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[InstSimplify] Handle nsz when simplifying X * 0.0 #142181

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Merged
merged 1 commit into from
May 31, 2025
Merged

[InstSimplify] Handle nsz when simplifying X * 0.0 #142181

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3 changes: 3 additions & 0 deletions llvm/lib/Analysis/InstructionSimplify.cpp
View file
Original file line number Diff line number Diff line change
@@ -5844,6 +5844,9 @@ static Value *simplifyFMAFMul(Value *Op0, Value *Op1, FastMathFlags FMF,
KnownFPClass Known =
computeKnownFPClass(Op0, FMF, fcInf | fcNan, /*Depth=*/0, Q);
if (Known.isKnownNever(fcInf | fcNan)) {
// if nsz is set, return 0.0
if (FMF.noSignedZeros())
return ConstantFP::getZero(Op0->getType());
// +normal number * (-)0.0 --> (-)0.0
if (Known.SignBit == false)
return Op1;
16 changes: 16 additions & 0 deletions llvm/test/Transforms/InstSimplify/floating-point-arithmetic.ll
View file
Original file line number Diff line number Diff line change
@@ -211,6 +211,22 @@ define double @fmul_nnan_ninf_nneg_n0.0_commute(i127 %x) {
ret double %r
}

define float @fmul_ninf_nnan_mul_zero_nsz(float nofpclass(inf nan) %f) {
; CHECK-LABEL: @fmul_ninf_nnan_mul_zero_nsz(
; CHECK-NEXT: ret float 0.000000e+00
;
%r = fmul nsz float %f, 0.0
ret float %r
}

define float @fmul_ninf_nnan_mul_nzero_nsz(float nofpclass(inf nan) %f) {
; CHECK-LABEL: @fmul_ninf_nnan_mul_nzero_nsz(
; CHECK-NEXT: ret float 0.000000e+00
;
%r = fmul nsz float %f, -0.0
ret float %r
}

define float @src_mul_nzero_neg(float nofpclass(inf nan pzero psub pnorm) %f) {
; CHECK-LABEL: @src_mul_nzero_neg(
; CHECK-NEXT: ret float 0.000000e+00
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