[llvm] r311217 - Filter out non-constant DIGlobalVariableExpressions reachable via the CU

[David Blaikie via llvm-commits]

On Fri., 18 Aug. 2017, 6:16 pm Adrian Prantl via llvm-commits <
llvm-commits at lists.llvm.org> wrote:

> Author: adrian
> Date: Fri Aug 18 18:15:06 2017
> New Revision: 311217
>
> URL: http://llvm.org/viewvc/llvm-project?rev=311217&view=rev
> Log:
> Filter out non-constant DIGlobalVariableExpressions reachable via the CU
>
> They won't affect the DWARF output, but they will mess with the
> sorting of the fragments. This fixes the crash reported in PR34159.
>
> https://bugs.llvm.org/show_bug.cgi?id=34159
>
> Modified:
>     llvm/trunk/lib/CodeGen/AsmPrinter/DwarfDebug.cpp
>     llvm/trunk/test/DebugInfo/X86/split-global.ll
>
> Modified: llvm/trunk/lib/CodeGen/AsmPrinter/DwarfDebug.cpp
> URL:
> http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/CodeGen/AsmPrinter/DwarfDebug.cpp?rev=311217&r1=311216&r2=311217&view=diff
>
> ==============================================================================
> --- llvm/trunk/lib/CodeGen/AsmPrinter/DwarfDebug.cpp (original)
> +++ llvm/trunk/lib/CodeGen/AsmPrinter/DwarfDebug.cpp Fri Aug 18 18:15:06
> 2017
> @@ -592,8 +592,15 @@ void DwarfDebug::beginModule() {
>      DwarfCompileUnit &CU = getOrCreateDwarfCompileUnit(CUNode);
>
>      // Global Variables.
> -    for (auto *GVE : CUNode->getGlobalVariables())
> -      GVMap[GVE->getVariable()].push_back({nullptr,
> GVE->getExpression()});
> +    for (auto *GVE : CUNode->getGlobalVariables()) {
> +      // Don't bother adding DIGlobalVariableExpressions listed in the CU
> if we
> +      // already know about the variable and it isn't adding a constant
> +      // expression.
> +      auto &GVMapEntry = GVMap[GVE->getVariable()];
> +      auto *Expr = GVE->getExpression();
> +      if (!GVMapEntry.size() || (Expr && Expr->isConstant()))
> +        GVMapEntry.push_back({nullptr, Expr});
> +    }
>      DenseSet<DIGlobalVariable *> Processed;
>      for (auto *GVE : CUNode->getGlobalVariables()) {
>        DIGlobalVariable *GV = GVE->getVariable();
>
> Modified: llvm/trunk/test/DebugInfo/X86/split-global.ll
> URL:
> http://llvm.org/viewvc/llvm-project/llvm/trunk/test/DebugInfo/X86/split-global.ll?rev=311217&r1=311216&r2=311217&view=diff
>
> ==============================================================================
> --- llvm/trunk/test/DebugInfo/X86/split-global.ll (original)
> +++ llvm/trunk/test/DebugInfo/X86/split-global.ll Fri Aug 18 18:15:06 2017
> @@ -39,7 +39,7 @@ target triple = "x86_64-apple-macosx10.1
>  !1 = distinct !DICompileUnit(language: DW_LANG_C99, file: !2, producer:
> "clang", isOptimized: false, runtimeVersion: 0, emissionKind: FullDebug,
> globals: !4)
>  !2 = !DIFile(filename: "g.c", directory: "/")
>  !3 = !{}
> -!4 = !{!12, !13, !14, !15, !17, !18}
> +!4 = !{!12, !13, !14, !15, !17, !18, !20}
>  !5 = distinct !DICompositeType(tag: DW_TAG_structure_type, file: !2,
> line: 1, size: 64, elements: !6)
>  !6 = !{!7, !9}
>  !7 = !DIDerivedType(tag: DW_TAG_member, name: "x", scope: !5, file: !2,
> line: 1, baseType: !8, size: 32)
> @@ -58,3 +58,4 @@ target triple = "x86_64-apple-macosx10.1
>  !18 = !DIGlobalVariableExpression(var: !19, expr:
> !DIExpression(DW_OP_constu, 2,
>                                               DW_OP_stack_value,
> DW_OP_LLVM_fragment, 32, 32))
>  !19 = distinct !DIGlobalVariable(name: "full_const", scope: !1, file: !2,
> line: 1, type: !5, isLocal: false, isDefinition: true)
> +!20 = !DIGlobalVariableExpression(var: !0)
>

Should this be/is this valid ir?


>
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