[llvm] r199424 - Fix a bug in InstCombine where we failed to preserve fast math flags when optimizing an FMUL expression.

[Owen Anderson]

Author: resistor
Date: Thu Jan 16 14:59:41 2014
New Revision: 199424

URL: http://llvm.org/viewvc/llvm-project?rev=199424&view=rev
Log:
Fix a bug in InstCombine where we failed to preserve fast math flags when optimizing an FMUL expression.

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=199424&r1=199423&r2=199424&view=diff
==============================================================================
--- llvm/trunk/lib/Transforms/InstCombine/InstCombineMulDivRem.cpp (original)
+++ llvm/trunk/lib/Transforms/InstCombine/InstCombineMulDivRem.cpp Thu Jan 16 14:59:41 2014
@@ -525,8 +525,11 @@ Instruction *InstCombiner::visitFMul(Bin
       Value *N1 = dyn_castFNegVal(Opnd1, IgnoreZeroSign);
 
       // -X * -Y => X*Y
-      if (N1)
-        return BinaryOperator::CreateFMul(N0, N1);
+      if (N1) {
+        Value *FMul = Builder->CreateFMul(N0, N1);
+        FMul->takeName(&I);
+        return ReplaceInstUsesWith(I, FMul);
+      }
 
       if (Opnd0->hasOneUse()) {
         // -X * Y => -(X*Y) (Promote negation as high as possible)

Modified: llvm/trunk/test/Transforms/InstCombine/fmul.ll
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/Transforms/InstCombine/fmul.ll?rev=199424&r1=199423&r2=199424&view=diff
==============================================================================
--- llvm/trunk/test/Transforms/InstCombine/fmul.ll (original)
+++ llvm/trunk/test/Transforms/InstCombine/fmul.ll Thu Jan 16 14:59:41 2014
@@ -24,10 +24,10 @@ define float @test2(float %x) {
 define float @test3(float %x, float %y) {
   %sub1 = fsub float -0.000000e+00, %x
   %sub2 = fsub float -0.000000e+00, %y
-  %mul = fmul float %sub1, %sub2
+  %mul = fmul fast float %sub1, %sub2
   ret float %mul
 ; CHECK-LABEL: @test3(
-; CHECK: fmul float %x, %y
+; CHECK: fmul fast float %x, %y
 }
 
 ; (0.0 - X) * (0.0 - Y) => X * Y
@@ -104,4 +104,3 @@ define float @test9(float %x) {
 ; CHECK: fsub
 }
 
-