diff options
Diffstat (limited to 'llvm/lib/Analysis/ValueTracking.cpp')
| -rw-r--r-- | llvm/lib/Analysis/ValueTracking.cpp | 14 |
1 files changed, 7 insertions, 7 deletions
diff --git a/llvm/lib/Analysis/ValueTracking.cpp b/llvm/lib/Analysis/ValueTracking.cpp index d337371..9a93b55 100644 --- a/llvm/lib/Analysis/ValueTracking.cpp +++ b/llvm/lib/Analysis/ValueTracking.cpp @@ -385,15 +385,15 @@ static void computeKnownBitsAddSub(bool Add, const Value *Op0, const Value *Op1, bool NSW, const APInt &DemandedElts, KnownBits &KnownOut, KnownBits &Known2, unsigned Depth, const Query &Q) { - unsigned BitWidth = KnownOut.getBitWidth(); + computeKnownBits(Op1, DemandedElts, KnownOut, Depth + 1, Q); - // If an initial sequence of bits in the result is not needed, the - // corresponding bits in the operands are not needed. - KnownBits LHSKnown(BitWidth); - computeKnownBits(Op0, DemandedElts, LHSKnown, Depth + 1, Q); - computeKnownBits(Op1, DemandedElts, Known2, Depth + 1, Q); + // If one operand is unknown and we have no nowrap information, + // the result will be unknown independently of the second operand. + if (KnownOut.isUnknown() && !NSW) + return; - KnownOut = KnownBits::computeForAddSub(Add, NSW, LHSKnown, Known2); + computeKnownBits(Op0, DemandedElts, Known2, Depth + 1, Q); + KnownOut = KnownBits::computeForAddSub(Add, NSW, Known2, KnownOut); } static void computeKnownBitsMul(const Value *Op0, const Value *Op1, bool NSW, |