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Add a few more simple fast-math constant propagations and cancellations.

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git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@167200 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Owen Anderson
2012-11-01 02:00:53 +00:00
parent 21caa9ef03
commit 607ebde651
2 changed files with 38 additions and 0 deletions
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18
lib/CodeGen/SelectionDAG/DAGCombiner.cpp
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@@ -5729,6 +5729,18 @@ SDValue DAGCombiner::visitFADD(SDNode *N) {
DAG.getNode(ISD::FADD, N->getDebugLoc(), VT,
N0.getOperand(1), N1));
// If allow, fold (fadd (fneg x), x) -> 0.0
if (DAG.getTarget().Options.UnsafeFPMath &&
N0.getOpcode() == ISD::FNEG && N0.getOperand(0) == N1) {
return DAG.getConstantFP(0.0, VT);
}
// If allow, fold (fadd x, (fneg x)) -> 0.0
if (DAG.getTarget().Options.UnsafeFPMath &&
N1.getOpcode() == ISD::FNEG && N1.getOperand(0) == N0) {
return DAG.getConstantFP(0.0, VT);
}
// In unsafe math mode, we can fold chains of FADD's of the same value
// into multiplications. This transform is not safe in general because
// we are reducing the number of rounding steps.
@@ -6038,6 +6050,12 @@ SDValue DAGCombiner::visitFMA(SDNode *N) {
EVT VT = N->getValueType(0);
DebugLoc dl = N->getDebugLoc();
if (DAG.getTarget().Options.UnsafeFPMath) {
if (N0CFP && N0CFP->isZero())
return N2;
if (N1CFP && N1CFP->isZero())
return N2;
}
if (N0CFP && N0CFP->isExactlyValue(1.0))
return DAG.getNode(ISD::FADD, N->getDebugLoc(), VT, N1, N2);
if (N1CFP && N1CFP->isExactlyValue(1.0))