Author: Alexandre Ganea Date: 2024-08-10T16:26:10-04:00 New Revision: 2ba1cc8ea53cd76fbeac79dad837dcae32cc7e59
URL: https://github.com/llvm/llvm-project/commit/2ba1cc8ea53cd76fbeac79dad837dcae32cc7e59 DIFF: https://github.com/llvm/llvm-project/commit/2ba1cc8ea53cd76fbeac79dad837dcae32cc7e59.diff LOG: [Clang][CodeGen] Fix bad codegen when building Clang with latest MSVC (#102681) Before this PR, when using the latest MSVC `Microsoft (R) C/C++ Optimizing Compiler Version 19.40.33813 for x64` one of the Clang unit test used to fail: `CodeGenObjC/gnustep2-direct-method.m`, see full failure log: [here](https://github.com/llvm/llvm-project/pull/100517#issuecomment-2266269490). This PR temporarily shuffles around the code to make the MSVC inliner/ optimizer happy and avoid the bug. MSVC bug report: https://developercommunity.visualstudio.com/t/Bad-code-generation-when-building-LLVM-w/10719589?port=1025&fsid=e572244a-cde7-4d75-a73d-9b8cd94204dd Added: Modified: clang/lib/CodeGen/CGObjCGNU.cpp Removed: ################################################################################ diff --git a/clang/lib/CodeGen/CGObjCGNU.cpp b/clang/lib/CodeGen/CGObjCGNU.cpp index 948b10954ebbe..ca5804018227e 100644 --- a/clang/lib/CodeGen/CGObjCGNU.cpp +++ b/clang/lib/CodeGen/CGObjCGNU.cpp @@ -2092,10 +2092,15 @@ class CGObjCGNUstep2 : public CGObjCGNUstep { auto *classStart = llvm::StructType::get(PtrTy, PtrTy, PtrTy, LongTy, LongTy); auto &astContext = CGM.getContext(); - auto flags = Builder.CreateLoad( - Address{Builder.CreateStructGEP(classStart, selfValue, 4), LongTy, - CharUnits::fromQuantity( - astContext.getTypeAlign(astContext.UnsignedLongTy))}); + // FIXME: The following few lines up to and including the call to + // `CreateLoad` were known to miscompile when MSVC 19.40.33813 is used + // to build Clang. When the bug is fixed in future MSVC releases, we + // should revert these lines to their previous state. See discussion in + // https://github.com/llvm/llvm-project/pull/102681 + llvm::Value *Val = Builder.CreateStructGEP(classStart, selfValue, 4); + auto Align = CharUnits::fromQuantity( + astContext.getTypeAlign(astContext.UnsignedLongTy)); + auto flags = Builder.CreateLoad(Address{Val, LongTy, Align}); auto isInitialized = Builder.CreateAnd(flags, ClassFlags::ClassFlagInitialized); llvm::BasicBlock *notInitializedBlock = _______________________________________________ cfe-commits mailing list cfe-commits@lists.llvm.org https://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-commits
