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[profcheck] Allow unknown function entry count #155918

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Merged
merged 1 commit into from
Sep 4, 2025
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[profcheck] Allow unknown function entry count #155918

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6 changes: 5 additions & 1 deletion llvm/include/llvm/IR/ProfDataUtils.h
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Expand Up @@ -180,7 +180,11 @@ inline uint32_t scaleBranchCount(uint64_t Count, uint64_t Scale) {
/// info.
LLVM_ABI void setExplicitlyUnknownBranchWeights(Instruction &I);

LLVM_ABI bool isExplicitlyUnknownBranchWeightsMetadata(const MDNode &MD);
/// Analogous to setExplicitlyUnknownBranchWeights, but for functions and their
/// entry counts.
LLVM_ABI void setExplicitlyUnknownFunctionEntryCount(Function &F);

LLVM_ABI bool isExplicitlyUnknownProfileMetadata(const MDNode &MD);
LLVM_ABI bool hasExplicitlyUnknownBranchWeights(const Instruction &I);

/// Scaling the profile data attached to 'I' using the ratio of S/T.
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12 changes: 10 additions & 2 deletions llvm/lib/IR/ProfDataUtils.cpp
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Expand Up @@ -250,7 +250,15 @@ void setExplicitlyUnknownBranchWeights(Instruction &I) {
MDB.createString(MDProfLabels::UnknownBranchWeightsMarker)));
}

bool isExplicitlyUnknownBranchWeightsMetadata(const MDNode &MD) {
void setExplicitlyUnknownFunctionEntryCount(Function &F) {
MDBuilder MDB(F.getContext());
F.setMetadata(
LLVMContext::MD_prof,
MDNode::get(F.getContext(),
MDB.createString(MDProfLabels::UnknownBranchWeightsMarker)));
}

bool isExplicitlyUnknownProfileMetadata(const MDNode &MD) {
if (MD.getNumOperands() != 1)
return false;
return MD.getOperand(0).equalsStr(MDProfLabels::UnknownBranchWeightsMarker);
Expand All @@ -260,7 +268,7 @@ bool hasExplicitlyUnknownBranchWeights(const Instruction &I) {
auto *MD = I.getMetadata(LLVMContext::MD_prof);
if (!MD)
return false;
return isExplicitlyUnknownBranchWeightsMetadata(*MD);
return isExplicitlyUnknownProfileMetadata(*MD);
}

void setBranchWeights(Instruction &I, ArrayRef<uint32_t> Weights,
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9 changes: 4 additions & 5 deletions llvm/lib/IR/Verifier.cpp
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Expand Up @@ -2529,12 +2529,11 @@ void Verifier::verifyFunctionMetadata(
for (const auto &Pair : MDs) {
if (Pair.first == LLVMContext::MD_prof) {
MDNode *MD = Pair.second;
if (isExplicitlyUnknownBranchWeightsMetadata(*MD)) {
CheckFailed("'unknown' !prof metadata should appear only on "
"instructions supporting the 'branch_weights' metadata",
MD);
// We may have functions that are synthesized by the compiler, e.g. in
// WPD, that we can't currently determine the entry count.
if (isExplicitlyUnknownProfileMetadata(*MD))
continue;
}

Check(MD->getNumOperands() >= 2,
"!prof annotations should have no less than 2 operands", MD);

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11 changes: 7 additions & 4 deletions llvm/lib/Transforms/Utils/ProfileVerify.cpp
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Expand Up @@ -155,12 +155,15 @@ PreservedAnalyses ProfileVerifierPass::run(Function &F,
FunctionAnalysisManager &FAM) {
const auto EntryCount = F.getEntryCount(/*AllowSynthetic=*/true);
if (!EntryCount) {
F.getContext().emitError("Profile verification failed: function entry "
"count missing (set to 0 if cold)");
auto *MD = F.getMetadata(LLVMContext::MD_prof);
if (!MD || !isExplicitlyUnknownProfileMetadata(*MD)) {
F.getContext().emitError("Profile verification failed: function entry "
"count missing (set to 0 if cold)");
return PreservedAnalyses::all();
}
} else if (EntryCount->getCount() == 0) {
return PreservedAnalyses::all();
}
if (EntryCount->getCount() == 0)
return PreservedAnalyses::all();
for (const auto &BB : F) {
if (AnnotateSelect) {
for (const auto &I : BB)
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4 changes: 2 additions & 2 deletions llvm/test/Verifier/branch-weight.ll
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Expand Up @@ -11,7 +11,7 @@
; RUN: opt -passes=verify %t/unknown-correct.ll --disable-output

; RUN: not opt -passes=verify %t/unknown-invalid.ll --disable-output 2>&1 | FileCheck %s --check-prefix=EXTRA-ARGS
; RUN: not opt -passes=verify %t/unknown-on-function1.ll --disable-output 2>&1 | FileCheck %s --check-prefix=ON-FUNCTION1
; RUN: opt -passes=verify %t/unknown-on-function1.ll -S -o - | FileCheck %s --check-prefix=ON-FUNCTION1
; RUN: not opt -passes=verify %t/unknown-on-function2.ll --disable-output 2>&1 | FileCheck %s --check-prefix=ON-FUNCTION2
; RUN: not opt -passes=verify %t/invalid-unknown-placement.ll --disable-output 2>&1 | FileCheck %s --check-prefix=INVALID-UNKNOWN-PLACEMENT

Expand Down Expand Up @@ -132,7 +132,7 @@ define void @test() !prof !0 {
}

!0 = !{!"unknown"}
; ON-FUNCTION1: 'unknown' !prof metadata should appear only on instructions supporting the 'branch_weights' metadata
; ON-FUNCTION1: define void @test() !prof !0

;--- unknown-on-function2.ll
define void @test() !prof !0 {
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