[llvm] [SampleProfileMatcher] Match basename with template arguments (PR #195957)
via llvm-commits
llvm-commits at lists.llvm.org
Tue May 5 16:51:01 PDT 2026
https://github.com/HighW4y2H3ll updated https://github.com/llvm/llvm-project/pull/195957
>From 27f28206de96f002bc8be7d4aa84abf83cb1c396 Mon Sep 17 00:00:00 2001
From: h2h <h2h at meta.com>
Date: Tue, 5 May 2026 15:28:29 -0700
Subject: [PATCH 1/2] [SampleProfileMatcher] Match basename with template
arguments
---
.../Transforms/IPO/SampleProfileMatcher.cpp | 33 ++++-
...probe-stale-profile-matching-template.prof | 13 ++
...n-probe-stale-profile-matching-template.ll | 133 ++++++++++++++++++
3 files changed, 173 insertions(+), 6 deletions(-)
create mode 100644 llvm/test/Transforms/SampleProfile/Inputs/non-probe-stale-profile-matching-template.prof
create mode 100644 llvm/test/Transforms/SampleProfile/non-probe-stale-profile-matching-template.ll
diff --git a/llvm/lib/Transforms/IPO/SampleProfileMatcher.cpp b/llvm/lib/Transforms/IPO/SampleProfileMatcher.cpp
index edebc294c9664..4591559fc01aa 100644
--- a/llvm/lib/Transforms/IPO/SampleProfileMatcher.cpp
+++ b/llvm/lib/Transforms/IPO/SampleProfileMatcher.cpp
@@ -753,15 +753,36 @@ static std::string getDemangledBaseName(ItaniumPartialDemangler &Demangler,
auto FunctionName = FName.str();
if (Demangler.partialDemangle(FunctionName.c_str()))
return std::string();
- size_t BaseNameSize = 0;
+
// The demangler API follows the __cxa_demangle one, and thus needs a
// pointer that originates from malloc (or nullptr) and the caller is
// responsible for free()-ing the buffer.
- char *BaseNamePtr = Demangler.getFunctionBaseName(nullptr, &BaseNameSize);
- std::string Result = (BaseNamePtr && BaseNameSize)
- ? std::string(BaseNamePtr, BaseNameSize)
- : std::string();
- free(BaseNamePtr);
+ size_t NameSize = 0;
+ // Get the full function name (namespace::base<templates>).
+ char *NamePtr = Demangler.getFunctionName(nullptr, &NameSize);
+ if (!NamePtr || !NameSize) {
+ free(NamePtr);
+ return std::string();
+ }
+ std::string Result(NamePtr, NameSize);
+ free(NamePtr);
+
+ // Strip the namespace/class context prefix to get "base<templates>".
+ size_t CtxSize = 0;
+ char *CtxPtr = Demangler.getFunctionDeclContextName(nullptr, &CtxSize);
+ if (CtxPtr && CtxSize) {
+ StringRef CtxStr(CtxPtr, CtxSize);
+ // Trim trailing null from context before comparing.
+ while (!CtxStr.empty() && CtxStr.back() == '\0')
+ CtxStr = CtxStr.drop_back();
+ StringRef ResultRef(Result);
+ if (ResultRef.starts_with(CtxStr) &&
+ ResultRef.size() > CtxStr.size() + 2 &&
+ ResultRef[CtxStr.size()] == ':' && ResultRef[CtxStr.size() + 1] == ':')
+ Result = ResultRef.substr(CtxStr.size() + 2).str();
+ }
+ free(CtxPtr);
+
// Trim trailing whitespace/null — getFunctionBaseName may include trailing
// characters in the reported size.
while (!Result.empty() && (Result.back() == ' ' || Result.back() == '\0'))
diff --git a/llvm/test/Transforms/SampleProfile/Inputs/non-probe-stale-profile-matching-template.prof b/llvm/test/Transforms/SampleProfile/Inputs/non-probe-stale-profile-matching-template.prof
new file mode 100644
index 0000000000000..18751606fa03b
--- /dev/null
+++ b/llvm/test/Transforms/SampleProfile/Inputs/non-probe-stale-profile-matching-template.prof
@@ -0,0 +1,13 @@
+main:9229397:0
+ 0: 0
+ 1: 47663
+ 2: 48723 _ZN3ns13fooIiEET_S1_:49018
+ 3: 49087 _Z3bari:49087
+ 4: 51871 _ZN3ns13fooIdEET_S1_:51871
+ 5: 51871 _Z3bari:51871
+_ZN3ns13fooIiEET_S1_:500000:100000
+ 1: 100000
+_ZN3ns13fooIdEET_S1_:500000:100000
+ 1: 100000
+_Z3bari:200000:100000
+ 1: 100000
diff --git a/llvm/test/Transforms/SampleProfile/non-probe-stale-profile-matching-template.ll b/llvm/test/Transforms/SampleProfile/non-probe-stale-profile-matching-template.ll
new file mode 100644
index 0000000000000..42c94207adfc6
--- /dev/null
+++ b/llvm/test/Transforms/SampleProfile/non-probe-stale-profile-matching-template.ll
@@ -0,0 +1,133 @@
+; REQUIRES: x86_64-linux
+; REQUIRES: asserts
+; RUN: opt < %s -passes=sample-profile -sample-profile-file=%S/Inputs/non-probe-stale-profile-matching-template.prof --salvage-stale-profile --salvage-unused-profile -S --debug-only=sample-profile,sample-profile-matcher,sample-profile-impl -profile-isfs 2>&1 | FileCheck %s
+
+; Test that stale profile matching correctly distinguishes template
+; specializations by preserving template arguments in the demangled base name.
+; The IR has ns2::foo<int> and ns2::foo<double>, while the profile was collected
+; from ns1::foo<int> and ns1::foo<double>. The matcher should pair each IR
+; function with the profile entry that has the same template arguments, not
+; conflate them under the bare name "foo".
+
+; Verify orphan functions are detected.
+; CHECK-DAG: Function _ZN3ns23fooIiEET_S1_ is not in profile or profile symbol list.
+; CHECK-DAG: Function _ZN3ns23fooIdEET_S1_ is not in profile or profile symbol list.
+
+; Verify basename matching preserves template arguments: foo<int> matches
+; foo<int>, foo<double> matches foo<double>, and they are not conflated.
+; CHECK-DAG: The functions _ZN3ns23fooIiEET_S1_(IR) and _ZN3ns13fooIiEET_S1_(Profile) share the same base name: foo<int>.
+; CHECK-DAG: Function:_ZN3ns23fooIiEET_S1_ matches profile:_ZN3ns13fooIiEET_S1_
+; CHECK-DAG: The functions _ZN3ns23fooIdEET_S1_(IR) and _ZN3ns13fooIdEET_S1_(Profile) share the same base name: foo<double>.
+; CHECK-DAG: Function:_ZN3ns23fooIdEET_S1_ matches profile:_ZN3ns13fooIdEET_S1_
+
+target datalayout = "e-m:e-p270:32:32-p271:32:32-p272:64:64-i64:64-i128:128-f80:128-n8:16:32:64-S128"
+target triple = "x86_64-unknown-linux-gnu"
+
+ at x = dso_local global i32 1, align 4
+
+define dso_local i32 @_Z3bari(i32 noundef %p) #0 !dbg !9 {
+entry:
+ ret i32 %p, !dbg !13
+}
+
+define dso_local i32 @_ZN3ns23fooIiEET_S1_(i32 noundef %x) #0 !dbg !14 {
+entry:
+ %add = add nsw i32 %x, 1, !dbg !15
+ ret i32 %add, !dbg !16
+}
+
+define dso_local double @_ZN3ns23fooIdEET_S1_(double noundef %x) #0 !dbg !17 {
+entry:
+ %add = fadd double %x, 1.000000e+00, !dbg !20
+ ret double %add, !dbg !21
+}
+
+define dso_local i32 @main() #1 !dbg !22 {
+entry:
+ br label %for.cond, !dbg !23
+
+for.cond:
+ %i.0 = phi i32 [ 0, %entry ], [ %inc, %for.body ], !dbg !24
+ %cmp = icmp slt i32 %i.0, 1000000, !dbg !25
+ br i1 %cmp, label %for.body, label %for.end, !dbg !26
+
+for.body:
+ %0 = load volatile i32, ptr @x, align 4, !dbg !27
+ %call = call i32 @_ZN3ns23fooIiEET_S1_(i32 noundef %0), !dbg !28
+ %1 = load volatile i32, ptr @x, align 4, !dbg !29
+ %add = add nsw i32 %1, %call, !dbg !29
+ store volatile i32 %add, ptr @x, align 4, !dbg !29
+ %2 = load volatile i32, ptr @x, align 4, !dbg !30
+ %call2 = call i32 @_Z3bari(i32 noundef %2), !dbg !31
+ %3 = load volatile i32, ptr @x, align 4, !dbg !32
+ %add3 = add nsw i32 %3, %call2, !dbg !32
+ store volatile i32 %add3, ptr @x, align 4, !dbg !32
+ %4 = load volatile i32, ptr @x, align 4, !dbg !33
+ %conv = sitofp i32 %4 to double, !dbg !33
+ %call4 = call double @_ZN3ns23fooIdEET_S1_(double noundef %conv), !dbg !34
+ %conv5 = fptosi double %call4 to i32, !dbg !34
+ %5 = load volatile i32, ptr @x, align 4, !dbg !35
+ %add6 = add nsw i32 %5, %conv5, !dbg !35
+ store volatile i32 %add6, ptr @x, align 4, !dbg !35
+ %6 = load volatile i32, ptr @x, align 4, !dbg !36
+ %call7 = call i32 @_Z3bari(i32 noundef %6), !dbg !37
+ %7 = load volatile i32, ptr @x, align 4, !dbg !38
+ %add8 = add nsw i32 %7, %call7, !dbg !38
+ store volatile i32 %add8, ptr @x, align 4, !dbg !38
+ %inc = add nsw i32 %i.0, 1, !dbg !39
+ br label %for.cond, !dbg !40, !llvm.loop !41
+
+for.end:
+ ret i32 0, !dbg !44
+}
+
+attributes #0 = { noinline nounwind uwtable "min-legal-vector-width"="0" "no-trapping-math"="true" "stack-protector-buffer-size"="8" "target-cpu"="x86-64" "target-features"="+cmov,+cx8,+fxsr,+mmx,+sse,+sse2,+x87" "tune-cpu"="generic" "use-sample-profile" }
+attributes #1 = { nounwind uwtable "min-legal-vector-width"="0" "no-trapping-math"="true" "stack-protector-buffer-size"="8" "target-cpu"="x86-64" "target-features"="+cmov,+cx8,+fxsr,+mmx,+sse,+sse2,+x87" "tune-cpu"="generic" "use-sample-profile" }
+
+!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 19.0.0git", isOptimized: true, runtimeVersion: 0, emissionKind: LineTablesOnly, splitDebugInlining: false, debugInfoForProfiling: true, nameTableKind: None)
+!1 = !DIFile(filename: "test.cpp", directory: "path")
+!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, !"PIE Level", i32 2}
+!7 = !{i32 7, !"uwtable", i32 2}
+!8 = !{!"clang version 19.0.0git"}
+!9 = distinct !DISubprogram(name: "bar", linkageName: "_Z3bari", scope: !10, file: !10, line: 2, type: !11, scopeLine: 2, flags: DIFlagPrototyped | DIFlagAllCallsDescribed, spFlags: DISPFlagDefinition | DISPFlagOptimized, unit: !0)
+!10 = !DIFile(filename: "test.cpp", directory: "path")
+!11 = !DISubroutineType(types: !12)
+!12 = !{}
+!13 = !DILocation(line: 3, column: 3, scope: !9)
+!14 = distinct !DISubprogram(name: "foo<int>", linkageName: "_ZN3ns23fooIiEET_S1_", scope: !10, file: !10, line: 6, type: !11, scopeLine: 6, flags: DIFlagPrototyped | DIFlagAllCallsDescribed, spFlags: DISPFlagDefinition | DISPFlagOptimized, unit: !0)
+!15 = !DILocation(line: 7, column: 12, scope: !14)
+!16 = !DILocation(line: 7, column: 3, scope: !14)
+!17 = distinct !DISubprogram(name: "foo<double>", linkageName: "_ZN3ns23fooIdEET_S1_", scope: !10, file: !10, line: 6, type: !11, scopeLine: 6, flags: DIFlagPrototyped | DIFlagAllCallsDescribed, spFlags: DISPFlagDefinition | DISPFlagOptimized, unit: !0)
+!20 = !DILocation(line: 7, column: 12, scope: !17)
+!21 = !DILocation(line: 7, column: 3, scope: !17)
+!22 = distinct !DISubprogram(name: "main", scope: !10, file: !10, line: 11, type: !11, scopeLine: 11, flags: DIFlagAllCallsDescribed, spFlags: DISPFlagDefinition | DISPFlagOptimized, unit: !0)
+!23 = !DILocation(line: 12, column: 3, scope: !22)
+!24 = !DILocation(line: 12, scope: !22)
+!25 = !DILocation(line: 12, column: 21, scope: !22)
+!26 = !DILocation(line: 12, column: 3, scope: !22)
+!27 = !DILocation(line: 13, column: 18, scope: !22)
+!28 = !DILocation(line: 13, column: 11, scope: !22)
+!29 = !DILocation(line: 13, column: 8, scope: !22)
+!30 = !DILocation(line: 14, column: 15, scope: !22)
+!31 = !DILocation(line: 14, column: 11, scope: !22)
+!32 = !DILocation(line: 14, column: 8, scope: !22)
+!33 = !DILocation(line: 15, column: 18, scope: !22)
+!34 = !DILocation(line: 15, column: 11, scope: !22)
+!35 = !DILocation(line: 15, column: 8, scope: !22)
+!36 = !DILocation(line: 16, column: 15, scope: !22)
+!37 = !DILocation(line: 16, column: 11, scope: !22)
+!38 = !DILocation(line: 16, column: 8, scope: !22)
+!39 = !DILocation(line: 12, column: 37, scope: !22)
+!40 = !DILocation(line: 12, column: 3, scope: !22)
+!41 = distinct !{!41, !42, !43}
+!42 = !DILocation(line: 12, column: 3, scope: !22)
+!43 = !DILocation(line: 17, column: 3, scope: !22)
+!44 = !DILocation(line: 18, column: 1, scope: !22)
>From 729b8ae930258ba66bbdcb9bece67f87c17be6e0 Mon Sep 17 00:00:00 2001
From: h2h <h2h at meta.com>
Date: Tue, 5 May 2026 16:05:32 -0700
Subject: [PATCH 2/2] format
---
llvm/lib/Transforms/IPO/SampleProfileMatcher.cpp | 3 +--
1 file changed, 1 insertion(+), 2 deletions(-)
diff --git a/llvm/lib/Transforms/IPO/SampleProfileMatcher.cpp b/llvm/lib/Transforms/IPO/SampleProfileMatcher.cpp
index 4591559fc01aa..1d874ad087748 100644
--- a/llvm/lib/Transforms/IPO/SampleProfileMatcher.cpp
+++ b/llvm/lib/Transforms/IPO/SampleProfileMatcher.cpp
@@ -776,8 +776,7 @@ static std::string getDemangledBaseName(ItaniumPartialDemangler &Demangler,
while (!CtxStr.empty() && CtxStr.back() == '\0')
CtxStr = CtxStr.drop_back();
StringRef ResultRef(Result);
- if (ResultRef.starts_with(CtxStr) &&
- ResultRef.size() > CtxStr.size() + 2 &&
+ if (ResultRef.starts_with(CtxStr) && ResultRef.size() > CtxStr.size() + 2 &&
ResultRef[CtxStr.size()] == ':' && ResultRef[CtxStr.size() + 1] == ':')
Result = ResultRef.substr(CtxStr.size() + 2).str();
}
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