[llvm] r309154 - Do a better job at emitting prefrabricated skeleton CUs.
Adrian Prantl via llvm-commits
llvm-commits at lists.llvm.org
Thu Jul 27 08:25:07 PDT 2017
> On Jul 26, 2017, at 8:59 PM, David Blaikie <dblaikie at gmail.com> wrote:
>
>
>
> On Wed, Jul 26, 2017 at 11:49 AM Adrian Prantl via llvm-commits <llvm-commits at lists.llvm.org> wrote:
> Author: adrian
> Date: Wed Jul 26 11:48:32 2017
> New Revision: 309154
>
> URL: http://llvm.org/viewvc/llvm-project?rev=309154&view=rev
> Log:
> Do a better job at emitting prefrabricated skeleton CUs.
>
> This is a better fix than r308708 for the problem introduced in
> r304020. It restores the skeleton CU testcases modified by that commit
> to their original form and most importantly ensures that
> frontend-generated skeleton CUs (such as used to point to Clang
> modules) come after the regular CUs. This broke for DICompileUnit
> nodes that don't have any immediate children because they are now
> constructed lazily instead of the order in which they are listed in
> !llvm.dbg.cu. After this commit we still don't guarantee that order,
> but we do guarantee that empty skeletons come last.
>
> Shipping versions of LLDB are very sensitive to the ordering of
> CUs. I'll track a fix for LLDB to be more permissive separately.
> This fixes a test failure in the LLDB testsuite.
>
> rdar://problem/33357252
>
> Modified:
> llvm/trunk/lib/CodeGen/AsmPrinter/DwarfDebug.cpp
> llvm/trunk/test/DebugInfo/Generic/skeletoncu.ll
> llvm/trunk/test/DebugInfo/dwo.ll
> llvm/trunk/test/DebugInfo/skeletoncu.ll
>
> Modified: llvm/trunk/lib/CodeGen/AsmPrinter/DwarfDebug.cpp
> URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/CodeGen/AsmPrinter/DwarfDebug.cpp?rev=309154&r1=309153&r2=309154&view=diff
> ==============================================================================
> --- llvm/trunk/lib/CodeGen/AsmPrinter/DwarfDebug.cpp (original)
> +++ llvm/trunk/lib/CodeGen/AsmPrinter/DwarfDebug.cpp Wed Jul 26 11:48:32 2017
> @@ -520,6 +520,14 @@ sortGlobalExprs(SmallVectorImpl<DwarfCom
> return GVEs;
> }
>
> +static bool isEmptyCU(DICompileUnit *CUNode) {
> + return CUNode->getEnumTypes().empty() &&
> + CUNode->getRetainedTypes().empty() &&
> + CUNode->getGlobalVariables().empty() &&
> + CUNode->getImportedEntities().empty() &&
> + CUNode->getMacros().empty();
> +}
> +
> // Emit all Dwarf sections that should come prior to the content. Create
> // global DIEs and emit initial debug info sections. This is invoked by
> // the target AsmPrinter.
> @@ -546,10 +554,7 @@ void DwarfDebug::beginModule() {
> }
>
> for (DICompileUnit *CUNode : M->debug_compile_units()) {
> - if (CUNode->getEnumTypes().empty() && CUNode->getRetainedTypes().empty() &&
> - CUNode->getGlobalVariables().empty() &&
> - CUNode->getImportedEntities().empty() && CUNode->getMacros().empty() &&
> - !CUNode->getDWOId())
> + if (isEmptyCU(CUNode))
> continue;
>
> DwarfCompileUnit &CU = getOrCreateDwarfCompileUnit(CUNode);
> @@ -683,6 +688,11 @@ void DwarfDebug::finalizeModuleInfo() {
> TLOF.getDwarfMacinfoSection()->getBeginSymbol());
> }
>
> + // Emit all frontend-produced Skeleton CUs, i.e., Clang modules.
> + for (auto *CUNode : MMI->getModule()->debug_compile_units())
> + if (CUNode->getDWOId() && isEmptyCU(CUNode))
> + getOrCreateDwarfCompileUnit(CUNode);
>
> I'm not sure I understand the motivation for the 'isEmptyCU' test here - seems like it could be removed? DWOId tells you it's a skeleton, so it will be empty, right? (but even if it's not empty, is that a problem? getOrCreateDwarfCompileUnit would be a no-op in that case? (the map lookup would succeed and nothing further would be done?))
It is correct that the check is redundant. I removed it in r309280.
-- adrian
>
> +
> // Compute DIE offsets and sizes.
> InfoHolder.computeSizeAndOffsets();
> if (useSplitDwarf())
>
> Modified: llvm/trunk/test/DebugInfo/Generic/skeletoncu.ll
> URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/DebugInfo/Generic/skeletoncu.ll?rev=309154&r1=309153&r2=309154&view=diff
> ==============================================================================
> --- llvm/trunk/test/DebugInfo/Generic/skeletoncu.ll (original)
> +++ llvm/trunk/test/DebugInfo/Generic/skeletoncu.ll Wed Jul 26 11:48:32 2017
> @@ -14,4 +14,3 @@
> !4 = !{i32 2, !"Debug Info Version", i32 3}
> !5 = !{!6}
> !6 = !DIBasicType(name: "int", size: 32, encoding: DW_ATE_signed)
> -
>
> Modified: llvm/trunk/test/DebugInfo/dwo.ll
> URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/DebugInfo/dwo.ll?rev=309154&r1=309153&r2=309154&view=diff
> ==============================================================================
> --- llvm/trunk/test/DebugInfo/dwo.ll (original)
> +++ llvm/trunk/test/DebugInfo/dwo.ll Wed Jul 26 11:48:32 2017
> @@ -1,17 +1,23 @@
> ; RUN: %llc_dwarf %s -filetype=obj -o %t
> ; RUN: llvm-dwarfdump -debug-dump=info %t | FileCheck %s
> +; REQUIRES: default_triple
> +;
> +; CHECK: DW_TAG_compile_unit
> +; CHECK-NOT: dwo_id
> +;
> +; The skeleton must come second or LLDB may get confused.
> ; CHECK: DW_TAG_compile_unit
> ; CHECK: DW_AT_GNU_dwo_id {{.*}}abcd
> -; CHECK-NOT: DW_AT_GNU_dwo_name
> -; REQUIRES: default_triple
> +; CHECK: DW_AT_GNU_dwo_name {{.*}}"my.dwo"
>
> -!llvm.dbg.cu = !{!0}
> +!llvm.dbg.cu = !{!7, !0}
> !llvm.module.flags = !{!3, !4}
>
> -!0 = distinct !DICompileUnit(language: DW_LANG_C99, file: !1, producer: "LLVM", isOptimized: false, runtimeVersion: 2, emissionKind: FullDebug, enums: !2, retainedTypes: !5, globals: !2, imports: !2, dwoId: 43981)
> +!0 = distinct !DICompileUnit(language: DW_LANG_C99, file: !1, producer: "Clang", isOptimized: false, runtimeVersion: 2, splitDebugFilename: "my.dwo", emissionKind: FullDebug, enums: !2, retainedTypes: !2, globals: !2, imports: !2, dwoId: 43981)
> !1 = !DIFile(filename: "<stdin>", directory: "/")
> !2 = !{}
> !3 = !{i32 2, !"Dwarf Version", i32 4}
> !4 = !{i32 2, !"Debug Info Version", i32 3}
> !5 = !{!6}
> !6 = !DIBasicType(name: "int", size: 32, encoding: DW_ATE_signed)
> +!7 = distinct !DICompileUnit(language: DW_LANG_C99, file: !1, producer: "Clang", isOptimized: false, runtimeVersion: 2, emissionKind: FullDebug, retainedTypes: !5)
>
> Modified: llvm/trunk/test/DebugInfo/skeletoncu.ll
> URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/DebugInfo/skeletoncu.ll?rev=309154&r1=309153&r2=309154&view=diff
> ==============================================================================
> --- llvm/trunk/test/DebugInfo/skeletoncu.ll (original)
> +++ llvm/trunk/test/DebugInfo/skeletoncu.ll Wed Jul 26 11:48:32 2017
> @@ -8,11 +8,9 @@
> !llvm.dbg.cu = !{!0}
> !llvm.module.flags = !{!3, !4}
>
> -!0 = distinct !DICompileUnit(language: DW_LANG_C99, file: !1, producer: "LLVM", isOptimized: false, runtimeVersion: 2, splitDebugFilename: "my.dwo", emissionKind: FullDebug, enums: !2, retainedTypes: !6, globals: !2, imports: !2, dwoId: 43981)
> +!0 = distinct !DICompileUnit(language: DW_LANG_C99, file: !1, producer: "LLVM", isOptimized: false, runtimeVersion: 2, splitDebugFilename: "my.dwo", emissionKind: FullDebug, enums: !2, retainedTypes: !2, globals: !2, imports: !2, dwoId: 43981)
> !1 = !DIFile(filename: "<stdin>", directory: "/")
> !2 = !{}
> !3 = !{i32 2, !"Dwarf Version", i32 4}
> !4 = !{i32 2, !"Debug Info Version", i32 3}
> -!5 = !DIBasicType(name: "int", size: 32, encoding: DW_ATE_signed)
> -!6 = !{!5}
>
>
>
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