forked from OSchip/llvm-project
Fix the dag combiner bug corresponding to PR1014.
llvm-svn: 31943
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@ -364,19 +364,19 @@ bool TargetLowering::SimplifyDemandedBits(SDOperand Op, uint64_t DemandedMask,
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if ((DemandedMask & KnownZero2) == DemandedMask)
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return TLO.CombineTo(Op, Op.getOperand(1));
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// If all of the unknown bits are known to be zero on one side or the other
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// (but not both) turn this into an *inclusive* or.
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// e.g. (A & C1)^(B & C2) -> (A & C1)|(B & C2) iff C1&C2 == 0
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if ((DemandedMask & ~KnownZero & ~KnownZero2) == 0)
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return TLO.CombineTo(Op, TLO.DAG.getNode(ISD::OR, Op.getValueType(),
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Op.getOperand(0),
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Op.getOperand(1)));
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// Output known-0 bits are known if clear or set in both the LHS & RHS.
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KnownZeroOut = (KnownZero & KnownZero2) | (KnownOne & KnownOne2);
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// Output known-1 are known to be set if set in only one of the LHS, RHS.
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KnownOneOut = (KnownZero & KnownOne2) | (KnownOne & KnownZero2);
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// If all of the unknown bits are known to be zero on one side or the other
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// (but not both) turn this into an *inclusive* or.
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// e.g. (A & C1)^(B & C2) -> (A & C1)|(B & C2) iff C1&C2 == 0
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if (uint64_t UnknownBits = DemandedMask & ~(KnownZeroOut|KnownOneOut))
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if ((UnknownBits & (KnownZero|KnownZero2)) == UnknownBits)
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return TLO.CombineTo(Op, TLO.DAG.getNode(ISD::OR, Op.getValueType(),
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Op.getOperand(0),
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Op.getOperand(1)));
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// If all of the demanded bits on one side are known, and all of the set
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// bits on that side are also known to be set on the other side, turn this
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// into an AND, as we know the bits will be cleared.
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