[PATCH] C99 partial re-initialization behavior (DR-253)
David Blaikie
dblaikie at gmail.com
Wed May 27 18:13:19 PDT 2015
Yeah, I can reproduce that. I can't say if this is something that could be
triggered without the source change. I don't know that much about this code.
I've been taking a fairly casual approach to this migration, because I just
can't actually dig into every line of code/use of pointee types. So if the
assertions ever do fire on valid code, I or someone will certainly have to
look into them, but I haven't done that work up front, generally.
On Wed, May 27, 2015 at 3:45 PM, Gao, Yunzhong <
yunzhong_gao at playstation.sony.com> wrote:
> Ah, sorry I did not provide more context before pulling you in.
>
> The assertion is related to GetElementPointer and I thought you may have
> worked on this recently;
> also there was no assertion before your r234096+r234097. I am not sure if
> the assertion indicates
> a real problem here because I had to modify the compiler source to show
> the problem. You probably
> know better.
>
>
> [Step#1] apply the following patch: it comments out an optimization.
>
> Index: llvm/tools/clang/lib/CodeGen/CGExprCXX.cpp
> ===================================================================
> --- llvm/tools/clang/lib/CodeGen/CGExprCXX.cpp (revision 238351)
> +++ llvm/tools/clang/lib/CodeGen/CGExprCXX.cpp (working copy)
> @@ -953,10 +953,12 @@
> assert(getContext().hasSameUnqualifiedType(ElementType,
> Init->getType()) &&
> "got wrong type of element to initialize");
>
> +#if 0
> // If we have an empty initializer list, we can usually use memset.
> if (auto *ILE = dyn_cast<InitListExpr>(Init))
> if (ILE->getNumInits() == 0 && TryMemsetInitialization())
> return;
> +#endif
>
> // Create the loop blocks.
> llvm::BasicBlock *EntryBB = Builder.GetInsertBlock();
>
>
> [Step#2] Compile the following test case:
>
> // test.cpp
> int n;
> struct T { int a; };
> void *r = new T[n][3]{ { 1, 2, 3 }, { 4, 5, 6 } };
>
>
> $ build/Debug+Asserts/bin/clang -S -std=c++11 -emit-llvm -o - test.cpp
> clang: llvm/include/llvm/IR/Instructions.h:842: static
> llvm::GetElementPtrInst* llvm::GetElementPtrInst::Create(llvm::Type*,
> llvm::Value*, llvm::ArrayRef<llvm::Value*>, const llvm::Twine&,
> llvm::Instruction*): Assertion `PointeeType ==
> cast<PointerType>(Ptr->getType()->getScalarType())->getElementType()'
> failed.
> 0 clang 0x00000000046113de
> llvm::sys::PrintStackTrace(llvm::raw_ostream&) + 44
> 1 clang 0x00000000046116f3
> 2 clang 0x00000000046101f4
> 3 libpthread.so.0 0x00007fedccedf340
> 4 libc.so.6 0x00007fedcc11bf79 gsignal + 57
> 5 libc.so.6 0x00007fedcc11f388 abort + 328
> 6 libc.so.6 0x00007fedcc114e36
> 7 libc.so.6 0x00007fedcc114ee2
> 8 clang 0x00000000017077ff
> 9 clang 0x00000000017078af
> 10 clang 0x0000000001764c8c
> 11 clang 0x00000000018f5662
> clang::CodeGen::CodeGenFunction::EmitNewArrayInitializer(clang::CXXNewExpr
> const*, clang::QualType, llvm::Type*, llvm::Value*, llvm::Value*,
> llvm::Value*) + 3100
> 12 clang 0x00000000018f57a6
> 13 clang 0x00000000018f6d60
> clang::CodeGen::CodeGenFunction::EmitCXXNewExpr(clang::CXXNewExpr const*) +
> 1950
> 14 clang 0x000000000190489c
> 15 clang 0x00000000019154af
> 16 clang 0x00000000019038d2
> 17 clang 0x00000000019095ba
> 18 clang 0x0000000001917257
> 19 clang 0x00000000019156d7
> 20 clang 0x00000000019038d2
> 21 clang 0x00000000019141b2
> clang::CodeGen::CodeGenFunction::EmitScalarExpr(clang::Expr const*, bool) +
> 128
> 22 clang 0x00000000018b2e75
> clang::CodeGen::CodeGenFunction::EmitScalarInit(clang::Expr const*,
> clang::ValueDecl const*, clang::CodeGen::LValue, bool) + 99
> 23 clang 0x00000000018bb9b2
> 24 clang 0x00000000018bc0b7
> clang::CodeGen::CodeGenFunction::EmitCXXGlobalVarDeclInit(clang::VarDecl
> const&, llvm::Constant*, bool) + 437
> 25 clang 0x00000000018bdd1f
> clang::CodeGen::CodeGenFunction::GenerateCXXGlobalVarDeclInitFunc(llvm::Function*,
> clang::VarDecl const*, llvm::GlobalVariable*, bool) + 501
> 26 clang 0x00000000018bcda1
> clang::CodeGen::CodeGenModule::EmitCXXGlobalVarDeclInitFunc(clang::VarDecl
> const*, llvm::GlobalVariable*, bool) + 615
> 27 clang 0x0000000001774193
> clang::CodeGen::CodeGenModule::EmitGlobalVarDefinition(clang::VarDecl
> const*) + 2291
> 28 clang 0x000000000177216f
> clang::CodeGen::CodeGenModule::EmitGlobalDefinition(clang::GlobalDecl,
> llvm::GlobalValue*) + 531
> 29 clang 0x00000000017719ca
> clang::CodeGen::CodeGenModule::EmitGlobal(clang::GlobalDecl) + 796
> 30 clang 0x00000000017792a2
> clang::CodeGen::CodeGenModule::EmitTopLevelDecl(clang::Decl*) + 438
> 31 clang 0x00000000016c6215
> 32 clang 0x00000000016aabb6
> 33 clang 0x00000000019ac057 clang::ParseAST(clang::Sema&, bool,
> bool) + 553
> 34 clang 0x00000000013a8fe2
> clang::ASTFrontendAction::ExecuteAction() + 322
> 35 clang 0x00000000016ad592
> clang::CodeGenAction::ExecuteAction() + 1486
> 36 clang 0x00000000013a8ac1 clang::FrontendAction::Execute() +
> 139
> 37 clang 0x000000000136c902
> clang::CompilerInstance::ExecuteAction(clang::FrontendAction&) + 772
> 38 clang 0x000000000132dadb
> clang::ExecuteCompilerInvocation(clang::CompilerInstance*) + 993
> 39 clang 0x0000000001318d68 cc1_main(llvm::ArrayRef<char
> const*>, char const*, void*) + 770
> 40 clang 0x0000000001327500
> 41 clang 0x0000000001327ae7 main + 1074
> 42 libc.so.6 0x00007fedcc106ec5 __libc_start_main + 245
> 43 clang 0x0000000001317469
> Stack dump:
> 0. Program arguments: build/Debug+Asserts/bin/clang -cc1 -triple
> x86_64-unknown-linux-gnu -emit-llvm -disable-free -main-file-name test.cpp
> -mrelocation-model static -mthread-model posix -mdisable-fp-elim
> -fmath-errno -masm-verbose -mconstructor-aliases -munwind-tables
> -fuse-init-array -target-cpu x86-64 -target-linker-version 2.24
> -dwarf-column-info -coverage-file /tmp/- -resource-dir
> build/Debug+Asserts/bin/../lib/clang/3.7.0 -internal-isystem
> /usr/lib/gcc/x86_64-linux-gnu/4.8/../../../../include/c++/4.8
> -internal-isystem
> /usr/lib/gcc/x86_64-linux-gnu/4.8/../../../../include/x86_64-linux-gnu/c++/4.8
> -internal-isystem
> /usr/lib/gcc/x86_64-linux-gnu/4.8/../../../../include/x86_64-linux-gnu/c++/4.8
> -internal-isystem
> /usr/lib/gcc/x86_64-linux-gnu/4.8/../../../../include/c++/4.8/backward
> -internal-isystem /usr/local/include -internal-isystem
> build/Debug+Asserts/bin/../lib/clang/3.7.0/include
> -internal-externc-isystem /usr/include/x86_64-linux-gnu
> -internal-externc-isystem /include -internal-externc-isystem /usr/include
> -std=c++11 -fdeprecated-macro -fdebug-compilation-dir /tmp -ferror-limit 19
> -fmessage-length 205 -mstackrealign -fobjc-runtime=gcc -fcxx-exceptions
> -fexceptions -fdiagnostics-show-option -o - -x c++ test.cpp
> 1. <eof> parser at end of file
> 2. test.cpp:4:7: LLVM IR generation of declaration 'r'
> 3. test.cpp:4:7: Generating code for declaration 'r'
> clang: error: unable to execute command: Aborted (core dumped)
> clang: error: clang frontend command failed due to signal (use -v to see
> invocation)
> clang version 3.7.0 (trunk 238351)
> Target: x86_64-unknown-linux-gnu
> Thread model: posix
> clang: note: diagnostic msg: PLEASE submit a bug report to
> http://llvm.org/bugs/ and include the crash backtrace, preprocessed
> source, and associated run script.
> clang: note: diagnostic msg:
> ********************
>
> PLEASE ATTACH THE FOLLOWING FILES TO THE BUG REPORT:
> Preprocessed source(s) and associated run script(s) are located at:
> clang: note: diagnostic msg: /tmp/test-d13456.cpp
> clang: note: diagnostic msg: /tmp/test-d13456.sh
> clang: note: diagnostic msg:
>
>
> ________________________________________
> From: David Blaikie [dblaikie at gmail.com]
> Sent: Wednesday, May 27, 2015 3:26 PM
> To: reviews+D5789+public+1cf6f6f096f4f610 at reviews.llvm.org
> Cc: Gao, Yunzhong; Richard Smith; dccitaliano at gmail.com; Robinson, Paul;
> arthur.j.odwyer+phab+github at gmail.com; Anton Korobeynikov; llvm cfe
> Subject: Re: [PATCH] C99 partial re-initialization behavior (DR-253)
>
> On Wed, May 27, 2015 at 1:34 PM, Yunzhong Gao <
> Yunzhong_Gao at playstation.sony.com<mailto:Yunzhong_Gao at playstation.sony.com>>
> wrote:
> Ping.
>
> Also add David Blaikie. He might have some insight on whether
> lib/CodeGen/CGExprCXX.cpp#952-953 indicates any actual problem.
>
> Don't think I have any particular light to shed here... if you/we want to
> dive into this deeper, the backtrace from the assertion might be useful.
>
> http://reviews.llvm.org/D5789?id=22530#inline-76127
>
>
> http://reviews.llvm.org/D5789
>
> EMAIL PREFERENCES
> http://reviews.llvm.org/settings/panel/emailpreferences/
>
>
>
>
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