diff options
Diffstat (limited to 'llvm/lib/Analysis/ValueTracking.cpp')
| -rw-r--r-- | llvm/lib/Analysis/ValueTracking.cpp | 8 |
1 files changed, 8 insertions, 0 deletions
diff --git a/llvm/lib/Analysis/ValueTracking.cpp b/llvm/lib/Analysis/ValueTracking.cpp index 5a8bd4b..ada31e0 100644 --- a/llvm/lib/Analysis/ValueTracking.cpp +++ b/llvm/lib/Analysis/ValueTracking.cpp @@ -816,6 +816,14 @@ static void computeKnownBitsFromAssume(const Value *V, KnownBits &Known, KnownBits RHSKnown(BitWidth); computeKnownBits(A, RHSKnown, Depth+1, Query(Q, I)); + // If the RHS is known zero, then this assumption must be wrong (nothing + // is unsigned less than zero). Signal a conflict and get out of here. + if (RHSKnown.isZero()) { + Known.Zero.setAllBits(); + Known.One.setAllBits(); + break; + } + // Whatever high bits in c are zero are known to be zero (if c is a power // of 2, then one more). if (isKnownToBeAPowerOfTwo(A, false, Depth + 1, Query(Q, I))) |