[PATCH] D69825: [Clang][Driver] Re-use the calling process instead of creating a new process for the cc1 invocation

[Dimitry Andric via Phabricator via llvm-commits]

dim added a comment.

In D69825#2070926 <https://reviews.llvm.org/D69825#2070926>, @hans wrote:

> In D69825#2063979 <https://reviews.llvm.org/D69825#2063979>, @dim wrote:
>
> > FWIW, this change causes https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=246630, see in particular https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=246630#c18.
> >
> > For some reason, not spawning a new process for the cc1 stage can lead to non-reproducible output. The exact cause is not known yet.
>
>
> Can you share the preprocessed source and compiler command-line for printf.c, either on the bug or here?


See https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=246630#c26, and I've also uploaded the repro files to https://www.andric.com/freebsd/clang/bug246630-repro.tar.xz.

Running rGa3220dffcb1 <https://reviews.llvm.org/rGa3220dffcb1da0cfe3e22a336141c76c78d474b7> under valgrind (on Linux) shows:

  ==120363== Conditional jump or move depends on uninitialised value(s)
  ==120363==    at 0x1634474: llvm::ConstantExpr::getGetElementPtr(llvm::Type*, llvm::Constant*, llvm::ArrayRef<llvm::Value*>, bool, llvm::Optional<unsigned int>, llvm::Type*) (Constants.cpp:2191)
  ==120363==    by 0x112D6D9: getGetElementPtr (Constants.h:1163)
  ==120363==    by 0x112D6D9: (anonymous namespace)::SymbolicallyEvaluateGEP(llvm::GEPOperator const*, llvm::ArrayRef<llvm::Constant*>, llvm::DataLayout const&, llvm::TargetLibraryInfo const*) (ConstantFolding.cpp:1005)
  ==120363==    by 0x112DF70: (anonymous namespace)::ConstantFoldInstOperandsImpl(llvm::Value const*, unsigned int, llvm::ArrayRef<llvm::Constant*>, llvm::DataLayout const&, llvm::TargetLibraryInfo const*) (ConstantFolding.cpp:1039)
  ==120363==    by 0x112C165: (anonymous namespace)::ConstantFoldConstantImpl(llvm::Constant const*, llvm::DataLayout const&, llvm::TargetLibraryInfo const*, llvm::SmallDenseMap<llvm::Constant*, llvm::Constant*, 4u, llvm::DenseMapInfo<llvm::Constant*>, llvm::detail::DenseMapPair<llvm::Constant*, llvm::Constant*> >&) [clone .part.0] (ConstantFolding.cpp:1114)
  ==120363==    by 0x112C5CF: llvm::ConstantFoldConstant(llvm::Constant const*, llvm::DataLayout const&, llvm::TargetLibraryInfo const*) (ConstantFolding.cpp:1194)
  ==120363==    by 0x188F410: prepareICWorklistFromFunction (InstructionCombining.cpp:3584)
  ==120363==    by 0x188F410: combineInstructionsOverFunction(llvm::Function&, llvm::InstCombineWorklist&, llvm::AAResults*, llvm::AssumptionCache&, llvm::TargetLibraryInfo&, llvm::DominatorTree&, llvm::OptimizationRemarkEmitter&, llvm::BlockFrequencyInfo*, llvm::ProfileSummaryInfo*, unsigned int, llvm::LoopInfo*) (InstructionCombining.cpp:3703)
  ==120363==    by 0x189205F: runOnFunction (InstructionCombining.cpp:3789)
  ==120363==    by 0x189205F: llvm::InstructionCombiningPass::runOnFunction(llvm::Function&) (InstructionCombining.cpp:3768)
  ==120363==    by 0x16F4352: llvm::FPPassManager::runOnFunction(llvm::Function&) (LegacyPassManager.cpp:1482)
  ==120363==    by 0x16F4DE8: llvm::FPPassManager::runOnModule(llvm::Module&) (LegacyPassManager.cpp:1518)
  ==120363==    by 0x16F51A2: runOnModule (LegacyPassManager.cpp:1583)
  ==120363==    by 0x16F51A2: llvm::legacy::PassManagerImpl::run(llvm::Module&) (LegacyPassManager.cpp:1695)
  ==120363==    by 0x1FF4CFE: EmitAssembly (BackendUtil.cpp:954)
  ==120363==    by 0x1FF4CFE: clang::EmitBackendOutput(clang::DiagnosticsEngine&, clang::HeaderSearchOptions const&, clang::CodeGenOptions const&, clang::TargetOptions const&, clang::LangOptions const&, llvm::DataLayout const&, llvm::Module*, clang::BackendAction, std::unique_ptr<llvm::raw_pwrite_stream, std::default_delete<llvm::raw_pwrite_stream> >) (BackendUtil.cpp:1677)
  ==120363==    by 0x2C471A8: clang::BackendConsumer::HandleTranslationUnit(clang::ASTContext&) (CodeGenAction.cpp:335)
  ==120363==  Uninitialised value was created by a stack allocation
  ==120363==    at 0x112C653: (anonymous namespace)::SymbolicallyEvaluateGEP(llvm::GEPOperator const*, llvm::ArrayRef<llvm::Constant*>, llvm::DataLayout const&, llvm::TargetLibraryInfo const*) (ConstantFolding.cpp:832)

Trying to reduce this now.


Repository:
  rG LLVM Github Monorepo

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