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Be careful not to request or look at bits shifted in from outside the size

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of the input.  This fixes the mediabench/gsm/toast failure last night.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@26138 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Chris Lattner 2006-02-13 06:09:08 +00:00
parent 50b5c2ebd9
commit c15637bafc
1 changed files with 9 additions and 3 deletions
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12
lib/Transforms/Scalar/InstructionCombining.cpp
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@ -939,20 +939,26 @@ bool InstCombiner::SimplifyDemandedBits(Value *V, uint64_t DemandedMask,
// Compute the new bits that are at the top now.
uint64_t HighBits = (1ULL << ShAmt)-1;
HighBits <<= I->getType()->getPrimitiveSizeInBits() - ShAmt;
uint64_t TypeMask = I->getType()->getIntegralTypeMask();
if (I->getType()->isUnsigned()) { // Unsigned shift right.
if (SimplifyDemandedBits(I->getOperand(0), DemandedMask << ShAmt,
if (SimplifyDemandedBits(I->getOperand(0),
(DemandedMask << ShAmt) & TypeMask,
KnownZero, KnownOne, Depth+1))
return true;
assert((KnownZero & KnownOne) == 0 && "Bits known to be one AND zero?");
KnownZero &= TypeMask;
KnownOne &= TypeMask;
KnownZero >>= ShAmt;
KnownOne >>= ShAmt;
KnownZero |= HighBits; // high bits known zero.
} else { // Signed shift right.
if (SimplifyDemandedBits(I->getOperand(0), DemandedMask << ShAmt,
if (SimplifyDemandedBits(I->getOperand(0),
(DemandedMask << ShAmt) & TypeMask,
KnownZero, KnownOne, Depth+1))
return true;
assert((KnownZero & KnownOne) == 0 && "Bits known to be one AND zero?");
KnownZero &= TypeMask;
KnownOne &= TypeMask;
KnownZero >>= SA->getValue();
KnownOne >>= SA->getValue();