diff options
Diffstat (limited to 'llvm/lib/Analysis/ValueTracking.cpp')
| -rw-r--r-- | llvm/lib/Analysis/ValueTracking.cpp | 24 |
1 files changed, 0 insertions, 24 deletions
diff --git a/llvm/lib/Analysis/ValueTracking.cpp b/llvm/lib/Analysis/ValueTracking.cpp index 38d9c290bfc..c401e08af92 100644 --- a/llvm/lib/Analysis/ValueTracking.cpp +++ b/llvm/lib/Analysis/ValueTracking.cpp @@ -255,30 +255,6 @@ static void computeKnownBitsAddSub(bool Add, const Value *Op0, const Value *Op1, APInt &KnownZero, APInt &KnownOne, APInt &KnownZero2, APInt &KnownOne2, unsigned Depth, const Query &Q) { - if (!Add) { - if (const ConstantInt *CLHS = dyn_cast<ConstantInt>(Op0)) { - // We know that the top bits of C-X are clear if X contains less bits - // than C (i.e. no wrap-around can happen). For example, 20-X is - // positive if we can prove that X is >= 0 and < 16. - if (!CLHS->getValue().isNegative()) { - unsigned BitWidth = KnownZero.getBitWidth(); - unsigned NLZ = (CLHS->getValue()+1).countLeadingZeros(); - // NLZ can't be BitWidth with no sign bit - APInt MaskV = APInt::getHighBitsSet(BitWidth, NLZ+1); - computeKnownBits(Op1, KnownZero2, KnownOne2, Depth + 1, Q); - - // If all of the MaskV bits are known to be zero, then we know the - // output top bits are zero, because we now know that the output is - // from [0-C]. - if ((KnownZero2 & MaskV) == MaskV) { - unsigned NLZ2 = CLHS->getValue().countLeadingZeros(); - // Top bits known zero. - KnownZero = APInt::getHighBitsSet(BitWidth, NLZ2); - } - } - } - } - unsigned BitWidth = KnownZero.getBitWidth(); // If an initial sequence of bits in the result is not needed, the |
