}
case Instruction::SExt: {
// Compute the bits in the result that are not present in the input.
- unsigned SrcBitWidth =I->getOperand(0)->getType()->getScalarSizeInBits();
+ unsigned SrcBitWidth = I->getOperand(0)->getType()->getScalarSizeInBits();
- APInt InputDemandedBits = DemandedMask &
- APInt::getLowBitsSet(BitWidth, SrcBitWidth);
+ APInt InputDemandedBits = DemandedMask.trunc(SrcBitWidth);
- APInt NewBits(APInt::getBitsSetFrom(BitWidth, SrcBitWidth));
// If any of the sign extended bits are demanded, we know that the sign
// bit is demanded.
- if ((NewBits & DemandedMask) != 0)
+ if (DemandedMask.getActiveBits() > SrcBitWidth)
InputDemandedBits.setBit(SrcBitWidth-1);
- InputDemandedBits = InputDemandedBits.trunc(SrcBitWidth);
- Known = Known.trunc(SrcBitWidth);
- if (SimplifyDemandedBits(I, 0, InputDemandedBits, Known, Depth + 1))
+ KnownBits InputKnown(SrcBitWidth);
+ if (SimplifyDemandedBits(I, 0, InputDemandedBits, InputKnown, Depth + 1))
return I;
- InputDemandedBits = InputDemandedBits.zext(BitWidth);
- Known = Known.zext(BitWidth);
- assert(!Known.hasConflict() && "Bits known to be one AND zero?");
-
- // If the sign bit of the input is known set or clear, then we know the
- // top bits of the result.
// If the input sign bit is known zero, or if the NewBits are not demanded
// convert this into a zero extension.
- if (Known.Zero[SrcBitWidth-1] || (NewBits & ~DemandedMask) == NewBits) {
- // Convert to ZExt cast
+ if (InputKnown.isNonNegative() ||
+ DemandedMask.getActiveBits() <= SrcBitWidth) {
+ // Convert to ZExt cast.
CastInst *NewCast = new ZExtInst(I->getOperand(0), VTy, I->getName());
return InsertNewInstWith(NewCast, *I);
- } else if (Known.One[SrcBitWidth-1]) { // Input sign bit known set
- Known.One |= NewBits;
- }
+ }
+
+ // If the sign bit of the input is known set or clear, then we know the
+ // top bits of the result.
+ Known = InputKnown.sext(BitWidth);
+ assert(!Known.hasConflict() && "Bits known to be one AND zero?");
break;
}
case Instruction::Add: