[llvm-commits] [llvm] r156023 - in /llvm/trunk: lib/CodeGen/SelectionDAG/DAGCombiner.cpp test/CodeGen/ARM/fmuls.ll

[Owen Anderson]

Author: resistor
Date: Wed May  2 16:32:35 2012
New Revision: 156023

URL: http://llvm.org/viewvc/llvm-project?rev=156023&view=rev
Log:
Teach DAG combine that multiplication by 1.0 can always be constant folded.

Modified:
    llvm/trunk/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
    llvm/trunk/test/CodeGen/ARM/fmuls.ll

Modified: llvm/trunk/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/CodeGen/SelectionDAG/DAGCombiner.cpp?rev=156023&r1=156022&r2=156023&view=diff
==============================================================================
--- llvm/trunk/lib/CodeGen/SelectionDAG/DAGCombiner.cpp (original)
+++ llvm/trunk/lib/CodeGen/SelectionDAG/DAGCombiner.cpp Wed May  2 16:32:35 2012
@@ -5715,6 +5715,9 @@
   if (DAG.getTarget().Options.UnsafeFPMath &&
       ISD::isBuildVectorAllZeros(N1.getNode()))
     return N1;
+  // fold (fmul A, 1.0) -> A
+  if (N1CFP && N1CFP->isExactlyValue(1.0))
+    return N0;
   // fold (fmul X, 2.0) -> (fadd X, X)
   if (N1CFP && N1CFP->isExactlyValue(+2.0))
     return DAG.getNode(ISD::FADD, N->getDebugLoc(), VT, N0, N0);

Modified: llvm/trunk/test/CodeGen/ARM/fmuls.ll
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/CodeGen/ARM/fmuls.ll?rev=156023&r1=156022&r2=156023&view=diff
==============================================================================
--- llvm/trunk/test/CodeGen/ARM/fmuls.ll (original)
+++ llvm/trunk/test/CodeGen/ARM/fmuls.ll Wed May  2 16:32:35 2012
@@ -21,3 +21,12 @@
 ; CORTEXA8: 	vmul.f32	d0, d1, d0
 ; CORTEXA9: test:
 ; CORTEXA9: 	vmul.f32	s{{.}}, s{{.}}, s{{.}}
+
+; VFP2: test2
+define float @test2(float %a) nounwind {
+; CHECK-NOT: mul
+; CHECK: mov pc, lr
+  %ret = fmul float %a, 1.0
+  ret float %ret
+}
+