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ValueTracking: Fix bugs in isKnownToBeAPowerOfTwo

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(add nsw x, (and x, y)) isn't a power of two if x is zero, it's zero
(add nsw x, (xor x, y)) isn't a power of two if y has bits set that aren't set in x


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@185954 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
David Majnemer
2013-07-09 18:11:10 +00:00
parent 29b7419428
commit ab6ceab8a6
2 changed files with 4 additions and 21 deletions
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10
lib/Analysis/ValueTracking.cpp
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@ -861,16 +861,14 @@ bool llvm::isKnownToBeAPowerOfTwo(Value *V, bool OrZero, unsigned Depth) {
// Adding a power of two to the same power of two is a power of two or
// zero.
if (BinaryOperator *XBO = dyn_cast<BinaryOperator>(X))
if (XBO->getOpcode() == Instruction::And ||
XBO->getOpcode() == Instruction::Xor)
if (XBO->getOpcode() == Instruction::And)
if (XBO->getOperand(0) == Y || XBO->getOperand(1) == Y)
if (isKnownToBeAPowerOfTwo(Y, /*OrZero*/true, Depth))
if (isKnownToBeAPowerOfTwo(Y, OrZero, Depth))
return true;
if (BinaryOperator *YBO = dyn_cast<BinaryOperator>(Y))
if (YBO->getOpcode() == Instruction::And ||
YBO->getOpcode() == Instruction::Xor)
if (YBO->getOpcode() == Instruction::And)
if (YBO->getOperand(0) == X || YBO->getOperand(1) == X)
if (isKnownToBeAPowerOfTwo(X, /*OrZero*/true, Depth))
if (isKnownToBeAPowerOfTwo(X, OrZero, Depth))
return true;
}