[llvm] r326377 - [InstCombine] simplify code for X * -1.0 --> -X; NFC

[Sanjay Patel via llvm-commits]

Author: spatel
Date: Wed Feb 28 14:30:04 2018
New Revision: 326377

URL: http://llvm.org/viewvc/llvm-project?rev=326377&view=rev
Log:
[InstCombine] simplify code for X * -1.0 --> -X; NFC

I've added random FMF to one of the tests to show those are propagated.

Modified:
    llvm/trunk/lib/Transforms/InstCombine/InstCombineMulDivRem.cpp
    llvm/trunk/test/Transforms/InstCombine/fmul.ll

Modified: llvm/trunk/lib/Transforms/InstCombine/InstCombineMulDivRem.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Transforms/InstCombine/InstCombineMulDivRem.cpp?rev=326377&r1=326376&r2=326377&view=diff
==============================================================================
--- llvm/trunk/lib/Transforms/InstCombine/InstCombineMulDivRem.cpp (original)
+++ llvm/trunk/lib/Transforms/InstCombine/InstCombineMulDivRem.cpp Wed Feb 28 14:30:04 2018
@@ -563,13 +563,9 @@ Instruction *InstCombiner::visitFMul(Bin
     if (match(Op0, m_FNeg(m_Value(X))))
       return BinaryOperator::CreateFMulFMF(X, ConstantExpr::getFNeg(C), &I);
 
-    // (fmul X, -1.0) --> (fsub -0.0, X)
-    if (match(C, m_SpecificFP(-1.0))) {
-      Constant *NegZero = ConstantFP::getNegativeZero(Op1->getType());
-      Instruction *RI = BinaryOperator::CreateFSub(NegZero, Op0);
-      RI->copyFastMathFlags(&I);
-      return RI;
-    }
+    // X * -1.0 --> -X
+    if (match(C, m_SpecificFP(-1.0)))
+      return BinaryOperator::CreateFNegFMF(Op0, &I);
 
     if (AllowReassociate && C->isFiniteNonZeroFP()) {
       // Let MDC denote an expression in one of these forms:

Modified: llvm/trunk/test/Transforms/InstCombine/fmul.ll
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/Transforms/InstCombine/fmul.ll?rev=326377&r1=326376&r2=326377&view=diff
==============================================================================
--- llvm/trunk/test/Transforms/InstCombine/fmul.ll (original)
+++ llvm/trunk/test/Transforms/InstCombine/fmul.ll Wed Feb 28 14:30:04 2018
@@ -153,10 +153,10 @@ define float @test9(float %x) {
 ; PR18532
 define <4 x float> @test10(<4 x float> %x) {
 ; CHECK-LABEL: @test10(
-; CHECK-NEXT:    [[MUL:%.*]] = fsub <4 x float> <float -0.000000e+00, float -0.000000e+00, float -0.000000e+00, float -0.000000e+00>, [[X:%.*]]
+; CHECK-NEXT:    [[MUL:%.*]] = fsub arcp afn <4 x float> <float -0.000000e+00, float -0.000000e+00, float -0.000000e+00, float -0.000000e+00>, [[X:%.*]]
 ; CHECK-NEXT:    ret <4 x float> [[MUL]]
 ;
-  %mul = fmul <4 x float> %x, <float -1.0, float -1.0, float -1.0, float -1.0>
+  %mul = fmul arcp afn <4 x float> %x, <float -1.0, float -1.0, float -1.0, float -1.0>
   ret <4 x float> %mul
 }