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[InstCombine] canonicalize fneg with llvm.sin 

This is a follow-up to rL339604 which did the same transform
for a sin libcall. The handling of intrinsics vs. libcalls
is unfortunately scattered, so I'm just adding this next to
the existing transform for llvm.cos for now.

This should resolve PR38458:
https://bugs.llvm.org/show_bug.cgi?id=38458
If the call was already negated, the negates will cancel
each other out.

llvm-svn: 340952
This commit is contained in:
Sanjay Patel 2018-08-29 18:27:49 +00:00
parent f5403d83e7
commit 0f29e953b7
2 changed files with 20 additions and 11 deletions
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19
llvm/lib/Transforms/InstCombine/InstCombineCalls.cpp
View File

@ -2124,16 +2124,25 @@ Instruction *InstCombiner::visitCallInst(CallInst &CI) {
}
case Intrinsic::cos:
case Intrinsic::amdgcn_cos: {
Value *SrcSrc;
Value *X;
Value *Src = II->getArgOperand(0);
if (match(Src, m_FNeg(m_Value(SrcSrc))) ||
match(Src, m_FAbs(m_Value(SrcSrc)))) {
if (match(Src, m_FNeg(m_Value(X))) || match(Src, m_FAbs(m_Value(X)))) {
// cos(-x) -> cos(x)
// cos(fabs(x)) -> cos(x)
II->setArgOperand(0, SrcSrc);
II->setArgOperand(0, X);
return II;
}
break;
}
case Intrinsic::sin: {
Value *X;
if (match(II->getArgOperand(0), m_OneUse(m_FNeg(m_Value(X))))) {
// sin(-x) --> -sin(x)
Value *NewSin = Builder.CreateIntrinsic(Intrinsic::sin, { X }, II);
Instruction *FNeg = BinaryOperator::CreateFNeg(NewSin);
FNeg->copyFastMathFlags(II);
return FNeg;
}
break;
}
case Intrinsic::ppc_altivec_lvx:

12
llvm/test/Transforms/InstCombine/cos-sin-intrinsic.ll
View File

@ -92,14 +92,14 @@ define <2 x float> @fabs_fneg_v2f32(<2 x float> %x) {
ret <2 x float> %cos
}
; TODO: Negate is canonicalized after sin.
; Negate is canonicalized after sin.
declare <2 x float> @llvm.sin.v2f32(<2 x float>)
define <2 x float> @fneg_sin(<2 x float> %x){
; CHECK-LABEL: @fneg_sin(
; CHECK-NEXT: [[NEGX:%.*]] = fsub <2 x float> <float -0.000000e+00, float -0.000000e+00>, [[X:%.*]]
; CHECK-NEXT: [[R:%.*]] = call <2 x float> @llvm.sin.v2f32(<2 x float> [[NEGX]])
; CHECK-NEXT: [[TMP1:%.*]] = call <2 x float> @llvm.sin.v2f32(<2 x float> [[X:%.*]])
; CHECK-NEXT: [[R:%.*]] = fsub <2 x float> <float -0.000000e+00, float -0.000000e+00>, [[TMP1]]
; CHECK-NEXT: ret <2 x float> [[R]]
;
%negx = fsub <2 x float> <float -0.0, float -0.0>, %x
@ -107,12 +107,12 @@ define <2 x float> @fneg_sin(<2 x float> %x){
ret <2 x float> %r
}
; TODO: FMF are not required, but they should propagate.
; FMF are not required, but they should propagate.
define <2 x float> @fneg_sin_fmf(<2 x float> %x){
; CHECK-LABEL: @fneg_sin_fmf(
; CHECK-NEXT: [[NEGX:%.*]] = fsub fast <2 x float> <float -0.000000e+00, float -0.000000e+00>, [[X:%.*]]
; CHECK-NEXT: [[R:%.*]] = call nnan arcp afn <2 x float> @llvm.sin.v2f32(<2 x float> [[NEGX]])
; CHECK-NEXT: [[TMP1:%.*]] = call nnan arcp afn <2 x float> @llvm.sin.v2f32(<2 x float> [[X:%.*]])
; CHECK-NEXT: [[R:%.*]] = fsub nnan arcp afn <2 x float> <float -0.000000e+00, float -0.000000e+00>, [[TMP1]]
; CHECK-NEXT: ret <2 x float> [[R]]
;
%negx = fsub fast <2 x float> <float -0.0, float -0.0>, %x