[llvm] r361151 - [InstSimplify] Teach fsub -0.0, (fneg X) ==> X about unary fneg

[Cameron McInally via llvm-commits]

Author: mcinally
Date: Mon May 20 06:13:35 2019
New Revision: 361151

URL: http://llvm.org/viewvc/llvm-project?rev=361151&view=rev
Log:
[InstSimplify] Teach fsub -0.0, (fneg X) ==> X about unary fneg

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

Modified:
    llvm/trunk/lib/Analysis/InstructionSimplify.cpp
    llvm/trunk/test/Transforms/InstSimplify/floating-point-arithmetic.ll

Modified: llvm/trunk/lib/Analysis/InstructionSimplify.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Analysis/InstructionSimplify.cpp?rev=361151&r1=361150&r2=361151&view=diff
==============================================================================
--- llvm/trunk/lib/Analysis/InstructionSimplify.cpp (original)
+++ llvm/trunk/lib/Analysis/InstructionSimplify.cpp Mon May 20 06:13:35 2019
@@ -4404,9 +4404,10 @@ static Value *SimplifyFSubInst(Value *Op
     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.

Modified: llvm/trunk/test/Transforms/InstSimplify/floating-point-arithmetic.ll
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/Transforms/InstSimplify/floating-point-arithmetic.ll?rev=361151&r1=361150&r2=361151&view=diff
==============================================================================
--- llvm/trunk/test/Transforms/InstSimplify/floating-point-arithmetic.ll (original)
+++ llvm/trunk/test/Transforms/InstSimplify/floating-point-arithmetic.ll Mon May 20 06:13:35 2019
@@ -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
 
 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_und
 
 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