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[InstCombine] Fix worklist management in select fold #77738

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merged 1 commit into from Jan 11, 2024
Merged

[InstCombine] Fix worklist management in select fold #77738

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4 changes: 2 additions & 2 deletions llvm/lib/Transforms/InstCombine/InstCombineSelect.cpp
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Expand Up @@ -1703,11 +1703,11 @@ Instruction *InstCombinerImpl::foldSelectInstWithICmp(SelectInst &SI,
if (CmpRHS != CmpLHS && isa<Constant>(CmpRHS) && !isa<Constant>(CmpLHS)) {
if (CmpLHS == TrueVal && Pred == ICmpInst::ICMP_EQ) {
// Transform (X == C) ? X : Y -> (X == C) ? C : Y
SI.setOperand(1, CmpRHS);
replaceOperand(SI, 1, CmpRHS);
Changed = true;
} else if (CmpLHS == FalseVal && Pred == ICmpInst::ICMP_NE) {
// Transform (X != C) ? Y : X -> (X != C) ? Y : C
SI.setOperand(2, CmpRHS);
replaceOperand(SI, 2, CmpRHS);
Changed = true;
}
}
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14 changes: 14 additions & 0 deletions llvm/test/Transforms/InstCombine/select.ll
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Expand Up @@ -3646,3 +3646,17 @@ loop:
exit:
ret i32 %rem
}

; (X == C) ? X : Y -> (X == C) ? C : Y
; Fixed #77553
define i32 @src_select_xxory_eq0_xorxy_y(i32 %x, i32 %y) {
; CHECK-LABEL: @src_select_xxory_eq0_xorxy_y(
; CHECK-NEXT: [[XOR0:%.*]] = icmp eq i32 [[X:%.*]], [[Y:%.*]]
; CHECK-NEXT: [[COND:%.*]] = select i1 [[XOR0]], i32 0, i32 [[Y]]
; CHECK-NEXT: ret i32 [[COND]]
;
%xor = xor i32 %x, %y
%xor0 = icmp eq i32 %xor, 0
%cond = select i1 %xor0, i32 %xor, i32 %y
ret i32 %cond
}