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[llvm][DebugInfo] Drop \01 mangling prefix when inserting linkage name into accelerator table #138852

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Merged
merged 3 commits into from
May 12, 2025
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[llvm][DebugInfo] Drop \01 mangling prefix when inserting linkage name into accelerator table #138852

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[llvm][DebugInfo] Drop \01 mangling prefix when inserting linkage nam…
Michael137 May 7, 2025
f692e4c
fixup! remove redundant comment
Michael137 May 7, 2025
3d9f2b1
Merge branch 'main' into llvm/mangling-escape-in-index
Michael137 May 12, 2025
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9 changes: 7 additions & 2 deletions llvm/lib/CodeGen/AsmPrinter/DwarfDebug.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -489,12 +489,17 @@ void DwarfDebug::addSubprogramNames(
if (SP->getName() != "")
addAccelName(Unit, NameTableKind, SP->getName(), Die);

// We drop the mangling escape prefix when emitting the DW_AT_linkage_name. So
// ensure we don't include it when inserting into the accelerator tables.
llvm::StringRef LinkageName =
GlobalValue::dropLLVMManglingEscape(SP->getLinkageName());

// If the linkage name is different than the name, go ahead and output that as
// well into the name table. Only do that if we are going to actually emit
// that name.
if (SP->getLinkageName() != "" && SP->getName() != SP->getLinkageName() &&
if (LinkageName != "" && SP->getName() != LinkageName &&
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@Michael137 mostly asking for myself, but is there a reason we check for "" instead of empty?

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Nope no reason in particular. This is the way the code was prior to my changes, so wanted to keep the diff as small as possible

(useAllLinkageNames() || InfoHolder.getAbstractScopeDIEs().lookup(SP)))
addAccelName(Unit, NameTableKind, SP->getLinkageName(), Die);
addAccelName(Unit, NameTableKind, LinkageName, Die);

// If this is an Objective-C selector name add it to the ObjC accelerator
// too.
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54 changes: 54 additions & 0 deletions llvm/test/DebugInfo/Generic/debug-names-asm-label.ll
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@@ -0,0 +1,54 @@
; Tests the mangling escape prefix gets stripped from the linkage name.
;
; RUN: %llc_dwarf -accel-tables=Dwarf -dwarf-linkage-names=All -filetype=obj -o %t < %s
;
; RUN: llvm-dwarfdump -debug-info -debug-names %t | FileCheck %s
; RUN: llvm-dwarfdump -debug-names -verify %t | FileCheck --check-prefix=VERIFY %s

; CHECK: .debug_info contents:
; CHECK: DW_AT_linkage_name ("bar")
; CHECK: .debug_names contents:
; CHECK: String: {{.*}} "bar"

; VERIFY: No errors.

; Input generated from the following C++ code using
; clang -g -S -emit-llvm -target aarch64-apple-macos

; void foo() asm("bar");
; void foo() {}
;
; void g() { foo(); }

define void @"\01bar"() !dbg !9 {
entry:
ret void, !dbg !13
}

define void @_Z1gv() !dbg !14 {
entry:
call void @"\01bar"(), !dbg !15
ret void, !dbg !16
}

!llvm.dbg.cu = !{!0}
!llvm.module.flags = !{!2, !3, !4, !5, !6, !7}
!llvm.ident = !{!8}

!0 = distinct !DICompileUnit(language: DW_LANG_C_plus_plus_14, file: !1, producer: "clang version 21.0.0git", isOptimized: false, runtimeVersion: 0, emissionKind: FullDebug, splitDebugInlining: false, nameTableKind: Apple, sysroot: "/")
!1 = !DIFile(filename: "asm.cpp", directory: "/tmp", checksumkind: CSK_MD5, checksum: "d053f9249cc5548d446ceb58411ad625")
!2 = !{i32 7, !"Dwarf Version", i32 5}
!3 = !{i32 2, !"Debug Info Version", i32 3}
!4 = !{i32 1, !"wchar_size", i32 4}
!5 = !{i32 8, !"PIC Level", i32 2}
!6 = !{i32 7, !"uwtable", i32 1}
!7 = !{i32 7, !"frame-pointer", i32 1}
!8 = !{!"clang version 21.0.0git"}
!9 = distinct !DISubprogram(name: "foo", linkageName: "\01bar", scope: !10, file: !10, line: 2, type: !11, scopeLine: 2, flags: DIFlagPrototyped, spFlags: DISPFlagDefinition, unit: !0)
!10 = !DIFile(filename: "asm.cpp", directory: "/tmp", checksumkind: CSK_MD5, checksum: "d053f9249cc5548d446ceb58411ad625")
!11 = !DISubroutineType(types: !12)
!12 = !{null}
!13 = !DILocation(line: 2, column: 13, scope: !9)
!14 = distinct !DISubprogram(name: "g", linkageName: "_Z1gv", scope: !10, file: !10, line: 4, type: !11, scopeLine: 4, flags: DIFlagPrototyped, spFlags: DISPFlagDefinition, unit: !0)
!15 = !DILocation(line: 4, column: 12, scope: !14)
!16 = !DILocation(line: 4, column: 19, scope: !14)
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