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[X86] Don't turn UINT_TO_FP into SINT_TO_FP during lowering. 

We already do this as a DAG combine. The version during lowering can only trigger if known bits changes something that improves known bits analysis. But this means we should be improving known bits analysis to work on the unlowered form instead.

llvm-svn: 319640
This commit is contained in:
Craig Topper 2017-12-04 05:38:44 +00:00
parent 67217d7eb4
commit 1151facf76
1 changed files with 0 additions and 6 deletions
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6
llvm/lib/Target/X86/X86ISelLowering.cpp
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@ -15820,12 +15820,6 @@ SDValue X86TargetLowering::LowerUINT_TO_FP(SDValue Op,
SDLoc dl(Op);
auto PtrVT = getPointerTy(DAG.getDataLayout());
// Since UINT_TO_FP is legal (it's marked custom), dag combiner won't
// optimize it to a SINT_TO_FP when the sign bit is known zero. Perform
// the optimization here.
if (DAG.SignBitIsZero(N0))
return DAG.getNode(ISD::SINT_TO_FP, dl, Op.getValueType(), N0);
if (Op.getSimpleValueType().isVector())
return lowerUINT_TO_FP_vec(Op, DAG);