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[DebugInfo][DWARF] Emit DW_AT_abstract_origin for concrete/inlined DW_TAG_lexical_blocks (#136205)

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During the discussion under
https://github.com/llvm/llvm-project/pull/119001, it was noticed that
concrete DW_TAG_lexical_blocks should refer to corresponding abstract
DW_TAG_lexical_blocks by having DW_AT_abstract_origin, to avoid
ambiguity. This behavior is implemented in GCC
(https://godbolt.org/z/Khrzdq1Wx), but not in LLVM.

Fixes https://github.com/llvm/llvm-project/issues/49297.
This commit is contained in:
Vladislav Dzhidzhoev
2025-04-24 19:44:18 +02:00
committed by GitHub
parent 8832a5950f
commit 1143a04f34
7 changed files with 104 additions and 8 deletions
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15
llvm/lib/CodeGen/AsmPrinter/DwarfCompileUnit.cpp
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@@ -782,6 +782,8 @@ DIE *DwarfCompileUnit::constructLexicalScopeDIE(LexicalScope *Scope) {
assert(!LexicalBlockDIEs.count(DS) &&
"Concrete out-of-line DIE for this scope exists!");
LexicalBlockDIEs[DS] = ScopeDIE;
} else {
InlinedLocalScopeDIEs[DS].push_back(ScopeDIE);
}
attachRangesOrLowHighPC(*ScopeDIE, Scope->getRanges());
@@ -1491,6 +1493,19 @@ void DwarfCompileUnit::finishEntityDefinition(const DbgEntity *Entity) {
getDwarfDebug().addAccelName(*this, CUNode->getNameTableKind(), Name, *Die);
}
void DwarfCompileUnit::attachLexicalScopesAbstractOrigins() {
auto AttachAO = [&](const DILocalScope *LS, DIE *ScopeDIE) {
if (auto *AbsLSDie = getAbstractScopeDIEs().lookup(LS))
addDIEEntry(*ScopeDIE, dwarf::DW_AT_abstract_origin, *AbsLSDie);
};
for (auto [LScope, ScopeDIE] : LexicalBlockDIEs)
AttachAO(LScope, ScopeDIE);
for (auto &[LScope, ScopeDIEs] : InlinedLocalScopeDIEs)
for (auto *ScopeDIE : ScopeDIEs)
AttachAO(LScope, ScopeDIE);
}
DbgEntity *DwarfCompileUnit::getExistingAbstractEntity(const DINode *Node) {
auto &AbstractEntities = getAbstractEntities();
auto I = AbstractEntities.find(Node);

5
llvm/lib/CodeGen/AsmPrinter/DwarfCompileUnit.h
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@@ -82,6 +82,10 @@ class DwarfCompileUnit final : public DwarfUnit {
// List of abstract local scopes (either DISubprogram or DILexicalBlock).
DenseMap<const DILocalScope *, DIE *> AbstractLocalScopeDIEs;
// List of inlined lexical block scopes that belong to subprograms within this
// CU.
DenseMap<const DILocalScope *, SmallVector<DIE *, 2>> InlinedLocalScopeDIEs;
DenseMap<const DINode *, std::unique_ptr<DbgEntity>> AbstractEntities;
/// DWO ID for correlating skeleton and split units.
@@ -299,6 +303,7 @@ public:
void finishSubprogramDefinition(const DISubprogram *SP);
void finishEntityDefinition(const DbgEntity *Entity);
void attachLexicalScopesAbstractOrigins();
/// Find abstract variable associated with Var.
using InlinedEntity = DbgValueHistoryMap::InlinedEntity;

1
llvm/lib/CodeGen/AsmPrinter/DwarfDebug.cpp
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@@ -1262,6 +1262,7 @@ void DwarfDebug::finalizeModuleInfo() {
auto &TheCU = *P.second;
if (TheCU.getCUNode()->isDebugDirectivesOnly())
continue;
TheCU.attachLexicalScopesAbstractOrigins();
// Emit DW_AT_containing_type attribute to connect types with their
// vtable holding type.
TheCU.constructContainingTypeDIEs();

15
llvm/test/DebugInfo/Generic/inline-scopes.ll
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@@ -20,16 +20,29 @@
; }
; Ensure that lexical_blocks within inlined_subroutines are preserved/emitted.
; CHECK: DW_TAG_subprogram
; CHECK-NEXT: DW_AT_linkage_name ("_Z2f1v")
; CHECK: [[ADDR1:0x[0-9a-f]+]]: DW_TAG_lexical_block
; CHECK: DW_TAG_subprogram
; CHECK-NEXT: DW_AT_linkage_name ("_Z2f2v")
; CHECK: [[ADDR2:0x[0-9a-f]+]]: DW_TAG_lexical_block
; CHECK: DW_TAG_inlined_subroutine
; CHECK-NOT: DW_TAG
; CHECK-NOT: NULL
; CHECK: DW_TAG_lexical_block
; CHECK: DW_TAG_lexical_block
; CHECK-NOT: {{DW_TAG|NULL}}
; CHECK: DW_AT_abstract_origin ([[ADDR1]]
; CHECK-NOT: DW_TAG
; CHECK-NOT: NULL
; CHECK: DW_TAG_variable
; Ensure that file changes don't interfere with creating inlined subroutines.
; (see the line directive inside 'f2' in thesource)
; CHECK: DW_TAG_inlined_subroutine
; CHECK-NOT: {{DW_TAG|NULL}}
; CHECK: DW_TAG_lexical_block
; CHECK-NOT: {{DW_TAG|NULL}}
; CHECK: DW_AT_abstract_origin ([[ADDR2]]
; CHECK-NOT: {{DW_TAG|NULL}}
; CHECK: DW_TAG_variable
; CHECK-NOT: DW_TAG
; CHECK: DW_AT_abstract_origin

56
llvm/test/DebugInfo/Generic/lexical-block-abstract-origin.ll Normal file
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@@ -0,0 +1,56 @@
; RUN: %llc_dwarf -filetype=obj -O0 %s -o - | llvm-dwarfdump -debug-info - | FileCheck %s
; Check that DW_AT_abstract_origin is generated for concrete lexical block.
; Generated from:
; inline __attribute__((always_inline)) int foo(int x) {
; {
; int y = x + 5;
; return y - 10;
; }
; }
;
; int bar(int x) {
; int y = foo(7);
; return y + 8;
; }
; CHECK: DW_TAG_subprogram
; CHECK-NEXT: DW_AT_name ("foo")
; CHECK-NOT: {{DW_TAG|NULL}}
; CHECK: [[LB:.*]]: DW_TAG_lexical_block
; CHECK: DW_TAG_inlined_subroutine
; CHECK-NEXT: DW_AT_abstract_origin {{.*}} "foo"
; CHECK-NOT: {{DW_TAG|NULL}}
; CHECK: DW_TAG_lexical_block
; CHECK-NOT: {{DW_TAG|NULL}}
; CHECK: DW_AT_abstract_origin {{.*}}[[LB]]
target datalayout = "e-m:o-p270:32:32-p271:32:32-p272:64:64-i64:64-i128:128-n32:64-S128-Fn32"
target triple = "arm64-apple-macosx15.0.0"
define i32 @bar() !dbg !9 {
entry:
%y.i = alloca i32, align 4
#dbg_declare(ptr %y.i, !22, !DIExpression(), !24)
store i32 0, ptr %y.i, align 4, !dbg !24
%1 = load i32, ptr %y.i, align 4
ret i32 %1
}
!llvm.dbg.cu = !{!0}
!llvm.module.flags = !{!3}
!0 = distinct !DICompileUnit(language: DW_LANG_C11, file: !1, emissionKind: FullDebug)
!1 = !DIFile(filename: "test.c", directory: "")
!3 = !{i32 2, !"Debug Info Version", i32 3}
!9 = distinct !DISubprogram(name: "bar", scope: !1, file: !1, line: 8, type: !10, spFlags: DISPFlagDefinition, unit: !0)
!10 = !DISubroutineType(types: !13)
!12 = !DIBasicType(name: "int", size: 32, encoding: DW_ATE_signed)
!13 = !{}
!19 = distinct !DISubprogram(name: "foo", scope: !1, file: !1, line: 1, type: !10, scopeLine: 1, spFlags: DISPFlagDefinition, unit: !0)
!21 = distinct !DILocation(line: 9, column: 11, scope: !9)
!22 = !DILocalVariable(name: "y", scope: !23, file: !1, line: 3, type: !12)
!23 = distinct !DILexicalBlock(scope: !19, file: !1, line: 2, column: 3)
!24 = !DILocation(line: 3, column: 9, scope: !23, inlinedAt: !21)

14
llvm/test/DebugInfo/X86/lexical-block-file-inline.ll
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@@ -28,9 +28,11 @@
; CHECK: DW_TAG_subprogram
; CHECK-NOT: {{DW_TAG|NULL}}
; CHECK: DW_AT_abstract_origin {{.*}} {[[Offset_bar:0x[0-9abcdef]+]]}
; CHECK-NOT: {{DW_TAG|NULL}}
; CHECK-NOT: {{DW_TAG|NULL}}
; CHECK: DW_TAG_lexical_block
; CHECK-NOT: {{DW_TAG|NULL}}
; CHECK-NOT: {{DW_TAG|NULL}}
; CHECK: DW_AT_abstract_origin {{.*}}[[Offset_lb:0x[0-9a-f]+]]
; CHECK-NOT: {{DW_TAG|NULL}}
; CHECK: DW_TAG_variable
;; Abstract "bar" function
@@ -40,7 +42,7 @@
; CHECK-NOT: {{DW_TAG|NULL}}
; CHECK: DW_AT_inline
; CHECK-NOT: {{DW_TAG|NULL}}
; CHECK: DW_TAG_lexical_block
; CHECK: [[Offset_lb]]: DW_TAG_lexical_block
; CHECK-NOT: {{DW_TAG|NULL}}
; CHECK: DW_TAG_variable
; CHECK-NOT: {{DW_TAG|NULL}}
@@ -56,8 +58,10 @@
; CHECK-NEXT: DW_AT_abstract_origin {{.*}} {[[Offset_bar]]}
; CHECK-NOT: {{DW_TAG|NULL}}
; CHECK: DW_TAG_lexical_block
; CHECK-NOT: {{DW_TAG|NULL}}
; CHECK: DW_TAG_variable
; CHECK-NOT: {{DW_TAG|NULL}}
; CHECK: DW_AT_abstract_origin {{.*}}[[Offset_lb]]
; CHECK-NOT: {{DW_TAG|NULL}}
; CHECK: DW_TAG_variable
; Function Attrs: alwaysinline nounwind
define i32 @_Z3barv() #0 !dbg !4 {

6
llvm/test/DebugInfo/X86/missing-abstract-variable.ll
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@@ -37,7 +37,7 @@
; CHECK-NOT: DW_TAG
; CHECK: DW_AT_name ("b")
; CHECK-NOT: {{DW_TAG|NULL}}
; CHECK: DW_TAG_lexical_block
; CHECK: [[LB_DECL:.*]]: DW_TAG_lexical_block
; CHECK-NOT: {{DW_TAG|NULL}}
; CHECK: DW_TAG_variable
; CHECK-NOT: DW_TAG
@@ -82,7 +82,9 @@
; CHECK-NOT: {{DW_TAG|NULL}}
; CHECK: DW_TAG_lexical_block
; CHECK-NOT: {{DW_TAG|NULL}}
; CHECK-NOT: {{DW_TAG|NULL}}
; CHECK: DW_AT_abstract_origin {{.*}}[[LB_DECL]]
; CHECK-NOT: {{DW_TAG|NULL}}
; CHECK: DW_TAG_variable
; CHECK-NOT: DW_TAG
; CHECK: DW_AT_abstract_origin {{.*}} "s"