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[MemProf] Update the declaration DISubprogram linkageName for clones #149864

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teresajohnson merged 2 commits into from
Jul 21, 2025
Merged

[MemProf] Update the declaration DISubprogram linkageName for clones #149864

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[MemProf] Update the declaration DISubprogram linkageName for clones
teresajohnson Jul 21, 2025
3319b55
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teresajohnson Jul 21, 2025
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26 changes: 20 additions & 6 deletions llvm/lib/Transforms/IPO/MemProfContextDisambiguation.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -3998,6 +3998,24 @@ void IndexCallsiteContextGraph::updateCall(CallInfo &CallerCall,
CI->Clones[CallerCall.cloneNo()] = CalleeFunc.cloneNo();
}

// Update the debug information attached to NewFunc to use the clone Name. Note
// this needs to be done for both any existing DISubprogram for the definition,
// as well as any separate declaration DISubprogram.
static void updateSubprogramLinkageName(Function *NewFunc, std::string Name) {
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@snehasish snehasish Jul 21, 2025

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Can this param be a StringRef to avoid a copy?

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@teresajohnson teresajohnson Jul 21, 2025

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done

assert(Name == NewFunc->getName());
auto *SP = NewFunc->getSubprogram();
if (!SP)
return;
auto *NewName = MDString::get(NewFunc->getParent()->getContext(), Name);
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@snehasish snehasish Jul 21, 2025

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nit: Is this an MDString version of the Name? Maybe rename the var if so.

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@teresajohnson teresajohnson Jul 21, 2025

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done

SP->replaceLinkageName(NewName);
DISubprogram *Decl = SP->getDeclaration();
if (!Decl)
return;
TempDISubprogram NewDecl = Decl->clone();
NewDecl->replaceLinkageName(NewName);
SP->replaceDeclaration(MDNode::replaceWithUniqued(std::move(NewDecl)));
}

CallsiteContextGraph<ModuleCallsiteContextGraph, Function,
Instruction *>::FuncInfo
ModuleCallsiteContextGraph::cloneFunctionForCallsite(
Expand All @@ -4009,9 +4027,7 @@ ModuleCallsiteContextGraph::cloneFunctionForCallsite(
std::string Name = getMemProfFuncName(Func.func()->getName(), CloneNo);
assert(!Func.func()->getParent()->getFunction(Name));
NewFunc->setName(Name);
if (auto *SP = NewFunc->getSubprogram())
SP->replaceLinkageName(
MDString::get(NewFunc->getParent()->getContext(), Name));
updateSubprogramLinkageName(NewFunc, Name);
for (auto &Inst : CallsWithMetadataInFunc) {
// This map always has the initial version in it.
assert(Inst.cloneNo() == 0);
Expand Down Expand Up @@ -4950,9 +4966,7 @@ static SmallVector<std::unique_ptr<ValueToValueMapTy>, 4> createFunctionClones(
PrevF->eraseFromParent();
} else
NewF->setName(Name);
if (auto *SP = NewF->getSubprogram())
SP->replaceLinkageName(
MDString::get(NewF->getParent()->getContext(), Name));
updateSubprogramLinkageName(NewF, Name);
ORE.emit(OptimizationRemark(DEBUG_TYPE, "MemprofClone", &F)
<< "created clone " << ore::NV("NewFunction", NewF));

Expand Down
6 changes: 4 additions & 2 deletions llvm/test/ThinLTO/X86/memprof-basic.ll
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Expand Up @@ -143,13 +143,14 @@ attributes #0 = { noinline optnone }
!12 = !{i64 789, i64 300}
!13 = distinct !DICompileUnit(language: DW_LANG_C_plus_plus_14, file: !14, producer: "clang version 21.0.0git ([email protected]:llvm/llvm-project.git e391301e0e4d9183fe06e69602e87b0bc889aeda)", isOptimized: true, runtimeVersion: 0, emissionKind: FullDebug, splitDebugInlining: false, nameTableKind: None)
!14 = !DIFile(filename: "basic.cc", directory: "", checksumkind: CSK_MD5, checksum: "8636c46e81402013b9d54e8307d2f149")
!15 = distinct !DISubprogram(name: "bar", linkageName: "_Z3barv", scope: !14, file: !14, line: 1, type: !16, scopeLine: 1, flags: DIFlagPrototyped, spFlags: DISPFlagDefinition, unit: !13)
!15 = distinct !DISubprogram(name: "bar", linkageName: "_Z3barv", scope: !14, file: !14, line: 1, type: !16, scopeLine: 1, flags: DIFlagPrototyped, spFlags: DISPFlagDefinition, unit: !13, declaration: !22)
!16 = !DISubroutineType(types: !17)
!17 = !{!18}
!18 = !DIDerivedType(tag: DW_TAG_pointer_type, baseType: !19, size: 64)
!19 = !DIBasicType(name: "char", size: 8, encoding: DW_ATE_signed_char)
!20 = !{i32 7, !"Dwarf Version", i32 5}
!21 = !{i32 2, !"Debug Info Version", i32 3}
!22 = !DISubprogram(name: "bar", linkageName: "_Z3barv", scope: !14, file: !14, line: 1, type: !16, scopeLine: 1, flags: DIFlagPrototyped, spFlags: DISPFlagOptimized)

; DUMP: CCG before cloning:
; DUMP: Callsite Context Graph:
Expand Down Expand Up @@ -321,7 +322,8 @@ attributes #0 = { noinline optnone }
; IR: attributes #[[NOTCOLD]] = { "memprof"="notcold" }
; IR: attributes #[[COLD]] = { "memprof"="cold" }
;; Make sure the clone's linkageName was updated.
; IR: ![[SP]] = distinct !DISubprogram(name: "bar", linkageName: "_Z3barv.memprof.1"
; IR: ![[SP]] = distinct !DISubprogram(name: "bar", linkageName: "_Z3barv.memprof.1", {{.*}} declaration: ![[SP2:[0-9]+]])
; IR: ![[SP2]] = !DISubprogram(name: "bar", linkageName: "_Z3barv.memprof.1"


; STATS: 1 memprof-context-disambiguation - Number of cold static allocations (possibly cloned)
Expand Down
6 changes: 4 additions & 2 deletions llvm/test/Transforms/MemProfContextDisambiguation/basic.ll
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Expand Up @@ -121,13 +121,14 @@ attributes #6 = { builtin }
!12 = !{i64 789, i64 300}
!13 = distinct !DICompileUnit(language: DW_LANG_C_plus_plus_14, file: !14, producer: "clang version 21.0.0git ([email protected]:llvm/llvm-project.git e391301e0e4d9183fe06e69602e87b0bc889aeda)", isOptimized: true, runtimeVersion: 0, emissionKind: FullDebug, splitDebugInlining: false, nameTableKind: None)
!14 = !DIFile(filename: "basic.cc", directory: "", checksumkind: CSK_MD5, checksum: "8636c46e81402013b9d54e8307d2f149")
!15 = distinct !DISubprogram(name: "bar", linkageName: "_Z3barv", scope: !14, file: !14, line: 1, type: !16, scopeLine: 1, flags: DIFlagPrototyped, spFlags: DISPFlagDefinition, unit: !13)
!15 = distinct !DISubprogram(name: "bar", linkageName: "_Z3barv", scope: !14, file: !14, line: 1, type: !16, scopeLine: 1, flags: DIFlagPrototyped, spFlags: DISPFlagDefinition, unit: !13, declaration: !22)
!16 = !DISubroutineType(types: !17)
!17 = !{!18}
!18 = !DIDerivedType(tag: DW_TAG_pointer_type, baseType: !19, size: 64)
!19 = !DIBasicType(name: "char", size: 8, encoding: DW_ATE_signed_char)
!20 = !{i32 7, !"Dwarf Version", i32 5}
!21 = !{i32 2, !"Debug Info Version", i32 3}
!22 = !DISubprogram(name: "bar", linkageName: "_Z3barv", scope: !14, file: !14, line: 1, type: !16, scopeLine: 1, flags: DIFlagPrototyped, spFlags: DISPFlagOptimized)

; DUMP: CCG before cloning:
; DUMP: Callsite Context Graph:
Expand Down Expand Up @@ -290,7 +291,8 @@ attributes #6 = { builtin }
; IR: attributes #[[NOTCOLD]] = { builtin "memprof"="notcold" }
; IR: attributes #[[COLD]] = { builtin "memprof"="cold" }
;; Make sure the clone's linkageName was updated.
; IR: ![[SP]] = distinct !DISubprogram(name: "bar", linkageName: "_Z3barv.memprof.1"
; IR: ![[SP]] = distinct !DISubprogram(name: "bar", linkageName: "_Z3barv.memprof.1", {{.*}} declaration: ![[SP2:[0-9]+]])
; IR: ![[SP2]] = !DISubprogram(name: "bar", linkageName: "_Z3barv.memprof.1"


; STATS: 1 memprof-context-disambiguation - Number of cold static allocations (possibly cloned)
Expand Down
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