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[InstCombine] Treat identical operands as one in pushFreezeToPreventPoisonFromPropagating #145348

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[InstCombine] Treat identical operands as one in pushFreezeToPreventPoisonFromPropagating #145348

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e325b41
[InstCombine] Precommit test
c-rhodes Jun 23, 2025
110cb6e
[InstCombine] Treat identical operands as one in pushFreezeToPreventP…
c-rhodes Jun 23, 2025
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4 changes: 3 additions & 1 deletion llvm/lib/Transforms/InstCombine/InstructionCombining.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -4774,7 +4774,9 @@ InstCombinerImpl::pushFreezeToPreventPoisonFromPropagating(FreezeInst &OrigFI) {
Use *MaybePoisonOperand = nullptr;
for (Use &U : OrigOpInst->operands()) {
if (isa<MetadataAsValue>(U.get()) ||
isGuaranteedNotToBeUndefOrPoison(U.get()))
isGuaranteedNotToBeUndefOrPoison(U.get()) ||
// Treat identical operands as a single operand.
(MaybePoisonOperand && MaybePoisonOperand->get() == U.get()))
continue;
if (!MaybePoisonOperand)
MaybePoisonOperand = &U;
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11 changes: 11 additions & 0 deletions llvm/test/Transforms/InstCombine/freeze.ll
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Expand Up @@ -142,6 +142,17 @@ define i32 @early_freeze_test3(i32 %v1) {
ret i32 %v4.fr
}

define i32 @early_freeze_test4(i32 %v1) {
; CHECK-LABEL: @early_freeze_test4(
; CHECK-NEXT: [[V2_FR:%.*]] = freeze i32 [[V2:%.*]]
; CHECK-NEXT: [[V3:%.*]] = mul i32 [[V2_FR]], [[V2_FR]]
; CHECK-NEXT: ret i32 [[V3]]
;
%v2 = mul i32 %v1, %v1
%v2.fr = freeze i32 %v2
ret i32 %v2.fr
}

; If replace all dominated uses of v to freeze(v).

define void @freeze_dominated_uses_test1(i32 %v) {
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