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Teach DAG combine that multiplication by 1.0 can always be constant folded.

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git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@156023 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Owen Anderson 2012-05-02 21:32:35 +00:00
parent 4599613dec
commit 363e4b90c0
2 changed files with 12 additions and 0 deletions
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3
lib/CodeGen/SelectionDAG/DAGCombiner.cpp
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@ -5715,6 +5715,9 @@ SDValue DAGCombiner::visitFMUL(SDNode *N) {
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);

9
test/CodeGen/ARM/fmuls.ll
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@ -21,3 +21,12 @@ entry:
; 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
}