r258507 - Module Debugging: Use a nonzero DWO id for precompiled headers.

[David Blaikie via cfe-commits]

On Fri, Jan 22, 2016 at 9:43 AM, Adrian Prantl via cfe-commits <
cfe-commits at lists.llvm.org> wrote:

> Author: adrian
> Date: Fri Jan 22 11:43:43 2016
> New Revision: 258507
>
> URL: http://llvm.org/viewvc/llvm-project?rev=258507&view=rev
> Log:
> Module Debugging: Use a nonzero DWO id for precompiled headers.
> PCH files don't have a module signature and LLVM uses a nonzero DWO id as
> an indicator for skeleton / module CUs. This change pins the DWO id for PCH
> files to a known constant value.
> The correct long-term solution here is to implement a module signature
> that is an actual dterministic hash (at the moment module signatures are
> just random nonzero numbers) and then enable this for PCH files as well.
>

^ is this on the books/planned at all?


>
> <rdar://problem/24290667>
>
> Modified:
>     cfe/trunk/lib/CodeGen/CGDebugInfo.cpp
>     cfe/trunk/lib/CodeGen/ObjectFilePCHContainerOperations.cpp
>     cfe/trunk/test/Modules/ExtDebugInfo.cpp
>     cfe/trunk/test/Modules/ModuleDebugInfo.cpp
>
> Modified: cfe/trunk/lib/CodeGen/CGDebugInfo.cpp
> URL:
> http://llvm.org/viewvc/llvm-project/cfe/trunk/lib/CodeGen/CGDebugInfo.cpp?rev=258507&r1=258506&r2=258507&view=diff
>
> ==============================================================================
> --- cfe/trunk/lib/CodeGen/CGDebugInfo.cpp (original)
> +++ cfe/trunk/lib/CodeGen/CGDebugInfo.cpp Fri Jan 22 11:43:43 2016
> @@ -1740,11 +1740,14 @@ CGDebugInfo::getOrCreateModuleRef(Extern
>
>    bool IsRootModule = M ? !M->Parent : true;
>    if (CreateSkeletonCU && IsRootModule) {
> +    // PCH files don't have a signature field in the control block,
> +    // but LLVM detects skeleton CUs by looking for a non-zero DWO id.
> +    uint64_t Signature = Mod.getSignature() ? Mod.getSignature() : ~1U;
>      llvm::DIBuilder DIB(CGM.getModule());
>      DIB.createCompileUnit(TheCU->getSourceLanguage(), Mod.getModuleName(),
>                            Mod.getPath(), TheCU->getProducer(), true,
>                            StringRef(), 0, Mod.getASTFile(),
> -                          llvm::DIBuilder::FullDebug, Mod.getSignature());
> +                          llvm::DIBuilder::FullDebug, Signature);
>      DIB.finalize();
>    }
>    llvm::DIModule *Parent =
>
> Modified: cfe/trunk/lib/CodeGen/ObjectFilePCHContainerOperations.cpp
> URL:
> http://llvm.org/viewvc/llvm-project/cfe/trunk/lib/CodeGen/ObjectFilePCHContainerOperations.cpp?rev=258507&r1=258506&r2=258507&view=diff
>
> ==============================================================================
> --- cfe/trunk/lib/CodeGen/ObjectFilePCHContainerOperations.cpp (original)
> +++ cfe/trunk/lib/CodeGen/ObjectFilePCHContainerOperations.cpp Fri Jan 22
> 11:43:43 2016
> @@ -219,7 +219,11 @@ public:
>
>      M->setTargetTriple(Ctx.getTargetInfo().getTriple().getTriple());
>      M->setDataLayout(Ctx.getTargetInfo().getDataLayoutString());
> -    Builder->getModuleDebugInfo()->setDwoId(Buffer->Signature);
> +
> +    // PCH files don't have a signature field in the control block,
> +    // but LLVM detects DWO CUs by looking for a non-zero DWO id.
> +    uint64_t Signature = Buffer->Signature ? Buffer->Signature : ~1U;
> +    Builder->getModuleDebugInfo()->setDwoId(Signature);
>
>      // Finalize the Builder.
>      if (Builder)
>
> Modified: cfe/trunk/test/Modules/ExtDebugInfo.cpp
> URL:
> http://llvm.org/viewvc/llvm-project/cfe/trunk/test/Modules/ExtDebugInfo.cpp?rev=258507&r1=258506&r2=258507&view=diff
>
> ==============================================================================
> --- cfe/trunk/test/Modules/ExtDebugInfo.cpp (original)
> +++ cfe/trunk/test/Modules/ExtDebugInfo.cpp Fri Jan 22 11:43:43 2016
> @@ -102,3 +102,7 @@ void foo() {
>
>
>  // CHECK: !DIImportedEntity(tag: DW_TAG_imported_declaration, scope: !0,
> entity: !"_ZTSN8DebugCXX6StructE", line: 24)
> +
> +// CHECK: !DICompileUnit(
> +// CHECK-SAME:           splitDebugFilename:
> +// CHECK-SAME:           dwoId:
>
> Modified: cfe/trunk/test/Modules/ModuleDebugInfo.cpp
> URL:
> http://llvm.org/viewvc/llvm-project/cfe/trunk/test/Modules/ModuleDebugInfo.cpp?rev=258507&r1=258506&r2=258507&view=diff
>
> ==============================================================================
> --- cfe/trunk/test/Modules/ModuleDebugInfo.cpp (original)
> +++ cfe/trunk/test/Modules/ModuleDebugInfo.cpp Fri Jan 22 11:43:43 2016
> @@ -8,7 +8,6 @@
>  // RUN: %clang_cc1 -triple %itanium_abi_triple -x objective-c++
> -std=c++11 -debug-info-kind=limited -fmodules -fmodule-format=obj
> -fimplicit-module-maps -DMODULES -fmodules-cache-path=%t %s -I %S/Inputs -I
> %t -emit-llvm -o %t.ll -mllvm -debug-only=pchcontainer &>%t-mod.ll
>  // RUN: cat %t-mod.ll | FileCheck %s
>  // RUN: cat %t-mod.ll | FileCheck --check-prefix=CHECK-NEG %s
> -// RUN: cat %t-mod.ll | FileCheck --check-prefix=CHECK-DWO %s
>
>  // PCH:
>  // RUN: %clang_cc1 -triple %itanium_abi_triple -x c++ -std=c++11
> -emit-pch -fmodule-format=obj -I %S/Inputs -o %t.pch %S/Inputs/DebugCXX.h
> -mllvm -debug-only=pchcontainer &>%t-pch.ll
> @@ -22,7 +21,7 @@
>  // CHECK: distinct !DICompileUnit(language: DW_LANG_{{.*}}C_plus_plus,
>  // CHECK-SAME:                    isOptimized: false,
>  // CHECK-SAME-NOT:                splitDebugFilename:
> -// CHECK-DWO:                     dwoId:
> +// CHECK:                         dwoId:
>
>  // CHECK: !DICompositeType(tag: DW_TAG_enumeration_type, name: "Enum"
>  // CHECK-SAME:             identifier: "_ZTSN8DebugCXX4EnumE")
>
>
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