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Fix a bug in APIntified ComputeMaskedBits(). 

llvm-svn: 35022
This commit is contained in:
Zhou Sheng 2007-03-08 05:42:00 +00:00
parent e94a2f8026
commit 387d7b1a35
1 changed files with 4 additions and 8 deletions
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12
llvm/lib/Transforms/Scalar/InstructionCombining.cpp
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@ -675,11 +675,9 @@ static void ComputeMaskedBits(Value *V, APInt Mask, APInt& KnownZero,
case Instruction::ZExt: {
// Compute the bits in the result that are not present in the input.
const IntegerType *SrcTy = cast<IntegerType>(I->getOperand(0)->getType());
APInt NotIn(~SrcTy->getMask());
APInt NewBits = APInt::getAllOnesValue(BitWidth) &
NotIn.zext(BitWidth);
APInt NewBits(APInt::getAllOnesValue(BitWidth).shl(SrcTy->getBitWidth()));
Mask &= ~NotIn;
Mask &= SrcTy->getMask().zext(BitWidth);
ComputeMaskedBits(I->getOperand(0), Mask, KnownZero, KnownOne, Depth+1);
assert((KnownZero & KnownOne) == 0 && "Bits known to be one AND zero?");
// The top bits are known to be zero.
@ -689,11 +687,9 @@ static void ComputeMaskedBits(Value *V, APInt Mask, APInt& KnownZero,
case Instruction::SExt: {
// Compute the bits in the result that are not present in the input.
const IntegerType *SrcTy = cast<IntegerType>(I->getOperand(0)->getType());
APInt NotIn(~SrcTy->getMask());
APInt NewBits = APInt::getAllOnesValue(BitWidth) &
NotIn.zext(BitWidth);
APInt NewBits(APInt::getAllOnesValue(BitWidth).shl(SrcTy->getBitWidth()));
Mask &= ~NotIn;
Mask &= SrcTy->getMask().zext(BitWidth);
ComputeMaskedBits(I->getOperand(0), Mask, KnownZero, KnownOne, Depth+1);
assert((KnownZero & KnownOne) == 0 && "Bits known to be one AND zero?");