Hi Steven, I think there was a mistake when picking this linkage. The appending linkage is really just for things that llvm itself special cases. By an historical artifact it was codegened just like external.
The attached patch changes it to external linkage. I tested that the produced .o file is bit by bit identical with this change. But I have to ask, what is the intended use? I was under the impression that the idea was to allow multiple .o files to have their IR embedded and have the liker concatenate them. Currently, with or without this patch, I expect you to get a duplicated symbol error. To implement the above the symbol should be internal end the GV added to llvm.used. Cheers, Rafael
diff --git a/lib/CodeGen/BackendUtil.cpp b/lib/CodeGen/BackendUtil.cpp index bffa621..4f0a3ca 100644 --- a/lib/CodeGen/BackendUtil.cpp +++ b/lib/CodeGen/BackendUtil.cpp @@ -820,9 +820,8 @@ void clang::EmbedBitcode(llvm::Module *M, const CodeGenOptions &CGOpts, } llvm::Constant *ModuleConstant = llvm::ConstantDataArray::get(M->getContext(), ModuleData); - // Use Appending linkage so it doesn't get optimized out. llvm::GlobalVariable *GV = new llvm::GlobalVariable( - *M, ModuleConstant->getType(), true, llvm::GlobalValue::AppendingLinkage, + *M, ModuleConstant->getType(), true, llvm::GlobalValue::ExternalLinkage, ModuleConstant); GV->setSection(getSectionNameForBitcode(T)); if (llvm::GlobalVariable *Old =
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