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For expression like 

"APInt::getAllOnesValue(ShiftAmt).zextOrCopy(BitWidth)",
to handle ShiftAmt == BitWidth situation, use zextOrCopy() instead of
zext().

llvm-svn: 35080
This commit is contained in:
Zhou Sheng 2007-03-13 06:40:59 +00:00
parent b9c3707e97
commit ebe634e662
1 changed files with 3 additions and 3 deletions
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6
llvm/lib/Transforms/Scalar/InstructionCombining.cpp
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@ -1995,7 +1995,7 @@ bool InstCombiner::SimplifyDemandedBits(Value *V, APInt DemandedMask,
RHSKnownZero <<= ShiftAmt; RHSKnownZero <<= ShiftAmt;
RHSKnownOne <<= ShiftAmt; RHSKnownOne <<= ShiftAmt;
// low bits known zero. // low bits known zero.
RHSKnownZero |= APInt::getAllOnesValue(ShiftAmt).zext(BitWidth); RHSKnownZero |= APInt::getAllOnesValue(ShiftAmt).zextOrCopy(BitWidth);
} }
break; break;
case Instruction::LShr: case Instruction::LShr:
@ -2012,7 +2012,7 @@ bool InstCombiner::SimplifyDemandedBits(Value *V, APInt DemandedMask,
assert((RHSKnownZero & RHSKnownOne) == 0 && assert((RHSKnownZero & RHSKnownOne) == 0 &&
"Bits known to be one AND zero?"); "Bits known to be one AND zero?");
// Compute the new bits that are at the top now. // Compute the new bits that are at the top now.
APInt HighBits(APInt::getAllOnesValue(ShiftAmt).zext(BitWidth).shl( APInt HighBits(APInt::getAllOnesValue(ShiftAmt).zextOrCopy(BitWidth).shl(
BitWidth - ShiftAmt)); BitWidth - ShiftAmt));
RHSKnownZero &= TypeMask; RHSKnownZero &= TypeMask;
RHSKnownOne &= TypeMask; RHSKnownOne &= TypeMask;
@ -2046,7 +2046,7 @@ bool InstCombiner::SimplifyDemandedBits(Value *V, APInt DemandedMask,
assert((RHSKnownZero & RHSKnownOne) == 0 && assert((RHSKnownZero & RHSKnownOne) == 0 &&
"Bits known to be one AND zero?"); "Bits known to be one AND zero?");
// Compute the new bits that are at the top now. // Compute the new bits that are at the top now.
APInt HighBits(APInt::getAllOnesValue(ShiftAmt).zext(BitWidth).shl( APInt HighBits(APInt::getAllOnesValue(ShiftAmt).zextOrCopy(BitWidth).shl(
BitWidth - ShiftAmt)); BitWidth - ShiftAmt));
RHSKnownZero &= TypeMask; RHSKnownZero &= TypeMask;
RHSKnownOne &= TypeMask; RHSKnownOne &= TypeMask;