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[InstSimplify] Teach fsub -0.0, (fneg X) ==> X about unary fneg

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Differential Revision: https://reviews.llvm.org/D62077

llvm-svn: 361151
This commit is contained in:
Cameron McInally 2019-05-20 13:13:35 +00:00
parent de484dcc25
commit 27148536f0
2 changed files with 5 additions and 10 deletions
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3
lib/Analysis/InstructionSimplify.cpp
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@ -4404,9 +4404,10 @@ static Value *SimplifyFSubInst(Value *Op0, Value *Op1, FastMathFlags FMF,
return Op0;
// fsub -0.0, (fsub -0.0, X) ==> X
// fsub -0.0, (fneg X) ==> X
Value *X;
if (match(Op0, m_NegZeroFP()) &&
match(Op1, m_FSub(m_NegZeroFP(), m_Value(X))))
match(Op1, m_FNeg(m_Value(X))))
return X;
// fsub 0.0, (fsub 0.0, X) ==> X if signed zeros are ignored.

12
test/Transforms/InstSimplify/floating-point-arithmetic.ll
View File

@ -60,9 +60,7 @@ define float @fsub_-0_-0_x(float %a) {
; fsub -0.0, (fneg X) ==> X
define float @fneg_x(float %a) {
; CHECK-LABEL: @fneg_x(
; CHECK-NEXT: %t1 = fneg float %a
; CHECK-NEXT: %ret = fsub float -0.000000e+00, %t1
; CHECK-NEXT: ret float %ret
; CHECK-NEXT: ret float [[A:%.*]]
;
%t1 = fneg float %a
%ret = fsub float -0.0, %t1
@ -80,9 +78,7 @@ define <2 x float> @fsub_-0_-0_x_vec(<2 x float> %a) {
define <2 x float> @fneg_x_vec(<2 x float> %a) {
; CHECK-LABEL: @fneg_x_vec(
; CHECK-NEXT: %t1 = fneg <2 x float> %a
; CHECK-NEXT: %ret = fsub <2 x float> <float -0.000000e+00, float -0.000000e+00>, %t1
; CHECK-NEXT: ret <2 x float> %ret
; CHECK-NEXT: ret <2 x float> [[A:%.*]]
;
%t1 = fneg <2 x float> %a
%ret = fsub <2 x float> <float -0.0, float -0.0>, %t1
@ -100,9 +96,7 @@ define <2 x float> @fsub_-0_-0_x_vec_undef_elts(<2 x float> %a) {
define <2 x float> @fneg_x_vec_undef_elts(<2 x float> %a) {
; CHECK-LABEL: @fneg_x_vec_undef_elts(
; CHECK-NEXT: %t1 = fneg <2 x float> %a
; CHECK-NEXT: %ret = fsub <2 x float> <float -0.000000e+00, float undef>, %t1
; CHECK-NEXT: ret <2 x float> %ret
; CHECK-NEXT: ret <2 x float> [[A:%.*]]
;
%t1 = fneg <2 x float> %a
%ret = fsub <2 x float> <float -0.0, float undef>, %t1