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[SelectionDAG] ComputeKnownBits - merge EXTRACT_VECTOR_ELT known/unknown index paths 

Match the approach in SimplifyDemandedBits/ComputeNumSignBits where we calculate the demanded elts and then have a common path for the ComputeKnownBits call.
This commit is contained in:
Simon Pilgrim 2020-01-23 11:28:00 +00:00
parent 98da49d979
commit 03cae086f4
1 changed files with 12 additions and 11 deletions
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23
llvm/lib/CodeGen/SelectionDAG/SelectionDAG.cpp
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@ -3241,20 +3241,21 @@ KnownBits SelectionDAG::computeKnownBits(SDValue Op, const APInt &DemandedElts,
EVT VecVT = InVec.getValueType();
const unsigned EltBitWidth = VecVT.getScalarSizeInBits();
const unsigned NumSrcElts = VecVT.getVectorNumElements();
// If BitWidth > EltBitWidth the value is anyext:ed. So we do not know
// anything about the extended bits.
if (BitWidth > EltBitWidth)
Known = Known.trunc(EltBitWidth);
ConstantSDNode *ConstEltNo = dyn_cast<ConstantSDNode>(EltNo);
if (ConstEltNo && ConstEltNo->getAPIntValue().ult(NumSrcElts)) {
// If we know the element index, just demand that vector element.
unsigned Idx = ConstEltNo->getZExtValue();
APInt DemandedElt = APInt::getOneBitSet(NumSrcElts, Idx);
Known = computeKnownBits(InVec, DemandedElt, Depth + 1);
} else {
// Unknown element index, so ignore DemandedElts and demand them all.
Known = computeKnownBits(InVec, Depth + 1);
}
// If we know the element index, just demand that vector element, else for
// an unknown element index, ignore DemandedElts and demand them all.
APInt DemandedSrcElts = APInt::getAllOnesValue(NumSrcElts);
auto *ConstEltNo = dyn_cast<ConstantSDNode>(EltNo);
if (ConstEltNo && ConstEltNo->getAPIntValue().ult(NumSrcElts))
DemandedSrcElts =
APInt::getOneBitSet(NumSrcElts, ConstEltNo->getZExtValue());
Known = computeKnownBits(InVec, DemandedSrcElts, Depth + 1);
if (BitWidth > EltBitWidth)
Known = Known.zext(BitWidth, false /* => any extend */);
break;
@ -3902,7 +3903,7 @@ unsigned SelectionDAG::ComputeNumSignBits(SDValue Op, const APInt &DemandedElts,
// If we know the element index, just demand that vector element, else for
// an unknown element index, ignore DemandedElts and demand them all.
APInt DemandedSrcElts = APInt::getAllOnesValue(NumSrcElts);
ConstantSDNode *ConstEltNo = dyn_cast<ConstantSDNode>(EltNo);
auto *ConstEltNo = dyn_cast<ConstantSDNode>(EltNo);
if (ConstEltNo && ConstEltNo->getAPIntValue().ult(NumSrcElts))
DemandedSrcElts =
APInt::getOneBitSet(NumSrcElts, ConstEltNo->getZExtValue());