Ok, I dug into this deeper. ASTContext.cpp:2811 (getVariableArrayDecayedType) intentionaly sets size to nullptr in this case for the purpose of turning it into a [*] type. OpenMP.cpp:236 (CodeGenFunction::GenerateOpenMPCapturedStmtFunction) calls this to replace variably modified type with this one. It definitely looks like this is on purpose as far as I can tell.
From: Keane, Erich Sent: Friday, October 7, 2016 11:56 AM To: 'David Blaikie' <dblai...@gmail.com>; reviews+d25373+public+d8ec2a4bb41b1...@reviews.llvm.org; cfe-commits@lists.llvm.org; david.majne...@gmail.com; 'Alexey Bataev' <a.bat...@hotmail.com> Cc: junb...@codeaurora.org Subject: RE: [PATCH] D25373: Fix for Bug 30639: CGDebugInfo Null dereference with OpenMP array access Added Alexey to the list, he’s the OMP Maintainer, so hopefully he knows better ☺ From: David Blaikie [mailto:dblai...@gmail.com] Sent: Friday, October 7, 2016 11:51 AM To: reviews+d25373+public+d8ec2a4bb41b1...@reviews.llvm.org<mailto:reviews+d25373+public+d8ec2a4bb41b1...@reviews.llvm.org>; Keane, Erich <erich.ke...@intel.com<mailto:erich.ke...@intel.com>>; cfe-commits@lists.llvm.org<mailto:cfe-commits@lists.llvm.org>; david.majne...@gmail.com<mailto:david.majne...@gmail.com>; guy.ben...@intel.com<mailto:guy.ben...@intel.com> Cc: junb...@codeaurora.org<mailto:junb...@codeaurora.org> Subject: Re: [PATCH] D25373: Fix for Bug 30639: CGDebugInfo Null dereference with OpenMP array access Could you explain how/why there's a null size expr? I would've thought it must have /some/ size for code generation purposes... On Fri, Oct 7, 2016 at 11:33 AM Erich Keane <erich.ke...@intel.com<mailto:erich.ke...@intel.com>> wrote: erichkeane created this revision. erichkeane added reviewers: cfe-commits, dblaikie, majnemer, gbenyei. erichkeane set the repository for this revision to rL LLVM. OpenMP creates a variable array type with a a null size-expr. The Debug generation failed to properly consider this case. This patch adds a null check to prevent a null dereference seg-fault in this case, plus adds a test. Repository: rL LLVM https://reviews.llvm.org/D25373 Files: lib/CodeGen/CGDebugInfo.cpp test/CodeGenCXX/debug-info-openmp-array.cpp Index: lib/CodeGen/CGDebugInfo.cpp =================================================================== --- lib/CodeGen/CGDebugInfo.cpp +++ lib/CodeGen/CGDebugInfo.cpp @@ -2181,7 +2181,8 @@ Count = CAT->getSize().getZExtValue(); else if (const auto *VAT = dyn_cast<VariableArrayType>(Ty)) { llvm::APSInt V; - if (VAT->getSizeExpr()->EvaluateAsInt(V, CGM.getContext())) + if (VAT->getSizeExpr() && + VAT->getSizeExpr()->EvaluateAsInt(V, CGM.getContext())) Count = V.getExtValue(); } Index: test/CodeGenCXX/debug-info-openmp-array.cpp =================================================================== --- test/CodeGenCXX/debug-info-openmp-array.cpp +++ test/CodeGenCXX/debug-info-openmp-array.cpp @@ -0,0 +1,17 @@ +// RUN: %clang -target x86_64-unknown-unknown -fverbose-asm -fopenmp -g -O0 -S -emit-llvm %s -o - | FileCheck %s + + +void f(int m) { + int i; + int cen[m]; +#pragma omp parallel for + for (i = 0; i < m; ++i) { + cen[i] = i; + } +} + +// CHECK: !DICompositeType(tag: DW_TAG_array_type, +// CHECK-NOT: size: +// CHECK-SAME: align: 32 +// CHECK-SAME: elements: [[ELEM_TYPE:![0-9]+]] +// CHECK: !DISubrange(count: -1)
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