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Make fast-isel try ISD::FNEG before resorting to bitcasts and xors. 

llvm-svn: 81493
This commit is contained in:
Dan Gohman 2009-09-11 00:36:43 +00:00
parent 89b090e51e
commit 9cbef32726
1 changed files with 9 additions and 1 deletions
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10
llvm/lib/CodeGen/SelectionDAG/FastISel.cpp
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@ -615,9 +615,17 @@ FastISel::SelectFNeg(User *I) {
unsigned OpReg = getRegForValue(BinaryOperator::getFNegArgument(I));
if (OpReg == 0) return false;
// If the target has ISD::FNEG, use it.
EVT VT = TLI.getValueType(I->getType());
unsigned ResultReg = FastEmit_r(VT.getSimpleVT(), VT.getSimpleVT(),
ISD::FNEG, OpReg);
if (ResultReg != 0) {
UpdateValueMap(I, ResultReg);
return true;
}
// Bitcast the value to integer, twiddle the sign bit with xor,
// and then bitcast it back to floating-point.
EVT VT = TLI.getValueType(I->getType());
if (VT.getSizeInBits() > 64) return false;
EVT IntVT = EVT::getIntegerVT(I->getContext(), VT.getSizeInBits());
if (!TLI.isTypeLegal(IntVT))