ELF: store metadata in named metadata section

src/clang-hash.cc

@@ -2,6 +2,8 @@
 #include "clang/AST/ASTConsumer.h"
 #include "clang/Frontend/CompilerInstance.h"
 #include "clang/Frontend/FrontendPluginRegistry.h"
+#include "clang/CodeGen/CodeGenAction.h"
+
 #include "llvm/Support/raw_ostream.h"
 
 #include "hash-visitor.h"
@@ -15,9 +17,8 @@ public:
     HashTranslationUnitConsumer(raw_ostream *OS) : toplevel_hash_stream(OS) {}
 
     virtual void HandleTranslationUnit(clang::ASTContext &Context) {
-        // Traversing the translation unit decl via a RecursiveASTVisitor
-        // will visit all nodes in the AST.
-        Visitor.hashDecl(Context.getTranslationUnitDecl());
+        TranslationUnitDecl *TU = Context.getTranslationUnitDecl();
+        Visitor.hashDecl(TU);
 
         // Context.getTranslationUnitDecl()->dump();
         unsigned processed_bytes;
@@ -30,6 +31,14 @@ public:
         llvm::errs() << "top-level-hash: " << hash << "\n";
         llvm::errs() << "processed bytes: " << processed_bytes << "\n";
 
+        StringRef val[2] = {"clang.asthash", hash};
+        TU->addAttr(NamedMetadataStringAttr::CreateImplicit(Context,
+                                                            "llvm.extra_sections", val, 2));
+
+        StringRef val2[2] = {"foo", hash};
+        TU->addAttr(NamedMetadataStringAttr::CreateImplicit(Context,
+                                                            "llvm.extra_sections", val2, 2));
+
     }
 private:
     raw_ostream *toplevel_hash_stream;
@@ -37,9 +46,11 @@ private:
 };
 
 class HashTranslationUnitAction : public PluginASTAction {
+    CompilerInstance *CI;
 protected:
     std::unique_ptr<ASTConsumer> CreateASTConsumer(CompilerInstance &CI,
                                                    llvm::StringRef) override {
+        this->CI = &CI;
 
         // Write hash database to .o.hash if the compiler produces a object file
         llvm::raw_ostream *Out = nullptr;