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InstCombine: fabs(x) * fabs(x) -> x * x

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llvm-svn: 259295
This commit is contained in:
Matt Arsenault 2016-01-30 05:02:00 +00:00
parent 3f3cb842c4
commit d68c0fe0a6
2 changed files with 44 additions and 4 deletions
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19
lib/Transforms/InstCombine/InstCombineMulDivRem.cpp
View File

@ -612,12 +612,23 @@ Instruction *InstCombiner::visitFMul(BinaryOperator &I) {
}
}
// sqrt(X) * sqrt(X) -> X
if (AllowReassociate && (Op0 == Op1))
if (IntrinsicInst *II = dyn_cast<IntrinsicInst>(Op0))
if (II->getIntrinsicID() == Intrinsic::sqrt)
if (Op0 == Op1) {
if (IntrinsicInst *II = dyn_cast<IntrinsicInst>(Op0)) {
// sqrt(X) * sqrt(X) -> X
if (AllowReassociate && II->getIntrinsicID() == Intrinsic::sqrt)
return ReplaceInstUsesWith(I, II->getOperand(0));
// fabs(X) * fabs(X) -> X * X
if (II->getIntrinsicID() == Intrinsic::fabs) {
Instruction *FMulVal = BinaryOperator::CreateFMul(II->getOperand(0),
II->getOperand(0),
I.getName());
FMulVal->copyFastMathFlags(&I);
return FMulVal;
}
}
}
// Under unsafe algebra do:
// X * log2(0.5*Y) = X*log2(Y) - X
if (AllowReassociate) {

29
test/Transforms/InstCombine/fmul.ll
View File

@ -152,3 +152,32 @@ define double @sqrt_squared2(double %f) {
; CHECK-NEXT: %mul2 = fmul double %sqrt, %f
; CHECK-NEXT: ret double %mul2
}
declare float @llvm.fabs.f32(float) nounwind readnone
; CHECK-LABEL @fabs_squared(
; CHECK: %mul = fmul float %x, %x
define float @fabs_squared(float %x) {
%x.fabs = call float @llvm.fabs.f32(float %x)
%mul = fmul float %x.fabs, %x.fabs
ret float %mul
}
; CHECK-LABEL @fabs_squared_fast(
; CHECK: %mul = fmul fast float %x, %x
define float @fabs_squared_fast(float %x) {
%x.fabs = call float @llvm.fabs.f32(float %x)
%mul = fmul fast float %x.fabs, %x.fabs
ret float %mul
}
; CHECK-LABEL @fabs_x_fabs(
; CHECK: call float @llvm.fabs.f32(float %x)
; CHECK: call float @llvm.fabs.f32(float %y)
; CHECK: %mul = fmul float %x.fabs, %y.fabs
define float @fabs_x_fabs(float %x, float %y) {
%x.fabs = call float @llvm.fabs.f32(float %x)
%y.fabs = call float @llvm.fabs.f32(float %y)
%mul = fmul float %x.fabs, %y.fabs
ret float %mul
}