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When tracking demanded bits, if any bits from the sext of an SRA are demanded,
then so is the input sign bit. This fixes mediabench/g721 on X86. llvm-svn: 28166
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@ -467,8 +467,14 @@ bool TargetLowering::SimplifyDemandedBits(SDOperand Op, uint64_t DemandedMask,
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HighBits <<= MVT::getSizeInBits(VT) - ShAmt;
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uint64_t TypeMask = MVT::getIntVTBitMask(VT);
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if (SimplifyDemandedBits(Op.getOperand(0),
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(DemandedMask << ShAmt) & TypeMask,
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uint64_t InDemandedMask = (DemandedMask << ShAmt) & TypeMask;
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// If any of the demanded bits are produced by the sign extension, we also
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// demand the input sign bit.
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if (HighBits & DemandedMask)
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InDemandedMask |= MVT::getIntVTSignBit(VT);
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if (SimplifyDemandedBits(Op.getOperand(0), InDemandedMask,
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KnownZero, KnownOne, TLO, Depth+1))
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return true;
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assert((KnownZero & KnownOne) == 0 && "Bits known to be one AND zero?");
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