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[ValueTracking] Add missing check for two-value PN recurrance matching #152700

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Merged
merged 4 commits into from
Aug 8, 2025
Merged

[ValueTracking] Add missing check for two-value PN recurrance matching #152700

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7549fd2
[ValueTracking] Add missing check for two-value PN recurrance matching
ivanradanov Aug 8, 2025
17613e1
Actually check >= operands
ivanradanov Aug 8, 2025
a5bc84b
Add lit test
ivanradanov Aug 8, 2025
f80ad3f
Add checks
ivanradanov Aug 8, 2025
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3 changes: 2 additions & 1 deletion llvm/lib/Analysis/ValueTracking.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -9147,7 +9147,8 @@ static bool matchTwoInputRecurrence(const PHINode *PN, InstTy *&Inst,
return false;

for (unsigned I = 0; I != 2; ++I) {
if (auto *Operation = dyn_cast<InstTy>(PN->getIncomingValue(I))) {
if (auto *Operation = dyn_cast<InstTy>(PN->getIncomingValue(I));
Operation && Operation->getNumOperands() >= 2) {
Value *LHS = Operation->getOperand(0);
Value *RHS = Operation->getOperand(1);
if (LHS != PN && RHS != PN)
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16 changes: 16 additions & 0 deletions llvm/test/Analysis/ValueTracking/pr152700.ll
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@@ -0,0 +1,16 @@
; Check that we do not crash (see PR #152700)
; RUN: opt < %s -passes=instcombine
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Suggested change
; RUN: opt < %s -passes=instcombine
; RUN: opt < %s -passes=instcombine | FileCheck %s

and generate check lines with update_test_checks.py. We prefer checking the output even for crash tests.


declare noundef i32 @llvm.nvvm.read.ptx.sreg.nctaid.x()
declare i32 @llvm.umin.i32(i32, i32)
define i32 @foo(i1 %c, i32 %arg) {
entry:
%i = call i32 @llvm.nvvm.read.ptx.sreg.nctaid.x()
br i1 %c, label %bb.1, label %bb.2
bb.1:
br label %bb.2
bb.2:
%phi = phi i32 [ %i, %entry ], [ 0, %bb.1 ]
%res = call i32 @llvm.umin.i32(i32 %phi, i32 %arg)
ret i32 %res
}
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