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[AMDGPU] Prevent infinite recursion in DAG.computeKnownBits()
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Authored by rampitec on Sep 1 2017, 12:41 PM.

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This revision is now accepted and ready to land.Sep 1 2017, 1:42 PM

This revision was automatically updated to reflect the committed changes.

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Show First 20 Lines • Show All 3,880 Lines • ▼ Show 20 Lines	case AMDGPUISD::FP16_ZEXT: {

// High bits are zero.		// High bits are zero.
Known.Zero = APInt::getHighBitsSet(BitWidth, BitWidth - 16);		Known.Zero = APInt::getHighBitsSet(BitWidth, BitWidth - 16);
break;		break;
}		}
case AMDGPUISD::MUL_U24:		case AMDGPUISD::MUL_U24:
case AMDGPUISD::MUL_I24: {		case AMDGPUISD::MUL_I24: {
KnownBits LHSKnown, RHSKnown;		KnownBits LHSKnown, RHSKnown;
DAG.computeKnownBits(Op.getOperand(0), LHSKnown);		DAG.computeKnownBits(Op.getOperand(0), LHSKnown, Depth + 1);
DAG.computeKnownBits(Op.getOperand(1), RHSKnown);		DAG.computeKnownBits(Op.getOperand(1), RHSKnown, Depth + 1);

unsigned TrailZ = LHSKnown.countMinTrailingZeros() +		unsigned TrailZ = LHSKnown.countMinTrailingZeros() +
RHSKnown.countMinTrailingZeros();		RHSKnown.countMinTrailingZeros();
Known.Zero.setLowBits(std::min(TrailZ, 32u));		Known.Zero.setLowBits(std::min(TrailZ, 32u));

unsigned LHSValBits = 32 - std::max(LHSKnown.countMinSignBits(), 8u);		unsigned LHSValBits = 32 - std::max(LHSKnown.countMinSignBits(), 8u);
unsigned RHSValBits = 32 - std::max(RHSKnown.countMinSignBits(), 8u);		unsigned RHSValBits = 32 - std::max(RHSKnown.countMinSignBits(), 8u);
unsigned MaxValBits = std::min(LHSValBits + RHSValBits, 32u);		unsigned MaxValBits = std::min(LHSValBits + RHSValBits, 32u);
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