argument.
      unsigned argIndex = FS.getArgIndex();
      if (argIndex < NumDataArgs) {
        // The check to see if the argIndex is valid will come later.
        // We set the bit here because we may exit early from this
        // function if we encounter some other error.
        CoveredArgs.set(argIndex);
      }
    
      // FreeBSD kernel extensions.
      if (CS.getKind() == ConversionSpecifier::FreeBSDbArg ||
          CS.getKind() == ConversionSpecifier::FreeBSDDArg) {
        // We need at least two arguments.
        if (!CheckNumArgs(FS, CS, startSpecifier, specifierLen, argIndex + 1))
          return false;
    
        // Claim the second argument.
        CoveredArgs.set(argIndex + 1);
    
        // Type check the first argument (int for %b, pointer for %D)
        const Expr *Ex = getDataArg(argIndex);
        const analyze_printf::ArgType &AT =
          (CS.getKind() == ConversionSpecifier::FreeBSDbArg) ?
            ArgType(S.Context.IntTy) : ArgType::CPointerTy;
        if (AT.isValid() && !AT.matchesType(S.Context, Ex->getType()))
          EmitFormatDiagnostic(
            S.PDiag(diag::warn_format_conversion_argument_type_mismatch)
            << AT.getRepresentativeTypeName(S.Context) << Ex->getType()
            << false << Ex->getSourceRange(),
            Ex->getLocStart(), /*IsStringLocation*/false,
            getSpecifierRange(startSpecifier, specifierLen));
    
        // Type check the second argument (char * for both %b and %D)
        Ex = getDataArg(argIndex + 1);
        const analyze_printf::ArgType &AT2 = ArgType::CStrTy;
        if (AT2.isValid() && !AT2.matchesType(S.Context, Ex->getType()))
          EmitFormatDiagnostic(
            S.PDiag(diag::warn_format_conversion_argument_type_mismatch)
            << AT2.getRepresentativeTypeName(S.Context) << Ex->getType()
            << false << Ex->getSourceRange(),
            Ex->getLocStart(), /*IsStringLocation*/false,
            getSpecifierRange(startSpecifier, specifierLen));
    
         return true;
      }
    
      // Check for using an Objective-C specific conversion specifier
      // in a non-ObjC literal.
      if (!allowsObjCArg() && CS.isObjCArg()) {
        return HandleInvalidPrintfConversionSpecifier(FS, startSpecifier,
                                                      specifierLen);
      }
    
      // %P can only be used with os_log.
      if (FSType != Sema::FST_OSLog && CS.getKind() == ConversionSpecifier::PArg) {
        return HandleInvalidPrintfConversionSpecifier(FS, startSpecifier,
                                                      specifierLen);
      }
    
      // %n is not allowed with os_log.
      if (FSType == Sema::FST_OSLog && CS.getKind() == ConversionSpecifier::nArg) {
        EmitFormatDiagnostic(S.PDiag(diag::warn_os_log_format_narg),
                             getLocationOfByte(CS.getStart()),
                             /*IsStringLocation*/ false,
                             getSpecifierRange(startSpecifier, specifierLen));
    
        return true;
      }
    
      // Only scalars are allowed for os_trace.
      if (FSType == Sema::FST_OSTrace &&
          (CS.getKind() == ConversionSpecifier::PArg ||
           CS.getKind() == ConversionSpecifier::sArg ||
           CS.getKind() == ConversionSpecifier::ObjCObjArg)) {
        return HandleInvalidPrintfConversionSpecifier(FS, startSpecifier,
                                                      specifierLen);
      }
    
      // Check for use of public/private annotation outside of os_log().
      if (FSType != Sema::FST_OSLog) {
        if (FS.isPublic().isSet()) {
          EmitFormatDiagnostic(S.PDiag(diag::warn_format_invalid_annotation)
                                   << "public",
                               getLocationOfByte(FS.isPublic().getPosition()),
                               /*IsStringLocation*/ false,
                               getSpecifierRange(startSpecifier, specifierLen));
        }
        if (FS.isPrivate().isSet()) {
          EmitFormatDiagnostic(S.PDiag(diag::warn_format_invalid_annotation)
                                   << "private",
                               getLocationOfByte(FS.isPrivate().getPosition()),
                               /*IsStringLocation*/ false,
                               getSpecifierRange(startSpecifier, specifierLen));
        }
      }
    
      // Check for invalid use of field width
      if (!FS.hasValidFieldWidth()) {
        HandleInvalidAmount(FS, FS.getFieldWidth(), /* field width */ 0,
            startSpecifier, specifierLen);
      }
    
      // Check for invalid use of precision
      if (!FS.hasValidPrecision()) {
        HandleInvalidAmount(FS, FS.getPrecision(), /* precision */ 1,
            startSpecifier, specifierLen);
      }
    
      // Precision is mandatory for %P specifier.
      if (CS.getKind() == ConversionSpecifier::PArg &&
          FS.getPrecision().getHowSpecified() == OptionalAmount::NotSpecified) {
        EmitFormatDiagnostic(S.PDiag(diag::warn_format_P_no_precision),
                             getLocationOfByte(startSpecifier),
                             /*IsStringLocation*/ false,
                             getSpecifierRange(startSpecifier, specifierLen));
      }
    
      // Check each flag does not conflict with any other component.
      if (!FS.hasValidThousandsGroupingPrefix())
        HandleFlag(FS, FS.hasThousandsGrouping(), startSpecifier, specifierLen);
      if (!FS.hasValidLeadingZeros())
        HandleFlag(FS, FS.hasLeadingZeros(), startSpecifier, specifierLen);
      if (!FS.hasValidPlusPrefix())
        HandleFlag(FS, FS.hasPlusPrefix(), startSpecifier, specifierLen);
      if (!FS.hasValidSpacePrefix())
        HandleFlag(FS, FS.hasSpacePrefix(), startSpecifier, specifierLen);
      if (!FS.hasValidAlternativeForm())
        HandleFlag(FS, FS.hasAlternativeForm(), startSpecifier, specifierLen);
      if (!FS.hasValidLeftJustified())
        HandleFlag(FS, FS.isLeftJustified(), startSpecifier, specifierLen);
    
      // Check that flags are not ignored by another flag
      if (FS.hasSpacePrefix() && FS.hasPlusPrefix()) // ' ' ignored by '+'
        HandleIgnoredFlag(FS, FS.hasSpacePrefix(), FS.hasPlusPrefix(),
            startSpecifier, specifierLen);
      if (FS.hasLeadingZeros() && FS.isLeftJustified()) // '0' ignored by '-'
        HandleIgnoredFlag(FS, FS.hasLeadingZeros(), FS.isLeftJustified(),
                startSpecifier, specifierLen);
    
      // Check the length modifier is valid with the given conversion specifier.
      if (!FS.hasValidLengthModifier(S.getASTContext().getTargetInfo()))
        HandleInvalidLengthModifier(FS, CS, startSpecifier, specifierLen,
                                    diag::warn_format_nonsensical_length);
      else if (!FS.hasStandardLengthModifier())
        HandleNonStandardLengthModifier(FS, startSpecifier, specifierLen);
      else if (!FS.hasStandardLengthConversionCombination())
        HandleInvalidLengthModifier(FS, CS, startSpecifier, specifierLen,
                                    diag::warn_format_non_standard_conversion_spec);
    
      if (!FS.hasStandardConversionSpecifier(S.getLangOpts()))
        HandleNonStandardConversionSpecifier(CS, startSpecifier, specifierLen);
    
      // The remaining checks depend on the data arguments.
      if (HasVAListArg)
        return true;
    
      if (!CheckNumArgs(FS, CS, startSpecifier, specifierLen, argIndex))
        return false;
    
      const Expr *Arg = getDataArg(argIndex);
      if (!Arg)
        return true;
    
      return checkFormatExpr(FS, startSpecifier, specifierLen, Arg);
    }
    
    static bool requiresParensToAddCast(const Expr *E) {
      // FIXME: We should have a general way to reason about operator
      // precedence and whether parens are actually needed here.
      // Take care of a few common cases where they aren't.
      const Expr *Inside = E->IgnoreImpCasts();
      if (const PseudoObjectExpr *POE = dyn_cast<PseudoObjectExpr>(Inside))
        Inside = POE->getSyntacticForm()->IgnoreImpCasts();
    
      switch (Inside->getStmtClass()) {
      case Stmt::ArraySubscriptExprClass:
      case Stmt::CallExprClass:
      case Stmt::CharacterLiteralClass:
      case Stmt::CXXBoolLiteralExprClass:
      case Stmt::DeclRefExprClass:
      case Stmt::FloatingLiteralClass:
      case Stmt::IntegerLiteralClass:
      case Stmt::MemberExprClass:
      case Stmt::ObjCArrayLiteralClass:
      case Stmt::ObjCBoolLiteralExprClass:
      case Stmt::ObjCBoxedExprClass:
      case Stmt::ObjCDictionaryLiteralClass:
      case Stmt::ObjCEncodeExprClass:
      case Stmt::ObjCIvarRefExprClass:
      case Stmt::ObjCMessageExprClass:
      case Stmt::ObjCPropertyRefExprClass:
      case Stmt::ObjCStringLiteralClass:
      case Stmt::ObjCSubscriptRefExprClass:
      case Stmt::ParenExprClass:
      case Stmt::StringLiteralClass:
      case Stmt::UnaryOperatorClass:
        return false;
      default:
        return true;
      }
    }
    
    static std::pair<QualType, StringRef>
    shouldNotPrintDirectly(const ASTContext &Context,
                           QualType IntendedTy,
                           const Expr *E) {
      // Use a 'while' to peel off layers of typedefs.
      QualType TyTy = IntendedTy;
      while (const TypedefType *UserTy = TyTy->getAs<TypedefType>()) {
        StringRef Name = UserTy->getDecl()->getName();
        QualType CastTy = llvm::StringSwitch<QualType>(Name)
          .Case("NSInteger", Context.LongTy)
          .Case("NSUInteger", Context.UnsignedLongTy)
          .Case("SInt32", Context.IntTy)
          .Case("UInt32", Context.UnsignedIntTy)
          .Default(QualType());
    
        if (!CastTy.isNull())
          return std::make_pair(CastTy, Name);
    
        TyTy = UserTy->desugar();
      }
    
      // Strip parens if necessary.
      if (const ParenExpr *PE = dyn_cast<ParenExpr>(E))
        return shouldNotPrintDirectly(Context,
                                      PE->getSubExpr()->getType(),
                                      PE->getSubExpr());
    
      // If this is a conditional expression, then its result type is constructed
      // via usual arithmetic conversions and thus there might be no necessary
      // typedef sugar there.  Recurse to operands to check for NSInteger &
      // Co. usage condition.
      if (const ConditionalOperator *CO = dyn_cast<ConditionalOperator>(E)) {
        QualType TrueTy, FalseTy;
        StringRef TrueName, FalseName;
    
        std::tie(TrueTy, TrueName) =
          shouldNotPrintDirectly(Context,
                                 CO->getTrueExpr()->getType(),
                                 CO->getTrueExpr());
        std::tie(FalseTy, FalseName) =
          shouldNotPrintDirectly(Context,
                                 CO->getFalseExpr()->getType(),
                                 CO->getFalseExpr());
    
        if (TrueTy == FalseTy)
          return std::make_pair(TrueTy, TrueName);
        else if (TrueTy.isNull())
          return std::make_pair(FalseTy, FalseName);
        else if (FalseTy.isNull())
          return std::make_pair(TrueTy, TrueName);
      }
    
      return std::make_pair(QualType(), StringRef());
    }
    
    bool
    CheckPrintfHandler::checkFormatExpr(const analyze_printf::PrintfSpecifier &FS,
                                        const char *StartSpecifier,
                                        unsigned SpecifierLen,
                                        const Expr *E) {
      using namespace analyze_format_string;
      using namespace analyze_printf;
      // Now type check the data expression that matches the
      // format specifier.
      const analyze_printf::ArgType &AT = FS.getArgType(S.Context, isObjCContext());
      if (!AT.isValid())
        return true;
    
      QualType ExprTy = E->getType();
      while (const TypeOfExprType *TET = dyn_cast<TypeOfExprType>(ExprTy)) {
        ExprTy = TET->getUnderlyingExpr()->getType();
      }
    
      analyze_printf::ArgType::MatchKind match = AT.matchesType(S.Context, ExprTy);
    
      if (match == analyze_printf::ArgType::Match) {
        return true;
      }
    
      // Look through argument promotions for our error message's reported type.
      // This includes the integral and floating promotions, but excludes array
      // and function pointer decay; seeing that an argument intended to be a
      // string has type 'char [6]' is probably more confusing than 'char *'.
      if (const ImplicitCastExpr *ICE = dyn_cast<ImplicitCastExpr>(E)) {
        if (ICE->getCastKind() == CK_IntegralCast ||
            ICE->getCastKind() == CK_FloatingCast) {
          E = ICE->getSubExpr();
          ExprTy = E->getType();
    
          // Check if we didn't match because of an implicit cast from a 'char'
          // or 'short' to an 'int'.  This is done because printf is a varargs
          // function.
          if (ICE->getType() == S.Context.IntTy ||
              ICE->getType() == S.Context.UnsignedIntTy) {
            // All further checking is done on the subexpression.
            if (AT.matchesType(S.Context, ExprTy))
              return true;
          }
        }
      } else if (const CharacterLiteral *CL = dyn_cast<CharacterLiteral>(E)) {
        // Special case for 'a', which has type 'int' in C.
        // Note, however, that we do /not/ want to treat multibyte constants like
        // 'MooV' as characters! This form is deprecated but still exists.
        if (ExprTy == S.Context.IntTy)
          if (llvm::isUIntN(S.Context.getCharWidth(), CL->getValue()))
            ExprTy = S.Context.CharTy;
      }
    
      // Look through enums to their underlying type.
      bool IsEnum = false;
      if (auto EnumTy = ExprTy->getAs<EnumType>()) {
        ExprTy = EnumTy->getDecl()->getIntegerType();
        IsEnum = true;
      }
    
      // %C in an Objective-C context prints a unichar, not a wchar_t.
      // If the argument is an integer of some kind, believe the %C and suggest
      // a cast instead of changing the conversion specifier.
      QualType IntendedTy = ExprTy;
      if (isObjCContext() &&
          FS.getConversionSpecifier().getKind() == ConversionSpecifier::CArg) {
        if (ExprTy->isIntegralOrUnscopedEnumerationType() &&
            !ExprTy->isCharType()) {
          // 'unichar' is defined as a typedef of unsigned short, but we should
          // prefer using the typedef if it is visible.
          IntendedTy = S.Context.UnsignedShortTy;
    
          // While we are here, check if the value is an IntegerLiteral that happens
          // to be within the valid range.
          if (const IntegerLiteral *IL = dyn_cast<IntegerLiteral>(E)) {
            const llvm::APInt &V = IL->getValue();
            if (V.getActiveBits() <= S.Context.getTypeSize(IntendedTy))
              return true;
          }
    
          LookupResult Result(S, &S.Context.Idents.get("unichar"), E->getLocStart(),
                              Sema::LookupOrdinaryName);
          if (S.LookupName(Result, S.getCurScope())) {
            NamedDecl *ND = Result.getFoundDecl();
            if (TypedefNameDecl *TD = dyn_cast<TypedefNameDecl>(ND))
              if (TD->getUnderlyingType() == IntendedTy)
                IntendedTy = S.Context.getTypedefType(TD);
          }
        }
      }
    
      // Special-case some of Darwin's platform-independence types by suggesting
      // casts to primitive types that are known to be large enough.
      bool ShouldNotPrintDirectly = false; StringRef CastTyName;
      if (S.Context.getTargetInfo().getTriple().isOSDarwin()) {
        QualType CastTy;
        std::tie(CastTy, CastTyName) = shouldNotPrintDirectly(S.Context, IntendedTy, E);
        if (!CastTy.isNull()) {
          IntendedTy = CastTy;
          ShouldNotPrintDirectly = true;
        }
      }
    
      // We may be able to offer a FixItHint if it is a supported type.
      PrintfSpecifier fixedFS = FS;
      bool success =
          fixedFS.fixType(IntendedTy, S.getLangOpts(), S.Context, isObjCContext());
    
      if (success) {
        // Get the fix string from the fixed format specifier
        SmallString<16> buf;
        llvm::raw_svector_ostream os(buf);
        fixedFS.toString(os);
    
        CharSourceRange SpecRange = getSpecifierRange(StartSpecifier, SpecifierLen);
    
        if (IntendedTy == ExprTy && !ShouldNotPrintDirectly) {
          unsigned diag = diag::warn_format_conversion_argument_type_mismatch;
          if (match == analyze_format_string::ArgType::NoMatchPedantic) {
            diag = diag::warn_format_conversion_argument_type_mismatch_pedantic;
          }
          // In this case, the specifier is wrong and should be changed to match
          // the argument.
          EmitFormatDiagnostic(S.PDiag(diag)
                                   << AT.getRepresentativeTypeName(S.Context)
                                   << IntendedTy << IsEnum << E->getSourceRange(),
                               E->getLocStart(),
                               /*IsStringLocation*/ false, SpecRange,
                               FixItHint::CreateReplacement(SpecRange, os.str()));
        } else {
          // The canonical type for formatting this value is different from the
          // actual type of the expression. (This occurs, for example, with Darwin's
          // NSInteger on 32-bit platforms, where it is typedef'd as 'int', but
          // should be printed as 'long' for 64-bit compatibility.)
          // Rather than emitting a normal format/argument mismatch, we want to
          // add a cast to the recommended type (and correct the format string
          // if necessary).
          SmallString<16> CastBuf;
          llvm::raw_svector_ostream CastFix(CastBuf);
          CastFix << "(";
          IntendedTy.print(CastFix, S.Context.getPrintingPolicy());
          CastFix << ")";
    
          SmallVector<FixItHint,4> Hints;
          if (!AT.matchesType(S.Context, IntendedTy))
            Hints.push_back(FixItHint::CreateReplacement(SpecRange, os.str()));
    
          if (const CStyleCastExpr *CCast = dyn_cast<CStyleCastExpr>(E)) {
            // If there's already a cast present, just replace it.
            SourceRange CastRange(CCast->getLParenLoc(), CCast->getRParenLoc());
            Hints.push_back(FixItHint::CreateReplacement(CastRange, CastFix.str()));
    
          } else if (!requiresParensToAddCast(E)) {
            // If the expression has high enough precedence,
            // just write the C-style cast.
            Hints.push_back(FixItHint::CreateInsertion(E->getLocStart(),
                                                       CastFix.str()));
          } else {
            // Otherwise, add parens around the expression as well as the cast.
            CastFix << "(";
            Hints.push_back(FixItHint::CreateInsertion(E->getLocStart(),
                                                       CastFix.str()));
    
            SourceLocation After = S.getLocForEndOfToken(E->getLocEnd());
            Hints.push_back(FixItHint::CreateInsertion(After, ")"));
          }
    
          if (ShouldNotPrintDirectly) {
            // The expression has a type that should not be printed directly.
            // We extract the name from the typedef because we don't want to show
            // the underlying type in the diagnostic.
            StringRef Name;
            if (const TypedefType *TypedefTy = dyn_cast<TypedefType>(ExprTy))
              Name = TypedefTy->getDecl()->getName();
            else
              Name = CastTyName;
            EmitFormatDiagnostic(S.PDiag(diag::warn_format_argument_needs_cast)
                                   << Name << IntendedTy << IsEnum
                                   << E->getSourceRange(),
                                 E->getLocStart(), /*IsStringLocation=*/false,
                                 SpecRange, Hints);
          } else {
            // In this case, the expression could be printed using a different
            // specifier, but we've decided that the specifier is probably correct 
            // and we should cast instead. Just use the normal warning message.
            EmitFormatDiagnostic(
              S.PDiag(diag::warn_format_conversion_argument_type_mismatch)
                << AT.getRepresentativeTypeName(S.Context) << ExprTy << IsEnum
                << E->getSourceRange(),
              E->getLocStart(), /*IsStringLocation*/false,
              SpecRange, Hints);
          }
        }
      } else {
        const CharSourceRange &CSR = getSpecifierRange(StartSpecifier,
                                                       SpecifierLen);
        // Since the warning for passing non-POD types to variadic functions
        // was deferred until now, we emit a warning for non-POD
        // arguments here.
        switch (S.isValidVarArgType(ExprTy)) {
        case Sema::VAK_Valid:
        case Sema::VAK_ValidInCXX11: {
          unsigned diag = diag::warn_format_conversion_argument_type_mismatch;
          if (match == analyze_printf::ArgType::NoMatchPedantic) {
            diag = diag::warn_format_conversion_argument_type_mismatch_pedantic;
          }
    
          EmitFormatDiagnostic(
              S.PDiag(diag) << AT.getRepresentativeTypeName(S.Context) << ExprTy
                            << IsEnum << CSR << E->getSourceRange(),
              E->getLocStart(), /*IsStringLocation*/ false, CSR);
          break;
        }
        case Sema::VAK_Undefined:
        case Sema::VAK_MSVCUndefined:
          EmitFormatDiagnostic(
            S.PDiag(diag::warn_non_pod_vararg_with_format_string)
              << S.getLangOpts().CPlusPlus11
              << ExprTy
              << CallType
              << AT.getRepresentativeTypeName(S.Context)
              << CSR
              << E->getSourceRange(),
            E->getLocStart(), /*IsStringLocation*/false, CSR);
          checkForCStrMembers(AT, E);
          break;
    
        case Sema::VAK_Invalid:
          if (ExprTy->isObjCObjectType())
            EmitFormatDiagnostic(
              S.PDiag(diag::err_cannot_pass_objc_interface_to_vararg_format)
                << S.getLangOpts().CPlusPlus11
                << ExprTy
                << CallType
                << AT.getRepresentativeTypeName(S.Context)
                << CSR
                << E->getSourceRange(),
              E->getLocStart(), /*IsStringLocation*/false, CSR);
          else
            // FIXME: If this is an initializer list, suggest removing the braces
            // or inserting a cast to the target type.
            S.Diag(E->getLocStart(), diag::err_cannot_pass_to_vararg_format)
              << isa<InitListExpr>(E) << ExprTy << CallType
              << AT.getRepresentativeTypeName(S.Context)
              << E->getSourceRange();
          break;
        }
    
        assert(FirstDataArg + FS.getArgIndex() < CheckedVarArgs.size() &&
               "format string specifier index out of range");
        CheckedVarArgs[FirstDataArg + FS.getArgIndex()] = true;
      }
    
      return true;
    }
    
    //===--- CHECK: Scanf format string checking ------------------------------===//
    
    namespace {  
    class CheckScanfHandler : public CheckFormatHandler {
    public:
      CheckScanfHandler(Sema &s, const FormatStringLiteral *fexpr,
                        const Expr *origFormatExpr, Sema::FormatStringType type,
                        unsigned firstDataArg, unsigned numDataArgs,
                        const char *beg, bool hasVAListArg,
                        ArrayRef<const Expr *> Args, unsigned formatIdx,
                        bool inFunctionCall, Sema::VariadicCallType CallType,
                        llvm::SmallBitVector &CheckedVarArgs,
                        UncoveredArgHandler &UncoveredArg)
          : CheckFormatHandler(s, fexpr, origFormatExpr, type, firstDataArg,
                               numDataArgs, beg, hasVAListArg, Args, formatIdx,
                               inFunctionCall, CallType, CheckedVarArgs,
                               UncoveredArg) {}
    
      bool HandleScanfSpecifier(const analyze_scanf::ScanfSpecifier &FS,
                                const char *startSpecifier,
                                unsigned specifierLen) override;
      
      bool HandleInvalidScanfConversionSpecifier(
              const analyze_scanf::ScanfSpecifier &FS,
              const char *startSpecifier,
              unsigned specifierLen) override;
    
      void HandleIncompleteScanList(const char *start, const char *end) override;
    };
    } // end anonymous namespace
    
    void CheckScanfHandler::HandleIncompleteScanList(const char *start,
                                                     const char *end) {
      EmitFormatDiagnostic(S.PDiag(diag::warn_scanf_scanlist_incomplete),
                           getLocationOfByte(end), /*IsStringLocation*/true,
                           getSpecifierRange(start, end - start));
    }
    
    bool CheckScanfHandler::HandleInvalidScanfConversionSpecifier(
                                            const analyze_scanf::ScanfSpecifier &FS,
                                            const char *startSpecifier,
                                            unsigned specifierLen) {
    
      const analyze_scanf::ScanfConversionSpecifier &CS =
        FS.getConversionSpecifier();
    
      return HandleInvalidConversionSpecifier(FS.getArgIndex(),
                                              getLocationOfByte(CS.getStart()),
                                              startSpecifier, specifierLen,
                                              CS.getStart(), CS.getLength());
    }
    
    bool CheckScanfHandler::HandleScanfSpecifier(
                                           const analyze_scanf::ScanfSpecifier &FS,
                                           const char *startSpecifier,
                                           unsigned specifierLen) {
      using namespace analyze_scanf;
      using namespace analyze_format_string;  
    
      const ScanfConversionSpecifier &CS = FS.getConversionSpecifier();
    
      // Handle case where '%' and '*' don't consume an argument.  These shouldn't
      // be used to decide if we are using positional arguments consistently.
      if (FS.consumesDataArgument()) {
        if (atFirstArg) {
          atFirstArg = false;
          usesPositionalArgs = FS.usesPositionalArg();
        }
        else if (usesPositionalArgs != FS.usesPositionalArg()) {
          HandlePositionalNonpositionalArgs(getLocationOfByte(CS.getStart()),
                                            startSpecifier, specifierLen);
          return false;
        }
      }
      
      // Check if the field with is non-zero.
      const OptionalAmount &Amt = FS.getFieldWidth();
      if (Amt.getHowSpecified() == OptionalAmount::Constant) {
        if (Amt.getConstantAmount() == 0) {
          const CharSourceRange &R = getSpecifierRange(Amt.getStart(),
                                                       Amt.getConstantLength());
          EmitFormatDiagnostic(S.PDiag(diag::warn_scanf_nonzero_width),
                               getLocationOfByte(Amt.getStart()),
                               /*IsStringLocation*/true, R,
                               FixItHint::CreateRemoval(R));
        }
      }
    
      if (!FS.consumesDataArgument()) {
        // FIXME: Technically specifying a precision or field width here
        // makes no sense.  Worth issuing a warning at some point.
        return true;
      }
    
      // Consume the argument.
      unsigned argIndex = FS.getArgIndex();
      if (argIndex < NumDataArgs) {
          // The check to see if the argIndex is valid will come later.
          // We set the bit here because we may exit early from this
          // function if we encounter some other error.
        CoveredArgs.set(argIndex);
      }
    
      // Check the length modifier is valid with the given conversion specifier.
      if (!FS.hasValidLengthModifier(S.getASTContext().getTargetInfo()))
        HandleInvalidLengthModifier(FS, CS, startSpecifier, specifierLen,
                                    diag::warn_format_nonsensical_length);
      else if (!FS.hasStandardLengthModifier())
        HandleNonStandardLengthModifier(FS, startSpecifier, specifierLen);
      else if (!FS.hasStandardLengthConversionCombination())
        HandleInvalidLengthModifier(FS, CS, startSpecifier, specifierLen,
                                    diag::warn_format_non_standard_conversion_spec);
    
      if (!FS.hasStandardConversionSpecifier(S.getLangOpts()))
        HandleNonStandardConversionSpecifier(CS, startSpecifier, specifierLen);
    
      // The remaining checks depend on the data arguments.
      if (HasVAListArg)
        return true;
    
      if (!CheckNumArgs(FS, CS, startSpecifier, specifierLen, argIndex))
        return false;
    
      // Check that the argument type matches the format specifier.
      const Expr *Ex = getDataArg(argIndex);
      if (!Ex)
        return true;
    
      const analyze_format_string::ArgType &AT = FS.getArgType(S.Context);
    
      if (!AT.isValid()) {
        return true;
      }
    
      analyze_format_string::ArgType::MatchKind match =
          AT.matchesType(S.Context, Ex->getType());
      if (match == analyze_format_string::ArgType::Match) {
        return true;
      }
    
      ScanfSpecifier fixedFS = FS;
      bool success = fixedFS.fixType(Ex->getType(), Ex->IgnoreImpCasts()->getType(),
                                     S.getLangOpts(), S.Context);
    
      unsigned diag = diag::warn_format_conversion_argument_type_mismatch;
      if (match == analyze_format_string::ArgType::NoMatchPedantic) {
        diag = diag::warn_format_conversion_argument_type_mismatch_pedantic;
      }
    
      if (success) {
        // Get the fix string from the fixed format specifier.
        SmallString<128> buf;
        llvm::raw_svector_ostream os(buf);
        fixedFS.toString(os);
    
        EmitFormatDiagnostic(
            S.PDiag(diag) << AT.getRepresentativeTypeName(S.Context)
                          << Ex->getType() << false << Ex->getSourceRange(),
            Ex->getLocStart(),
            /*IsStringLocation*/ false,
            getSpecifierRange(startSpecifier, specifierLen),
            FixItHint::CreateReplacement(
                getSpecifierRange(startSpecifier, specifierLen), os.str()));
      } else {
        EmitFormatDiagnostic(S.PDiag(diag)
                                 << AT.getRepresentativeTypeName(S.Context)
                                 << Ex->getType() << false << Ex->getSourceRange(),
                             Ex->getLocStart(),
                             /*IsStringLocation*/ false,
                             getSpecifierRange(startSpecifier, specifierLen));
      }
    
      return true;
    }
    
    static void CheckFormatString(Sema &S, const FormatStringLiteral *FExpr,
                                  const Expr *OrigFormatExpr,
                                  ArrayRef<const Expr *> Args,
                                  bool HasVAListArg, unsigned format_idx,
                                  unsigned firstDataArg,
                                  Sema::FormatStringType Type,
                                  bool inFunctionCall,
                                  Sema::VariadicCallType CallType,
                                  llvm::SmallBitVector &CheckedVarArgs,
                                  UncoveredArgHandler &UncoveredArg) {
      // CHECK: is the format string a wide literal?
      if (!FExpr->isAscii() && !FExpr->isUTF8()) {
        CheckFormatHandler::EmitFormatDiagnostic(
          S, inFunctionCall, Args[format_idx],
          S.PDiag(diag::warn_format_string_is_wide_literal), FExpr->getLocStart(),
          /*IsStringLocation*/true, OrigFormatExpr->getSourceRange());
        return;
      }
    
      // Str - The format string.  NOTE: this is NOT null-terminated!
      StringRef StrRef = FExpr->getString();
      const char *Str = StrRef.data();
      // Account for cases where the string literal is truncated in a declaration.
      const ConstantArrayType *T =
        S.Context.getAsConstantArrayType(FExpr->getType());
      assert(T && "String literal not of constant array type!");
      size_t TypeSize = T->getSize().getZExtValue();
      size_t StrLen = std::min(std::max(TypeSize, size_t(1)) - 1, StrRef.size());
      const unsigned numDataArgs = Args.size() - firstDataArg;
    
      // Emit a warning if the string literal is truncated and does not contain an
      // embedded null character.
      if (TypeSize <= StrRef.size() &&
          StrRef.substr(0, TypeSize).find('\0') == StringRef::npos) {
        CheckFormatHandler::EmitFormatDiagnostic(
            S, inFunctionCall, Args[format_idx],
            S.PDiag(diag::warn_printf_format_string_not_null_terminated),
            FExpr->getLocStart(),
            /*IsStringLocation=*/true, OrigFormatExpr->getSourceRange());
        return;
      }
    
      // CHECK: empty format string?
      if (StrLen == 0 && numDataArgs > 0) {
        CheckFormatHandler::EmitFormatDiagnostic(
          S, inFunctionCall, Args[format_idx],
          S.PDiag(diag::warn_empty_format_string), FExpr->getLocStart(),
          /*IsStringLocation*/true, OrigFormatExpr->getSourceRange());
        return;
      }
    
      if (Type == Sema::FST_Printf || Type == Sema::FST_NSString ||
          Type == Sema::FST_FreeBSDKPrintf || Type == Sema::FST_OSLog ||
          Type == Sema::FST_OSTrace) {
        CheckPrintfHandler H(
            S, FExpr, OrigFormatExpr, Type, firstDataArg, numDataArgs,
            (Type == Sema::FST_NSString || Type == Sema::FST_OSTrace), Str,
            HasVAListArg, Args, format_idx, inFunctionCall, CallType,
            CheckedVarArgs, UncoveredArg);
    
        if (!analyze_format_string::ParsePrintfString(H, Str, Str + StrLen,
                                                      S.getLangOpts(),
                                                      S.Context.getTargetInfo(),
                                                Type == Sema::FST_FreeBSDKPrintf))
          H.DoneProcessing();
      } else if (Type == Sema::FST_Scanf) {
        CheckScanfHandler H(S, FExpr, OrigFormatExpr, Type, firstDataArg,
                            numDataArgs, Str, HasVAListArg, Args, format_idx,
                            inFunctionCall, CallType, CheckedVarArgs, UncoveredArg);
    
        if (!analyze_format_string::ParseScanfString(H, Str, Str + StrLen,
                                                     S.getLangOpts(),
                                                     S.Context.getTargetInfo()))
          H.DoneProcessing();
      } // TODO: handle other formats
    }
    
    bool Sema::FormatStringHasSArg(const StringLiteral *FExpr) {
      // Str - The format string.  NOTE: this is NOT null-terminated!
      StringRef StrRef = FExpr->getString();
      const char *Str = StrRef.data();
      // Account for cases where the string literal is truncated in a declaration.
      const ConstantArrayType *T = Context.getAsConstantArrayType(FExpr->getType());
      assert(T && "String literal not of constant array type!");
      size_t TypeSize = T->getSize().getZExtValue();
      size_t StrLen = std::min(std::max(TypeSize, size_t(1)) - 1, StrRef.size());
      return analyze_format_string::ParseFormatStringHasSArg(Str, Str + StrLen,
                                                             getLangOpts(),
                                                             Context.getTargetInfo());
    }
    
    //===--- CHECK: Warn on use of wrong absolute value function. -------------===//
    
    // Returns the related absolute value function that is larger, of 0 if one
    // does not exist.
    static unsigned getLargerAbsoluteValueFunction(unsigned AbsFunction) {
      switch (AbsFunction) {
      default:
        return 0;
    
      case Builtin::BI__builtin_abs:
        return Builtin::BI__builtin_labs;
      case Builtin::BI__builtin_labs:
        return Builtin::BI__builtin_llabs;
      case Builtin::BI__builtin_llabs:
        return 0;
    
      case Builtin::BI__builtin_fabsf:
        return Builtin::BI__builtin_fabs;
      case Builtin::BI__builtin_fabs:
        return Builtin::BI__builtin_fabsl;
      case Builtin::BI__builtin_fabsl:
        return 0;
    
      case Builtin::BI__builtin_cabsf:
        return Builtin::BI__builtin_cabs;
      case Builtin::BI__builtin_cabs:
        return Builtin::BI__builtin_cabsl;
      case Builtin::BI__builtin_cabsl:
        return 0;
    
      case Builtin::BIabs:
        return Builtin::BIlabs;
      case Builtin::BIlabs:
        return Builtin::BIllabs;
      case Builtin::BIllabs:
        return 0;
    
      case Builtin::BIfabsf:
        return Builtin::BIfabs;
      case Builtin::BIfabs:
        return Builtin::BIfabsl;
      case Builtin::BIfabsl:
        return 0;
    
      case Builtin::BIcabsf:
       return Builtin::BIcabs;
      case Builtin::BIcabs:
        return Builtin::BIcabsl;
      case Builtin::BIcabsl:
        return 0;
      }
    }
    
    // Returns the argument type of the absolute value function.
    static QualType getAbsoluteValueArgumentType(ASTContext &Context,
                                                 unsigned AbsType) {
      if (AbsType == 0)
        return QualType();
    
      ASTContext::GetBuiltinTypeError Error = ASTContext::GE_None;
      QualType BuiltinType = Context.GetBuiltinType(AbsType, Error);
      if (Error != ASTContext::GE_None)
        return QualType();
    
      const FunctionProtoType *FT = BuiltinType->getAs<FunctionProtoType>();
      if (!FT)
        return QualType();
    
      if (FT->getNumParams() != 1)
        return QualType();
    
      return FT->getParamType(0);
    }
    
    // Returns the best absolute value function, or zero, based on type and
    // current absolute value function.
    static unsigned getBestAbsFunction(ASTContext &Context, QualType ArgType,
                                       unsigned AbsFunctionKind) {
      unsigned BestKind = 0;
      uint64_t ArgSize = Context.getTypeSize(ArgType);
      for (unsigned Kind = AbsFunctionKind; Kind != 0;
           Kind = getLargerAbsoluteValueFunction(Kind)) {
        QualType ParamType = getAbsoluteValueArgumentType(Context, Kind);
        if (Context.getTypeSize(ParamType) >= ArgSize) {
          if (BestKind == 0)
            BestKind = Kind;
          else if (Context.hasSameType(ParamType, ArgType)) {
            BestKind = Kind;
            break;
          }
        }
      }
      return BestKind;
    }
    
    enum AbsoluteValueKind {
      AVK_Integer,
      AVK_Floating,
      AVK_Complex
    };
    
    static AbsoluteValueKind getAbsoluteValueKind(QualType T) {
      if (T->isIntegralOrEnumerationType())
        return AVK_Integer;
      if (T->isRealFloatingType())
        return AVK_Floating;
      if (T->isAnyComplexType())
        return AVK_Complex;
    
      llvm_unreachable("Type not integer, floating, or complex");
    }
    
    // Changes the absolute value function to a different type.  Preserves whether
    // the function is a builtin.
    static unsigned changeAbsFunction(unsigned AbsKind,
                                      AbsoluteValueKind ValueKind) {
      switch (ValueKind) {
      case AVK_Integer:
        switch (AbsKind) {
        default:
          return 0;
        case Builtin::BI__builtin_fabsf:
        case Builtin::BI__builtin_fabs:
        case Builtin::BI__builtin_fabsl:
        case Builtin::BI__builtin_cabsf:
        case Builtin::BI__builtin_cabs:
        case Builtin::BI__builtin_cabsl:
          return Builtin::BI__builtin_abs;
        case Builtin::BIfabsf:
        case Builtin::BIfabs:
        case Builtin::BIfabsl:
        case Builtin::BIcabsf:
        case Builtin::BIcabs:
        case Builtin::BIcabsl:
          return Builtin::BIabs;
        }
      case AVK_Floating:
        switch (AbsKind) {
        default:
          return 0;
        case Builtin::BI__builtin_abs:
        case Builtin::BI__builtin_labs:
        case Builtin::BI__builtin_llabs:
        case Builtin::BI__builtin_cabsf:
        case Builtin::BI__builtin_cabs:
        case Builtin::BI__builtin_cabsl:
          return Builtin::BI__builtin_fabsf;
        case Builtin::BIabs:
        case Builtin::BIlabs:
        case Builtin::BIllabs:
        case Builtin::BIcabsf:
        case Builtin::BIcabs:
        case Builtin::BIcabsl:
          return Builtin::BIfabsf;
        }
      case AVK_Complex:
        switch (AbsKind) {
        default:
          return 0;
        case Builtin::BI__builtin_abs:
        case Builtin::BI__builtin_labs:
        case Builtin::BI__builtin_llabs:
        case Builtin::BI__builtin_fabsf:
        case Builtin::BI__builtin_fabs:
        case Builtin::BI__builtin_fabsl:
          return Builtin::BI__builtin_cabsf;
        case Builtin::BIabs:
        case Builtin::BIlabs:
        case Builtin::BIllabs:
        case Builtin::BIfabsf:
        case Builtin::BIfabs:
        case Builtin::BIfabsl:
          return Builtin::BIcabsf;
        }
      }
      llvm_unreachable("Unable to convert function");
    }
    
    static unsigned getAbsoluteValueFunctionKind(const FunctionDecl *FDecl) {
      const IdentifierInfo *FnInfo = FDecl->getIdentifier();
      if (!FnInfo)
        return 0;
    
      switch (FDecl->getBuiltinID()) {
      default:
        return 0;
      case Builtin::BI__builtin_abs:
      case Builtin::BI__builtin_fabs:
      case Builtin::BI__builtin_fabsf:
      case Builtin::BI__builtin_fabsl:
      case Builtin::BI__builtin_labs:
      case Builtin::BI__builtin_llabs:
      case Builtin::BI__builtin_cabs:
      case Builtin::BI__builtin_cabsf:
      case Builtin::BI__builtin_cabsl:
      case Builtin::BIabs:
      case Builtin::BIlabs:
      case Builtin::BIllabs:
      case Builtin::BIfabs:
      case Builtin::BIfabsf:
      case Builtin::BIfabsl:
      case Builtin::BIcabs:
      case Builtin::BIcabsf:
      case Builtin::BIcabsl:
        return FDecl->getBuiltinID();
      }
      llvm_unreachable("Unknown Builtin type");
    }
    
    // If the replacement is valid, emit a note with replacement function.
    // Additionally, suggest including the proper header if not already included.
    static void emitReplacement(Sema &S, SourceLocation Loc, SourceRange Range,
                                unsigned AbsKind, QualType ArgType) {
      bool EmitHeaderHint = true;
      const char *HeaderName = nullptr;
      const char *FunctionName = nullptr;
      if (S.getLangOpts().CPlusPlus && !ArgType->isAnyComplexType()) {
        FunctionName = "std::abs";
        if (ArgType->isIntegralOrEnumerationType()) {
          HeaderName = "cstdlib";
        } else if (ArgType->isRealFloatingType()) {
          HeaderName = "cmath";
        } else {
          llvm_unreachable("Invalid Type");
        }
    
        // Lookup all std::abs
        if (NamespaceDecl *Std = S.getStdNamespace()) {
          LookupResult R(S, &S.Context.Idents.get("abs"), Loc, Sema::LookupAnyName);
          R.suppressDiagnostics();
          S.LookupQualifiedName(R, Std);
    
          for (const auto *I : R) {
            const FunctionDecl *FDecl = nullptr;
            if (const UsingShadowDecl *UsingD = dyn_cast<UsingShadowDecl>(I)) {
              FDecl = dyn_cast<FunctionDecl>(UsingD->getTargetDecl());
            } else {
              FDecl = dyn_cast<FunctionDecl>(I);
            }
            if (!FDecl)
              continue;
    
            // Found std::abs(), check that they are the right ones.
            if (FDecl->getNumParams() != 1)
              continue;
    
            // Check that the parameter type can handle the argument.
            QualType ParamType = FDecl->getParamDecl(0)->getType();
            if (getAbsoluteValueKind(ArgType) == getAbsoluteValueKind(ParamType) &&
                S.Context.getTypeSize(ArgType) <=
                    S.Context.getTypeSize(ParamType)) {
              // Found a function, don't need the header hint.
              EmitHeaderHint = false;
              break;
            }
          }
        }
      } else {
        FunctionName = S.Context.BuiltinInfo.getName(AbsKind);
        HeaderName = S.Context.BuiltinInfo.getHeaderName(AbsKind);
    
        if (HeaderName) {
          DeclarationName DN(&S.Context.Idents.get(FunctionName));
          LookupResult R(S, DN, Loc, Sema::LookupAnyName);
          R.suppressDiagnostics();
          S.LookupName(R, S.getCurScope());
    
          if (R.isSingleResult()) {
            FunctionDecl *FD = dyn_cast<FunctionDecl>(R.getFoundDecl());
            if (FD && FD->getBuiltinID() == AbsKind) {
              EmitHeaderHint = false;
            } else {
              return;
            }
          } else if (!R.empty()) {
            return;
          }
        }
      }
    
      S.Diag(Loc, diag::note_replace_abs_function)
          << FunctionName << FixItHint::CreateReplacement(Range, FunctionName);
    
      if (!HeaderName)
        return;
    
      if (!EmitHeaderHint)
        return;
    
      S.Diag(Loc, diag::note_include_header_or_declare) << HeaderName
                                                        << FunctionName;
    }
    
    template <std::size_t StrLen>
    static bool IsStdFunction(const FunctionDecl *FDecl,
                              const char (&Str)[StrLen]) {
      if (!FDecl)
        return false;
      if (!FDecl->getIdentifier() || !FDecl->getIdentifier()->isStr(Str))
        return false;
      if (!FDecl->isInStdNamespace())
        return false;
    
      return true;
    }
    
    // Warn when using the wrong abs() function.
    void Sema::CheckAbsoluteValueFunction(const CallExpr *Call,
                                          const FunctionDecl *FDecl) {
      if (Call->getNumArgs() != 1)
        return;
    
      unsigned AbsKind = getAbsoluteValueFunctionKind(FDecl);
      bool IsStdAbs = IsStdFunction(FDecl, "abs");
      if (AbsKind == 0 && !IsStdAbs)
        return;
    
      QualType ArgType = Call->getArg(0)->IgnoreParenImpCasts()->getType();
      QualType ParamType = Call->getArg(0)->getType();
    
      // Unsigned types cannot be negative.  Suggest removing the absolute value
      // function call.
      if (ArgType->isUnsignedIntegerType()) {
        const char *FunctionName =
            IsStdAbs ? "std::abs" : Context.BuiltinInfo.getName(AbsKind);
        Diag(Call->getExprLoc(), diag::warn_unsigned_abs) << ArgType << ParamType;
        Diag(Call->getExprLoc(), diag::note_remove_abs)
            << FunctionName
            << FixItHint::CreateRemoval(Call->getCallee()->getSourceRange());
        return;
      }
    
      // Taking the absolute value of a pointer is very suspicious, they probably
      // wanted to index into an array, dereference a pointer, call a function, etc.
      if (ArgType->isPointerType() || ArgType->canDecayToPointerType()) {
        unsigned DiagType = 0;
        if (ArgType->isFunctionType())
          DiagType = 1;
        else if (ArgType->isArrayType())
          DiagType = 2;
    
        Diag(Call->getExprLoc(), diag::warn_pointer_abs) << DiagType << ArgType;
        return;
      }
    
      // std::abs has overloads which prevent most of the absolute value problems
      // from occurring.
      if (IsStdAbs)
        return;
    
      AbsoluteValueKind ArgValueKind = getAbsoluteValueKind(ArgType);
      AbsoluteValueKind ParamValueKind = getAbsoluteValueKind(ParamType);
    
      // The argument and parameter are the same kind.  Check if they are the right
      // size.
      if (ArgValueKind == ParamValueKind) {
        if (Context.getTypeSize(ArgType) <= Context.getTypeSize(ParamType))
          return;
    
        unsigned NewAbsKind = getBestAbsFunction(Context, ArgType, AbsKind);
        Diag(Call->getExprLoc(), diag::warn_abs_too_small)
            << FDecl << ArgType << ParamType;
    
        if (NewAbsKind == 0)
          return;
    
        emitReplacement(*this, Call->getExprLoc(),
                        Call->getCallee()->getSourceRange(), NewAbsKind, ArgType);
        return;
      }
    
      // ArgValueKind != ParamValueKind
      // The wrong type of absolute value function was used.  Attempt to find the
      // proper one.
      unsigned NewAbsKind = changeAbsFunction(AbsKind, ArgValueKind);
      NewAbsKind = getBestAbsFunction(Context, ArgType, NewAbsKind);
      if (NewAbsKind == 0)
        return;
    
      Diag(Call->getExprLoc(), diag::warn_wrong_absolute_value_type)
          << FDecl << ParamValueKind << ArgValueKind;
    
      emitReplacement(*this, Call->getExprLoc(),
                      Call->getCallee()->getSourceRange(), NewAbsKind, ArgType);
    }
    
    //===--- CHECK: Warn on use of std::max and unsigned zero. r---------------===//
    void Sema::CheckMaxUnsignedZero(const CallExpr *Call,
                                    const FunctionDecl *FDecl) {
      if (!Call || !FDecl) return;
    
      // Ignore template specializations and macros.
      if (!ActiveTemplateInstantiations.empty()) return;
      if (Call->getExprLoc().isMacroID()) return;
    
      // Only care about the one template argument, two function parameter std::max
      if (Call->getNumArgs() != 2) return;
      if (!IsStdFunction(FDecl, "max")) return;
      const auto * ArgList = FDecl->getTemplateSpecializationArgs();
      if (!ArgList) return;
      if (ArgList->size() != 1) return;
    
      // Check that template type argument is unsigned integer.
      const auto& TA = ArgList->get(0);
      if (TA.getKind() != TemplateArgument::Type) return;
      QualType ArgType = TA.getAsType();
      if (!ArgType->isUnsignedIntegerType()) return;
    
      // See if either argument is a literal zero.
      auto IsLiteralZeroArg = [](const Expr* E) -> bool {
        const auto *MTE = dyn_cast<MaterializeTemporaryExpr>(E);
        if (!MTE) return false;
        const auto *Num = dyn_cast<IntegerLiteral>(MTE->GetTemporaryExpr());
        if (!Num) return false;
        if (Num->getValue() != 0) return false;
        return true;
      };
    
      const Expr *FirstArg = Call->getArg(0);
      const Expr *SecondArg = Call->getArg(1);
      const bool IsFirstArgZero = IsLiteralZeroArg(FirstArg);
      const bool IsSecondArgZero = IsLiteralZeroArg(SecondArg);
    
      // Only warn when exactly one argument is zero.
      if (IsFirstArgZero == IsSecondArgZero) return;
    
      SourceRange FirstRange = FirstArg->getSourceRange();
      SourceRange SecondRange = SecondArg->getSourceRange();
    
      SourceRange ZeroRange = IsFirstArgZero ? FirstRange : SecondRange;
    
      Diag(Call->getExprLoc(), diag::warn_max_unsigned_zero)
          << IsFirstArgZero << Call->getCallee()->getSourceRange() << ZeroRange;
    
      // Deduce what parts to remove so that "std::max(0u, foo)" becomes "(foo)".
      SourceRange RemovalRange;
      if (IsFirstArgZero) {
        RemovalRange = SourceRange(FirstRange.getBegin(),
                                   SecondRange.getBegin().getLocWithOffset(-1));
      } else {
        RemovalRange = SourceRange(getLocForEndOfToken(FirstRange.getEnd()),
                                   SecondRange.getEnd());
      }
    
      Diag(Call->getExprLoc(), diag::note_remove_max_call)
            << FixItHint::CreateRemoval(Call->getCallee()->getSourceRange())
            << FixItHint::CreateRemoval(RemovalRange);
    }
    
    //===--- CHECK: Standard memory functions ---------------------------------===//
    
    /// \brief Takes the expression passed to the size_t parameter of functions
    /// such as memcmp, strncat, etc and warns if it's a comparison.
    ///
    /// This is to catch typos like `if (memcmp(&a, &b, sizeof(a) > 0))`.
    static bool CheckMemorySizeofForComparison(Sema &S, const Expr *E,
                                               IdentifierInfo *FnName,
                                               SourceLocation FnLoc,
                                               SourceLocation RParenLoc) {
      const BinaryOperator *Size = dyn_cast<BinaryOperator>(E);
      if (!Size)
        return false;
    
      // if E is binop and op is >, <, >=, <=, ==, &&, ||:
      if (!Size->isComparisonOp() && !Size->isEqualityOp() && !Size->isLogicalOp())
        return false;
    
      SourceRange SizeRange = Size->getSourceRange();
      S.Diag(Size->getOperatorLoc(), diag::warn_memsize_comparison)
          << SizeRange << FnName;
      S.Diag(FnLoc, diag::note_memsize_comparison_paren)
          << FnName << FixItHint::CreateInsertion(
                           S.getLocForEndOfToken(Size->getLHS()->getLocEnd()), ")")
          << FixItHint::CreateRemoval(RParenLoc);
      S.Diag(SizeRange.getBegin(), diag::note_memsize_comparison_cast_silence)
          << FixItHint::CreateInsertion(SizeRange.getBegin(), "(size_t)(")
          << FixItHint::CreateInsertion(S.getLocForEndOfToken(SizeRange.getEnd()),
                                        ")");
    
      return true;
    }
    
    /// \brief Determine whether the given type is or contains a dynamic class type
    /// (e.g., whether it has a vtable).
    static const CXXRecordDecl *getContainedDynamicClass(QualType T,
                                                         bool &IsContained) {
      // Look through array types while ignoring qualifiers.
      const Type *Ty = T->getBaseElementTypeUnsafe();
      IsContained = false;
    
      const CXXRecordDecl *RD = Ty->getAsCXXRecordDecl();
      RD = RD ? RD->getDefinition() : nullptr;
      if (!RD || RD->isInvalidDecl())
        return nullptr;
    
      if (RD->isDynamicClass())
        return RD;
    
      // Check all the fields.  If any bases were dynamic, the class is dynamic.
      // It's impossible for a class to transitively contain itself by value, so
      // infinite recursion is impossible.
      for (auto *FD : RD->fields()) {
        bool SubContained;
        if (const CXXRecordDecl *ContainedRD =
                getContainedDynamicClass(FD->getType(), SubContained)) {
          IsContained = true;
          return ContainedRD;
        }
      }
    
      return nullptr;
    }
    
    /// \brief If E is a sizeof expression, returns its argument expression,
    /// otherwise returns NULL.
    static const Expr *getSizeOfExprArg(const Expr *E) {
      if (const UnaryExprOrTypeTraitExpr *SizeOf =
          dyn_cast<UnaryExprOrTypeTraitExpr>(E))
        if (SizeOf->getKind() == clang::UETT_SizeOf && !SizeOf->isArgumentType())
          return SizeOf->getArgumentExpr()->IgnoreParenImpCasts();
    
      return nullptr;
    }
    
    /// \brief If E is a sizeof expression, returns its argument type.
    static QualType getSizeOfArgType(const Expr *E) {
      if (const UnaryExprOrTypeTraitExpr *SizeOf =
          dyn_cast<UnaryExprOrTypeTraitExpr>(E))
        if (SizeOf->getKind() == clang::UETT_SizeOf)
          return SizeOf->getTypeOfArgument();
    
      return QualType();
    }
    
    /// \brief Check for dangerous or invalid arguments to memset().
    ///
    /// This issues warnings on known problematic, dangerous or unspecified
    /// arguments to the standard 'memset', 'memcpy', 'memmove', and 'memcmp'
    /// function calls.
    ///
    /// \param Call The call expression to diagnose.
    void Sema::CheckMemaccessArguments(const CallExpr *Call,
                                       unsigned BId,
                                       IdentifierInfo *FnName) {
      assert(BId != 0);
    
      // It is possible to have a non-standard definition of memset.  Validate
      // we have enough arguments, and if not, abort further checking.
      unsigned ExpectedNumArgs =
          (BId == Builtin::BIstrndup || BId == Builtin::BIbzero ? 2 : 3);
      if (Call->getNumArgs() < ExpectedNumArgs)
        return;
    
      unsigned LastArg = (BId == Builtin::BImemset || BId == Builtin::BIbzero ||
                          BId == Builtin::BIstrndup ? 1 : 2);
      unsigned LenArg =
          (BId == Builtin::BIbzero || BId == Builtin::BIstrndup ? 1 : 2);
      const Expr *LenExpr = Call->getArg(LenArg)->IgnoreParenImpCasts();
    
      if (CheckMemorySizeofForComparison(*this, LenExpr, FnName,
                                         Call->getLocStart(), Call->getRParenLoc()))
        return;
    
      // We have special checking when the length is a sizeof expression.
      QualType SizeOfArgTy = getSizeOfArgType(LenExpr);
      const Expr *SizeOfArg = getSizeOfExprArg(LenExpr);
      llvm::FoldingSetNodeID SizeOfArgID;
    
      // Although widely used, 'bzero' is not a standard function. Be more strict
      // with the argument types before allowing diagnostics and only allow the
      // form bzero(ptr, sizeof(...)).
      QualType FirstArgTy = Call->getArg(0)->IgnoreParenImpCasts()->getType();
      if (BId == Builtin::BIbzero && !FirstArgTy->getAs<PointerType>())
        return;
    
      for (unsigned ArgIdx = 0; ArgIdx != LastArg; ++ArgIdx) {
        const Expr *Dest = Call->getArg(ArgIdx)->IgnoreParenImpCasts();
        SourceRange ArgRange = Call->getArg(ArgIdx)->getSourceRange();
    
        QualType DestTy = Dest->getType();
        QualType PointeeTy;
        if (const PointerType *DestPtrTy = DestTy->getAs<PointerType>()) {
          PointeeTy = DestPtrTy->getPointeeType();
    
          // Never warn about void type pointers. This can be used to suppress
          // false positives.
          if (PointeeTy->isVoidType())
            continue;
    
          // Catch "memset(p, 0, sizeof(p))" -- needs to be sizeof(*p). Do this by
          // actually comparing the expressions for equality. Because computing the
          // expression IDs can be expensive, we only do this if the diagnostic is
          // enabled.
          if (SizeOfArg &&
              !Diags.isIgnored(diag::warn_sizeof_pointer_expr_memaccess,
                               SizeOfArg->getExprLoc())) {
            // We only compute IDs for expressions if the warning is enabled, and
            // cache the sizeof arg's ID.
            if (SizeOfArgID == llvm::FoldingSetNodeID())
              SizeOfArg->Profile(SizeOfArgID, Context, true);
            llvm::FoldingSetNodeID DestID;
            Dest->Profile(DestID, Context, true);
            if (DestID == SizeOfArgID) {
              // TODO: For strncpy() and friends, this could suggest sizeof(dst)
              //       over sizeof(src) as well.
              unsigned ActionIdx = 0; // Default is to suggest dereferencing.
              StringRef ReadableName = FnName->getName();
    
              if (const UnaryOperator *UnaryOp = dyn_cast<UnaryOperator>(Dest))
                if (UnaryOp->getOpcode() == UO_AddrOf)
                  ActionIdx = 1; // If its an address-of operator, just remove it.
              if (!PointeeTy->isIncompleteType() &&
                  (Context.getTypeSize(PointeeTy) == Context.getCharWidth()))
                ActionIdx = 2; // If the pointee's size is sizeof(char),
                               // suggest an explicit length.
    
              // If the function is defined as a builtin macro, do not show macro
              // expansion.
              SourceLocation SL = SizeOfArg->getExprLoc();
              SourceRange DSR = Dest->getSourceRange();
              SourceRange SSR = SizeOfArg->getSourceRange();
              SourceManager &SM = getSourceManager();
    
              if (SM.isMacroArgExpansion(SL)) {
                ReadableName = Lexer::getImmediateMacroName(SL, SM, LangOpts);
                SL = SM.getSpellingLoc(SL);
                DSR = SourceRange(SM.getSpellingLoc(DSR.getBegin()),
                                 SM.getSpellingLoc(DSR.getEnd()));
                SSR = SourceRange(SM.getSpellingLoc(SSR.getBegin()),
                                 SM.getSpellingLoc(SSR.getEnd()));
              }
    
              DiagRuntimeBehavior(SL, SizeOfArg,
                                  PDiag(diag::warn_sizeof_pointer_expr_memaccess)
                                    << ReadableName
                                    << PointeeTy
                                    << DestTy
                                    << DSR
                                    << SSR);
              DiagRuntimeBehavior(SL, SizeOfArg,
                             PDiag(diag::warn_sizeof_pointer_expr_memaccess_note)
                                    << ActionIdx
                                    << SSR);
    
              break;
            }
          }
    
          // Also check for cases where the sizeof argument is the exact same
          // type as the memory argument, and where it points to a user-defined
          // record type.
          if (SizeOfArgTy != QualType()) {
            if (PointeeTy->isRecordType() &&
                Context.typesAreCompatible(SizeOfArgTy, DestTy)) {
              DiagRuntimeBehavior(LenExpr->getExprLoc(), Dest,
                                  PDiag(diag::warn_sizeof_pointer_type_memaccess)
                                    << FnName << SizeOfArgTy << ArgIdx
                                    << PointeeTy << Dest->getSourceRange()
                                    << LenExpr->getSourceRange());
              break;
            }
          }
        } else if (DestTy->isArrayType()) {
          PointeeTy = DestTy;
        }
    
        if (PointeeTy == QualType())
          continue;
    
        // Always complain about dynamic classes.
        bool IsContained;
        if (const CXXRecordDecl *ContainedRD =
                getContainedDynamicClass(PointeeTy, IsContained)) {
    
          unsigned OperationType = 0;
          // "overwritten" if we're warning about the destination for any call
          // but memcmp; otherwise a verb appropriate to the call.
          if (ArgIdx != 0 || BId == Builtin::BImemcmp) {
            if (BId == Builtin::BImemcpy)
              OperationType = 1;
            else if(BId == Builtin::BImemmove)
              OperationType = 2;
            else if (BId == Builtin::BImemcmp)
              OperationType = 3;
          }
            
          DiagRuntimeBehavior(
            Dest->getExprLoc(), Dest,
            PDiag(diag::warn_dyn_class_memaccess)
              << (BId == Builtin::BImemcmp ? ArgIdx + 2 : ArgIdx)
              << FnName << IsContained << ContainedRD << OperationType
              << Call->getCallee()->getSourceRange());
        } else if (PointeeTy.hasNonTrivialObjCLifetime() &&
                 BId != Builtin::BImemset)
          DiagRuntimeBehavior(
            Dest->getExprLoc(), Dest,
            PDiag(diag::warn_arc_object_memaccess)
              << ArgIdx << FnName << PointeeTy
              << Call->getCallee()->getSourceRange());
        else
          continue;
    
        DiagRuntimeBehavior(
          Dest->getExprLoc(), Dest,
          PDiag(diag::note_bad_memaccess_silence)
            << FixItHint::CreateInsertion(ArgRange.getBegin(), "(void*)"));
        break;
      }
    }
    
    // A little helper routine: ignore addition and subtraction of integer literals.
    // This intentionally does not ignore all integer constant expressions because
    // we don't want to remove sizeof().
    static const Expr *ignoreLiteralAdditions(const Expr *Ex, ASTContext &Ctx) {
      Ex = Ex->IgnoreParenCasts();
    
      for (;;) {
        const BinaryOperator * BO = dyn_cast<BinaryOperator>(Ex);
        if (!BO || !BO->isAdditiveOp())
          break;
    
        const Expr *RHS = BO->getRHS()->IgnoreParenCasts();
        const Expr *LHS = BO->getLHS()->IgnoreParenCasts();
        
        if (isa<IntegerLiteral>(RHS))
          Ex = LHS;
        else if (isa<IntegerLiteral>(LHS))
          Ex = RHS;
        else
          break;
      }
    
      return Ex;
    }
    
    static bool isConstantSizeArrayWithMoreThanOneElement(QualType Ty,
                                                          ASTContext &Context) {
      // Only handle constant-sized or VLAs, but not flexible members.
      if (const ConstantArrayType *CAT = Context.getAsConstantArrayType(Ty)) {
        // Only issue the FIXIT for arrays of size > 1.
        if (CAT->getSize().getSExtValue() <= 1)
          return false;
      } else if (!Ty->isVariableArrayType()) {
        return false;
      }
      return true;
    }
    
    // Warn if the user has made the 'size' argument to strlcpy or strlcat
    // be the size of the source, instead of the destination.
    void Sema::CheckStrlcpycatArguments(const CallExpr *Call,
                                        IdentifierInfo *FnName) {
    
      // Don't crash if the user has the wrong number of arguments
      unsigned NumArgs = Call->getNumArgs();
      if ((NumArgs != 3) && (NumArgs != 4))
        return;
    
      const Expr *SrcArg = ignoreLiteralAdditions(Call->getArg(1), Context);
      const Expr *SizeArg = ignoreLiteralAdditions(Call->getArg(2), Context);
      const Expr *CompareWithSrc = nullptr;
    
      if (CheckMemorySizeofForComparison(*this, SizeArg, FnName,
                                         Call->getLocStart(), Call->getRParenLoc()))
        return;
      
      // Look for 'strlcpy(dst, x, sizeof(x))'
      if (const Expr *Ex = getSizeOfExprArg(SizeArg))
        CompareWithSrc = Ex;
      else {
        // Look for 'strlcpy(dst, x, strlen(x))'
        if (const CallExpr *SizeCall = dyn_cast<CallExpr>(SizeArg)) {
          if (SizeCall->getBuiltinCallee() == Builtin::BIstrlen &&
              SizeCall->getNumArgs() == 1)
            CompareWithSrc = ignoreLiteralAdditions(SizeCall->getArg(0), Context);
        }
      }
    
      if (!CompareWithSrc)
        return;
    
      // Determine if the argument to sizeof/strlen is equal to the source
      // argument.  In principle there's all kinds of things you could do
      // here, for instance creating an == expression and evaluating it with
      // EvaluateAsBooleanCondition, but this uses a more direct technique:
      const DeclRefExpr *SrcArgDRE = dyn_cast<DeclRefExpr>(SrcArg);
      if (!SrcArgDRE)
        return;
      
      const DeclRefExpr *CompareWithSrcDRE = dyn_cast<DeclRefExpr>(CompareWithSrc);
      if (!CompareWithSrcDRE || 
          SrcArgDRE->getDecl() != CompareWithSrcDRE->getDecl())
        return;
      
      const Expr *OriginalSizeArg = Call->getArg(2);
      Diag(CompareWithSrcDRE->getLocStart(), diag::warn_strlcpycat_wrong_size)
        << OriginalSizeArg->getSourceRange() << FnName;
      
      // Output a FIXIT hint if the destination is an array (rather than a
      // pointer to an array).  This could be enhanced to handle some
      // pointers if we know the actual size, like if DstArg is 'array+2'
      // we could say 'sizeof(array)-2'.
      const Expr *DstArg = Call->getArg(0)->IgnoreParenImpCasts();
      if (!isConstantSizeArrayWithMoreThanOneElement(DstArg->getType(), Context))
        return;
    
      SmallString<128> sizeString;
      llvm::raw_svector_ostream OS(sizeString);
      OS << "sizeof(";
      DstArg->printPretty(OS, nullptr, getPrintingPolicy());
      OS << ")";
      
      Diag(OriginalSizeArg->getLocStart(), diag::note_strlcpycat_wrong_size)
        << FixItHint::CreateReplacement(OriginalSizeArg->getSourceRange(),
                                        OS.str());
    }
    
    /// Check if two expressions refer to the same declaration.
    static bool referToTheSameDecl(const Expr *E1, const Expr *E2) {
      if (const DeclRefExpr *D1 = dyn_cast_or_null<DeclRefExpr>(E1))
        if (const DeclRefExpr *D2 = dyn_cast_or_null<DeclRefExpr>(E2))
          return D1->getDecl() == D2->getDecl();
      return false;
    }
    
    static const Expr *getStrlenExprArg(const Expr *E) {
      if (const CallExpr *CE = dyn_cast<CallExpr>(E)) {
        const FunctionDecl *FD = CE->getDirectCallee();
        if (!FD || FD->getMemoryFunctionKind() != Builtin::BIstrlen)
          return nullptr;
        return CE->getArg(0)->IgnoreParenCasts();
      }
      return nullptr;
    }
    
    // Warn on anti-patterns as the 'size' argument to strncat.
    // The correct size argument should look like following:
    //   strncat(dst, src, sizeof(dst) - strlen(dest) - 1);
    void Sema::CheckStrncatArguments(const CallExpr *CE,
                                     IdentifierInfo *FnName) {
      // Don't crash if the user has the wrong number of arguments.
      if (CE->getNumArgs() < 3)
        return;
      const Expr *DstArg = CE->getArg(0)->IgnoreParenCasts();
      const Expr *SrcArg = CE->getArg(1)->IgnoreParenCasts();
      const Expr *LenArg = CE->getArg(2)->IgnoreParenCasts();
    
      if (CheckMemorySizeofForComparison(*this, LenArg, FnName, CE->getLocStart(),
                                         CE->getRParenLoc()))
        return;
    
      // Identify common expressions, which are wrongly used as the size argument
      // to strncat and may lead to buffer overflows.
      unsigned PatternType = 0;
      if (const Expr *SizeOfArg = getSizeOfExprArg(LenArg)) {
        // - sizeof(dst)
        if (referToTheSameDecl(SizeOfArg, DstArg))
          PatternType = 1;
        // - sizeof(src)
        else if (referToTheSameDecl(SizeOfArg, SrcArg))
          PatternType = 2;
      } else if (const BinaryOperator *BE = dyn_cast<BinaryOperator>(LenArg)) {
        if (BE->getOpcode() == BO_Sub) {
          const Expr *L = BE->getLHS()->IgnoreParenCasts();
          const Expr *R = BE->getRHS()->IgnoreParenCasts();
          // - sizeof(dst) - strlen(dst)
          if (referToTheSameDecl(DstArg, getSizeOfExprArg(L)) &&
              referToTheSameDecl(DstArg, getStrlenExprArg(R)))
            PatternType = 1;
          // - sizeof(src) - (anything)
          else if (referToTheSameDecl(SrcArg, getSizeOfExprArg(L)))
            PatternType = 2;
        }
      }
    
      if (PatternType == 0)
        return;
    
      // Generate the diagnostic.
      SourceLocation SL = LenArg->getLocStart();
      SourceRange SR = LenArg->getSourceRange();
      SourceManager &SM = getSourceManager();
    
      // If the function is defined as a builtin macro, do not show macro expansion.
      if (SM.isMacroArgExpansion(SL)) {
        SL = SM.getSpellingLoc(SL);
        SR = SourceRange(SM.getSpellingLoc(SR.getBegin()),
                         SM.getSpellingLoc(SR.getEnd()));
      }
    
      // Check if the destination is an array (rather than a pointer to an array).
      QualType DstTy = DstArg->getType();
      bool isKnownSizeArray = isConstantSizeArrayWithMoreThanOneElement(DstTy,
                                                                        Context);
      if (!isKnownSizeArray) {
        if (PatternType == 1)
          Diag(SL, diag::warn_strncat_wrong_size) << SR;
        else
          Diag(SL, diag::warn_strncat_src_size) << SR;
        return;
      }
    
      if (PatternType == 1)
        Diag(SL, diag::warn_strncat_large_size) << SR;
      else
        Diag(SL, diag::warn_strncat_src_size) << SR;
    
      SmallString<128> sizeString;
      llvm::raw_svector_ostream OS(sizeString);
      OS << "sizeof(";
      DstArg->printPretty(OS, nullptr, getPrintingPolicy());
      OS << ") - ";
      OS << "strlen(";
      DstArg->printPretty(OS, nullptr, getPrintingPolicy());
      OS << ") - 1";
    
      Diag(SL, diag::note_strncat_wrong_size)
        << FixItHint::CreateReplacement(SR, OS.str());
    }
    
    //===--- CHECK: Return Address of Stack Variable --------------------------===//
    
    static const Expr *EvalVal(const Expr *E,
                               SmallVectorImpl<const DeclRefExpr *> &refVars,
                               const Decl *ParentDecl);
    static const Expr *EvalAddr(const Expr *E,
                                SmallVectorImpl<const DeclRefExpr *> &refVars,
                                const Decl *ParentDecl);
    
    /// CheckReturnStackAddr - Check if a return statement returns the address
    ///   of a stack variable.
    static void
    CheckReturnStackAddr(Sema &S, Expr *RetValExp, QualType lhsType,
                         SourceLocation ReturnLoc) {
    
      const Expr *stackE = nullptr;
      SmallVector<const DeclRefExpr *, 8> refVars;
    
      // Perform checking for returned stack addresses, local blocks,
      // label addresses or references to temporaries.
      if (lhsType->isPointerType() ||
          (!S.getLangOpts().ObjCAutoRefCount && lhsType->isBlockPointerType())) {
        stackE = EvalAddr(RetValExp, refVars, /*ParentDecl=*/nullptr);
      } else if (lhsType->isReferenceType()) {
        stackE = EvalVal(RetValExp, refVars, /*ParentDecl=*/nullptr);
      }
    
      if (!stackE)
        return; // Nothing suspicious was found.
    
      // Parameters are initalized in the calling scope, so taking the address
      // of a parameter reference doesn't need a warning.
      for (auto *DRE : refVars)
        if (isa<ParmVarDecl>(DRE->getDecl()))
          return;
    
      SourceLocation diagLoc;
      SourceRange diagRange;
      if (refVars.empty()) {
        diagLoc = stackE->getLocStart();
        diagRange = stackE->getSourceRange();
      } else {
        // We followed through a reference variable. 'stackE' contains the
        // problematic expression but we will warn at the return statement pointing
        // at the reference variable. We will later display the "trail" of
        // reference variables using notes.
        diagLoc = refVars[0]->getLocStart();
        diagRange = refVars[0]->getSourceRange();
      }
    
      if (const DeclRefExpr *DR = dyn_cast<DeclRefExpr>(stackE)) {
        // address of local var
        S.Diag(diagLoc, diag::warn_ret_stack_addr_ref) << lhsType->isReferenceType()
         << DR->getDecl()->getDeclName() << diagRange;
      } else if (isa<BlockExpr>(stackE)) { // local block.
        S.Diag(diagLoc, diag::err_ret_local_block) << diagRange;
      } else if (isa<AddrLabelExpr>(stackE)) { // address of label.
        S.Diag(diagLoc, diag::warn_ret_addr_label) << diagRange;
      } else { // local temporary.
        // If there is an LValue->RValue conversion, then the value of the
        // reference type is used, not the reference.
        if (auto *ICE = dyn_cast<ImplicitCastExpr>(RetValExp)) {
          if (ICE->getCastKind() == CK_LValueToRValue) {
            return;
          }
        }
        S.Diag(diagLoc, diag::warn_ret_local_temp_addr_ref)
         << lhsType->isReferenceType() << diagRange;
      }
    
      // Display the "trail" of reference variables that we followed until we
      // found the problematic expression using notes.
      for (unsigned i = 0, e = refVars.size(); i != e; ++i) {
        const VarDecl *VD = cast<VarDecl>(refVars[i]->getDecl());
        // If this var binds to another reference var, show the range of the next
        // var, otherwise the var binds to the problematic expression, in which case
        // show the range of the expression.
        SourceRange range = (i < e - 1) ? refVars[i + 1]->getSourceRange()
                                        : stackE->getSourceRange();
        S.Diag(VD->getLocation(), diag::note_ref_var_local_bind)
            << VD->getDeclName() << range;
      }
    }
    
    /// EvalAddr - EvalAddr and EvalVal are mutually recursive functions that
    ///  check if the expression in a return statement evaluates to an address
    ///  to a location on the stack, a local block, an address of a label, or a
    ///  reference to local temporary. The recursion is used to traverse the
    ///  AST of the return expression, with recursion backtracking when we
    ///  encounter a subexpression that (1) clearly does not lead to one of the
    ///  above problematic expressions (2) is something we cannot determine leads to
    ///  a problematic expression based on such local checking.
    ///
    ///  Both EvalAddr and EvalVal follow through reference variables to evaluate
    ///  the expression that they point to. Such variables are added to the
    ///  'refVars' vector so that we know what the reference variable "trail" was.
    ///
    ///  EvalAddr processes expressions that are pointers that are used as
    ///  references (and not L-values).  EvalVal handles all other values.
    ///  At the base case of the recursion is a check for the above problematic
    ///  expressions.
    ///
    ///  This implementation handles:
    ///
    ///   * pointer-to-pointer casts
    ///   * implicit conversions from array references to pointers
    ///   * taking the address of fields
    ///   * arbitrary interplay between "&" and "*" operators
    ///   * pointer arithmetic from an address of a stack variable
    ///   * taking the address of an array element where the array is on the stack
    static const Expr *EvalAddr(const Expr *E,
                                SmallVectorImpl<const DeclRefExpr *> &refVars,
                                const Decl *ParentDecl) {
      if (E->isTypeDependent())
        return nullptr;
    
      // We should only be called for evaluating pointer expressions.
      assert((E->getType()->isAnyPointerType() ||
              E->getType()->isBlockPointerType() ||
              E->getType()->isObjCQualifiedIdType()) &&
             "EvalAddr only works on pointers");
    
      E = E->IgnoreParens();
    
      // Our "symbolic interpreter" is just a dispatch off the currently
      // viewed AST node.  We then recursively traverse the AST by calling
      // EvalAddr and EvalVal appropriately.
      switch (E->getStmtClass()) {
      case Stmt::DeclRefExprClass: {
        const DeclRefExpr *DR = cast<DeclRefExpr>(E);
    
        // If we leave the immediate function, the lifetime isn't about to end.
        if (DR->refersToEnclosingVariableOrCapture())
          return nullptr;
    
        if (const VarDecl *V = dyn_cast<VarDecl>(DR->getDecl()))
          // If this is a reference variable, follow through to the expression that
          // it points to.
          if (V->hasLocalStorage() &&
              V->getType()->isReferenceType() && V->hasInit()) {
            // Add the reference variable to the "trail".
            refVars.push_back(DR);
            return EvalAddr(V->getInit(), refVars, ParentDecl);
          }
    
        return nullptr;
      }
    
      case Stmt::UnaryOperatorClass: {
        // The only unary operator that make sense to handle here
        // is AddrOf.  All others don't make sense as pointers.
        const UnaryOperator *U = cast<UnaryOperator>(E);
    
        if (U->getOpcode() == UO_AddrOf)
          return EvalVal(U->getSubExpr(), refVars, ParentDecl);
        return nullptr;
      }
    
      case Stmt::BinaryOperatorClass: {
        // Handle pointer arithmetic.  All other binary operators are not valid
        // in this context.
        const BinaryOperator *B = cast<BinaryOperator>(E);
        BinaryOperatorKind op = B->getOpcode();
    
        if (op != BO_Add && op != BO_Sub)
          return nullptr;
    
        const Expr *Base = B->getLHS();
    
        // Determine which argument is the real pointer base.  It could be
        // the RHS argument instead of the LHS.
        if (!Base->getType()->isPointerType())
          Base = B->getRHS();
    
        assert(Base->getType()->isPointerType());
        return EvalAddr(Base, refVars, ParentDecl);
      }
    
      // For conditional operators we need to see if either the LHS or RHS are
      // valid DeclRefExpr*s.  If one of them is valid, we return it.
      case Stmt::ConditionalOperatorClass: {
        const ConditionalOperator *C = cast<ConditionalOperator>(E);
    
        // Handle the GNU extension for missing LHS.
        // FIXME: That isn't a ConditionalOperator, so doesn't get here.
        if (const Expr *LHSExpr = C->getLHS()) {
          // In C++, we can have a throw-expression, which has 'void' type.
          if (!LHSExpr->getType()->isVoidType())
            if (const Expr *LHS = EvalAddr(LHSExpr, refVars, ParentDecl))
              return LHS;
        }
    
        // In C++, we can have a throw-expression, which has 'void' type.
        if (C->getRHS()->getType()->isVoidType())
          return nullptr;
    
        return EvalAddr(C->getRHS(), refVars, ParentDecl);
      }
    
      case Stmt::BlockExprClass:
        if (cast<BlockExpr>(E)->getBlockDecl()->hasCaptures())
          return E; // local block.
        return nullptr;
    
      case Stmt::AddrLabelExprClass:
        return E; // address of label.
    
      case Stmt::ExprWithCleanupsClass:
        return EvalAddr(cast<ExprWithCleanups>(E)->getSubExpr(), refVars,
                        ParentDecl);
    
      // For casts, we need to handle conversions from arrays to
      // pointer values, and pointer-to-pointer conversions.
      case Stmt::ImplicitCastExprClass:
      case Stmt::CStyleCastExprClass:
      case Stmt::CXXFunctionalCastExprClass:
      case Stmt::ObjCBridgedCastExprClass:
      case Stmt::CXXStaticCastExprClass:
      case Stmt::CXXDynamicCastExprClass:
      case Stmt::CXXConstCastExprClass:
      case Stmt::CXXReinterpretCastExprClass: {
        const Expr* SubExpr = cast<CastExpr>(E)->getSubExpr();
        switch (cast<CastExpr>(E)->getCastKind()) {
        case CK_LValueToRValue:
        case CK_NoOp:
        case CK_BaseToDerived:
        case CK_DerivedToBase:
        case CK_UncheckedDerivedToBase:
        case CK_Dynamic:
        case CK_CPointerToObjCPointerCast:
        case CK_BlockPointerToObjCPointerCast:
        case CK_AnyPointerToBlockPointerCast:
          return EvalAddr(SubExpr, refVars, ParentDecl);
    
        case CK_ArrayToPointerDecay:
          return EvalVal(SubExpr, refVars, ParentDecl);
    
        case CK_BitCast:
          if (SubExpr->getType()->isAnyPointerType() ||
              SubExpr->getType()->isBlockPointerType() ||
              SubExpr->getType()->isObjCQualifiedIdType())
            return EvalAddr(SubExpr, refVars, ParentDecl);
          else
            return nullptr;
    
        default:
          return nullptr;
        }
      }
    
      case Stmt::MaterializeTemporaryExprClass:
        if (const Expr *Result =
                EvalAddr(cast<MaterializeTemporaryExpr>(E)->GetTemporaryExpr(),
                         refVars, ParentDecl))
          return Result;
        return E;
    
      // Everything else: we simply don't reason about them.
      default:
        return nullptr;
      }
    }
    
    ///  EvalVal - This function is complements EvalAddr in the mutual recursion.
    ///   See the comments for EvalAddr for more details.
    static const Expr *EvalVal(const Expr *E,
                               SmallVectorImpl<const DeclRefExpr *> &refVars,
                               const Decl *ParentDecl) {
      do {
        // We should only be called for evaluating non-pointer expressions, or
        // expressions with a pointer type that are not used as references but
        // instead
        // are l-values (e.g., DeclRefExpr with a pointer type).
    
        // Our "symbolic interpreter" is just a dispatch off the currently
        // viewed AST node.  We then recursively traverse the AST by calling
        // EvalAddr and EvalVal appropriately.
    
        E = E->IgnoreParens();
        switch (E->getStmtClass()) {
        case Stmt::ImplicitCastExprClass: {
          const ImplicitCastExpr *IE = cast<ImplicitCastExpr>(E);
          if (IE->getValueKind() == VK_LValue) {
            E = IE->getSubExpr();
            continue;
          }
          return nullptr;
        }
    
        case Stmt::ExprWithCleanupsClass:
          return EvalVal(cast<ExprWithCleanups>(E)->getSubExpr(), refVars,
                         ParentDecl);
    
        case Stmt::DeclRefExprClass: {
          // When we hit a DeclRefExpr we are looking at code that refers to a
          // variable's name. If it's not a reference variable we check if it has
          // local storage within the function, and if so, return the expression.
          const DeclRefExpr *DR = cast<DeclRefExpr>(E);
    
          // If we leave the immediate function, the lifetime isn't about to end.
          if (DR->refersToEnclosingVariableOrCapture())
            return nullptr;
    
          if (const VarDecl *V = dyn_cast<VarDecl>(DR->getDecl())) {
            // Check if it refers to itself, e.g. "int& i = i;".
            if (V == ParentDecl)
              return DR;
    
            if (V->hasLocalStorage()) {
              if (!V->getType()->isReferenceType())
                return DR;
    
              // Reference variable, follow through to the expression that
              // it points to.
              if (V->hasInit()) {
                // Add the reference variable to the "trail".
                refVars.push_back(DR);
                return EvalVal(V->getInit(), refVars, V);
              }
            }
          }
    
          return nullptr;
        }
    
        case Stmt::UnaryOperatorClass: {
          // The only unary operator that make sense to handle here
          // is Deref.  All others don't resolve to a "name."  This includes
          // handling all sorts of rvalues passed to a unary operator.
          const UnaryOperator *U = cast<UnaryOperator>(E);
    
          if (U->getOpcode() == UO_Deref)
            return EvalAddr(U->getSubExpr(), refVars, ParentDecl);
    
          return nullptr;
        }
    
        case Stmt::ArraySubscriptExprClass: {
          // Array subscripts are potential references to data on the stack.  We
          // retrieve the DeclRefExpr* for the array variable if it indeed
          // has local storage.
          const auto *ASE = cast<ArraySubscriptExpr>(E);
          if (ASE->isTypeDependent())
            return nullptr;
          return EvalAddr(ASE->getBase(), refVars, ParentDecl);
        }
    
        case Stmt::OMPArraySectionExprClass: {
          return EvalAddr(cast<OMPArraySectionExpr>(E)->getBase(), refVars,
                          ParentDecl);
        }
    
        case Stmt::ConditionalOperatorClass: {
          // For conditional operators we need to see if either the LHS or RHS are
          // non-NULL Expr's.  If one is non-NULL, we return it.
          const ConditionalOperator *C = cast<ConditionalOperator>(E);
    
          // Handle the GNU extension for missing LHS.
          if (const Expr *LHSExpr = C->getLHS()) {
            // In C++, we can have a throw-expression, which has 'void' type.
            if (!LHSExpr->getType()->isVoidType())
              if (const Expr *LHS = EvalVal(LHSExpr, refVars, ParentDecl))
                return LHS;
          }
    
          // In C++, we can have a throw-expression, which has 'void' type.
          if (C->getRHS()->getType()->isVoidType())
            return nullptr;
    
          return EvalVal(C->getRHS(), refVars, ParentDecl);
        }
    
        // Accesses to members are potential references to data on the stack.
        case Stmt::MemberExprClass: {
          const MemberExpr *M = cast<MemberExpr>(E);
    
          // Check for indirect access.  We only want direct field accesses.
          if (M->isArrow())
            return nullptr;
    
          // Check whether the member type is itself a reference, in which case
          // we're not going to refer to the member, but to what the member refers
          // to.
          if (M->getMemberDecl()->getType()->isReferenceType())
            return nullptr;
    
          return EvalVal(M->getBase(), refVars, ParentDecl);
        }
    
        case Stmt::MaterializeTemporaryExprClass:
          if (const Expr *Result =
                  EvalVal(cast<MaterializeTemporaryExpr>(E)->GetTemporaryExpr(),
                          refVars, ParentDecl))
            return Result;
          return E;
    
        default:
          // Check that we don't return or take the address of a reference to a
          // temporary. This is only useful in C++.
          if (!E->isTypeDependent() && E->isRValue())
            return E;
    
          // Everything else: we simply don't reason about them.
          return nullptr;
        }
      } while (true);
    }
    
    void
    Sema::CheckReturnValExpr(Expr *RetValExp, QualType lhsType,
                             SourceLocation ReturnLoc,
                             bool isObjCMethod,
                             const AttrVec *Attrs,
                             const FunctionDecl *FD) {
      CheckReturnStackAddr(*this, RetValExp, lhsType, ReturnLoc);
    
      // Check if the return value is null but should not be.
      if (((Attrs && hasSpecificAttr<ReturnsNonNullAttr>(*Attrs)) ||
           (!isObjCMethod && isNonNullType(Context, lhsType))) &&
          CheckNonNullExpr(*this, RetValExp))
        Diag(ReturnLoc, diag::warn_null_ret)
          << (isObjCMethod ? 1 : 0) << RetValExp->getSourceRange();
    
      // C++11 [basic.stc.dynamic.allocation]p4:
      //   If an allocation function declared with a non-throwing
      //   exception-specification fails to allocate storage, it shall return
      //   a null pointer. Any other allocation function that fails to allocate
      //   storage shall indicate failure only by throwing an exception [...]
      if (FD) {
        OverloadedOperatorKind Op = FD->getOverloadedOperator();
        if (Op == OO_New || Op == OO_Array_New) {
          const FunctionProtoType *Proto
            = FD->getType()->castAs<FunctionProtoType>();
          if (!Proto->isNothrow(Context, /*ResultIfDependent*/true) &&
              CheckNonNullExpr(*this, RetValExp))
            Diag(ReturnLoc, diag::warn_operator_new_returns_null)
              << FD << getLangOpts().CPlusPlus11;
        }
      }
    }
    
    //===--- CHECK: Floating-Point comparisons (-Wfloat-equal) ---------------===//
    
    /// Check for comparisons of floating point operands using != and ==.
    /// Issue a warning if these are no self-comparisons, as they are not likely
    /// to do what the programmer intended.
    void Sema::CheckFloatComparison(SourceLocation Loc, Expr* LHS, Expr *RHS) {
      Expr* LeftExprSansParen = LHS->IgnoreParenImpCasts();
      Expr* RightExprSansParen = RHS->IgnoreParenImpCasts();
    
      // Special case: check for x == x (which is OK).
      // Do not emit warnings for such cases.
      if (DeclRefExpr* DRL = dyn_cast<DeclRefExpr>(LeftExprSansParen))
        if (DeclRefExpr* DRR = dyn_cast<DeclRefExpr>(RightExprSansParen))
          if (DRL->getDecl() == DRR->getDecl())
            return;
    
      // Special case: check for comparisons against literals that can be exactly
      //  represented by APFloat.  In such cases, do not emit a warning.  This
      //  is a heuristic: often comparison against such literals are used to
      //  detect if a value in a variable has not changed.  This clearly can
      //  lead to false negatives.
      if (FloatingLiteral* FLL = dyn_cast<FloatingLiteral>(LeftExprSansParen)) {
        if (FLL->isExact())
          return;
      } else
        if (FloatingLiteral* FLR = dyn_cast<FloatingLiteral>(RightExprSansParen))
          if (FLR->isExact())
            return;
    
      // Check for comparisons with builtin types.
      if (CallExpr* CL = dyn_cast<CallExpr>(LeftExprSansParen))
        if (CL->getBuiltinCallee())
          return;
    
      if (CallExpr* CR = dyn_cast<CallExpr>(RightExprSansParen))
        if (CR->getBuiltinCallee())
          return;
    
      // Emit the diagnostic.
      Diag(Loc, diag::warn_floatingpoint_eq)
        << LHS->getSourceRange() << RHS->getSourceRange();
    }
    
    //===--- CHECK: Integer mixed-sign comparisons (-Wsign-compare) --------===//
    //===--- CHECK: Lossy implicit conversions (-Wconversion) --------------===//
    
    namespace {
    
    /// Structure recording the 'active' range of an integer-valued
    /// expression.
    struct IntRange {
      /// The number of bits active in the int.
      unsigned Width;
    
      /// True if the int is known not to have negative values.
      bool NonNegative;
    
      IntRange(unsigned Width, bool NonNegative)
        : Width(Width), NonNegative(NonNegative)
      {}
    
      /// Returns the range of the bool type.
      static IntRange forBoolType() {
        return IntRange(1, true);
      }
    
      /// Returns the range of an opaque value of the given integral type.
      static IntRange forValueOfType(ASTContext &C, QualType T) {
        return forValueOfCanonicalType(C,
                              T->getCanonicalTypeInternal().getTypePtr());
      }
    
      /// Returns the range of an opaque value of a canonical integral type.
      static IntRange forValueOfCanonicalType(ASTContext &C, const Type *T) {
        assert(T->isCanonicalUnqualified());
    
        if (const VectorType *VT = dyn_cast<VectorType>(T))
          T = VT->getElementType().getTypePtr();
        if (const ComplexType *CT = dyn_cast<ComplexType>(T))
          T = CT->getElementType().getTypePtr();
        if (const AtomicType *AT = dyn_cast<AtomicType>(T))
          T = AT->getValueType().getTypePtr();
    
        // For enum types, use the known bit width of the enumerators.
        if (const EnumType *ET = dyn_cast<EnumType>(T)) {
          EnumDecl *Enum = ET->getDecl();
          if (!Enum->isCompleteDefinition())
            return IntRange(C.getIntWidth(QualType(T, 0)), false);
    
          unsigned NumPositive = Enum->getNumPositiveBits();
          unsigned NumNegative = Enum->getNumNegativeBits();
    
          if (NumNegative == 0)
            return IntRange(NumPositive, true/*NonNegative*/);
          else
            return IntRange(std::max(NumPositive + 1, NumNegative),
                            false/*NonNegative*/);
        }
    
        const BuiltinType *BT = cast<BuiltinType>(T);
        assert(BT->isInteger());
    
        return IntRange(C.getIntWidth(QualType(T, 0)), BT->isUnsignedInteger());
      }
    
      /// Returns the "target" range of a canonical integral type, i.e.
      /// the range of values expressible in the type.
      ///
      /// This matches forValueOfCanonicalType except that enums have the
      /// full range of their type, not the range of their enumerators.
      static IntRange forTargetOfCanonicalType(ASTContext &C, const Type *T) {
        assert(T->isCanonicalUnqualified());
    
        if (const VectorType *VT = dyn_cast<VectorType>(T))
          T = VT->getElementType().getTypePtr();
        if (const ComplexType *CT = dyn_cast<ComplexType>(T))
          T = CT->getElementType().getTypePtr();
        if (const AtomicType *AT = dyn_cast<AtomicType>(T))
          T = AT->getValueType().getTypePtr();
        if (const EnumType *ET = dyn_cast<EnumType>(T))
          T = C.getCanonicalType(ET->getDecl()->getIntegerType()).getTypePtr();
    
        const BuiltinType *BT = cast<BuiltinType>(T);
        assert(BT->isInteger());
    
        return IntRange(C.getIntWidth(QualType(T, 0)), BT->isUnsignedInteger());
      }
    
      /// Returns the supremum of two ranges: i.e. their conservative merge.
      static IntRange join(IntRange L, IntRange R) {
        return IntRange(std::max(L.Width, R.Width),
                        L.NonNegative && R.NonNegative);
      }
    
      /// Returns the infinum of two ranges: i.e. their aggressive merge.
      static IntRange meet(IntRange L, IntRange R) {
        return IntRange(std::min(L.Width, R.Width),
                        L.NonNegative || R.NonNegative);
      }
    };
    
    IntRange GetValueRange(ASTContext &C, llvm::APSInt &value, unsigned MaxWidth) {
      if (value.isSigned() && value.isNegative())
        return IntRange(value.getMinSignedBits(), false);
    
      if (value.getBitWidth() > MaxWidth)
        value = value.trunc(MaxWidth);
    
      // isNonNegative() just checks the sign bit without considering
      // signedness.
      return IntRange(value.getActiveBits(), true);
    }
    
    IntRange GetValueRange(ASTContext &C, APValue &result, QualType Ty,
                           unsigned MaxWidth) {
      if (result.isInt())
        return GetValueRange(C, result.getInt(), MaxWidth);
    
      if (result.isVector()) {
        IntRange R = GetValueRange(C, result.getVectorElt(0), Ty, MaxWidth);
        for (unsigned i = 1, e = result.getVectorLength(); i != e; ++i) {
          IntRange El = GetValueRange(C, result.getVectorElt(i), Ty, MaxWidth);
          R = IntRange::join(R, El);
        }
        return R;
      }
    
      if (result.isComplexInt()) {
        IntRange R = GetValueRange(C, result.getComplexIntReal(), MaxWidth);
        IntRange I = GetValueRange(C, result.getComplexIntImag(), MaxWidth);
        return IntRange::join(R, I);
      }
    
      // This can happen with lossless casts to intptr_t of "based" lvalues.
      // Assume it might use arbitrary bits.
      // FIXME: The only reason we need to pass the type in here is to get
      // the sign right on this one case.  It would be nice if APValue
      // preserved this.
      assert(result.isLValue() || result.isAddrLabelDiff());
      return IntRange(MaxWidth, Ty->isUnsignedIntegerOrEnumerationType());
    }
    
    QualType GetExprType(const Expr *E) {
      QualType Ty = E->getType();
      if (const AtomicType *AtomicRHS = Ty->getAs<AtomicType>())
        Ty = AtomicRHS->getValueType();
      return Ty;
    }
    
    /// Pseudo-evaluate the given integer expression, estimating the
    /// range of values it might take.
    ///
    /// \param MaxWidth - the width to which the value will be truncated
    IntRange GetExprRange(ASTContext &C, const Expr *E, unsigned MaxWidth) {
      E = E->IgnoreParens();
    
      // Try a full evaluation first.
      Expr::EvalResult result;
      if (E->EvaluateAsRValue(result, C))
        return GetValueRange(C, result.Val, GetExprType(E), MaxWidth);
    
      // I think we only want to look through implicit casts here; if the
      // user has an explicit widening cast, we should treat the value as
      // being of the new, wider type.
      if (const auto *CE = dyn_cast<ImplicitCastExpr>(E)) {
        if (CE->getCastKind() == CK_NoOp || CE->getCastKind() == CK_LValueToRValue)
          return GetExprRange(C, CE->getSubExpr(), MaxWidth);
    
        IntRange OutputTypeRange = IntRange::forValueOfType(C, GetExprType(CE));
    
        bool isIntegerCast = CE->getCastKind() == CK_IntegralCast ||
                             CE->getCastKind() == CK_BooleanToSignedIntegral;
    
        // Assume that non-integer casts can span the full range of the type.
        if (!isIntegerCast)
          return OutputTypeRange;
    
        IntRange SubRange
          = GetExprRange(C, CE->getSubExpr(),
                         std::min(MaxWidth, OutputTypeRange.Width));
    
        // Bail out if the subexpr's range is as wide as the cast type.
        if (SubRange.Width >= OutputTypeRange.Width)
          return OutputTypeRange;
    
        // Otherwise, we take the smaller width, and we're non-negative if
        // either the output type or the subexpr is.
        return IntRange(SubRange.Width,
                        SubRange.NonNegative || OutputTypeRange.NonNegative);
      }
    
      if (const auto *CO = dyn_cast<ConditionalOperator>(E)) {
        // If we can fold the condition, just take that operand.
        bool CondResult;
        if (CO->getCond()->EvaluateAsBooleanCondition(CondResult, C))
          return GetExprRange(C, CondResult ? CO->getTrueExpr()
                                            : CO->getFalseExpr(),
                              MaxWidth);
    
        // Otherwise, conservatively merge.
        IntRange L = GetExprRange(C, CO->getTrueExpr(), MaxWidth);
        IntRange R = GetExprRange(C, CO->getFalseExpr(), MaxWidth);
        return IntRange::join(L, R);
      }
    
      if (const auto *BO = dyn_cast<BinaryOperator>(E)) {
        switch (BO->getOpcode()) {
    
        // Boolean-valued operations are single-bit and positive.
        case BO_LAnd:
        case BO_LOr:
        case BO_LT:
        case BO_GT:
        case BO_LE:
        case BO_GE:
        case BO_EQ:
        case BO_NE:
          return IntRange::forBoolType();
    
        // The type of the assignments is the type of the LHS, so the RHS
        // is not necessarily the same type.
        case BO_MulAssign:
        case BO_DivAssign:
        case BO_RemAssign:
        case BO_AddAssign:
        case BO_SubAssign:
        case BO_XorAssign:
        case BO_OrAssign:
          // TODO: bitfields?
          return IntRange::forValueOfType(C, GetExprType(E));
    
        // Simple assignments just pass through the RHS, which will have
        // been coerced to the LHS type.
        case BO_Assign:
          // TODO: bitfields?
          return GetExprRange(C, BO->getRHS(), MaxWidth);
    
        // Operations with opaque sources are black-listed.
        case BO_PtrMemD:
        case BO_PtrMemI:
          return IntRange::forValueOfType(C, GetExprType(E));
    
        // Bitwise-and uses the *infinum* of the two source ranges.
        case BO_And:
        case BO_AndAssign:
          return IntRange::meet(GetExprRange(C, BO->getLHS(), MaxWidth),
                                GetExprRange(C, BO->getRHS(), MaxWidth));
    
        // Left shift gets black-listed based on a judgement call.
        case BO_Shl:
          // ...except that we want to treat '1 << (blah)' as logically
          // positive.  It's an important idiom.
          if (IntegerLiteral *I
                = dyn_cast<IntegerLiteral>(BO->getLHS()->IgnoreParenCasts())) {
            if (I->getValue() == 1) {
              IntRange R = IntRange::forValueOfType(C, GetExprType(E));
              return IntRange(R.Width, /*NonNegative*/ true);
            }
          }
          // fallthrough
    
        case BO_ShlAssign:
          return IntRange::forValueOfType(C, GetExprType(E));
    
        // Right shift by a constant can narrow its left argument.
        case BO_Shr:
        case BO_ShrAssign: {
          IntRange L = GetExprRange(C, BO->getLHS(), MaxWidth);
    
          // If the shift amount is a positive constant, drop the width by
          // that much.
          llvm::APSInt shift;
          if (BO->getRHS()->isIntegerConstantExpr(shift, C) &&
              shift.isNonNegative()) {
            unsigned zext = shift.getZExtValue();
            if (zext >= L.Width)
              L.Width = (L.NonNegative ? 0 : 1);
            else
              L.Width -= zext;
          }
    
          return L;
        }
    
        // Comma acts as its right operand.
        case BO_Comma:
          return GetExprRange(C, BO->getRHS(), MaxWidth);
    
        // Black-list pointer subtractions.
        case BO_Sub:
          if (BO->getLHS()->getType()->isPointerType())
            return IntRange::forValueOfType(C, GetExprType(E));
          break;
    
        // The width of a division result is mostly determined by the size
        // of the LHS.
        case BO_Div: {
          // Don't 'pre-truncate' the operands.
          unsigned opWidth = C.getIntWidth(GetExprType(E));
          IntRange L = GetExprRange(C, BO->getLHS(), opWidth);
    
          // If the divisor is constant, use that.
          llvm::APSInt divisor;
          if (BO->getRHS()->isIntegerConstantExpr(divisor, C)) {
            unsigned log2 = divisor.logBase2(); // floor(log_2(divisor))
            if (log2 >= L.Width)
              L.Width = (L.NonNegative ? 0 : 1);
            else
              L.Width = std::min(L.Width - log2, MaxWidth);
            return L;
          }
    
          // Otherwise, just use the LHS's width.
          IntRange R = GetExprRange(C, BO->getRHS(), opWidth);
          return IntRange(L.Width, L.NonNegative && R.NonNegative);
        }
    
        // The result of a remainder can't be larger than the result of
        // either side.
        case BO_Rem: {
          // Don't 'pre-truncate' the operands.
          unsigned opWidth = C.getIntWidth(GetExprType(E));
          IntRange L = GetExprRange(C, BO->getLHS(), opWidth);
          IntRange R = GetExprRange(C, BO->getRHS(), opWidth);
    
          IntRange meet = IntRange::meet(L, R);
          meet.Width = std::min(meet.Width, MaxWidth);
          return meet;
        }
    
        // The default behavior is okay for these.
        case BO_Mul:
        case BO_Add:
        case BO_Xor:
        case BO_Or:
          break;
        }
    
        // The default case is to treat the operation as if it were closed
        // on the narrowest type that encompasses both operands.
        IntRange L = GetExprRange(C, BO->getLHS(), MaxWidth);
        IntRange R = GetExprRange(C, BO->getRHS(), MaxWidth);
        return IntRange::join(L, R);
      }
    
      if (const auto *UO = dyn_cast<UnaryOperator>(E)) {
        switch (UO->getOpcode()) {
        // Boolean-valued operations are white-listed.
        case UO_LNot:
          return IntRange::forBoolType();
    
        // Operations with opaque sources are black-listed.
        case UO_Deref:
        case UO_AddrOf: // should be impossible
          return IntRange::forValueOfType(C, GetExprType(E));
    
        default:
          return GetExprRange(C, UO->getSubExpr(), MaxWidth);
        }
      }
    
      if (const auto *OVE = dyn_cast<OpaqueValueExpr>(E))
        return GetExprRange(C, OVE->getSourceExpr(), MaxWidth);
    
      if (const auto *BitField = E->getSourceBitField())
        return IntRange(BitField->getBitWidthValue(C),
                        BitField->getType()->isUnsignedIntegerOrEnumerationType());
    
      return IntRange::forValueOfType(C, GetExprType(E));
    }
    
    IntRange GetExprRange(ASTContext &C, const Expr *E) {
      return GetExprRange(C, E, C.getIntWidth(GetExprType(E)));
    }
    
    /// Checks whether the given value, which currently has the given
    /// source semantics, has the same value when coerced through the
    /// target semantics.
    bool IsSameFloatAfterCast(const llvm::APFloat &value,
                              const llvm::fltSemantics &Src,
                              const llvm::fltSemantics &Tgt) {
      llvm::APFloat truncated = value;
    
      bool ignored;
      truncated.convert(Src, llvm::APFloat::rmNearestTiesToEven, &ignored);
      truncated.convert(Tgt, llvm::APFloat::rmNearestTiesToEven, &ignored);
    
      return truncated.bitwiseIsEqual(value);
    }
    
    /// Checks whether the given value, which currently has the given
    /// source semantics, has the same value when coerced through the
    /// target semantics.
    ///
    /// The value might be a vector of floats (or a complex number).
    bool IsSameFloatAfterCast(const APValue &value,
                              const llvm::fltSemantics &Src,
                              const llvm::fltSemantics &Tgt) {
      if (value.isFloat())
        return IsSameFloatAfterCast(value.getFloat(), Src, Tgt);
    
      if (value.isVector()) {
        for (unsigned i = 0, e = value.getVectorLength(); i != e; ++i)
          if (!IsSameFloatAfterCast(value.getVectorElt(i), Src, Tgt))
            return false;
        return true;
      }
    
      assert(value.isComplexFloat());
      return (IsSameFloatAfterCast(value.getComplexFloatReal(), Src, Tgt) &&
              IsSameFloatAfterCast(value.getComplexFloatImag(), Src, Tgt));
    }
    
    void AnalyzeImplicitConversions(Sema &S, Expr *E, SourceLocation CC);
    
    bool IsZero(Sema &S, Expr *E) {
      // Suppress cases where we are comparing against an enum constant.
      if (const DeclRefExpr *DR =
          dyn_cast<DeclRefExpr>(E->IgnoreParenImpCasts()))
        if (isa<EnumConstantDecl>(DR->getDecl()))
          return false;
    
      // Suppress cases where the '0' value is expanded from a macro.
      if (E->getLocStart().isMacroID())
        return false;
    
      llvm::APSInt Value;
      return E->isIntegerConstantExpr(Value, S.Context) && Value == 0;
    }
    
    bool HasEnumType(Expr *E) {
      // Strip off implicit integral promotions.
      while (ImplicitCastExpr *ICE = dyn_cast<ImplicitCastExpr>(E)) {
        if (ICE->getCastKind() != CK_IntegralCast &&
            ICE->getCastKind() != CK_NoOp)
          break;
        E = ICE->getSubExpr();
      }
    
      return E->getType()->isEnumeralType();
    }
    
    void CheckTrivialUnsignedComparison(Sema &S, BinaryOperator *E) {
      // Disable warning in template instantiations.
      if (!S.ActiveTemplateInstantiations.empty())
        return;
    
      BinaryOperatorKind op = E->getOpcode();
      if (E->isValueDependent())
        return;
    
      if (op == BO_LT && IsZero(S, E->getRHS())) {
        S.Diag(E->getOperatorLoc(), diag::warn_lunsigned_always_true_comparison)
          << "< 0" << "false" << HasEnumType(E->getLHS())
          << E->getLHS()->getSourceRange() << E->getRHS()->getSourceRange();
      } else if (op == BO_GE && IsZero(S, E->getRHS())) {
        S.Diag(E->getOperatorLoc(), diag::warn_lunsigned_always_true_comparison)
          << ">= 0" << "true" << HasEnumType(E->getLHS())
          << E->getLHS()->getSourceRange() << E->getRHS()->getSourceRange();
      } else if (op == BO_GT && IsZero(S, E->getLHS())) {
        S.Diag(E->getOperatorLoc(), diag::warn_runsigned_always_true_comparison)
          << "0 >" << "false" << HasEnumType(E->getRHS())
          << E->getLHS()->getSourceRange() << E->getRHS()->getSourceRange();
      } else if (op == BO_LE && IsZero(S, E->getLHS())) {
        S.Diag(E->getOperatorLoc(), diag::warn_runsigned_always_true_comparison)
          << "0 <=" << "true" << HasEnumType(E->getRHS())
          << E->getLHS()->getSourceRange() << E->getRHS()->getSourceRange();
      }
    }
    
    void DiagnoseOutOfRangeComparison(Sema &S, BinaryOperator *E, Expr *Constant,
                                      Expr *Other, const llvm::APSInt &Value,
                                      bool RhsConstant) {
      // Disable warning in template instantiations.
      if (!S.ActiveTemplateInstantiations.empty())
        return;
    
      // TODO: Investigate using GetExprRange() to get tighter bounds
      // on the bit ranges.
      QualType OtherT = Other->getType();
      if (const auto *AT = OtherT->getAs<AtomicType>())
        OtherT = AT->getValueType();
      IntRange OtherRange = IntRange::forValueOfType(S.Context, OtherT);
      unsigned OtherWidth = OtherRange.Width;
    
      bool OtherIsBooleanType = Other->isKnownToHaveBooleanValue();
    
      // 0 values are handled later by CheckTrivialUnsignedComparison().
      if ((Value == 0) && (!OtherIsBooleanType))
        return;
    
      BinaryOperatorKind op = E->getOpcode();
      bool IsTrue = true;
    
      // Used for diagnostic printout.
      enum {
        LiteralConstant = 0,
        CXXBoolLiteralTrue,
        CXXBoolLiteralFalse
      } LiteralOrBoolConstant = LiteralConstant;
    
      if (!OtherIsBooleanType) {
        QualType ConstantT = Constant->getType();
        QualType CommonT = E->getLHS()->getType();
    
        if (S.Context.hasSameUnqualifiedType(OtherT, ConstantT))
          return;
        assert((OtherT->isIntegerType() && ConstantT->isIntegerType()) &&
               "comparison with non-integer type");
    
        bool ConstantSigned = ConstantT->isSignedIntegerType();
        bool CommonSigned = CommonT->isSignedIntegerType();
    
        bool EqualityOnly = false;
    
        if (CommonSigned) {
          // The common type is signed, therefore no signed to unsigned conversion.
          if (!OtherRange.NonNegative) {
            // Check that the constant is representable in type OtherT.
            if (ConstantSigned) {
              if (OtherWidth >= Value.getMinSignedBits())
                return;
            } else { // !ConstantSigned
              if (OtherWidth >= Value.getActiveBits() + 1)
                return;
            }
          } else { // !OtherSigned
                   // Check that the constant is representable in type OtherT.
            // Negative values are out of range.
            if (ConstantSigned) {
              if (Value.isNonNegative() && OtherWidth >= Value.getActiveBits())
                return;
            } else { // !ConstantSigned
              if (OtherWidth >= Value.getActiveBits())
                return;
            }
          }
        } else { // !CommonSigned
          if (OtherRange.NonNegative) {
            if (OtherWidth >= Value.getActiveBits())
              return;
          } else { // OtherSigned
            assert(!ConstantSigned &&
                   "Two signed types converted to unsigned types.");
            // Check to see if the constant is representable in OtherT.
            if (OtherWidth > Value.getActiveBits())
              return;
            // Check to see if the constant is equivalent to a negative value
            // cast to CommonT.
            if (S.Context.getIntWidth(ConstantT) ==
                    S.Context.getIntWidth(CommonT) &&
                Value.isNegative() && Value.getMinSignedBits() <= OtherWidth)
              return;
            // The constant value rests between values that OtherT can represent
            // after conversion.  Relational comparison still works, but equality
            // comparisons will be tautological.
            EqualityOnly = true;
          }
        }
    
        bool PositiveConstant = !ConstantSigned || Value.isNonNegative();
    
        if (op == BO_EQ || op == BO_NE) {
          IsTrue = op == BO_NE;
        } else if (EqualityOnly) {
          return;
        } else if (RhsConstant) {
          if (op == BO_GT || op == BO_GE)
            IsTrue = !PositiveConstant;
          else // op == BO_LT || op == BO_LE
            IsTrue = PositiveConstant;
        } else {
          if (op == BO_LT || op == BO_LE)
            IsTrue = !PositiveConstant;
          else // op == BO_GT || op == BO_GE
            IsTrue = PositiveConstant;
        }
      } else {
        // Other isKnownToHaveBooleanValue
        enum CompareBoolWithConstantResult { AFals, ATrue, Unkwn };
        enum ConstantValue { LT_Zero, Zero, One, GT_One, SizeOfConstVal };
        enum ConstantSide { Lhs, Rhs, SizeOfConstSides };
    
        static const struct LinkedConditions {
          CompareBoolWithConstantResult BO_LT_OP[SizeOfConstSides][SizeOfConstVal];
          CompareBoolWithConstantResult BO_GT_OP[SizeOfConstSides][SizeOfConstVal];
          CompareBoolWithConstantResult BO_LE_OP[SizeOfConstSides][SizeOfConstVal];
          CompareBoolWithConstantResult BO_GE_OP[SizeOfConstSides][SizeOfConstVal];
          CompareBoolWithConstantResult BO_EQ_OP[SizeOfConstSides][SizeOfConstVal];
          CompareBoolWithConstantResult BO_NE_OP[SizeOfConstSides][SizeOfConstVal];
    
        } TruthTable = {
            // Constant on LHS.              | Constant on RHS.              |
            // LT_Zero| Zero  | One   |GT_One| LT_Zero| Zero  | One   |GT_One|
            { { ATrue, Unkwn, AFals, AFals }, { AFals, AFals, Unkwn, ATrue } },
            { { AFals, AFals, Unkwn, ATrue }, { ATrue, Unkwn, AFals, AFals } },
            { { ATrue, ATrue, Unkwn, AFals }, { AFals, Unkwn, ATrue, ATrue } },
            { { AFals, Unkwn, ATrue, ATrue }, { ATrue, ATrue, Unkwn, AFals } },
            { { AFals, Unkwn, Unkwn, AFals }, { AFals, Unkwn, Unkwn, AFals } },
            { { ATrue, Unkwn, Unkwn, ATrue }, { ATrue, Unkwn, Unkwn, ATrue } }
          };
    
        bool ConstantIsBoolLiteral = isa<CXXBoolLiteralExpr>(Constant);
    
        enum ConstantValue ConstVal = Zero;
        if (Value.isUnsigned() || Value.isNonNegative()) {
          if (Value == 0) {
            LiteralOrBoolConstant =
                ConstantIsBoolLiteral ? CXXBoolLiteralFalse : LiteralConstant;
            ConstVal = Zero;
          } else if (Value == 1) {
            LiteralOrBoolConstant =
                ConstantIsBoolLiteral ? CXXBoolLiteralTrue : LiteralConstant;
            ConstVal = One;
          } else {
            LiteralOrBoolConstant = LiteralConstant;
            ConstVal = GT_One;
          }
        } else {
          ConstVal = LT_Zero;
        }
    
        CompareBoolWithConstantResult CmpRes;
    
        switch (op) {
        case BO_LT:
          CmpRes = TruthTable.BO_LT_OP[RhsConstant][ConstVal];
          break;
        case BO_GT:
          CmpRes = TruthTable.BO_GT_OP[RhsConstant][ConstVal];
          break;
        case BO_LE:
          CmpRes = TruthTable.BO_LE_OP[RhsConstant][ConstVal];
          break;
        case BO_GE:
          CmpRes = TruthTable.BO_GE_OP[RhsConstant][ConstVal];
          break;
        case BO_EQ:
          CmpRes = TruthTable.BO_EQ_OP[RhsConstant][ConstVal];
          break;
        case BO_NE:
          CmpRes = TruthTable.BO_NE_OP[RhsConstant][ConstVal];
          break;
        default:
          CmpRes = Unkwn;
          break;
        }
    
        if (CmpRes == AFals) {
          IsTrue = false;
        } else if (CmpRes == ATrue) {
          IsTrue = true;
        } else {
          return;
        }
      }
    
      // If this is a comparison to an enum constant, include that
      // constant in the diagnostic.
      const EnumConstantDecl *ED = nullptr;
      if (const DeclRefExpr *DR = dyn_cast<DeclRefExpr>(Constant))
        ED = dyn_cast<EnumConstantDecl>(DR->getDecl());
    
      SmallString<64> PrettySourceValue;
      llvm::raw_svector_ostream OS(PrettySourceValue);
      if (ED)
        OS << '\'' << *ED << "' (" << Value << ")";
      else
        OS << Value;
    
      S.DiagRuntimeBehavior(
        E->getOperatorLoc(), E,
        S.PDiag(diag::warn_out_of_range_compare)
            << OS.str() << LiteralOrBoolConstant
            << OtherT << (OtherIsBooleanType && !OtherT->isBooleanType()) << IsTrue
            << E->getLHS()->getSourceRange() << E->getRHS()->getSourceRange());
    }
    
    /// Analyze the operands of the given comparison.  Implements the
    /// fallback case from AnalyzeComparison.
    void AnalyzeImpConvsInComparison(Sema &S, BinaryOperator *E) {
      AnalyzeImplicitConversions(S, E->getLHS(), E->getOperatorLoc());
      AnalyzeImplicitConversions(S, E->getRHS(), E->getOperatorLoc());
    }
    
    /// \brief Implements -Wsign-compare.
    ///
    /// \param E the binary operator to check for warnings
    void AnalyzeComparison(Sema &S, BinaryOperator *E) {
      // The type the comparison is being performed in.
      QualType T = E->getLHS()->getType();
    
      // Only analyze comparison operators where both sides have been converted to
      // the same type.
      if (!S.Context.hasSameUnqualifiedType(T, E->getRHS()->getType()))
        return AnalyzeImpConvsInComparison(S, E);
    
      // Don't analyze value-dependent comparisons directly.
      if (E->isValueDependent())
        return AnalyzeImpConvsInComparison(S, E);
    
      Expr *LHS = E->getLHS()->IgnoreParenImpCasts();
      Expr *RHS = E->getRHS()->IgnoreParenImpCasts();
      
      bool IsComparisonConstant = false;
      
      // Check whether an integer constant comparison results in a value
      // of 'true' or 'false'.
      if (T->isIntegralType(S.Context)) {
        llvm::APSInt RHSValue;
        bool IsRHSIntegralLiteral = 
          RHS->isIntegerConstantExpr(RHSValue, S.Context);
        llvm::APSInt LHSValue;
        bool IsLHSIntegralLiteral = 
          LHS->isIntegerConstantExpr(LHSValue, S.Context);
        if (IsRHSIntegralLiteral && !IsLHSIntegralLiteral)
            DiagnoseOutOfRangeComparison(S, E, RHS, LHS, RHSValue, true);
        else if (!IsRHSIntegralLiteral && IsLHSIntegralLiteral)
          DiagnoseOutOfRangeComparison(S, E, LHS, RHS, LHSValue, false);
        else
          IsComparisonConstant = 
            (IsRHSIntegralLiteral && IsLHSIntegralLiteral);
      } else if (!T->hasUnsignedIntegerRepresentation())
          IsComparisonConstant = E->isIntegerConstantExpr(S.Context);
      
      // We don't do anything special if this isn't an unsigned integral
      // comparison:  we're only interested in integral comparisons, and
      // signed comparisons only happen in cases we don't care to warn about.
      //
      // We also don't care about value-dependent expressions or expressions
      // whose result is a constant.
      if (!T->hasUnsignedIntegerRepresentation() || IsComparisonConstant)
        return AnalyzeImpConvsInComparison(S, E);
      
      // Check to see if one of the (unmodified) operands is of different
      // signedness.
      Expr *signedOperand, *unsignedOperand;
      if (LHS->getType()->hasSignedIntegerRepresentation()) {
        assert(!RHS->getType()->hasSignedIntegerRepresentation() &&
               "unsigned comparison between two signed integer expressions?");
        signedOperand = LHS;
        unsignedOperand = RHS;
      } else if (RHS->getType()->hasSignedIntegerRepresentation()) {
        signedOperand = RHS;
        unsignedOperand = LHS;
      } else {
        CheckTrivialUnsignedComparison(S, E);
        return AnalyzeImpConvsInComparison(S, E);
      }
    
      // Otherwise, calculate the effective range of the signed operand.
      IntRange signedRange = GetExprRange(S.Context, signedOperand);
    
      // Go ahead and analyze implicit conversions in the operands.  Note
      // that we skip the implicit conversions on both sides.
      AnalyzeImplicitConversions(S, LHS, E->getOperatorLoc());
      AnalyzeImplicitConversions(S, RHS, E->getOperatorLoc());
    
      // If the signed range is non-negative, -Wsign-compare won't fire,
      // but we should still check for comparisons which are always true
      // or false.
      if (signedRange.NonNegative)
        return CheckTrivialUnsignedComparison(S, E);
    
      // For (in)equality comparisons, if the unsigned operand is a
      // constant which cannot collide with a overflowed signed operand,
      // then reinterpreting the signed operand as unsigned will not
      // change the result of the comparison.
      if (E->isEqualityOp()) {
        unsigned comparisonWidth = S.Context.getIntWidth(T);
        IntRange unsignedRange = GetExprRange(S.Context, unsignedOperand);
    
        // We should never be unable to prove that the unsigned operand is
        // non-negative.
        assert(unsignedRange.NonNegative && "unsigned range includes negative?");
    
        if (unsignedRange.Width < comparisonWidth)
          return;
      }
    
      S.DiagRuntimeBehavior(E->getOperatorLoc(), E,
        S.PDiag(diag::warn_mixed_sign_comparison)
          << LHS->getType() << RHS->getType()
          << LHS->getSourceRange() << RHS->getSourceRange());
    }
    
    /// Analyzes an attempt to assign the given value to a bitfield.
    ///
    /// Returns true if there was something fishy about the attempt.
    bool AnalyzeBitFieldAssignment(Sema &S, FieldDecl *Bitfield, Expr *Init,
                                   SourceLocation InitLoc) {
      assert(Bitfield->isBitField());
      if (Bitfield->isInvalidDecl())
        return false;
    
      // White-list bool bitfields.
      QualType BitfieldType = Bitfield->getType();
      if (BitfieldType->isBooleanType())
         return false;
    
      if (BitfieldType->isEnumeralType()) {
        EnumDecl *BitfieldEnumDecl = BitfieldType->getAs<EnumType>()->getDecl();
        // If the underlying enum type was not explicitly specified as an unsigned
        // type and the enum contain only positive values, MSVC++ will cause an
        // inconsistency by storing this as a signed type.
        if (S.getLangOpts().CPlusPlus11 &&
            !BitfieldEnumDecl->getIntegerTypeSourceInfo() &&
            BitfieldEnumDecl->getNumPositiveBits() > 0 &&
            BitfieldEnumDecl->getNumNegativeBits() == 0) {
          S.Diag(InitLoc, diag::warn_no_underlying_type_specified_for_enum_bitfield)
            << BitfieldEnumDecl->getNameAsString();
        }
      }
    
      if (Bitfield->getType()->isBooleanType())
        return false;
    
      // Ignore value- or type-dependent expressions.
      if (Bitfield->getBitWidth()->isValueDependent() ||
          Bitfield->getBitWidth()->isTypeDependent() ||
          Init->isValueDependent() ||
          Init->isTypeDependent())
        return false;
    
      Expr *OriginalInit = Init->IgnoreParenImpCasts();
    
      llvm::APSInt Value;
      if (!OriginalInit->EvaluateAsInt(Value, S.Context, Expr::SE_AllowSideEffects))
        return false;
    
      unsigned OriginalWidth = Value.getBitWidth();
      unsigned FieldWidth = Bitfield->getBitWidthValue(S.Context);
    
      if (!Value.isSigned() || Value.isNegative())
        if (UnaryOperator *UO = dyn_cast<UnaryOperator>(OriginalInit))
          if (UO->getOpcode() == UO_Minus || UO->getOpcode() == UO_Not)
            OriginalWidth = Value.getMinSignedBits();
    
      if (OriginalWidth <= FieldWidth)
        return false;
    
      // Compute the value which the bitfield will contain.
      llvm::APSInt TruncatedValue = Value.trunc(FieldWidth);
      TruncatedValue.setIsSigned(BitfieldType->isSignedIntegerType());
    
      // Check whether the stored value is equal to the original value.
      TruncatedValue = TruncatedValue.extend(OriginalWidth);
      if (llvm::APSInt::isSameValue(Value, TruncatedValue))
        return false;
    
      // Special-case bitfields of width 1: booleans are naturally 0/1, and
      // therefore don't strictly fit into a signed bitfield of width 1.
      if (FieldWidth == 1 && Value == 1)
        return false;
    
      std::string PrettyValue = Value.toString(10);
      std::string PrettyTrunc = TruncatedValue.toString(10);
    
      S.Diag(InitLoc, diag::warn_impcast_bitfield_precision_constant)
        << PrettyValue << PrettyTrunc << OriginalInit->getType()
        << Init->getSourceRange();
    
      return true;
    }
    
    /// Analyze the given simple or compound assignment for warning-worthy
    /// operations.
    void AnalyzeAssignment(Sema &S, BinaryOperator *E) {
      // Just recurse on the LHS.
      AnalyzeImplicitConversions(S, E->getLHS(), E->getOperatorLoc());
    
      // We want to recurse on the RHS as normal unless we're assigning to
      // a bitfield.
      if (FieldDecl *Bitfield = E->getLHS()->getSourceBitField()) {
        if (AnalyzeBitFieldAssignment(S, Bitfield, E->getRHS(),
                                      E->getOperatorLoc())) {
          // Recurse, ignoring any implicit conversions on the RHS.
          return AnalyzeImplicitConversions(S, E->getRHS()->IgnoreParenImpCasts(),
                                            E->getOperatorLoc());
        }
      }
    
      AnalyzeImplicitConversions(S, E->getRHS(), E->getOperatorLoc());
    }
    
    /// Diagnose an implicit cast;  purely a helper for CheckImplicitConversion.
    void DiagnoseImpCast(Sema &S, Expr *E, QualType SourceType, QualType T, 
                         SourceLocation CContext, unsigned diag,
                         bool pruneControlFlow = false) {
      if (pruneControlFlow) {
        S.DiagRuntimeBehavior(E->getExprLoc(), E,
                              S.PDiag(diag)
                                << SourceType << T << E->getSourceRange()
                                << SourceRange(CContext));
        return;
      }
      S.Diag(E->getExprLoc(), diag)
        << SourceType << T << E->getSourceRange() << SourceRange(CContext);
    }
    
    /// Diagnose an implicit cast;  purely a helper for CheckImplicitConversion.
    void DiagnoseImpCast(Sema &S, Expr *E, QualType T, SourceLocation CContext,
                         unsigned diag, bool pruneControlFlow = false) {
      DiagnoseImpCast(S, E, E->getType(), T, CContext, diag, pruneControlFlow);
    }
    
    
    /// Diagnose an implicit cast from a floating point value to an integer value.
    void DiagnoseFloatingImpCast(Sema &S, Expr *E, QualType T,
    
                                 SourceLocation CContext) {
      const bool IsBool = T->isSpecificBuiltinType(BuiltinType::Bool);
      const bool PruneWarnings = !S.ActiveTemplateInstantiations.empty();
    
      Expr *InnerE = E->IgnoreParenImpCasts();
      // We also want to warn on, e.g., "int i = -1.234"
      if (UnaryOperator *UOp = dyn_cast<UnaryOperator>(InnerE))
        if (UOp->getOpcode() == UO_Minus || UOp->getOpcode() == UO_Plus)
          InnerE = UOp->getSubExpr()->IgnoreParenImpCasts();
    
      const bool IsLiteral =
          isa<FloatingLiteral>(E) || isa<FloatingLiteral>(InnerE);
    
      llvm::APFloat Value(0.0);
      bool IsConstant =
        E->EvaluateAsFloat(Value, S.Context, Expr::SE_AllowSideEffects);
      if (!IsConstant) {
        return DiagnoseImpCast(S, E, T, CContext,
                               diag::warn_impcast_float_integer, PruneWarnings);
      }
    
      bool isExact = false;
    
      llvm::APSInt IntegerValue(S.Context.getIntWidth(T),
                                T->hasUnsignedIntegerRepresentation());
      if (Value.convertToInteger(IntegerValue, llvm::APFloat::rmTowardZero,
                                 &isExact) == llvm::APFloat::opOK &&
          isExact) {
        if (IsLiteral) return;
        return DiagnoseImpCast(S, E, T, CContext, diag::warn_impcast_float_integer,
                               PruneWarnings);
      }
    
      unsigned DiagID = 0;
      if (IsLiteral) {
        // Warn on floating point literal to integer.
        DiagID = diag::warn_impcast_literal_float_to_integer;
      } else if (IntegerValue == 0) {
        if (Value.isZero()) {  // Skip -0.0 to 0 conversion.
          return DiagnoseImpCast(S, E, T, CContext,
                                 diag::warn_impcast_float_integer, PruneWarnings);
        }
        // Warn on non-zero to zero conversion.
        DiagID = diag::warn_impcast_float_to_integer_zero;
      } else {
        if (IntegerValue.isUnsigned()) {
          if (!IntegerValue.isMaxValue()) {
            return DiagnoseImpCast(S, E, T, CContext,
                                   diag::warn_impcast_float_integer, PruneWarnings);
          }
        } else {  // IntegerValue.isSigned()
          if (!IntegerValue.isMaxSignedValue() &&
              !IntegerValue.isMinSignedValue()) {
            return DiagnoseImpCast(S, E, T, CContext,
                                   diag::warn_impcast_float_integer, PruneWarnings);
          }
        }
        // Warn on evaluatable floating point expression to integer conversion.
        DiagID = diag::warn_impcast_float_to_integer;
      }
    
      // FIXME: Force the precision of the source value down so we don't print
      // digits which are usually useless (we don't really care here if we
      // truncate a digit by accident in edge cases).  Ideally, APFloat::toString
      // would automatically print the shortest representation, but it's a bit
      // tricky to implement.
      SmallString<16> PrettySourceValue;
      unsigned precision = llvm::APFloat::semanticsPrecision(Value.getSemantics());
      precision = (precision * 59 + 195) / 196;
      Value.toString(PrettySourceValue, precision);
    
      SmallString<16> PrettyTargetValue;
      if (IsBool)
        PrettyTargetValue = Value.isZero() ? "false" : "true";
      else
        IntegerValue.toString(PrettyTargetValue);
    
      if (PruneWarnings) {
        S.DiagRuntimeBehavior(E->getExprLoc(), E,
                              S.PDiag(DiagID)
                                  << E->getType() << T.getUnqualifiedType()
                                  << PrettySourceValue << PrettyTargetValue
                                  << E->getSourceRange() << SourceRange(CContext));
      } else {
        S.Diag(E->getExprLoc(), DiagID)
            << E->getType() << T.getUnqualifiedType() << PrettySourceValue
            << PrettyTargetValue << E->getSourceRange() << SourceRange(CContext);
      }
    }
    
    std::string PrettyPrintInRange(const llvm::APSInt &Value, IntRange Range) {
      if (!Range.Width) return "0";
    
      llvm::APSInt ValueInRange = Value;
      ValueInRange.setIsSigned(!Range.NonNegative);
      ValueInRange = ValueInRange.trunc(Range.Width);
      return ValueInRange.toString(10);
    }
    
    bool IsImplicitBoolFloatConversion(Sema &S, Expr *Ex, bool ToBool) {
      if (!isa<ImplicitCastExpr>(Ex))
        return false;
    
      Expr *InnerE = Ex->IgnoreParenImpCasts();
      const Type *Target = S.Context.getCanonicalType(Ex->getType()).getTypePtr();
      const Type *Source =
        S.Context.getCanonicalType(InnerE->getType()).getTypePtr();
      if (Target->isDependentType())
        return false;
    
      const BuiltinType *FloatCandidateBT =
        dyn_cast<BuiltinType>(ToBool ? Source : Target);
      const Type *BoolCandidateType = ToBool ? Target : Source;
    
      return (BoolCandidateType->isSpecificBuiltinType(BuiltinType::Bool) &&
              FloatCandidateBT && (FloatCandidateBT->isFloatingPoint()));
    }
    
    void CheckImplicitArgumentConversions(Sema &S, CallExpr *TheCall,
                                          SourceLocation CC) {
      unsigned NumArgs = TheCall->getNumArgs();
      for (unsigned i = 0; i < NumArgs; ++i) {
        Expr *CurrA = TheCall->getArg(i);
        if (!IsImplicitBoolFloatConversion(S, CurrA, true))
          continue;
    
        bool IsSwapped = ((i > 0) &&
            IsImplicitBoolFloatConversion(S, TheCall->getArg(i - 1), false));
        IsSwapped |= ((i < (NumArgs - 1)) &&
            IsImplicitBoolFloatConversion(S, TheCall->getArg(i + 1), false));
        if (IsSwapped) {
          // Warn on this floating-point to bool conversion.
          DiagnoseImpCast(S, CurrA->IgnoreParenImpCasts(),
                          CurrA->getType(), CC,
                          diag::warn_impcast_floating_point_to_bool);
        }
      }
    }
    
    void DiagnoseNullConversion(Sema &S, Expr *E, QualType T, SourceLocation CC) {
      if (S.Diags.isIgnored(diag::warn_impcast_null_pointer_to_integer,
                            E->getExprLoc()))
        return;
    
      // Don't warn on functions which have return type nullptr_t.
      if (isa<CallExpr>(E))
        return;
    
      // Check for NULL (GNUNull) or nullptr (CXX11_nullptr).
      const Expr::NullPointerConstantKind NullKind =
          E->isNullPointerConstant(S.Context, Expr::NPC_ValueDependentIsNotNull);
      if (NullKind != Expr::NPCK_GNUNull && NullKind != Expr::NPCK_CXX11_nullptr)
        return;
    
      // Return if target type is a safe conversion.
      if (T->isAnyPointerType() || T->isBlockPointerType() ||
          T->isMemberPointerType() || !T->isScalarType() || T->isNullPtrType())
        return;
    
      SourceLocation Loc = E->getSourceRange().getBegin();
    
      // Venture through the macro stacks to get to the source of macro arguments.
      // The new location is a better location than the complete location that was
      // passed in.
      while (S.SourceMgr.isMacroArgExpansion(Loc))
        Loc = S.SourceMgr.getImmediateMacroCallerLoc(Loc);
    
      while (S.SourceMgr.isMacroArgExpansion(CC))
        CC = S.SourceMgr.getImmediateMacroCallerLoc(CC);
    
      // __null is usually wrapped in a macro.  Go up a macro if that is the case.
      if (NullKind == Expr::NPCK_GNUNull && Loc.isMacroID()) {
        StringRef MacroName = Lexer::getImmediateMacroNameForDiagnostics(
            Loc, S.SourceMgr, S.getLangOpts());
        if (MacroName == "NULL")
          Loc = S.SourceMgr.getImmediateExpansionRange(Loc).first;
      }
    
      // Only warn if the null and context location are in the same macro expansion.
      if (S.SourceMgr.getFileID(Loc) != S.SourceMgr.getFileID(CC))
        return;
    
      S.Diag(Loc, diag::warn_impcast_null_pointer_to_integer)
          << (NullKind == Expr::NPCK_CXX11_nullptr) << T << clang::SourceRange(CC)
          << FixItHint::CreateReplacement(Loc,
                                          S.getFixItZeroLiteralForType(T, Loc));
    }
    
    void checkObjCArrayLiteral(Sema &S, QualType TargetType,
                               ObjCArrayLiteral *ArrayLiteral);
    void checkObjCDictionaryLiteral(Sema &S, QualType TargetType,
                                    ObjCDictionaryLiteral *DictionaryLiteral);
    
    /// Check a single element within a collection literal against the
    /// target element type.
    void checkObjCCollectionLiteralElement(Sema &S, QualType TargetElementType,
                                           Expr *Element, unsigned ElementKind) {
      // Skip a bitcast to 'id' or qualified 'id'.
      if (auto ICE = dyn_cast<ImplicitCastExpr>(Element)) {
        if (ICE->getCastKind() == CK_BitCast &&
            ICE->getSubExpr()->getType()->getAs<ObjCObjectPointerType>())
          Element = ICE->getSubExpr();
      }
    
      QualType ElementType = Element->getType();
      ExprResult ElementResult(Element);
      if (ElementType->getAs<ObjCObjectPointerType>() &&
          S.CheckSingleAssignmentConstraints(TargetElementType,
                                             ElementResult,
                                             false, false)
            != Sema::Compatible) {
        S.Diag(Element->getLocStart(),
               diag::warn_objc_collection_literal_element)
          << ElementType << ElementKind << TargetElementType
          << Element->getSourceRange();
      }
    
      if (auto ArrayLiteral = dyn_cast<ObjCArrayLiteral>(Element))
        checkObjCArrayLiteral(S, TargetElementType, ArrayLiteral);
      else if (auto DictionaryLiteral = dyn_cast<ObjCDictionaryLiteral>(Element))
        checkObjCDictionaryLiteral(S, TargetElementType, DictionaryLiteral);
    }
    
    /// Check an Objective-C array literal being converted to the given
    /// target type.
    void checkObjCArrayLiteral(Sema &S, QualType TargetType,
                               ObjCArrayLiteral *ArrayLiteral) {
      if (!S.NSArrayDecl)
        return;
    
      const auto *TargetObjCPtr = TargetType->getAs<ObjCObjectPointerType>();
      if (!TargetObjCPtr)
        return;
    
      if (TargetObjCPtr->isUnspecialized() ||
          TargetObjCPtr->getInterfaceDecl()->getCanonicalDecl()
            != S.NSArrayDecl->getCanonicalDecl())
        return;
    
      auto TypeArgs = TargetObjCPtr->getTypeArgs();
      if (TypeArgs.size() != 1)
        return;
    
      QualType TargetElementType = TypeArgs[0];
      for (unsigned I = 0, N = ArrayLiteral->getNumElements(); I != N; ++I) {
        checkObjCCollectionLiteralElement(S, TargetElementType,
                                          ArrayLiteral->getElement(I),
                                          0);
      }
    }
    
    /// Check an Objective-C dictionary literal being converted to the given
    /// target type.
    void checkObjCDictionaryLiteral(Sema &S, QualType TargetType,
                                    ObjCDictionaryLiteral *DictionaryLiteral) {
      if (!S.NSDictionaryDecl)
        return;
    
      const auto *TargetObjCPtr = TargetType->getAs<ObjCObjectPointerType>();
      if (!TargetObjCPtr)
        return;
    
      if (TargetObjCPtr->isUnspecialized() ||
          TargetObjCPtr->getInterfaceDecl()->getCanonicalDecl()
            != S.NSDictionaryDecl->getCanonicalDecl())
        return;
    
      auto TypeArgs = TargetObjCPtr->getTypeArgs();
      if (TypeArgs.size() != 2)
        return;
    
      QualType TargetKeyType = TypeArgs[0];
      QualType TargetObjectType = TypeArgs[1];
      for (unsigned I = 0, N = DictionaryLiteral->getNumElements(); I != N; ++I) {
        auto Element = DictionaryLiteral->getKeyValueElement(I);
        checkObjCCollectionLiteralElement(S, TargetKeyType, Element.Key, 1);
        checkObjCCollectionLiteralElement(S, TargetObjectType, Element.Value, 2);
      }
    }
    
    // Helper function to filter out cases for constant width constant conversion.
    // Don't warn on char array initialization or for non-decimal values.
    bool isSameWidthConstantConversion(Sema &S, Expr *E, QualType T,
                                       SourceLocation CC) {
      // If initializing from a constant, and the constant starts with '0',
      // then it is a binary, octal, or hexadecimal.  Allow these constants
      // to fill all the bits, even if there is a sign change.
      if (auto *IntLit = dyn_cast<IntegerLiteral>(E->IgnoreParenImpCasts())) {
        const char FirstLiteralCharacter =
            S.getSourceManager().getCharacterData(IntLit->getLocStart())[0];
        if (FirstLiteralCharacter == '0')
          return false;
      }
    
      // If the CC location points to a '{', and the type is char, then assume
      // assume it is an array initialization.
      if (CC.isValid() && T->isCharType()) {
        const char FirstContextCharacter =
            S.getSourceManager().getCharacterData(CC)[0];
        if (FirstContextCharacter == '{')
          return false;
      }
    
      return true;
    }
    
    void CheckImplicitConversion(Sema &S, Expr *E, QualType T,
                                 SourceLocation CC, bool *ICContext = nullptr) {
      if (E->isTypeDependent() || E->isValueDependent()) return;
    
      const Type *Source = S.Context.getCanonicalType(E->getType()).getTypePtr();
      const Type *Target = S.Context.getCanonicalType(T).getTypePtr();
      if (Source == Target) return;
      if (Target->isDependentType()) return;
    
      // If the conversion context location is invalid don't complain. We also
      // don't want to emit a warning if the issue occurs from the expansion of
      // a system macro. The problem is that 'getSpellingLoc()' is slow, so we
      // delay this check as long as possible. Once we detect we are in that
      // scenario, we just return.
      if (CC.isInvalid())
        return;
    
      // Diagnose implicit casts to bool.
      if (Target->isSpecificBuiltinType(BuiltinType::Bool)) {
        if (isa<StringLiteral>(E))
          // Warn on string literal to bool.  Checks for string literals in logical
          // and expressions, for instance, assert(0 && "error here"), are
          // prevented by a check in AnalyzeImplicitConversions().
          return DiagnoseImpCast(S, E, T, CC,
                                 diag::warn_impcast_string_literal_to_bool);
        if (isa<ObjCStringLiteral>(E) || isa<ObjCArrayLiteral>(E) ||
            isa<ObjCDictionaryLiteral>(E) || isa<ObjCBoxedExpr>(E)) {
          // This covers the literal expressions that evaluate to Objective-C
          // objects.
          return DiagnoseImpCast(S, E, T, CC,
                                 diag::warn_impcast_objective_c_literal_to_bool);
        }
        if (Source->isPointerType() || Source->canDecayToPointerType()) {
          // Warn on pointer to bool conversion that is always true.
          S.DiagnoseAlwaysNonNullPointer(E, Expr::NPCK_NotNull, /*IsEqual*/ false,
                                         SourceRange(CC));
        }
      }
    
      // Check implicit casts from Objective-C collection literals to specialized
      // collection types, e.g., NSArray<NSString *> *.
      if (auto *ArrayLiteral = dyn_cast<ObjCArrayLiteral>(E))
        checkObjCArrayLiteral(S, QualType(Target, 0), ArrayLiteral);
      else if (auto *DictionaryLiteral = dyn_cast<ObjCDictionaryLiteral>(E))
        checkObjCDictionaryLiteral(S, QualType(Target, 0), DictionaryLiteral);
    
      // Strip vector types.
      if (isa<VectorType>(Source)) {
        if (!isa<VectorType>(Target)) {
          if (S.SourceMgr.isInSystemMacro(CC))
            return;
          return DiagnoseImpCast(S, E, T, CC, diag::warn_impcast_vector_scalar);
        }
        
        // If the vector cast is cast between two vectors of the same size, it is
        // a bitcast, not a conversion.
        if (S.Context.getTypeSize(Source) == S.Context.getTypeSize(Target))
          return;
    
        Source = cast<VectorType>(Source)->getElementType().getTypePtr();
        Target = cast<VectorType>(Target)->getElementType().getTypePtr();
      }
      if (auto VecTy = dyn_cast<VectorType>(Target))
        Target = VecTy->getElementType().getTypePtr();
    
      // Strip complex types.
      if (isa<ComplexType>(Source)) {
        if (!isa<ComplexType>(Target)) {
          if (S.SourceMgr.isInSystemMacro(CC))
            return;
    
          return DiagnoseImpCast(S, E, T, CC, diag::warn_impcast_complex_scalar);
        }
    
        Source = cast<ComplexType>(Source)->getElementType().getTypePtr();
        Target = cast<ComplexType>(Target)->getElementType().getTypePtr();
      }
    
      const BuiltinType *SourceBT = dyn_cast<BuiltinType>(Source);
      const BuiltinType *TargetBT = dyn_cast<BuiltinType>(Target);
    
      // If the source is floating point...
      if (SourceBT && SourceBT->isFloatingPoint()) {
        // ...and the target is floating point...
        if (TargetBT && TargetBT->isFloatingPoint()) {
          // ...then warn if we're dropping FP rank.
    
          // Builtin FP kinds are ordered by increasing FP rank.
          if (SourceBT->getKind() > TargetBT->getKind()) {
            // Don't warn about float constants that are precisely
            // representable in the target type.
            Expr::EvalResult result;
            if (E->EvaluateAsRValue(result, S.Context)) {
              // Value might be a float, a float vector, or a float complex.
              if (IsSameFloatAfterCast(result.Val,
                       S.Context.getFloatTypeSemantics(QualType(TargetBT, 0)),
                       S.Context.getFloatTypeSemantics(QualType(SourceBT, 0))))
                return;
            }
    
            if (S.SourceMgr.isInSystemMacro(CC))
              return;
    
            DiagnoseImpCast(S, E, T, CC, diag::warn_impcast_float_precision);
          }
          // ... or possibly if we're increasing rank, too
          else if (TargetBT->getKind() > SourceBT->getKind()) {
            if (S.SourceMgr.isInSystemMacro(CC))
              return;
    
            DiagnoseImpCast(S, E, T, CC, diag::warn_impcast_double_promotion);
          }
          return;
        }
    
        // If the target is integral, always warn.
        if (TargetBT && TargetBT->isInteger()) {
          if (S.SourceMgr.isInSystemMacro(CC))
            return;
    
          DiagnoseFloatingImpCast(S, E, T, CC);
        }
    
        // Detect the case where a call result is converted from floating-point to
        // to bool, and the final argument to the call is converted from bool, to
        // discover this typo:
        //
        //    bool b = fabs(x < 1.0);  // should be "bool b = fabs(x) < 1.0;"
        //
        // FIXME: This is an incredibly special case; is there some more general
        // way to detect this class of misplaced-parentheses bug?
        if (Target->isBooleanType() && isa<CallExpr>(E)) {
          // Check last argument of function call to see if it is an
          // implicit cast from a type matching the type the result
          // is being cast to.
          CallExpr *CEx = cast<CallExpr>(E);
          if (unsigned NumArgs = CEx->getNumArgs()) {
            Expr *LastA = CEx->getArg(NumArgs - 1);
            Expr *InnerE = LastA->IgnoreParenImpCasts();
            if (isa<ImplicitCastExpr>(LastA) &&
                InnerE->getType()->isBooleanType()) {
              // Warn on this floating-point to bool conversion
              DiagnoseImpCast(S, E, T, CC,
                              diag::warn_impcast_floating_point_to_bool);
            }
          }
        }
        return;
      }
    
      DiagnoseNullConversion(S, E, T, CC);
    
      S.DiscardMisalignedMemberAddress(Target, E);
    
      if (!Source->isIntegerType() || !Target->isIntegerType())
        return;
    
      // TODO: remove this early return once the false positives for constant->bool
      // in templates, macros, etc, are reduced or removed.
      if (Target->isSpecificBuiltinType(BuiltinType::Bool))
        return;
    
      IntRange SourceRange = GetExprRange(S.Context, E);
      IntRange TargetRange = IntRange::forTargetOfCanonicalType(S.Context, Target);
    
      if (SourceRange.Width > TargetRange.Width) {
        // If the source is a constant, use a default-on diagnostic.
        // TODO: this should happen for bitfield stores, too.
        llvm::APSInt Value(32);
        if (E->EvaluateAsInt(Value, S.Context, Expr::SE_AllowSideEffects)) {
          if (S.SourceMgr.isInSystemMacro(CC))
            return;
    
          std::string PrettySourceValue = Value.toString(10);
          std::string PrettyTargetValue = PrettyPrintInRange(Value, TargetRange);
    
          S.DiagRuntimeBehavior(E->getExprLoc(), E,
            S.PDiag(diag::warn_impcast_integer_precision_constant)
                << PrettySourceValue << PrettyTargetValue
                << E->getType() << T << E->getSourceRange()
                << clang::SourceRange(CC));
          return;
        }
    
        // People want to build with -Wshorten-64-to-32 and not -Wconversion.
        if (S.SourceMgr.isInSystemMacro(CC))
          return;
    
        if (TargetRange.Width == 32 && S.Context.getIntWidth(E->getType()) == 64)
          return DiagnoseImpCast(S, E, T, CC, diag::warn_impcast_integer_64_32,
                                 /* pruneControlFlow */ true);
        return DiagnoseImpCast(S, E, T, CC, diag::warn_impcast_integer_precision);
      }
    
      if (TargetRange.Width == SourceRange.Width && !TargetRange.NonNegative &&
          SourceRange.NonNegative && Source->isSignedIntegerType()) {
        // Warn when doing a signed to signed conversion, warn if the positive
        // source value is exactly the width of the target type, which will
        // cause a negative value to be stored.
    
        llvm::APSInt Value;
        if (E->EvaluateAsInt(Value, S.Context, Expr::SE_AllowSideEffects) &&
            !S.SourceMgr.isInSystemMacro(CC)) {
          if (isSameWidthConstantConversion(S, E, T, CC)) {
            std::string PrettySourceValue = Value.toString(10);
            std::string PrettyTargetValue = PrettyPrintInRange(Value, TargetRange);
    
            S.DiagRuntimeBehavior(
                E->getExprLoc(), E,
                S.PDiag(diag::warn_impcast_integer_precision_constant)
                    << PrettySourceValue << PrettyTargetValue << E->getType() << T
                    << E->getSourceRange() << clang::SourceRange(CC));
            return;
          }
        }
    
        // Fall through for non-constants to give a sign conversion warning.
      }
    
      if ((TargetRange.NonNegative && !SourceRange.NonNegative) ||
          (!TargetRange.NonNegative && SourceRange.NonNegative &&
           SourceRange.Width == TargetRange.Width)) {
        if (S.SourceMgr.isInSystemMacro(CC))
          return;
    
        unsigned DiagID = diag::warn_impcast_integer_sign;
    
        // Traditionally, gcc has warned about this under -Wsign-compare.
        // We also want to warn about it in -Wconversion.
        // So if -Wconversion is off, use a completely identical diagnostic
        // in the sign-compare group.
        // The conditional-checking code will 
        if (ICContext) {
          DiagID = diag::warn_impcast_integer_sign_conditional;
          *ICContext = true;
        }
    
        return DiagnoseImpCast(S, E, T, CC, DiagID);
      }
    
      // Diagnose conversions between different enumeration types.
      // In C, we pretend that the type of an EnumConstantDecl is its enumeration
      // type, to give us better diagnostics.
      QualType SourceType = E->getType();
      if (!S.getLangOpts().CPlusPlus) {
        if (DeclRefExpr *DRE = dyn_cast<DeclRefExpr>(E))
          if (EnumConstantDecl *ECD = dyn_cast<EnumConstantDecl>(DRE->getDecl())) {
            EnumDecl *Enum = cast<EnumDecl>(ECD->getDeclContext());
            SourceType = S.Context.getTypeDeclType(Enum);
            Source = S.Context.getCanonicalType(SourceType).getTypePtr();
          }
      }
      
      if (const EnumType *SourceEnum = Source->getAs<EnumType>())
        if (const EnumType *TargetEnum = Target->getAs<EnumType>())
          if (SourceEnum->getDecl()->hasNameForLinkage() &&
              TargetEnum->getDecl()->hasNameForLinkage() &&
              SourceEnum != TargetEnum) {
            if (S.SourceMgr.isInSystemMacro(CC))
              return;
    
            return DiagnoseImpCast(S, E, SourceType, T, CC, 
                                   diag::warn_impcast_different_enum_types);
          }
    }
    
    void CheckConditionalOperator(Sema &S, ConditionalOperator *E,
                                  SourceLocation CC, QualType T);
    
    void CheckConditionalOperand(Sema &S, Expr *E, QualType T,
                                 SourceLocation CC, bool &ICContext) {
      E = E->IgnoreParenImpCasts();
    
      if (isa<ConditionalOperator>(E))
        return CheckConditionalOperator(S, cast<ConditionalOperator>(E), CC, T);
    
      AnalyzeImplicitConversions(S, E, CC);
      if (E->getType() != T)
        return CheckImplicitConversion(S, E, T, CC, &ICContext);
    }
    
    void CheckConditionalOperator(Sema &S, ConditionalOperator *E,
                                  SourceLocation CC, QualType T) {
      AnalyzeImplicitConversions(S, E->getCond(), E->getQuestionLoc());
    
      bool Suspicious = false;
      CheckConditionalOperand(S, E->getTrueExpr(), T, CC, Suspicious);
      CheckConditionalOperand(S, E->getFalseExpr(), T, CC, Suspicious);
    
      // If -Wconversion would have warned about either of the candidates
      // for a signedness conversion to the context type...
      if (!Suspicious) return;
    
      // ...but it's currently ignored...
      if (!S.Diags.isIgnored(diag::warn_impcast_integer_sign_conditional, CC))
        return;
    
      // ...then check whether it would have warned about either of the
      // candidates for a signedness conversion to the condition type.
      if (E->getType() == T) return;
     
      Suspicious = false;
      CheckImplicitConversion(S, E->getTrueExpr()->IgnoreParenImpCasts(),
                              E->getType(), CC, &Suspicious);
      if (!Suspicious)
        CheckImplicitConversion(S, E->getFalseExpr()->IgnoreParenImpCasts(),
                                E->getType(), CC, &Suspicious);
    }
    
    /// CheckBoolLikeConversion - Check conversion of given expression to boolean.
    /// Input argument E is a logical expression.
    void CheckBoolLikeConversion(Sema &S, Expr *E, SourceLocation CC) {
      if (S.getLangOpts().Bool)
        return;
      CheckImplicitConversion(S, E->IgnoreParenImpCasts(), S.Context.BoolTy, CC);
    }
    
    /// AnalyzeImplicitConversions - Find and report any interesting
    /// implicit conversions in the given expression.  There are a couple
    /// of competing diagnostics here, -Wconversion and -Wsign-compare.
    void AnalyzeImplicitConversions(Sema &S, Expr *OrigE, SourceLocation CC) {
      QualType T = OrigE->getType();
      Expr *E = OrigE->IgnoreParenImpCasts();
    
      if (E->isTypeDependent() || E->isValueDependent())
        return;
      
      // For conditional operators, we analyze the arguments as if they
      // were being fed directly into the output.
      if (isa<ConditionalOperator>(E)) {
        ConditionalOperator *CO = cast<ConditionalOperator>(E);
        CheckConditionalOperator(S, CO, CC, T);
        return;
      }
    
      // Check implicit argument conversions for function calls.
      if (CallExpr *Call = dyn_cast<CallExpr>(E))
        CheckImplicitArgumentConversions(S, Call, CC);
    
      // Go ahead and check any implicit conversions we might have skipped.
      // The non-canonical typecheck is just an optimization;
      // CheckImplicitConversion will filter out dead implicit conversions.
      if (E->getType() != T)
        CheckImplicitConversion(S, E, T, CC);
    
      // Now continue drilling into this expression.
    
      if (PseudoObjectExpr *POE = dyn_cast<PseudoObjectExpr>(E)) {
        // The bound subexpressions in a PseudoObjectExpr are not reachable
        // as transitive children.
        // FIXME: Use a more uniform representation for this.
        for (auto *SE : POE->semantics())
          if (auto *OVE = dyn_cast<OpaqueValueExpr>(SE))
            AnalyzeImplicitConversions(S, OVE->getSourceExpr(), CC);
      }
    
      // Skip past explicit casts.
      if (isa<ExplicitCastExpr>(E)) {
        E = cast<ExplicitCastExpr>(E)->getSubExpr()->IgnoreParenImpCasts();
        return AnalyzeImplicitConversions(S, E, CC);
      }
    
      if (BinaryOperator *BO = dyn_cast<BinaryOperator>(E)) {
        // Do a somewhat different check with comparison operators.
        if (BO->isComparisonOp())
          return AnalyzeComparison(S, BO);
    
        // And with simple assignments.
        if (BO->getOpcode() == BO_Assign)
          return AnalyzeAssignment(S, BO);
      }
    
      // These break the otherwise-useful invariant below.  Fortunately,
      // we don't really need to recurse into them, because any internal
      // expressions should have been analyzed already when they were
      // built into statements.
      if (isa<StmtExpr>(E)) return;
    
      // Don't descend into unevaluated contexts.
      if (isa<UnaryExprOrTypeTraitExpr>(E)) return;
    
      // Now just recurse over the expression's children.
      CC = E->getExprLoc();
      BinaryOperator *BO = dyn_cast<BinaryOperator>(E);
      bool IsLogicalAndOperator = BO && BO->getOpcode() == BO_LAnd;
      for (Stmt *SubStmt : E->children()) {
        Expr *ChildExpr = dyn_cast_or_null<Expr>(SubStmt);
        if (!ChildExpr)
          continue;
    
        if (IsLogicalAndOperator &&
            isa<StringLiteral>(ChildExpr->IgnoreParenImpCasts()))
          // Ignore checking string literals that are in logical and operators.
          // This is a common pattern for asserts.
          continue;
        AnalyzeImplicitConversions(S, ChildExpr, CC);
      }
    
      if (BO && BO->isLogicalOp()) {
        Expr *SubExpr = BO->getLHS()->IgnoreParenImpCasts();
        if (!IsLogicalAndOperator || !isa<StringLiteral>(SubExpr))
          ::CheckBoolLikeConversion(S, SubExpr, BO->getExprLoc());
    
        SubExpr = BO->getRHS()->IgnoreParenImpCasts();
        if (!IsLogicalAndOperator || !isa<StringLiteral>(SubExpr))
          ::CheckBoolLikeConversion(S, SubExpr, BO->getExprLoc());
      }
    
      if (const UnaryOperator *U = dyn_cast<UnaryOperator>(E))
        if (U->getOpcode() == UO_LNot)
          ::CheckBoolLikeConversion(S, U->getSubExpr(), CC);
    }
    
    } // end anonymous namespace
    
    /// Diagnose integer type and any valid implicit convertion to it.
    static bool checkOpenCLEnqueueIntType(Sema &S, Expr *E, const QualType &IntT) {
      // Taking into account implicit conversions,
      // allow any integer.
      if (!E->getType()->isIntegerType()) {
        S.Diag(E->getLocStart(),
               diag::err_opencl_enqueue_kernel_invalid_local_size_type);
        return true;
      }
      // Potentially emit standard warnings for implicit conversions if enabled
      // using -Wconversion.
      CheckImplicitConversion(S, E, IntT, E->getLocStart());
      return false;
    }
    
    // Helper function for Sema::DiagnoseAlwaysNonNullPointer.
    // Returns true when emitting a warning about taking the address of a reference.
    static bool CheckForReference(Sema &SemaRef, const Expr *E,
                                  const PartialDiagnostic &PD) {
      E = E->IgnoreParenImpCasts();
    
      const FunctionDecl *FD = nullptr;
    
      if (const DeclRefExpr *DRE = dyn_cast<DeclRefExpr>(E)) {
        if (!DRE->getDecl()->getType()->isReferenceType())
          return false;
      } else if (const MemberExpr *M = dyn_cast<MemberExpr>(E)) {
        if (!M->getMemberDecl()->getType()->isReferenceType())
          return false;
      } else if (const CallExpr *Call = dyn_cast<CallExpr>(E)) {
        if (!Call->getCallReturnType(SemaRef.Context)->isReferenceType())
          return false;
        FD = Call->getDirectCallee();
      } else {
        return false;
      }
    
      SemaRef.Diag(E->getExprLoc(), PD);
    
      // If possible, point to location of function.
      if (FD) {
        SemaRef.Diag(FD->getLocation(), diag::note_reference_is_return_value) << FD;
      }
    
      return true;
    }
    
    // Returns true if the SourceLocation is expanded from any macro body.
    // Returns false if the SourceLocation is invalid, is from not in a macro
    // expansion, or is from expanded from a top-level macro argument.
    static bool IsInAnyMacroBody(const SourceManager &SM, SourceLocation Loc) {
      if (Loc.isInvalid())
        return false;
    
      while (Loc.isMacroID()) {
        if (SM.isMacroBodyExpansion(Loc))
          return true;
        Loc = SM.getImmediateMacroCallerLoc(Loc);
      }
    
      return false;
    }
    
    /// \brief Diagnose pointers that are always non-null.
    /// \param E the expression containing the pointer
    /// \param NullKind NPCK_NotNull if E is a cast to bool, otherwise, E is
    /// compared to a null pointer
    /// \param IsEqual True when the comparison is equal to a null pointer
    /// \param Range Extra SourceRange to highlight in the diagnostic
    void Sema::DiagnoseAlwaysNonNullPointer(Expr *E,
                                            Expr::NullPointerConstantKind NullKind,
                                            bool IsEqual, SourceRange Range) {
      if (!E)
        return;
    
      // Don't warn inside macros.
      if (E->getExprLoc().isMacroID()) {
        const SourceManager &SM = getSourceManager();
        if (IsInAnyMacroBody(SM, E->getExprLoc()) ||
            IsInAnyMacroBody(SM, Range.getBegin()))
          return;
      }
      E = E->IgnoreImpCasts();
    
      const bool IsCompare = NullKind != Expr::NPCK_NotNull;
    
      if (isa<CXXThisExpr>(E)) {
        unsigned DiagID = IsCompare ? diag::warn_this_null_compare
                                    : diag::warn_this_bool_conversion;
        Diag(E->getExprLoc(), DiagID) << E->getSourceRange() << Range << IsEqual;
        return;
      }
    
      bool IsAddressOf = false;
    
      if (UnaryOperator *UO = dyn_cast<UnaryOperator>(E)) {
        if (UO->getOpcode() != UO_AddrOf)
          return;
        IsAddressOf = true;
        E = UO->getSubExpr();
      }
    
      if (IsAddressOf) {
        unsigned DiagID = IsCompare
                              ? diag::warn_address_of_reference_null_compare
                              : diag::warn_address_of_reference_bool_conversion;
        PartialDiagnostic PD = PDiag(DiagID) << E->getSourceRange() << Range
                                             << IsEqual;
        if (CheckForReference(*this, E, PD)) {
          return;
        }
      }
    
      auto ComplainAboutNonnullParamOrCall = [&](const Attr *NonnullAttr) {
        bool IsParam = isa<NonNullAttr>(NonnullAttr);
        std::string Str;
        llvm::raw_string_ostream S(Str);
        E->printPretty(S, nullptr, getPrintingPolicy());
        unsigned DiagID = IsCompare ? diag::warn_nonnull_expr_compare
                                    : diag::warn_cast_nonnull_to_bool;
        Diag(E->getExprLoc(), DiagID) << IsParam << S.str()
          << E->getSourceRange() << Range << IsEqual;
        Diag(NonnullAttr->getLocation(), diag::note_declared_nonnull) << IsParam;
      };
    
      // If we have a CallExpr that is tagged with returns_nonnull, we can complain.
      if (auto *Call = dyn_cast<CallExpr>(E->IgnoreParenImpCasts())) {
        if (auto *Callee = Call->getDirectCallee()) {
          if (const Attr *A = Callee->getAttr<ReturnsNonNullAttr>()) {
            ComplainAboutNonnullParamOrCall(A);
            return;
          }
        }
      }
    
      // Expect to find a single Decl.  Skip anything more complicated.
      ValueDecl *D = nullptr;
      if (DeclRefExpr *R = dyn_cast<DeclRefExpr>(E)) {
        D = R->getDecl();
      } else if (MemberExpr *M = dyn_cast<MemberExpr>(E)) {
        D = M->getMemberDecl();
      }
    
      // Weak Decls can be null.
      if (!D || D->isWeak())
        return;
    
      // Check for parameter decl with nonnull attribute
      if (const auto* PV = dyn_cast<ParmVarDecl>(D)) {
        if (getCurFunction() &&
            !getCurFunction()->ModifiedNonNullParams.count(PV)) {
          if (const Attr *A = PV->getAttr<NonNullAttr>()) {
            ComplainAboutNonnullParamOrCall(A);
            return;
          }
    
          if (const auto *FD = dyn_cast<FunctionDecl>(PV->getDeclContext())) {
            auto ParamIter = llvm::find(FD->parameters(), PV);
            assert(ParamIter != FD->param_end());
            unsigned ParamNo = std::distance(FD->param_begin(), ParamIter);
    
            for (const auto *NonNull : FD->specific_attrs<NonNullAttr>()) {
              if (!NonNull->args_size()) {
                  ComplainAboutNonnullParamOrCall(NonNull);
                  return;
              }
    
              for (unsigned ArgNo : NonNull->args()) {
                if (ArgNo == ParamNo) {
                  ComplainAboutNonnullParamOrCall(NonNull);
                  return;
                }
              }
            }
          }
        }
      }
    
      QualType T = D->getType();
      const bool IsArray = T->isArrayType();
      const bool IsFunction = T->isFunctionType();
    
      // Address of function is used to silence the function warning.
      if (IsAddressOf && IsFunction) {
        return;
      }
    
      // Found nothing.
      if (!IsAddressOf && !IsFunction && !IsArray)
        return;
    
      // Pretty print the expression for the diagnostic.
      std::string Str;
      llvm::raw_string_ostream S(Str);
      E->printPretty(S, nullptr, getPrintingPolicy());
    
      unsigned DiagID = IsCompare ? diag::warn_null_pointer_compare
                                  : diag::warn_impcast_pointer_to_bool;
      enum {
        AddressOf,
        FunctionPointer,
        ArrayPointer
      } DiagType;
      if (IsAddressOf)
        DiagType = AddressOf;
      else if (IsFunction)
        DiagType = FunctionPointer;
      else if (IsArray)
        DiagType = ArrayPointer;
      else
        llvm_unreachable("Could not determine diagnostic.");
      Diag(E->getExprLoc(), DiagID) << DiagType << S.str() << E->getSourceRange()
                                    << Range << IsEqual;
    
      if (!IsFunction)
        return;
    
      // Suggest '&' to silence the function warning.
      Diag(E->getExprLoc(), diag::note_function_warning_silence)
          << FixItHint::CreateInsertion(E->getLocStart(), "&");
    
      // Check to see if '()' fixit should be emitted.
      QualType ReturnType;
      UnresolvedSet<4> NonTemplateOverloads;
      tryExprAsCall(*E, ReturnType, NonTemplateOverloads);
      if (ReturnType.isNull())
        return;
    
      if (IsCompare) {
        // There are two cases here.  If there is null constant, the only suggest
        // for a pointer return type.  If the null is 0, then suggest if the return
        // type is a pointer or an integer type.
        if (!ReturnType->isPointerType()) {
          if (NullKind == Expr::NPCK_ZeroExpression ||
              NullKind == Expr::NPCK_ZeroLiteral) {
            if (!ReturnType->isIntegerType())
              return;
          } else {
            return;
          }
        }
      } else { // !IsCompare
        // For function to bool, only suggest if the function pointer has bool
        // return type.
        if (!ReturnType->isSpecificBuiltinType(BuiltinType::Bool))
          return;
      }
      Diag(E->getExprLoc(), diag::note_function_to_function_call)
          << FixItHint::CreateInsertion(getLocForEndOfToken(E->getLocEnd()), "()");
    }
    
    /// Diagnoses "dangerous" implicit conversions within the given
    /// expression (which is a full expression).  Implements -Wconversion
    /// and -Wsign-compare.
    ///
    /// \param CC the "context" location of the implicit conversion, i.e.
    ///   the most location of the syntactic entity requiring the implicit
    ///   conversion
    void Sema::CheckImplicitConversions(Expr *E, SourceLocation CC) {
      // Don't diagnose in unevaluated contexts.
      if (isUnevaluatedContext())
        return;
    
      // Don't diagnose for value- or type-dependent expressions.
      if (E->isTypeDependent() || E->isValueDependent())
        return;
    
      // Check for array bounds violations in cases where the check isn't triggered
      // elsewhere for other Expr types (like BinaryOperators), e.g. when an
      // ArraySubscriptExpr is on the RHS of a variable initialization.
      CheckArrayAccess(E);
    
      // This is not the right CC for (e.g.) a variable initialization.
      AnalyzeImplicitConversions(*this, E, CC);
    }
    
    /// CheckBoolLikeConversion - Check conversion of given expression to boolean.
    /// Input argument E is a logical expression.
    void Sema::CheckBoolLikeConversion(Expr *E, SourceLocation CC) {
      ::CheckBoolLikeConversion(*this, E, CC);
    }
    
    /// Diagnose when expression is an integer constant expression and its evaluation
    /// results in integer overflow
    void Sema::CheckForIntOverflow (Expr *E) {
      // Use a work list to deal with nested struct initializers.
      SmallVector<Expr *, 2> Exprs(1, E);
    
      do {
        Expr *E = Exprs.pop_back_val();
    
        if (isa<BinaryOperator>(E->IgnoreParenCasts())) {
          E->IgnoreParenCasts()->EvaluateForOverflow(Context);
          continue;
        }
    
        if (auto InitList = dyn_cast<InitListExpr>(E))
          Exprs.append(InitList->inits().begin(), InitList->inits().end());
      } while (!Exprs.empty());
    }
    
    namespace {
    /// \brief Visitor for expressions which looks for unsequenced operations on the
    /// same object.
    class SequenceChecker : public EvaluatedExprVisitor<SequenceChecker> {
      typedef EvaluatedExprVisitor<SequenceChecker> Base;
    
      /// \brief A tree of sequenced regions within an expression. Two regions are
      /// unsequenced if one is an ancestor or a descendent of the other. When we
      /// finish processing an expression with sequencing, such as a comma
      /// expression, we fold its tree nodes into its parent, since they are
      /// unsequenced with respect to nodes we will visit later.
      class SequenceTree {
        struct Value {
          explicit Value(unsigned Parent) : Parent(Parent), Merged(false) {}
          unsigned Parent : 31;
          unsigned Merged : 1;
        };
        SmallVector<Value, 8> Values;
    
      public:
        /// \brief A region within an expression which may be sequenced with respect
        /// to some other region.
        class Seq {
          explicit Seq(unsigned N) : Index(N) {}
          unsigned Index;
          friend class SequenceTree;
        public:
          Seq() : Index(0) {}
        };
    
        SequenceTree() { Values.push_back(Value(0)); }
        Seq root() const { return Seq(0); }
    
        /// \brief Create a new sequence of operations, which is an unsequenced
        /// subset of \p Parent. This sequence of operations is sequenced with
        /// respect to other children of \p Parent.
        Seq allocate(Seq Parent) {
          Values.push_back(Value(Parent.Index));
          return Seq(Values.size() - 1);
        }
    
        /// \brief Merge a sequence of operations into its parent.
        void merge(Seq S) {
          Values[S.Index].Merged = true;
        }
    
        /// \brief Determine whether two operations are unsequenced. This operation
        /// is asymmetric: \p Cur should be the more recent sequence, and \p Old
        /// should have been merged into its parent as appropriate.
        bool isUnsequenced(Seq Cur, Seq Old) {
          unsigned C = representative(Cur.Index);
          unsigned Target = representative(Old.Index);
          while (C >= Target) {
            if (C == Target)
              return true;
            C = Values[C].Parent;
          }
          return false;
        }
    
      private:
        /// \brief Pick a representative for a sequence.
        unsigned representative(unsigned K) {
          if (Values[K].Merged)
            // Perform path compression as we go.
            return Values[K].Parent = representative(Values[K].Parent);
          return K;
        }
      };
    
      /// An object for which we can track unsequenced uses.
      typedef NamedDecl *Object;
    
      /// Different flavors of object usage which we track. We only track the
      /// least-sequenced usage of each kind.
      enum UsageKind {
        /// A read of an object. Multiple unsequenced reads are OK.
        UK_Use,
        /// A modification of an object which is sequenced before the value
        /// computation of the expression, such as ++n in C++.
        UK_ModAsValue,
        /// A modification of an object which is not sequenced before the value
        /// computation of the expression, such as n++.
        UK_ModAsSideEffect,
    
        UK_Count = UK_ModAsSideEffect + 1
      };
    
      struct Usage {
        Usage() : Use(nullptr), Seq() {}
        Expr *Use;
        SequenceTree::Seq Seq;
      };
    
      struct UsageInfo {
        UsageInfo() : Diagnosed(false) {}
        Usage Uses[UK_Count];
        /// Have we issued a diagnostic for this variable already?
        bool Diagnosed;
      };
      typedef llvm::SmallDenseMap<Object, UsageInfo, 16> UsageInfoMap;
    
      Sema &SemaRef;
      /// Sequenced regions within the expression.
      SequenceTree Tree;
      /// Declaration modifications and references which we have seen.
      UsageInfoMap UsageMap;
      /// The region we are currently within.
      SequenceTree::Seq Region;
      /// Filled in with declarations which were modified as a side-effect
      /// (that is, post-increment operations).
      SmallVectorImpl<std::pair<Object, Usage> > *ModAsSideEffect;
      /// Expressions to check later. We defer checking these to reduce
      /// stack usage.
      SmallVectorImpl<Expr *> &WorkList;
    
      /// RAII object wrapping the visitation of a sequenced subexpression of an
      /// expression. At the end of this process, the side-effects of the evaluation
      /// become sequenced with respect to the value computation of the result, so
      /// we downgrade any UK_ModAsSideEffect within the evaluation to
      /// UK_ModAsValue.
      struct SequencedSubexpression {
        SequencedSubexpression(SequenceChecker &Self)
          : Self(Self), OldModAsSideEffect(Self.ModAsSideEffect) {
          Self.ModAsSideEffect = &ModAsSideEffect;
        }
        ~SequencedSubexpression() {
          for (auto &M : llvm::reverse(ModAsSideEffect)) {
            UsageInfo &U = Self.UsageMap[M.first];
            auto &SideEffectUsage = U.Uses[UK_ModAsSideEffect];
            Self.addUsage(U, M.first, SideEffectUsage.Use, UK_ModAsValue);
            SideEffectUsage = M.second;
          }
          Self.ModAsSideEffect = OldModAsSideEffect;
        }
    
        SequenceChecker &Self;
        SmallVector<std::pair<Object, Usage>, 4> ModAsSideEffect;
        SmallVectorImpl<std::pair<Object, Usage> > *OldModAsSideEffect;
      };
    
      /// RAII object wrapping the visitation of a subexpression which we might
      /// choose to evaluate as a constant. If any subexpression is evaluated and
      /// found to be non-constant, this allows us to suppress the evaluation of
      /// the outer expression.
      class EvaluationTracker {
      public:
        EvaluationTracker(SequenceChecker &Self)
            : Self(Self), Prev(Self.EvalTracker), EvalOK(true) {
          Self.EvalTracker = this;
        }
        ~EvaluationTracker() {
          Self.EvalTracker = Prev;
          if (Prev)
            Prev->EvalOK &= EvalOK;
        }
    
        bool evaluate(const Expr *E, bool &Result) {
          if (!EvalOK || E->isValueDependent())
            return false;
          EvalOK = E->EvaluateAsBooleanCondition(Result, Self.SemaRef.Context);
          return EvalOK;
        }
    
      private:
        SequenceChecker &Self;
        EvaluationTracker *Prev;
        bool EvalOK;
      } *EvalTracker;
    
      /// \brief Find the object which is produced by the specified expression,
      /// if any.
      Object getObject(Expr *E, bool Mod) const {
        E = E->IgnoreParenCasts();
        if (UnaryOperator *UO = dyn_cast<UnaryOperator>(E)) {
          if (Mod && (UO->getOpcode() == UO_PreInc || UO->getOpcode() == UO_PreDec))
            return getObject(UO->getSubExpr(), Mod);
        } else if (BinaryOperator *BO = dyn_cast<BinaryOperator>(E)) {
          if (BO->getOpcode() == BO_Comma)
            return getObject(BO->getRHS(), Mod);
          if (Mod && BO->isAssignmentOp())
            return getObject(BO->getLHS(), Mod);
        } else if (MemberExpr *ME = dyn_cast<MemberExpr>(E)) {
          // FIXME: Check for more interesting cases, like "x.n = ++x.n".
          if (isa<CXXThisExpr>(ME->getBase()->IgnoreParenCasts()))
            return ME->getMemberDecl();
        } else if (DeclRefExpr *DRE = dyn_cast<DeclRefExpr>(E))
          // FIXME: If this is a reference, map through to its value.
          return DRE->getDecl();
        return nullptr;
      }
    
      /// \brief Note that an object was modified or used by an expression.
      void addUsage(UsageInfo &UI, Object O, Expr *Ref, UsageKind UK) {
        Usage &U = UI.Uses[UK];
        if (!U.Use || !Tree.isUnsequenced(Region, U.Seq)) {
          if (UK == UK_ModAsSideEffect && ModAsSideEffect)
            ModAsSideEffect->push_back(std::make_pair(O, U));
          U.Use = Ref;
          U.Seq = Region;
        }
      }
      /// \brief Check whether a modification or use conflicts with a prior usage.
      void checkUsage(Object O, UsageInfo &UI, Expr *Ref, UsageKind OtherKind,
                      bool IsModMod) {
        if (UI.Diagnosed)
          return;
    
        const Usage &U = UI.Uses[OtherKind];
        if (!U.Use || !Tree.isUnsequenced(Region, U.Seq))
          return;
    
        Expr *Mod = U.Use;
        Expr *ModOrUse = Ref;
        if (OtherKind == UK_Use)
          std::swap(Mod, ModOrUse);
    
        SemaRef.Diag(Mod->getExprLoc(),
                     IsModMod ? diag::warn_unsequenced_mod_mod
                              : diag::warn_unsequenced_mod_use)
          << O << SourceRange(ModOrUse->getExprLoc());
        UI.Diagnosed = true;
      }
    
      void notePreUse(Object O, Expr *Use) {
        UsageInfo &U = UsageMap[O];
        // Uses conflict with other modifications.
        checkUsage(O, U, Use, UK_ModAsValue, false);
      }
      void notePostUse(Object O, Expr *Use) {
        UsageInfo &U = UsageMap[O];
        checkUsage(O, U, Use, UK_ModAsSideEffect, false);
        addUsage(U, O, Use, UK_Use);
      }
    
      void notePreMod(Object O, Expr *Mod) {
        UsageInfo &U = UsageMap[O];
        // Modifications conflict with other modifications and with uses.
        checkUsage(O, U, Mod, UK_ModAsValue, true);
        checkUsage(O, U, Mod, UK_Use, false);
      }
      void notePostMod(Object O, Expr *Use, UsageKind UK) {
        UsageInfo &U = UsageMap[O];
        checkUsage(O, U, Use, UK_ModAsSideEffect, true);
        addUsage(U, O, Use, UK);
      }
    
    public:
      SequenceChecker(Sema &S, Expr *E, SmallVectorImpl<Expr *> &WorkList)
          : Base(S.Context), SemaRef(S), Region(Tree.root()),
            ModAsSideEffect(nullptr), WorkList(WorkList), EvalTracker(nullptr) {
        Visit(E);
      }
    
      void VisitStmt(Stmt *S) {
        // Skip all statements which aren't expressions for now.
      }
    
      void VisitExpr(Expr *E) {
        // By default, just recurse to evaluated subexpressions.
        Base::VisitStmt(E);
      }
    
      void VisitCastExpr(CastExpr *E) {
        Object O = Object();
        if (E->getCastKind() == CK_LValueToRValue)
          O = getObject(E->getSubExpr(), false);
    
        if (O)
          notePreUse(O, E);
        VisitExpr(E);
        if (O)
          notePostUse(O, E);
      }
    
      void VisitBinComma(BinaryOperator *BO) {
        // C++11 [expr.comma]p1:
        //   Every value computation and side effect associated with the left
        //   expression is sequenced before every value computation and side
        //   effect associated with the right expression.
        SequenceTree::Seq LHS = Tree.allocate(Region);
        SequenceTree::Seq RHS = Tree.allocate(Region);
        SequenceTree::Seq OldRegion = Region;
    
        {
          SequencedSubexpression SeqLHS(*this);
          Region = LHS;
          Visit(BO->getLHS());
        }
    
        Region = RHS;
        Visit(BO->getRHS());
    
        Region = OldRegion;
    
        // Forget that LHS and RHS are sequenced. They are both unsequenced
        // with respect to other stuff.
        Tree.merge(LHS);
        Tree.merge(RHS);
      }
    
      void VisitBinAssign(BinaryOperator *BO) {
        // The modification is sequenced after the value computation of the LHS
        // and RHS, so check it before inspecting the operands and update the
        // map afterwards.
        Object O = getObject(BO->getLHS(), true);
        if (!O)
          return VisitExpr(BO);
    
        notePreMod(O, BO);
    
        // C++11 [expr.ass]p7:
        //   E1 op= E2 is equivalent to E1 = E1 op E2, except that E1 is evaluated
        //   only once.
        //
        // Therefore, for a compound assignment operator, O is considered used
        // everywhere except within the evaluation of E1 itself.
        if (isa<CompoundAssignOperator>(BO))
          notePreUse(O, BO);
    
        Visit(BO->getLHS());
    
        if (isa<CompoundAssignOperator>(BO))
          notePostUse(O, BO);
    
        Visit(BO->getRHS());
    
        // C++11 [expr.ass]p1:
        //   the assignment is sequenced [...] before the value computation of the
        //   assignment expression.
        // C11 6.5.16/3 has no such rule.
        notePostMod(O, BO, SemaRef.getLangOpts().CPlusPlus ? UK_ModAsValue
                                                           : UK_ModAsSideEffect);
      }
    
      void VisitCompoundAssignOperator(CompoundAssignOperator *CAO) {
        VisitBinAssign(CAO);
      }
    
      void VisitUnaryPreInc(UnaryOperator *UO) { VisitUnaryPreIncDec(UO); }
      void VisitUnaryPreDec(UnaryOperator *UO) { VisitUnaryPreIncDec(UO); }
      void VisitUnaryPreIncDec(UnaryOperator *UO) {
        Object O = getObject(UO->getSubExpr(), true);
        if (!O)
          return VisitExpr(UO);
    
        notePreMod(O, UO);
        Visit(UO->getSubExpr());
        // C++11 [expr.pre.incr]p1:
        //   the expression ++x is equivalent to x+=1
        notePostMod(O, UO, SemaRef.getLangOpts().CPlusPlus ? UK_ModAsValue
                                                           : UK_ModAsSideEffect);
      }
    
      void VisitUnaryPostInc(UnaryOperator *UO) { VisitUnaryPostIncDec(UO); }
      void VisitUnaryPostDec(UnaryOperator *UO) { VisitUnaryPostIncDec(UO); }
      void VisitUnaryPostIncDec(UnaryOperator *UO) {
        Object O = getObject(UO->getSubExpr(), true);
        if (!O)
          return VisitExpr(UO);
    
        notePreMod(O, UO);
        Visit(UO->getSubExpr());
        notePostMod(O, UO, UK_ModAsSideEffect);
      }
    
      /// Don't visit the RHS of '&&' or '||' if it might not be evaluated.
      void VisitBinLOr(BinaryOperator *BO) {
        // The side-effects of the LHS of an '&&' are sequenced before the
        // value computation of the RHS, and hence before the value computation
        // of the '&&' itself, unless the LHS evaluates to zero. We treat them
        // as if they were unconditionally sequenced.
        EvaluationTracker Eval(*this);
        {
          SequencedSubexpression Sequenced(*this);
          Visit(BO->getLHS());
        }
    
        bool Result;
        if (Eval.evaluate(BO->getLHS(), Result)) {
          if (!Result)
            Visit(BO->getRHS());
        } else {
          // Check for unsequenced operations in the RHS, treating it as an
          // entirely separate evaluation.
          //
          // FIXME: If there are operations in the RHS which are unsequenced
          // with respect to operations outside the RHS, and those operations
          // are unconditionally evaluated, diagnose them.
          WorkList.push_back(BO->getRHS());
        }
      }
      void VisitBinLAnd(BinaryOperator *BO) {
        EvaluationTracker Eval(*this);
        {
          SequencedSubexpression Sequenced(*this);
          Visit(BO->getLHS());
        }
    
        bool Result;
        if (Eval.evaluate(BO->getLHS(), Result)) {
          if (Result)
            Visit(BO->getRHS());
        } else {
          WorkList.push_back(BO->getRHS());
        }
      }
    
      // Only visit the condition, unless we can be sure which subexpression will
      // be chosen.
      void VisitAbstractConditionalOperator(AbstractConditionalOperator *CO) {
        EvaluationTracker Eval(*this);
        {
          SequencedSubexpression Sequenced(*this);
          Visit(CO->getCond());
        }
    
        bool Result;
        if (Eval.evaluate(CO->getCond(), Result))
          Visit(Result ? CO->getTrueExpr() : CO->getFalseExpr());
        else {
          WorkList.push_back(CO->getTrueExpr());
          WorkList.push_back(CO->getFalseExpr());
        }
      }
    
      void VisitCallExpr(CallExpr *CE) {
        // C++11 [intro.execution]p15:
        //   When calling a function [...], every value computation and side effect
        //   associated with any argument expression, or with the postfix expression
        //   designating the called function, is sequenced before execution of every
        //   expression or statement in the body of the function [and thus before
        //   the value computation of its result].
        SequencedSubexpression Sequenced(*this);
        Base::VisitCallExpr(CE);
    
        // FIXME: CXXNewExpr and CXXDeleteExpr implicitly call functions.
      }
    
      void VisitCXXConstructExpr(CXXConstructExpr *CCE) {
        // This is a call, so all subexpressions are sequenced before the result.
        SequencedSubexpression Sequenced(*this);
    
        if (!CCE->isListInitialization())
          return VisitExpr(CCE);
    
        // In C++11, list initializations are sequenced.
        SmallVector<SequenceTree::Seq, 32> Elts;
        SequenceTree::Seq Parent = Region;
        for (CXXConstructExpr::arg_iterator I = CCE->arg_begin(),
                                            E = CCE->arg_end();
             I != E; ++I) {
          Region = Tree.allocate(Parent);
          Elts.push_back(Region);
          Visit(*I);
        }
    
        // Forget that the initializers are sequenced.
        Region = Parent;
        for (unsigned I = 0; I < Elts.size(); ++I)
          Tree.merge(Elts[I]);
      }
    
      void VisitInitListExpr(InitListExpr *ILE) {
        if (!SemaRef.getLangOpts().CPlusPlus11)
          return VisitExpr(ILE);
    
        // In C++11, list initializations are sequenced.
        SmallVector<SequenceTree::Seq, 32> Elts;
        SequenceTree::Seq Parent = Region;
        for (unsigned I = 0; I < ILE->getNumInits(); ++I) {
          Expr *E = ILE->getInit(I);
          if (!E) continue;
          Region = Tree.allocate(Parent);
          Elts.push_back(Region);
          Visit(E);
        }
    
        // Forget that the initializers are sequenced.
        Region = Parent;
        for (unsigned I = 0; I < Elts.size(); ++I)
          Tree.merge(Elts[I]);
      }
    };
    } // end anonymous namespace
    
    void Sema::CheckUnsequencedOperations(Expr *E) {
      SmallVector<Expr *, 8> WorkList;
      WorkList.push_back(E);
      while (!WorkList.empty()) {
        Expr *Item = WorkList.pop_back_val();
        SequenceChecker(*this, Item, WorkList);
      }
    }
    
    void Sema::CheckCompletedExpr(Expr *E, SourceLocation CheckLoc,
                                  bool IsConstexpr) {
      CheckImplicitConversions(E, CheckLoc);
      if (!E->isInstantiationDependent())
        CheckUnsequencedOperations(E);
      if (!IsConstexpr && !E->isValueDependent())
        CheckForIntOverflow(E);
      DiagnoseMisalignedMembers();
    }
    
    void Sema::CheckBitFieldInitialization(SourceLocation InitLoc,
                                           FieldDecl *BitField,
                                           Expr *Init) {
      (void) AnalyzeBitFieldAssignment(*this, BitField, Init, InitLoc);
    }
    
    static void diagnoseArrayStarInParamType(Sema &S, QualType PType,
                                             SourceLocation Loc) {
      if (!PType->isVariablyModifiedType())
        return;
      if (const auto *PointerTy = dyn_cast<PointerType>(PType)) {
        diagnoseArrayStarInParamType(S, PointerTy->getPointeeType(), Loc);
        return;
      }
      if (const auto *ReferenceTy = dyn_cast<ReferenceType>(PType)) {
        diagnoseArrayStarInParamType(S, ReferenceTy->getPointeeType(), Loc);
        return;
      }
      if (const auto *ParenTy = dyn_cast<ParenType>(PType)) {
        diagnoseArrayStarInParamType(S, ParenTy->getInnerType(), Loc);
        return;
      }
    
      const ArrayType *AT = S.Context.getAsArrayType(PType);
      if (!AT)
        return;
    
      if (AT->getSizeModifier() != ArrayType::Star) {
        diagnoseArrayStarInParamType(S, AT->getElementType(), Loc);
        return;
      }
    
      S.Diag(Loc, diag::err_array_star_in_function_definition);
    }
    
    /// CheckParmsForFunctionDef - Check that the parameters of the given
    /// function are appropriate for the definition of a function. This
    /// takes care of any checks that cannot be performed on the
    /// declaration itself, e.g., that the types of each of the function
    /// parameters are complete.
    bool Sema::CheckParmsForFunctionDef(ArrayRef<ParmVarDecl *> Parameters,
                                        bool CheckParameterNames) {
      bool HasInvalidParm = false;
      for (ParmVarDecl *Param : Parameters) {
        // C99 6.7.5.3p4: the parameters in a parameter type list in a
        // function declarator that is part of a function definition of
        // that function shall not have incomplete type.
        //
        // This is also C++ [dcl.fct]p6.
        if (!Param->isInvalidDecl() &&
            RequireCompleteType(Param->getLocation(), Param->getType(),
                                diag::err_typecheck_decl_incomplete_type)) {
          Param->setInvalidDecl();
          HasInvalidParm = true;
        }
    
        // C99 6.9.1p5: If the declarator includes a parameter type list, the
        // declaration of each parameter shall include an identifier.
        if (CheckParameterNames &&
            Param->getIdentifier() == nullptr &&
            !Param->isImplicit() &&
            !getLangOpts().CPlusPlus)
          Diag(Param->getLocation(), diag::err_parameter_name_omitted);
    
        // C99 6.7.5.3p12:
        //   If the function declarator is not part of a definition of that
        //   function, parameters may have incomplete type and may use the [*]
        //   notation in their sequences of declarator specifiers to specify
        //   variable length array types.
        QualType PType = Param->getOriginalType();
        // FIXME: This diagnostic should point the '[*]' if source-location
        // information is added for it.
        diagnoseArrayStarInParamType(*this, PType, Param->getLocation());
    
        // MSVC destroys objects passed by value in the callee.  Therefore a
        // function definition which takes such a parameter must be able to call the
        // object's destructor.  However, we don't perform any direct access check
        // on the dtor.
        if (getLangOpts().CPlusPlus && Context.getTargetInfo()
                                           .getCXXABI()
                                           .areArgsDestroyedLeftToRightInCallee()) {
          if (!Param->isInvalidDecl()) {
            if (const RecordType *RT = Param->getType()->getAs<RecordType>()) {
              CXXRecordDecl *ClassDecl = cast<CXXRecordDecl>(RT->getDecl());
              if (!ClassDecl->isInvalidDecl() &&
                  !ClassDecl->hasIrrelevantDestructor() &&
                  !ClassDecl->isDependentContext()) {
                CXXDestructorDecl *Destructor = LookupDestructor(ClassDecl);
                MarkFunctionReferenced(Param->getLocation(), Destructor);
                DiagnoseUseOfDecl(Destructor, Param->getLocation());
              }
            }
          }
        }
    
        // Parameters with the pass_object_size attribute only need to be marked
        // constant at function definitions. Because we lack information about
        // whether we're on a declaration or definition when we're instantiating the
        // attribute, we need to check for constness here.
        if (const auto *Attr = Param->getAttr<PassObjectSizeAttr>())
          if (!Param->getType().isConstQualified())
            Diag(Param->getLocation(), diag::err_attribute_pointers_only)
                << Attr->getSpelling() << 1;
      }
    
      return HasInvalidParm;
    }
    
    /// A helper function to get the alignment of a Decl referred to by DeclRefExpr
    /// or MemberExpr.
    static CharUnits getDeclAlign(Expr *E, CharUnits TypeAlign,
                                  ASTContext &Context) {
      if (const auto *DRE = dyn_cast<DeclRefExpr>(E))
        return Context.getDeclAlign(DRE->getDecl());
    
      if (const auto *ME = dyn_cast<MemberExpr>(E))
        return Context.getDeclAlign(ME->getMemberDecl());
    
      return TypeAlign;
    }
    
    /// CheckCastAlign - Implements -Wcast-align, which warns when a
    /// pointer cast increases the alignment requirements.
    void Sema::CheckCastAlign(Expr *Op, QualType T, SourceRange TRange) {
      // This is actually a lot of work to potentially be doing on every
      // cast; don't do it if we're ignoring -Wcast_align (as is the default).
      if (getDiagnostics().isIgnored(diag::warn_cast_align, TRange.getBegin()))
        return;
    
      // Ignore dependent types.
      if (T->isDependentType() || Op->getType()->isDependentType())
        return;
    
      // Require that the destination be a pointer type.
      const PointerType *DestPtr = T->getAs<PointerType>();
      if (!DestPtr) return;
    
      // If the destination has alignment 1, we're done.
      QualType DestPointee = DestPtr->getPointeeType();
      if (DestPointee->isIncompleteType()) return;
      CharUnits DestAlign = Context.getTypeAlignInChars(DestPointee);
      if (DestAlign.isOne()) return;
    
      // Require that the source be a pointer type.
      const PointerType *SrcPtr = Op->getType()->getAs<PointerType>();
      if (!SrcPtr) return;
      QualType SrcPointee = SrcPtr->getPointeeType();
    
      // Whitelist casts from cv void*.  We already implicitly
      // whitelisted casts to cv void*, since they have alignment 1.
      // Also whitelist casts involving incomplete types, which implicitly
      // includes 'void'.
      if (SrcPointee->isIncompleteType()) return;
    
      CharUnits SrcAlign = Context.getTypeAlignInChars(SrcPointee);
    
      if (auto *CE = dyn_cast<CastExpr>(Op)) {
        if (CE->getCastKind() == CK_ArrayToPointerDecay)
          SrcAlign = getDeclAlign(CE->getSubExpr(), SrcAlign, Context);
      } else if (auto *UO = dyn_cast<UnaryOperator>(Op)) {
        if (UO->getOpcode() == UO_AddrOf)
          SrcAlign = getDeclAlign(UO->getSubExpr(), SrcAlign, Context);
      }
    
      if (SrcAlign >= DestAlign) return;
    
      Diag(TRange.getBegin(), diag::warn_cast_align)
        << Op->getType() << T
        << static_cast<unsigned>(SrcAlign.getQuantity())
        << static_cast<unsigned>(DestAlign.getQuantity())
        << TRange << Op->getSourceRange();
    }
    
    /// \brief Check whether this array fits the idiom of a size-one tail padded
    /// array member of a struct.
    ///
    /// We avoid emitting out-of-bounds access warnings for such arrays as they are
    /// commonly used to emulate flexible arrays in C89 code.
    static bool IsTailPaddedMemberArray(Sema &S, const llvm::APInt &Size,
                                        const NamedDecl *ND) {
      if (Size != 1 || !ND) return false;
    
      const FieldDecl *FD = dyn_cast<FieldDecl>(ND);
      if (!FD) return false;
    
      // Don't consider sizes resulting from macro expansions or template argument
      // substitution to form C89 tail-padded arrays.
    
      TypeSourceInfo *TInfo = FD->getTypeSourceInfo();
      while (TInfo) {
        TypeLoc TL = TInfo->getTypeLoc();
        // Look through typedefs.
        if (TypedefTypeLoc TTL = TL.getAs<TypedefTypeLoc>()) {
          const TypedefNameDecl *TDL = TTL.getTypedefNameDecl();
          TInfo = TDL->getTypeSourceInfo();
          continue;
        }
        if (ConstantArrayTypeLoc CTL = TL.getAs<ConstantArrayTypeLoc>()) {
          const Expr *SizeExpr = dyn_cast<IntegerLiteral>(CTL.getSizeExpr());
          if (!SizeExpr || SizeExpr->getExprLoc().isMacroID())
            return false;
        }
        break;
      }
    
      const RecordDecl *RD = dyn_cast<RecordDecl>(FD->getDeclContext());
      if (!RD) return false;
      if (RD->isUnion()) return false;
      if (const CXXRecordDecl *CRD = dyn_cast<CXXRecordDecl>(RD)) {
        if (!CRD->isStandardLayout()) return false;
      }
    
      // See if this is the last field decl in the record.
      const Decl *D = FD;
      while ((D = D->getNextDeclInContext()))
        if (isa<FieldDecl>(D))
          return false;
      return true;
    }
    
    void Sema::CheckArrayAccess(const Expr *BaseExpr, const Expr *IndexExpr,
                                const ArraySubscriptExpr *ASE,
                                bool AllowOnePastEnd, bool IndexNegated) {
      IndexExpr = IndexExpr->IgnoreParenImpCasts();
      if (IndexExpr->isValueDependent())
        return;
    
      const Type *EffectiveType =
          BaseExpr->getType()->getPointeeOrArrayElementType();
      BaseExpr = BaseExpr->IgnoreParenCasts();
      const ConstantArrayType *ArrayTy =
        Context.getAsConstantArrayType(BaseExpr->getType());
      if (!ArrayTy)
        return;
    
      llvm::APSInt index;
      if (!IndexExpr->EvaluateAsInt(index, Context, Expr::SE_AllowSideEffects))
        return;
      if (IndexNegated)
        index = -index;
    
      const NamedDecl *ND = nullptr;
      if (const DeclRefExpr *DRE = dyn_cast<DeclRefExpr>(BaseExpr))
        ND = dyn_cast<NamedDecl>(DRE->getDecl());
      if (const MemberExpr *ME = dyn_cast<MemberExpr>(BaseExpr))
        ND = dyn_cast<NamedDecl>(ME->getMemberDecl());
    
      if (index.isUnsigned() || !index.isNegative()) {
        llvm::APInt size = ArrayTy->getSize();
        if (!size.isStrictlyPositive())
          return;
    
        const Type *BaseType = BaseExpr->getType()->getPointeeOrArrayElementType();
        if (BaseType != EffectiveType) {
          // Make sure we're comparing apples to apples when comparing index to size
          uint64_t ptrarith_typesize = Context.getTypeSize(EffectiveType);
          uint64_t array_typesize = Context.getTypeSize(BaseType);
          // Handle ptrarith_typesize being zero, such as when casting to void*
          if (!ptrarith_typesize) ptrarith_typesize = 1;
          if (ptrarith_typesize != array_typesize) {
            // There's a cast to a different size type involved
            uint64_t ratio = array_typesize / ptrarith_typesize;
            // TODO: Be smarter about handling cases where array_typesize is not a
            // multiple of ptrarith_typesize
            if (ptrarith_typesize * ratio == array_typesize)
              size *= llvm::APInt(size.getBitWidth(), ratio);
          }
        }
    
        if (size.getBitWidth() > index.getBitWidth())
          index = index.zext(size.getBitWidth());
        else if (size.getBitWidth() < index.getBitWidth())
          size = size.zext(index.getBitWidth());
    
        // For array subscripting the index must be less than size, but for pointer
        // arithmetic also allow the index (offset) to be equal to size since
        // computing the next address after the end of the array is legal and
        // commonly done e.g. in C++ iterators and range-based for loops.
        if (AllowOnePastEnd ? index.ule(size) : index.ult(size))
          return;
    
        // Also don't warn for arrays of size 1 which are members of some
        // structure. These are often used to approximate flexible arrays in C89
        // code.
        if (IsTailPaddedMemberArray(*this, size, ND))
          return;
    
        // Suppress the warning if the subscript expression (as identified by the
        // ']' location) and the index expression are both from macro expansions
        // within a system header.
        if (ASE) {
          SourceLocation RBracketLoc = SourceMgr.getSpellingLoc(
              ASE->getRBracketLoc());
          if (SourceMgr.isInSystemHeader(RBracketLoc)) {
            SourceLocation IndexLoc = SourceMgr.getSpellingLoc(
                IndexExpr->getLocStart());
            if (SourceMgr.isWrittenInSameFile(RBracketLoc, IndexLoc))
              return;
          }
        }
    
        unsigned DiagID = diag::warn_ptr_arith_exceeds_bounds;
        if (ASE)
          DiagID = diag::warn_array_index_exceeds_bounds;
    
        DiagRuntimeBehavior(BaseExpr->getLocStart(), BaseExpr,
                            PDiag(DiagID) << index.toString(10, true)
                              << size.toString(10, true)
                              << (unsigned)size.getLimitedValue(~0U)
                              << IndexExpr->getSourceRange());
      } else {
        unsigned DiagID = diag::warn_array_index_precedes_bounds;
        if (!ASE) {
          DiagID = diag::warn_ptr_arith_precedes_bounds;
          if (index.isNegative()) index = -index;
        }
    
        DiagRuntimeBehavior(BaseExpr->getLocStart(), BaseExpr,
                            PDiag(DiagID) << index.toString(10, true)
                              << IndexExpr->getSourceRange());
      }
    
      if (!ND) {
        // Try harder to find a NamedDecl to point at in the note.
        while (const ArraySubscriptExpr *ASE =
               dyn_cast<ArraySubscriptExpr>(BaseExpr))
          BaseExpr = ASE->getBase()->IgnoreParenCasts();
        if (const DeclRefExpr *DRE = dyn_cast<DeclRefExpr>(BaseExpr))
          ND = dyn_cast<NamedDecl>(DRE->getDecl());
        if (const MemberExpr *ME = dyn_cast<MemberExpr>(BaseExpr))
          ND = dyn_cast<NamedDecl>(ME->getMemberDecl());
      }
    
      if (ND)
        DiagRuntimeBehavior(ND->getLocStart(), BaseExpr,
                            PDiag(diag::note_array_index_out_of_bounds)
                              << ND->getDeclName());
    }
    
    void Sema::CheckArrayAccess(const Expr *expr) {
      int AllowOnePastEnd = 0;
      while (expr) {
        expr = expr->IgnoreParenImpCasts();
        switch (expr->getStmtClass()) {
          case Stmt::ArraySubscriptExprClass: {
            const ArraySubscriptExpr *ASE = cast<ArraySubscriptExpr>(expr);
            CheckArrayAccess(ASE->getBase(), ASE->getIdx(), ASE,
                             AllowOnePastEnd > 0);
            return;
          }
          case Stmt::OMPArraySectionExprClass: {
            const OMPArraySectionExpr *ASE = cast<OMPArraySectionExpr>(expr);
            if (ASE->getLowerBound())
              CheckArrayAccess(ASE->getBase(), ASE->getLowerBound(),
                               /*ASE=*/nullptr, AllowOnePastEnd > 0);
            return;
          }
          case Stmt::UnaryOperatorClass: {
            // Only unwrap the * and & unary operators
            const UnaryOperator *UO = cast<UnaryOperator>(expr);
            expr = UO->getSubExpr();
            switch (UO->getOpcode()) {
              case UO_AddrOf:
                AllowOnePastEnd++;
                break;
              case UO_Deref:
                AllowOnePastEnd--;
                break;
              default:
                return;
            }
            break;
          }
          case Stmt::ConditionalOperatorClass: {
            const ConditionalOperator *cond = cast<ConditionalOperator>(expr);
            if (const Expr *lhs = cond->getLHS())
              CheckArrayAccess(lhs);
            if (const Expr *rhs = cond->getRHS())
              CheckArrayAccess(rhs);
            return;
          }
          default:
            return;
        }
      }
    }
    
    //===--- CHECK: Objective-C retain cycles ----------------------------------//
    
    namespace {
      struct RetainCycleOwner {
        RetainCycleOwner() : Variable(nullptr), Indirect(false) {}
        VarDecl *Variable;
        SourceRange Range;
        SourceLocation Loc;
        bool Indirect;
    
        void setLocsFrom(Expr *e) {
          Loc = e->getExprLoc();
          Range = e->getSourceRange();
        }
      };
    } // end anonymous namespace
    
    /// Consider whether capturing the given variable can possibly lead to
    /// a retain cycle.
    static bool considerVariable(VarDecl *var, Expr *ref, RetainCycleOwner &owner) {
      // In ARC, it's captured strongly iff the variable has __strong
      // lifetime.  In MRR, it's captured strongly if the variable is
      // __block and has an appropriate type.
      if (var->getType().getObjCLifetime() != Qualifiers::OCL_Strong)
        return false;
    
      owner.Variable = var;
      if (ref)
        owner.setLocsFrom(ref);
      return true;
    }
    
    static bool findRetainCycleOwner(Sema &S, Expr *e, RetainCycleOwner &owner) {
      while (true) {
        e = e->IgnoreParens();
        if (CastExpr *cast = dyn_cast<CastExpr>(e)) {
          switch (cast->getCastKind()) {
          case CK_BitCast:
          case CK_LValueBitCast:
          case CK_LValueToRValue:
          case CK_ARCReclaimReturnedObject:
            e = cast->getSubExpr();
            continue;
    
          default:
            return false;
          }
        }
    
        if (ObjCIvarRefExpr *ref = dyn_cast<ObjCIvarRefExpr>(e)) {
          ObjCIvarDecl *ivar = ref->getDecl();
          if (ivar->getType().getObjCLifetime() != Qualifiers::OCL_Strong)
            return false;
    
          // Try to find a retain cycle in the base.
          if (!findRetainCycleOwner(S, ref->getBase(), owner))
            return false;
    
          if (ref->isFreeIvar()) owner.setLocsFrom(ref);
          owner.Indirect = true;
          return true;
        }
    
        if (DeclRefExpr *ref = dyn_cast<DeclRefExpr>(e)) {
          VarDecl *var = dyn_cast<VarDecl>(ref->getDecl());
          if (!var) return false;
          return considerVariable(var, ref, owner);
        }
    
        if (MemberExpr *member = dyn_cast<MemberExpr>(e)) {
          if (member->isArrow()) return false;
    
          // Don't count this as an indirect ownership.
          e = member->getBase();
          continue;
        }
    
        if (PseudoObjectExpr *pseudo = dyn_cast<PseudoObjectExpr>(e)) {
          // Only pay attention to pseudo-objects on property references.
          ObjCPropertyRefExpr *pre
            = dyn_cast<ObjCPropertyRefExpr>(pseudo->getSyntacticForm()
                                                  ->IgnoreParens());
          if (!pre) return false;
          if (pre->isImplicitProperty()) return false;
          ObjCPropertyDecl *property = pre->getExplicitProperty();
          if (!property->isRetaining() &&
              !(property->getPropertyIvarDecl() &&
                property->getPropertyIvarDecl()->getType()
                  .getObjCLifetime() == Qualifiers::OCL_Strong))
              return false;
    
          owner.Indirect = true;
          if (pre->isSuperReceiver()) {
            owner.Variable = S.getCurMethodDecl()->getSelfDecl();
            if (!owner.Variable)
              return false;
            owner.Loc = pre->getLocation();
            owner.Range = pre->getSourceRange();
            return true;
          }
          e = const_cast<Expr*>(cast<OpaqueValueExpr>(pre->getBase())
                                  ->getSourceExpr());
          continue;
        }
    
        // Array ivars?
    
        return false;
      }
    }
    
    namespace {
      struct FindCaptureVisitor : EvaluatedExprVisitor<FindCaptureVisitor> {
        FindCaptureVisitor(ASTContext &Context, VarDecl *variable)
          : EvaluatedExprVisitor<FindCaptureVisitor>(Context),
            Context(Context), Variable(variable), Capturer(nullptr),
            VarWillBeReased(false) {}
        ASTContext &Context;
        VarDecl *Variable;
        Expr *Capturer;
        bool VarWillBeReased;
    
        void VisitDeclRefExpr(DeclRefExpr *ref) {
          if (ref->getDecl() == Variable && !Capturer)
            Capturer = ref;
        }
    
        void VisitObjCIvarRefExpr(ObjCIvarRefExpr *ref) {
          if (Capturer) return;
          Visit(ref->getBase());
          if (Capturer && ref->isFreeIvar())
            Capturer = ref;
        }
    
        void VisitBlockExpr(BlockExpr *block) {
          // Look inside nested blocks 
          if (block->getBlockDecl()->capturesVariable(Variable))
            Visit(block->getBlockDecl()->getBody());
        }
        
        void VisitOpaqueValueExpr(OpaqueValueExpr *OVE) {
          if (Capturer) return;
          if (OVE->getSourceExpr())
            Visit(OVE->getSourceExpr());
        }
        void VisitBinaryOperator(BinaryOperator *BinOp) {
          if (!Variable || VarWillBeReased || BinOp->getOpcode() != BO_Assign)
            return;
          Expr *LHS = BinOp->getLHS();
          if (const DeclRefExpr *DRE = dyn_cast_or_null<DeclRefExpr>(LHS)) {
            if (DRE->getDecl() != Variable)
              return;
            if (Expr *RHS = BinOp->getRHS()) {
              RHS = RHS->IgnoreParenCasts();
              llvm::APSInt Value;
              VarWillBeReased =
                (RHS && RHS->isIntegerConstantExpr(Value, Context) && Value == 0);
            }
          }
        }
      };
    } // end anonymous namespace
    
    /// Check whether the given argument is a block which captures a
    /// variable.
    static Expr *findCapturingExpr(Sema &S, Expr *e, RetainCycleOwner &owner) {
      assert(owner.Variable && owner.Loc.isValid());
    
      e = e->IgnoreParenCasts();
    
      // Look through [^{...} copy] and Block_copy(^{...}).
      if (ObjCMessageExpr *ME = dyn_cast<ObjCMessageExpr>(e)) {
        Selector Cmd = ME->getSelector();
        if (Cmd.isUnarySelector() && Cmd.getNameForSlot(0) == "copy") {
          e = ME->getInstanceReceiver();
          if (!e)
            return nullptr;
          e = e->IgnoreParenCasts();
        }
      } else if (CallExpr *CE = dyn_cast<CallExpr>(e)) {
        if (CE->getNumArgs() == 1) {
          FunctionDecl *Fn = dyn_cast_or_null<FunctionDecl>(CE->getCalleeDecl());
          if (Fn) {
            const IdentifierInfo *FnI = Fn->getIdentifier();
            if (FnI && FnI->isStr("_Block_copy")) {
              e = CE->getArg(0)->IgnoreParenCasts();
            }
          }
        }
      }
      
      BlockExpr *block = dyn_cast<BlockExpr>(e);
      if (!block || !block->getBlockDecl()->capturesVariable(owner.Variable))
        return nullptr;
    
      FindCaptureVisitor visitor(S.Context, owner.Variable);
      visitor.Visit(block->getBlockDecl()->getBody());
      return visitor.VarWillBeReased ? nullptr : visitor.Capturer;
    }
    
    static void diagnoseRetainCycle(Sema &S, Expr *capturer,
                                    RetainCycleOwner &owner) {
      assert(capturer);
      assert(owner.Variable && owner.Loc.isValid());
    
      S.Diag(capturer->getExprLoc(), diag::warn_arc_retain_cycle)
        << owner.Variable << capturer->getSourceRange();
      S.Diag(owner.Loc, diag::note_arc_retain_cycle_owner)
        << owner.Indirect << owner.Range;
    }
    
    /// Check for a keyword selector that starts with the word 'add' or
    /// 'set'.
    static bool isSetterLikeSelector(Selector sel) {
      if (sel.isUnarySelector()) return false;
    
      StringRef str = sel.getNameForSlot(0);
      while (!str.empty() && str.front() == '_') str = str.substr(1);
      if (str.startswith("set"))
        str = str.substr(3);
      else if (str.startswith("add")) {
        // Specially whitelist 'addOperationWithBlock:'.
        if (sel.getNumArgs() == 1 && str.startswith("addOperationWithBlock"))
          return false;
        str = str.substr(3);
      }
      else
        return false;
    
      if (str.empty()) return true;
      return !isLowercase(str.front());
    }
    
    static Optional<int> GetNSMutableArrayArgumentIndex(Sema &S,
                                                        ObjCMessageExpr *Message) {
      bool IsMutableArray = S.NSAPIObj->isSubclassOfNSClass(
                                                    Message->getReceiverInterface(),
                                                    NSAPI::ClassId_NSMutableArray);
      if (!IsMutableArray) {
        return None;
      }
    
      Selector Sel = Message->getSelector();
    
      Optional<NSAPI::NSArrayMethodKind> MKOpt =
        S.NSAPIObj->getNSArrayMethodKind(Sel);
      if (!MKOpt) {
        return None;
      }
    
      NSAPI::NSArrayMethodKind MK = *MKOpt;
    
      switch (MK) {
        case NSAPI::NSMutableArr_addObject:
        case NSAPI::NSMutableArr_insertObjectAtIndex:
        case NSAPI::NSMutableArr_setObjectAtIndexedSubscript:
          return 0;
        case NSAPI::NSMutableArr_replaceObjectAtIndex:
          return 1;
    
        default:
          return None;
      }
    
      return None;
    }
    
    static
    Optional<int> GetNSMutableDictionaryArgumentIndex(Sema &S,
                                                      ObjCMessageExpr *Message) {
      bool IsMutableDictionary = S.NSAPIObj->isSubclassOfNSClass(
                                                Message->getReceiverInterface(),
                                                NSAPI::ClassId_NSMutableDictionary);
      if (!IsMutableDictionary) {
        return None;
      }
    
      Selector Sel = Message->getSelector();
    
      Optional<NSAPI::NSDictionaryMethodKind> MKOpt =
        S.NSAPIObj->getNSDictionaryMethodKind(Sel);
      if (!MKOpt) {
        return None;
      }
    
      NSAPI::NSDictionaryMethodKind MK = *MKOpt;
    
      switch (MK) {
        case NSAPI::NSMutableDict_setObjectForKey:
        case NSAPI::NSMutableDict_setValueForKey:
        case NSAPI::NSMutableDict_setObjectForKeyedSubscript:
          return 0;
    
        default:
          return None;
      }
    
      return None;
    }
    
    static Optional<int> GetNSSetArgumentIndex(Sema &S, ObjCMessageExpr *Message) {
      bool IsMutableSet = S.NSAPIObj->isSubclassOfNSClass(
                                                    Message->getReceiverInterface(),
                                                    NSAPI::ClassId_NSMutableSet);
    
      bool IsMutableOrderedSet = S.NSAPIObj->isSubclassOfNSClass(
                                                Message->getReceiverInterface(),
                                                NSAPI::ClassId_NSMutableOrderedSet);
      if (!IsMutableSet && !IsMutableOrderedSet) {
        return None;
      }
    
      Selector Sel = Message->getSelector();
    
      Optional<NSAPI::NSSetMethodKind> MKOpt = S.NSAPIObj->getNSSetMethodKind(Sel);
      if (!MKOpt) {
        return None;
      }
    
      NSAPI::NSSetMethodKind MK = *MKOpt;
    
      switch (MK) {
        case NSAPI::NSMutableSet_addObject:
        case NSAPI::NSOrderedSet_setObjectAtIndex:
        case NSAPI::NSOrderedSet_setObjectAtIndexedSubscript:
        case NSAPI::NSOrderedSet_insertObjectAtIndex:
          return 0;
        case NSAPI::NSOrderedSet_replaceObjectAtIndexWithObject:
          return 1;
      }
    
      return None;
    }
    
    void Sema::CheckObjCCircularContainer(ObjCMessageExpr *Message) {
      if (!Message->isInstanceMessage()) {
        return;
      }
    
      Optional<int> ArgOpt;
    
      if (!(ArgOpt = GetNSMutableArrayArgumentIndex(*this, Message)) &&
          !(ArgOpt = GetNSMutableDictionaryArgumentIndex(*this, Message)) &&
          !(ArgOpt = GetNSSetArgumentIndex(*this, Message))) {
        return;
      }
    
      int ArgIndex = *ArgOpt;
    
      Expr *Arg = Message->getArg(ArgIndex)->IgnoreImpCasts();
      if (OpaqueValueExpr *OE = dyn_cast<OpaqueValueExpr>(Arg)) {
        Arg = OE->getSourceExpr()->IgnoreImpCasts();
      }
    
      if (Message->getReceiverKind() == ObjCMessageExpr::SuperInstance) {
        if (DeclRefExpr *ArgRE = dyn_cast<DeclRefExpr>(Arg)) {
          if (ArgRE->isObjCSelfExpr()) {
            Diag(Message->getSourceRange().getBegin(),
                 diag::warn_objc_circular_container)
              << ArgRE->getDecl()->getName() << StringRef("super");
          }
        }
      } else {
        Expr *Receiver = Message->getInstanceReceiver()->IgnoreImpCasts();
    
        if (OpaqueValueExpr *OE = dyn_cast<OpaqueValueExpr>(Receiver)) {
          Receiver = OE->getSourceExpr()->IgnoreImpCasts();
        }
    
        if (DeclRefExpr *ReceiverRE = dyn_cast<DeclRefExpr>(Receiver)) {
          if (DeclRefExpr *ArgRE = dyn_cast<DeclRefExpr>(Arg)) {
            if (ReceiverRE->getDecl() == ArgRE->getDecl()) {
              ValueDecl *Decl = ReceiverRE->getDecl();
              Diag(Message->getSourceRange().getBegin(),
                   diag::warn_objc_circular_container)
                << Decl->getName() << Decl->getName();
              if (!ArgRE->isObjCSelfExpr()) {
                Diag(Decl->getLocation(),
                     diag::note_objc_circular_container_declared_here)
                  << Decl->getName();
              }
            }
          }
        } else if (ObjCIvarRefExpr *IvarRE = dyn_cast<ObjCIvarRefExpr>(Receiver)) {
          if (ObjCIvarRefExpr *IvarArgRE = dyn_cast<ObjCIvarRefExpr>(Arg)) {
            if (IvarRE->getDecl() == IvarArgRE->getDecl()) {
              ObjCIvarDecl *Decl = IvarRE->getDecl();
              Diag(Message->getSourceRange().getBegin(),
                   diag::warn_objc_circular_container)
                << Decl->getName() << Decl->getName();
              Diag(Decl->getLocation(),
                   diag::note_objc_circular_container_declared_here)
                << Decl->getName();
            }
          }
        }
      }
    }
    
    /// Check a message send to see if it's likely to cause a retain cycle.
    void Sema::checkRetainCycles(ObjCMessageExpr *msg) {
      // Only check instance methods whose selector looks like a setter.
      if (!msg->isInstanceMessage() || !isSetterLikeSelector(msg->getSelector()))
        return;
    
      // Try to find a variable that the receiver is strongly owned by.
      RetainCycleOwner owner;
      if (msg->getReceiverKind() == ObjCMessageExpr::Instance) {
        if (!findRetainCycleOwner(*this, msg->getInstanceReceiver(), owner))
          return;
      } else {
        assert(msg->getReceiverKind() == ObjCMessageExpr::SuperInstance);
        owner.Variable = getCurMethodDecl()->getSelfDecl();
        owner.Loc = msg->getSuperLoc();
        owner.Range = msg->getSuperLoc();
      }
    
      // Check whether the receiver is captured by any of the arguments.
      for (unsigned i = 0, e = msg->getNumArgs(); i != e; ++i)
        if (Expr *capturer = findCapturingExpr(*this, msg->getArg(i), owner))
          return diagnoseRetainCycle(*this, capturer, owner);
    }
    
    /// Check a property assign to see if it's likely to cause a retain cycle.
    void Sema::checkRetainCycles(Expr *receiver, Expr *argument) {
      RetainCycleOwner owner;
      if (!findRetainCycleOwner(*this, receiver, owner))
        return;
    
      if (Expr *capturer = findCapturingExpr(*this, argument, owner))
        diagnoseRetainCycle(*this, capturer, owner);
    }
    
    void Sema::checkRetainCycles(VarDecl *Var, Expr *Init) {
      RetainCycleOwner Owner;
      if (!considerVariable(Var, /*DeclRefExpr=*/nullptr, Owner))
        return;
      
      // Because we don't have an expression for the variable, we have to set the
      // location explicitly here.
      Owner.Loc = Var->getLocation();
      Owner.Range = Var->getSourceRange();
      
      if (Expr *Capturer = findCapturingExpr(*this, Init, Owner))
        diagnoseRetainCycle(*this, Capturer, Owner);
    }
    
    static bool checkUnsafeAssignLiteral(Sema &S, SourceLocation Loc,
                                         Expr *RHS, bool isProperty) {
      // Check if RHS is an Objective-C object literal, which also can get
      // immediately zapped in a weak reference.  Note that we explicitly
      // allow ObjCStringLiterals, since those are designed to never really die.
      RHS = RHS->IgnoreParenImpCasts();
    
      // This enum needs to match with the 'select' in
      // warn_objc_arc_literal_assign (off-by-1).
      Sema::ObjCLiteralKind Kind = S.CheckLiteralKind(RHS);
      if (Kind == Sema::LK_String || Kind == Sema::LK_None)
        return false;
    
      S.Diag(Loc, diag::warn_arc_literal_assign)
        << (unsigned) Kind
        << (isProperty ? 0 : 1)
        << RHS->getSourceRange();
    
      return true;
    }
    
    static bool checkUnsafeAssignObject(Sema &S, SourceLocation Loc,
                                        Qualifiers::ObjCLifetime LT,
                                        Expr *RHS, bool isProperty) {
      // Strip off any implicit cast added to get to the one ARC-specific.
      while (ImplicitCastExpr *cast = dyn_cast<ImplicitCastExpr>(RHS)) {
        if (cast->getCastKind() == CK_ARCConsumeObject) {
          S.Diag(Loc, diag::warn_arc_retained_assign)
            << (LT == Qualifiers::OCL_ExplicitNone)
            << (isProperty ? 0 : 1)
            << RHS->getSourceRange();
          return true;
        }
        RHS = cast->getSubExpr();
      }
    
      if (LT == Qualifiers::OCL_Weak &&
          checkUnsafeAssignLiteral(S, Loc, RHS, isProperty))
        return true;
    
      return false;
    }
    
    bool Sema::checkUnsafeAssigns(SourceLocation Loc,
                                  QualType LHS, Expr *RHS) {
      Qualifiers::ObjCLifetime LT = LHS.getObjCLifetime();
    
      if (LT != Qualifiers::OCL_Weak && LT != Qualifiers::OCL_ExplicitNone)
        return false;
    
      if (checkUnsafeAssignObject(*this, Loc, LT, RHS, false))
        return true;
    
      return false;
    }
    
    void Sema::checkUnsafeExprAssigns(SourceLocation Loc,
                                  Expr *LHS, Expr *RHS) {
      QualType LHSType;
      // PropertyRef on LHS type need be directly obtained from
      // its declaration as it has a PseudoType.
      ObjCPropertyRefExpr *PRE
        = dyn_cast<ObjCPropertyRefExpr>(LHS->IgnoreParens());
      if (PRE && !PRE->isImplicitProperty()) {
        const ObjCPropertyDecl *PD = PRE->getExplicitProperty();
        if (PD)
          LHSType = PD->getType();
      }
      
      if (LHSType.isNull())
        LHSType = LHS->getType();
    
      Qualifiers::ObjCLifetime LT = LHSType.getObjCLifetime();
    
      if (LT == Qualifiers::OCL_Weak) {
        if (!Diags.isIgnored(diag::warn_arc_repeated_use_of_weak, Loc))
          getCurFunction()->markSafeWeakUse(LHS);
      }
    
      if (checkUnsafeAssigns(Loc, LHSType, RHS))
        return;
    
      // FIXME. Check for other life times.
      if (LT != Qualifiers::OCL_None)
        return;
      
      if (PRE) {
        if (PRE->isImplicitProperty())
          return;
        const ObjCPropertyDecl *PD = PRE->getExplicitProperty();
        if (!PD)
          return;
        
        unsigned Attributes = PD->getPropertyAttributes();
        if (Attributes & ObjCPropertyDecl::OBJC_PR_assign) {
          // when 'assign' attribute was not explicitly specified
          // by user, ignore it and rely on property type itself
          // for lifetime info.
          unsigned AsWrittenAttr = PD->getPropertyAttributesAsWritten();
          if (!(AsWrittenAttr & ObjCPropertyDecl::OBJC_PR_assign) &&
              LHSType->isObjCRetainableType())
            return;
            
          while (ImplicitCastExpr *cast = dyn_cast<ImplicitCastExpr>(RHS)) {
            if (cast->getCastKind() == CK_ARCConsumeObject) {
              Diag(Loc, diag::warn_arc_retained_property_assign)
              << RHS->getSourceRange();
              return;
            }
            RHS = cast->getSubExpr();
          }
        }
        else if (Attributes & ObjCPropertyDecl::OBJC_PR_weak) {
          if (checkUnsafeAssignObject(*this, Loc, Qualifiers::OCL_Weak, RHS, true))
            return;
        }
      }
    }
    
    //===--- CHECK: Empty statement body (-Wempty-body) ---------------------===//
    
    namespace {
    bool ShouldDiagnoseEmptyStmtBody(const SourceManager &SourceMgr,
                                     SourceLocation StmtLoc,
                                     const NullStmt *Body) {
      // Do not warn if the body is a macro that expands to nothing, e.g:
      //
      // #define CALL(x)
      // if (condition)
      //   CALL(0);
      //
      if (Body->hasLeadingEmptyMacro())
        return false;
    
      // Get line numbers of statement and body.
      bool StmtLineInvalid;
      unsigned StmtLine = SourceMgr.getPresumedLineNumber(StmtLoc,
                                                          &StmtLineInvalid);
      if (StmtLineInvalid)
        return false;
    
      bool BodyLineInvalid;
      unsigned BodyLine = SourceMgr.getSpellingLineNumber(Body->getSemiLoc(),
                                                          &BodyLineInvalid);
      if (BodyLineInvalid)
        return false;
    
      // Warn if null statement and body are on the same line.
      if (StmtLine != BodyLine)
        return false;
    
      return true;
    }
    } // end anonymous namespace
    
    void Sema::DiagnoseEmptyStmtBody(SourceLocation StmtLoc,
                                     const Stmt *Body,
                                     unsigned DiagID) {
      // Since this is a syntactic check, don't emit diagnostic for template
      // instantiations, this just adds noise.
      if (CurrentInstantiationScope)
        return;
    
      // The body should be a null statement.
      const NullStmt *NBody = dyn_cast<NullStmt>(Body);
      if (!NBody)
        return;
    
      // Do the usual checks.
      if (!ShouldDiagnoseEmptyStmtBody(SourceMgr, StmtLoc, NBody))
        return;
    
      Diag(NBody->getSemiLoc(), DiagID);
      Diag(NBody->getSemiLoc(), diag::note_empty_body_on_separate_line);
    }
    
    void Sema::DiagnoseEmptyLoopBody(const Stmt *S,
                                     const Stmt *PossibleBody) {
      assert(!CurrentInstantiationScope); // Ensured by caller
    
      SourceLocation StmtLoc;
      const Stmt *Body;
      unsigned DiagID;
      if (const ForStmt *FS = dyn_cast<ForStmt>(S)) {
        StmtLoc = FS->getRParenLoc();
        Body = FS->getBody();
        DiagID = diag::warn_empty_for_body;
      } else if (const WhileStmt *WS = dyn_cast<WhileStmt>(S)) {
        StmtLoc = WS->getCond()->getSourceRange().getEnd();
        Body = WS->getBody();
        DiagID = diag::warn_empty_while_body;
      } else
        return; // Neither `for' nor `while'.
    
      // The body should be a null statement.
      const NullStmt *NBody = dyn_cast<NullStmt>(Body);
      if (!NBody)
        return;
    
      // Skip expensive checks if diagnostic is disabled.
      if (Diags.isIgnored(DiagID, NBody->getSemiLoc()))
        return;
    
      // Do the usual checks.
      if (!ShouldDiagnoseEmptyStmtBody(SourceMgr, StmtLoc, NBody))
        return;
    
      // `for(...);' and `while(...);' are popular idioms, so in order to keep
      // noise level low, emit diagnostics only if for/while is followed by a
      // CompoundStmt, e.g.:
      //    for (int i = 0; i < n; i++);
      //    {
      //      a(i);
      //    }
      // or if for/while is followed by a statement with more indentation
      // than for/while itself:
      //    for (int i = 0; i < n; i++);
      //      a(i);
      bool ProbableTypo = isa<CompoundStmt>(PossibleBody);
      if (!ProbableTypo) {
        bool BodyColInvalid;
        unsigned BodyCol = SourceMgr.getPresumedColumnNumber(
                                 PossibleBody->getLocStart(),
                                 &BodyColInvalid);
        if (BodyColInvalid)
          return;
    
        bool StmtColInvalid;
        unsigned StmtCol = SourceMgr.getPresumedColumnNumber(
                                 S->getLocStart(),
                                 &StmtColInvalid);
        if (StmtColInvalid)
          return;
    
        if (BodyCol > StmtCol)
          ProbableTypo = true;
      }
    
      if (ProbableTypo) {
        Diag(NBody->getSemiLoc(), DiagID);
        Diag(NBody->getSemiLoc(), diag::note_empty_body_on_separate_line);
      }
    }
    
    //===--- CHECK: Warn on self move with std::move. -------------------------===//
    
    /// DiagnoseSelfMove - Emits a warning if a value is moved to itself.
    void Sema::DiagnoseSelfMove(const Expr *LHSExpr, const Expr *RHSExpr,
                                 SourceLocation OpLoc) {
      if (Diags.isIgnored(diag::warn_sizeof_pointer_expr_memaccess, OpLoc))
        return;
    
      if (!ActiveTemplateInstantiations.empty())
        return;
    
      // Strip parens and casts away.
      LHSExpr = LHSExpr->IgnoreParenImpCasts();
      RHSExpr = RHSExpr->IgnoreParenImpCasts();
    
      // Check for a call expression
      const CallExpr *CE = dyn_cast<CallExpr>(RHSExpr);
      if (!CE || CE->getNumArgs() != 1)
        return;
    
      // Check for a call to std::move
      const FunctionDecl *FD = CE->getDirectCallee();
      if (!FD || !FD->isInStdNamespace() || !FD->getIdentifier() ||
          !FD->getIdentifier()->isStr("move"))
        return;
    
      // Get argument from std::move
      RHSExpr = CE->getArg(0);
    
      const DeclRefExpr *LHSDeclRef = dyn_cast<DeclRefExpr>(LHSExpr);
      const DeclRefExpr *RHSDeclRef = dyn_cast<DeclRefExpr>(RHSExpr);
    
      // Two DeclRefExpr's, check that the decls are the same.
      if (LHSDeclRef && RHSDeclRef) {
        if (!LHSDeclRef->getDecl() || !RHSDeclRef->getDecl())
          return;
        if (LHSDeclRef->getDecl()->getCanonicalDecl() !=
            RHSDeclRef->getDecl()->getCanonicalDecl())
          return;
    
        Diag(OpLoc, diag::warn_self_move) << LHSExpr->getType()
                                            << LHSExpr->getSourceRange()
                                            << RHSExpr->getSourceRange();
        return;
      }
    
      // Member variables require a different approach to check for self moves.
      // MemberExpr's are the same if every nested MemberExpr refers to the same
      // Decl and that the base Expr's are DeclRefExpr's with the same Decl or
      // the base Expr's are CXXThisExpr's.
      const Expr *LHSBase = LHSExpr;
      const Expr *RHSBase = RHSExpr;
      const MemberExpr *LHSME = dyn_cast<MemberExpr>(LHSExpr);
      const MemberExpr *RHSME = dyn_cast<MemberExpr>(RHSExpr);
      if (!LHSME || !RHSME)
        return;
    
      while (LHSME && RHSME) {
        if (LHSME->getMemberDecl()->getCanonicalDecl() !=
            RHSME->getMemberDecl()->getCanonicalDecl())
          return;
    
        LHSBase = LHSME->getBase();
        RHSBase = RHSME->getBase();
        LHSME = dyn_cast<MemberExpr>(LHSBase);
        RHSME = dyn_cast<MemberExpr>(RHSBase);
      }
    
      LHSDeclRef = dyn_cast<DeclRefExpr>(LHSBase);
      RHSDeclRef = dyn_cast<DeclRefExpr>(RHSBase);
      if (LHSDeclRef && RHSDeclRef) {
        if (!LHSDeclRef->getDecl() || !RHSDeclRef->getDecl())
          return;
        if (LHSDeclRef->getDecl()->getCanonicalDecl() !=
            RHSDeclRef->getDecl()->getCanonicalDecl())
          return;
    
        Diag(OpLoc, diag::warn_self_move) << LHSExpr->getType()
                                            << LHSExpr->getSourceRange()
                                            << RHSExpr->getSourceRange();
        return;
      }
    
      if (isa<CXXThisExpr>(LHSBase) && isa<CXXThisExpr>(RHSBase))
        Diag(OpLoc, diag::warn_self_move) << LHSExpr->getType()
                                            << LHSExpr->getSourceRange()
                                            << RHSExpr->getSourceRange();
    }
    
    //===--- Layout compatibility ----------------------------------------------//
    
    namespace {
    
    bool isLayoutCompatible(ASTContext &C, QualType T1, QualType T2);
    
    /// \brief Check if two enumeration types are layout-compatible.
    bool isLayoutCompatible(ASTContext &C, EnumDecl *ED1, EnumDecl *ED2) {
      // C++11 [dcl.enum] p8:
      // Two enumeration types are layout-compatible if they have the same
      // underlying type.
      return ED1->isComplete() && ED2->isComplete() &&
             C.hasSameType(ED1->getIntegerType(), ED2->getIntegerType());
    }
    
    /// \brief Check if two fields are layout-compatible.
    bool isLayoutCompatible(ASTContext &C, FieldDecl *Field1, FieldDecl *Field2) {
      if (!isLayoutCompatible(C, Field1->getType(), Field2->getType()))
        return false;
    
      if (Field1->isBitField() != Field2->isBitField())
        return false;
    
      if (Field1->isBitField()) {
        // Make sure that the bit-fields are the same length.
        unsigned Bits1 = Field1->getBitWidthValue(C);
        unsigned Bits2 = Field2->getBitWidthValue(C);
    
        if (Bits1 != Bits2)
          return false;
      }
    
      return true;
    }
    
    /// \brief Check if two standard-layout structs are layout-compatible.
    /// (C++11 [class.mem] p17)
    bool isLayoutCompatibleStruct(ASTContext &C,
                                  RecordDecl *RD1,
                                  RecordDecl *RD2) {
      // If both records are C++ classes, check that base classes match.
      if (const CXXRecordDecl *D1CXX = dyn_cast<CXXRecordDecl>(RD1)) {
        // If one of records is a CXXRecordDecl we are in C++ mode,
        // thus the other one is a CXXRecordDecl, too.
        const CXXRecordDecl *D2CXX = cast<CXXRecordDecl>(RD2);
        // Check number of base classes.
        if (D1CXX->getNumBases() != D2CXX->getNumBases())
          return false;
    
        // Check the base classes.
        for (CXXRecordDecl::base_class_const_iterator
                   Base1 = D1CXX->bases_begin(),
               BaseEnd1 = D1CXX->bases_end(),
                  Base2 = D2CXX->bases_begin();
             Base1 != BaseEnd1;
             ++Base1, ++Base2) {
          if (!isLayoutCompatible(C, Base1->getType(), Base2->getType()))
            return false;
        }
      } else if (const CXXRecordDecl *D2CXX = dyn_cast<CXXRecordDecl>(RD2)) {
        // If only RD2 is a C++ class, it should have zero base classes.
        if (D2CXX->getNumBases() > 0)
          return false;
      }
    
      // Check the fields.
      RecordDecl::field_iterator Field2 = RD2->field_begin(),
                                 Field2End = RD2->field_end(),
                                 Field1 = RD1->field_begin(),
                                 Field1End = RD1->field_end();
      for ( ; Field1 != Field1End && Field2 != Field2End; ++Field1, ++Field2) {
        if (!isLayoutCompatible(C, *Field1, *Field2))
          return false;
      }
      if (Field1 != Field1End || Field2 != Field2End)
        return false;
    
      return true;
    }
    
    /// \brief Check if two standard-layout unions are layout-compatible.
    /// (C++11 [class.mem] p18)
    bool isLayoutCompatibleUnion(ASTContext &C,
                                 RecordDecl *RD1,
                                 RecordDecl *RD2) {
      llvm::SmallPtrSet<FieldDecl *, 8> UnmatchedFields;
      for (auto *Field2 : RD2->fields())
        UnmatchedFields.insert(Field2);
    
      for (auto *Field1 : RD1->fields()) {
        llvm::SmallPtrSet<FieldDecl *, 8>::iterator
            I = UnmatchedFields.begin(),
            E = UnmatchedFields.end();
    
        for ( ; I != E; ++I) {
          if (isLayoutCompatible(C, Field1, *I)) {
            bool Result = UnmatchedFields.erase(*I);
            (void) Result;
            assert(Result);
            break;
          }
        }
        if (I == E)
          return false;
      }
    
      return UnmatchedFields.empty();
    }
    
    bool isLayoutCompatible(ASTContext &C, RecordDecl *RD1, RecordDecl *RD2) {
      if (RD1->isUnion() != RD2->isUnion())
        return false;
    
      if (RD1->isUnion())
        return isLayoutCompatibleUnion(C, RD1, RD2);
      else
        return isLayoutCompatibleStruct(C, RD1, RD2);
    }
    
    /// \brief Check if two types are layout-compatible in C++11 sense.
    bool isLayoutCompatible(ASTContext &C, QualType T1, QualType T2) {
      if (T1.isNull() || T2.isNull())
        return false;
    
      // C++11 [basic.types] p11:
      // If two types T1 and T2 are the same type, then T1 and T2 are
      // layout-compatible types.
      if (C.hasSameType(T1, T2))
        return true;
    
      T1 = T1.getCanonicalType().getUnqualifiedType();
      T2 = T2.getCanonicalType().getUnqualifiedType();
    
      const Type::TypeClass TC1 = T1->getTypeClass();
      const Type::TypeClass TC2 = T2->getTypeClass();
    
      if (TC1 != TC2)
        return false;
    
      if (TC1 == Type::Enum) {
        return isLayoutCompatible(C,
                                  cast<EnumType>(T1)->getDecl(),
                                  cast<EnumType>(T2)->getDecl());
      } else if (TC1 == Type::Record) {
        if (!T1->isStandardLayoutType() || !T2->isStandardLayoutType())
          return false;
    
        return isLayoutCompatible(C,
                                  cast<RecordType>(T1)->getDecl(),
                                  cast<RecordType>(T2)->getDecl());
      }
    
      return false;
    }
    } // end anonymous namespace
    
    //===--- CHECK: pointer_with_type_tag attribute: datatypes should match ----//
    
    namespace {
    /// \brief Given a type tag expression find the type tag itself.
    ///
    /// \param TypeExpr Type tag expression, as it appears in user's code.
    ///
    /// \param VD Declaration of an identifier that appears in a type tag.
    ///
    /// \param MagicValue Type tag magic value.
    bool FindTypeTagExpr(const Expr *TypeExpr, const ASTContext &Ctx,
                         const ValueDecl **VD, uint64_t *MagicValue) {
      while(true) {
        if (!TypeExpr)
          return false;
    
        TypeExpr = TypeExpr->IgnoreParenImpCasts()->IgnoreParenCasts();
    
        switch (TypeExpr->getStmtClass()) {
        case Stmt::UnaryOperatorClass: {
          const UnaryOperator *UO = cast<UnaryOperator>(TypeExpr);
          if (UO->getOpcode() == UO_AddrOf || UO->getOpcode() == UO_Deref) {
            TypeExpr = UO->getSubExpr();
            continue;
          }
          return false;
        }
    
        case Stmt::DeclRefExprClass: {
          const DeclRefExpr *DRE = cast<DeclRefExpr>(TypeExpr);
          *VD = DRE->getDecl();
          return true;
        }
    
        case Stmt::IntegerLiteralClass: {
          const IntegerLiteral *IL = cast<IntegerLiteral>(TypeExpr);
          llvm::APInt MagicValueAPInt = IL->getValue();
          if (MagicValueAPInt.getActiveBits() <= 64) {
            *MagicValue = MagicValueAPInt.getZExtValue();
            return true;
          } else
            return false;
        }
    
        case Stmt::BinaryConditionalOperatorClass:
        case Stmt::ConditionalOperatorClass: {
          const AbstractConditionalOperator *ACO =
              cast<AbstractConditionalOperator>(TypeExpr);
          bool Result;
          if (ACO->getCond()->EvaluateAsBooleanCondition(Result, Ctx)) {
            if (Result)
              TypeExpr = ACO->getTrueExpr();
            else
              TypeExpr = ACO->getFalseExpr();
            continue;
          }
          return false;
        }
    
        case Stmt::BinaryOperatorClass: {
          const BinaryOperator *BO = cast<BinaryOperator>(TypeExpr);
          if (BO->getOpcode() == BO_Comma) {
            TypeExpr = BO->getRHS();
            continue;
          }
          return false;
        }
    
        default:
          return false;
        }
      }
    }
    
    /// \brief Retrieve the C type corresponding to type tag TypeExpr.
    ///
    /// \param TypeExpr Expression that specifies a type tag.
    ///
    /// \param MagicValues Registered magic values.
    ///
    /// \param FoundWrongKind Set to true if a type tag was found, but of a wrong
    ///        kind.
    ///
    /// \param TypeInfo Information about the corresponding C type.
    ///
    /// \returns true if the corresponding C type was found.
    bool GetMatchingCType(
            const IdentifierInfo *ArgumentKind,
            const Expr *TypeExpr, const ASTContext &Ctx,
            const llvm::DenseMap<Sema::TypeTagMagicValue,
                                 Sema::TypeTagData> *MagicValues,
            bool &FoundWrongKind,
            Sema::TypeTagData &TypeInfo) {
      FoundWrongKind = false;
    
      // Variable declaration that has type_tag_for_datatype attribute.
      const ValueDecl *VD = nullptr;
    
      uint64_t MagicValue;
    
      if (!FindTypeTagExpr(TypeExpr, Ctx, &VD, &MagicValue))
        return false;
    
      if (VD) {
        if (TypeTagForDatatypeAttr *I = VD->getAttr<TypeTagForDatatypeAttr>()) {
          if (I->getArgumentKind() != ArgumentKind) {
            FoundWrongKind = true;
            return false;
          }
          TypeInfo.Type = I->getMatchingCType();
          TypeInfo.LayoutCompatible = I->getLayoutCompatible();
          TypeInfo.MustBeNull = I->getMustBeNull();
          return true;
        }
        return false;
      }
    
      if (!MagicValues)
        return false;
    
      llvm::DenseMap<Sema::TypeTagMagicValue,
                     Sema::TypeTagData>::const_iterator I =
          MagicValues->find(std::make_pair(ArgumentKind, MagicValue));
      if (I == MagicValues->end())
        return false;
    
      TypeInfo = I->second;
      return true;
    }
    } // end anonymous namespace
    
    void Sema::RegisterTypeTagForDatatype(const IdentifierInfo *ArgumentKind,
                                          uint64_t MagicValue, QualType Type,
                                          bool LayoutCompatible,
                                          bool MustBeNull) {
      if (!TypeTagForDatatypeMagicValues)
        TypeTagForDatatypeMagicValues.reset(
            new llvm::DenseMap<TypeTagMagicValue, TypeTagData>);
    
      TypeTagMagicValue Magic(ArgumentKind, MagicValue);
      (*TypeTagForDatatypeMagicValues)[Magic] =
          TypeTagData(Type, LayoutCompatible, MustBeNull);
    }
    
    namespace {
    bool IsSameCharType(QualType T1, QualType T2) {
      const BuiltinType *BT1 = T1->getAs<BuiltinType>();
      if (!BT1)
        return false;
    
      const BuiltinType *BT2 = T2->getAs<BuiltinType>();
      if (!BT2)
        return false;
    
      BuiltinType::Kind T1Kind = BT1->getKind();
      BuiltinType::Kind T2Kind = BT2->getKind();
    
      return (T1Kind == BuiltinType::SChar  && T2Kind == BuiltinType::Char_S) ||
             (T1Kind == BuiltinType::UChar  && T2Kind == BuiltinType::Char_U) ||
             (T1Kind == BuiltinType::Char_U && T2Kind == BuiltinType::UChar) ||
             (T1Kind == BuiltinType::Char_S && T2Kind == BuiltinType::SChar);
    }
    } // end anonymous namespace
    
    void Sema::CheckArgumentWithTypeTag(const ArgumentWithTypeTagAttr *Attr,
                                        const Expr * const *ExprArgs) {
      const IdentifierInfo *ArgumentKind = Attr->getArgumentKind();
      bool IsPointerAttr = Attr->getIsPointer();
    
      const Expr *TypeTagExpr = ExprArgs[Attr->getTypeTagIdx()];
      bool FoundWrongKind;
      TypeTagData TypeInfo;
      if (!GetMatchingCType(ArgumentKind, TypeTagExpr, Context,
                            TypeTagForDatatypeMagicValues.get(),
                            FoundWrongKind, TypeInfo)) {
        if (FoundWrongKind)
          Diag(TypeTagExpr->getExprLoc(),
               diag::warn_type_tag_for_datatype_wrong_kind)
            << TypeTagExpr->getSourceRange();
        return;
      }
    
      const Expr *ArgumentExpr = ExprArgs[Attr->getArgumentIdx()];
      if (IsPointerAttr) {
        // Skip implicit cast of pointer to `void *' (as a function argument).
        if (const ImplicitCastExpr *ICE = dyn_cast<ImplicitCastExpr>(ArgumentExpr))
          if (ICE->getType()->isVoidPointerType() &&
              ICE->getCastKind() == CK_BitCast)
            ArgumentExpr = ICE->getSubExpr();
      }
      QualType ArgumentType = ArgumentExpr->getType();
    
      // Passing a `void*' pointer shouldn't trigger a warning.
      if (IsPointerAttr && ArgumentType->isVoidPointerType())
        return;
    
      if (TypeInfo.MustBeNull) {
        // Type tag with matching void type requires a null pointer.
        if (!ArgumentExpr->isNullPointerConstant(Context,
                                                 Expr::NPC_ValueDependentIsNotNull)) {
          Diag(ArgumentExpr->getExprLoc(),
               diag::warn_type_safety_null_pointer_required)
              << ArgumentKind->getName()
              << ArgumentExpr->getSourceRange()
              << TypeTagExpr->getSourceRange();
        }
        return;
      }
    
      QualType RequiredType = TypeInfo.Type;
      if (IsPointerAttr)
        RequiredType = Context.getPointerType(RequiredType);
    
      bool mismatch = false;
      if (!TypeInfo.LayoutCompatible) {
        mismatch = !Context.hasSameType(ArgumentType, RequiredType);
    
        // C++11 [basic.fundamental] p1:
        // Plain char, signed char, and unsigned char are three distinct types.
        //
        // But we treat plain `char' as equivalent to `signed char' or `unsigned
        // char' depending on the current char signedness mode.
        if (mismatch)
          if ((IsPointerAttr && IsSameCharType(ArgumentType->getPointeeType(),
                                               RequiredType->getPointeeType())) ||
              (!IsPointerAttr && IsSameCharType(ArgumentType, RequiredType)))
            mismatch = false;
      } else
        if (IsPointerAttr)
          mismatch = !isLayoutCompatible(Context,
                                         ArgumentType->getPointeeType(),
                                         RequiredType->getPointeeType());
        else
          mismatch = !isLayoutCompatible(Context, ArgumentType, RequiredType);
    
      if (mismatch)
        Diag(ArgumentExpr->getExprLoc(), diag::warn_type_safety_type_mismatch)
            << ArgumentType << ArgumentKind
            << TypeInfo.LayoutCompatible << RequiredType
            << ArgumentExpr->getSourceRange()
            << TypeTagExpr->getSourceRange();
    }
    
    void Sema::AddPotentialMisalignedMembers(Expr *E, RecordDecl *RD, ValueDecl *MD,
                                             CharUnits Alignment) {
      MisalignedMembers.emplace_back(E, RD, MD, Alignment);
    }
    
    void Sema::DiagnoseMisalignedMembers() {
      for (MisalignedMember &m : MisalignedMembers) {
        const NamedDecl *ND = m.RD;
        if (ND->getName().empty()) {
          if (const TypedefNameDecl *TD = m.RD->getTypedefNameForAnonDecl())
            ND = TD;
        }
        Diag(m.E->getLocStart(), diag::warn_taking_address_of_packed_member)
            << m.MD << ND << m.E->getSourceRange();
      }
      MisalignedMembers.clear();
    }
    
    void Sema::DiscardMisalignedMemberAddress(const Type *T, Expr *E) {
      E = E->IgnoreParens();
      if (!T->isPointerType() && !T->isIntegerType())
        return;
      if (isa<UnaryOperator>(E) &&
          cast<UnaryOperator>(E)->getOpcode() == UO_AddrOf) {
        auto *Op = cast<UnaryOperator>(E)->getSubExpr()->IgnoreParens();
        if (isa<MemberExpr>(Op)) {
          auto MA = std::find(MisalignedMembers.begin(), MisalignedMembers.end(),
                              MisalignedMember(Op));
          if (MA != MisalignedMembers.end() &&
              (T->isIntegerType() ||
               (T->isPointerType() &&
                Context.getTypeAlignInChars(T->getPointeeType()) <= MA->Alignment)))
            MisalignedMembers.erase(MA);
        }
      }
    }
    
    void Sema::RefersToMemberWithReducedAlignment(
        Expr *E,
        llvm::function_ref<void(Expr *, RecordDecl *, FieldDecl *, CharUnits)>
            Action) {
      const auto *ME = dyn_cast<MemberExpr>(E);
      if (!ME)
        return;
    
      // For a chain of MemberExpr like "a.b.c.d" this list
      // will keep FieldDecl's like [d, c, b].
      SmallVector<FieldDecl *, 4> ReverseMemberChain;
      const MemberExpr *TopME = nullptr;
      bool AnyIsPacked = false;
      do {
        QualType BaseType = ME->getBase()->getType();
        if (ME->isArrow())
          BaseType = BaseType->getPointeeType();
        RecordDecl *RD = BaseType->getAs<RecordType>()->getDecl();
    
        ValueDecl *MD = ME->getMemberDecl();
        auto *FD = dyn_cast<FieldDecl>(MD);
        // We do not care about non-data members.
        if (!FD || FD->isInvalidDecl())
          return;
    
        AnyIsPacked =
            AnyIsPacked || (RD->hasAttr<PackedAttr>() || MD->hasAttr<PackedAttr>());
        ReverseMemberChain.push_back(FD);
    
        TopME = ME;
        ME = dyn_cast<MemberExpr>(ME->getBase()->IgnoreParens());
      } while (ME);
      assert(TopME && "We did not compute a topmost MemberExpr!");
    
      // Not the scope of this diagnostic.
      if (!AnyIsPacked)
        return;
    
      const Expr *TopBase = TopME->getBase()->IgnoreParenImpCasts();
      const auto *DRE = dyn_cast<DeclRefExpr>(TopBase);
      // TODO: The innermost base of the member expression may be too complicated.
      // For now, just disregard these cases. This is left for future
      // improvement.
      if (!DRE && !isa<CXXThisExpr>(TopBase))
          return;
    
      // Alignment expected by the whole expression.
      CharUnits ExpectedAlignment = Context.getTypeAlignInChars(E->getType());
    
      // No need to do anything else with this case.
      if (ExpectedAlignment.isOne())
        return;
    
      // Synthesize offset of the whole access.
      CharUnits Offset;
      for (auto I = ReverseMemberChain.rbegin(); I != ReverseMemberChain.rend();
           I++) {
        Offset += Context.toCharUnitsFromBits(Context.getFieldOffset(*I));
      }
    
      // Compute the CompleteObjectAlignment as the alignment of the whole chain.
      CharUnits CompleteObjectAlignment = Context.getTypeAlignInChars(
          ReverseMemberChain.back()->getParent()->getTypeForDecl());
    
      // The base expression of the innermost MemberExpr may give
      // stronger guarantees than the class containing the member.
      if (DRE && !TopME->isArrow()) {
        const ValueDecl *VD = DRE->getDecl();
        if (!VD->getType()->isReferenceType())
          CompleteObjectAlignment =
              std::max(CompleteObjectAlignment, Context.getDeclAlign(VD));
      }
    
      // Check if the synthesized offset fulfills the alignment.
      if (Offset % ExpectedAlignment != 0 ||
          // It may fulfill the offset it but the effective alignment may still be
          // lower than the expected expression alignment.
          CompleteObjectAlignment < ExpectedAlignment) {
        // If this happens, we want to determine a sensible culprit of this.
        // Intuitively, watching the chain of member expressions from right to
        // left, we start with the required alignment (as required by the field
        // type) but some packed attribute in that chain has reduced the alignment.
        // It may happen that another packed structure increases it again. But if
        // we are here such increase has not been enough. So pointing the first
        // FieldDecl that either is packed or else its RecordDecl is,
        // seems reasonable.
        FieldDecl *FD = nullptr;
        CharUnits Alignment;
        for (FieldDecl *FDI : ReverseMemberChain) {
          if (FDI->hasAttr<PackedAttr>() ||
              FDI->getParent()->hasAttr<PackedAttr>()) {
            FD = FDI;
            Alignment = std::min(
                Context.getTypeAlignInChars(FD->getType()),
                Context.getTypeAlignInChars(FD->getParent()->getTypeForDecl()));
            break;
          }
        }
        assert(FD && "We did not find a packed FieldDecl!");
        Action(E, FD->getParent(), FD, Alignment);
      }
    }
    
    void Sema::CheckAddressOfPackedMember(Expr *rhs) {
      using namespace std::placeholders;
      RefersToMemberWithReducedAlignment(
          rhs, std::bind(&Sema::AddPotentialMisalignedMembers, std::ref(*this), _1,
                         _2, _3, _4));
    }