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[InstSimplify] Fold {u,s}{min,max} x, poison -> poison #138166

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Merged
merged 1 commit into from
May 1, 2025
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[InstSimplify] Fold {u,s}{min,max} x, poison -> poison #138166

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4 changes: 4 additions & 0 deletions llvm/lib/Analysis/InstructionSimplify.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -6549,6 +6549,10 @@ Value *llvm::simplifyBinaryIntrinsic(Intrinsic::ID IID, Type *ReturnType,
if (match(Op0, m_ImmConstant()))
std::swap(Op0, Op1);

// Propagate poison.
if (isa<PoisonValue>(Op1))
return Op1;

// Assume undef is the limit value.
if (Q.isUndefValue(Op1))
return ConstantInt::get(
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8 changes: 4 additions & 4 deletions llvm/test/Transforms/InstSimplify/maxmin_intrinsics.ll
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Original file line number Diff line number Diff line change
Expand Up @@ -75,7 +75,7 @@ define i81 @smax_undef(i81 %x) {

define i81 @smax_poison(i81 %x) {
; CHECK-LABEL: @smax_poison(
; CHECK-NEXT: ret i81 1208925819614629174706175
; CHECK-NEXT: ret i81 poison
;
%r = call i81 @llvm.smax.i81(i81 poison, i81 %x)
ret i81 %r
Expand All @@ -91,7 +91,7 @@ define i3 @smin_undef(i3 %x) {

define i3 @smin_poison(i3 %x) {
; CHECK-LABEL: @smin_poison(
; CHECK-NEXT: ret i3 -4
; CHECK-NEXT: ret i3 poison
;
%r = call i3 @llvm.smin.i3(i3 %x, i3 poison)
ret i3 %r
Expand All @@ -107,7 +107,7 @@ define <2 x i8> @umax_undef(<2 x i8> %x) {

define <2 x i8> @umax_poison(<2 x i8> %x) {
; CHECK-LABEL: @umax_poison(
; CHECK-NEXT: ret <2 x i8> splat (i8 -1)
; CHECK-NEXT: ret <2 x i8> poison
;
%r = call <2 x i8> @llvm.umax.v2i8(<2 x i8> poison, <2 x i8> %x)
ret <2 x i8> %r
Expand All @@ -123,7 +123,7 @@ define <2 x i8> @umin_undef(<2 x i8> %x) {

define <2 x i8> @umin_poison(<2 x i8> %x) {
; CHECK-LABEL: @umin_poison(
; CHECK-NEXT: ret <2 x i8> zeroinitializer
; CHECK-NEXT: ret <2 x i8> poison
;
%r = call <2 x i8> @llvm.umin.v2i8(<2 x i8> %x, <2 x i8> poison)
ret <2 x i8> %r
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