diff options
| -rw-r--r-- | lib/Transforms/Scalar/InstructionCombining.cpp | 4 |
1 files changed, 4 insertions, 0 deletions
diff --git a/lib/Transforms/Scalar/InstructionCombining.cpp b/lib/Transforms/Scalar/InstructionCombining.cpp index 2a227423b6..01fcfabeba 100644 --- a/lib/Transforms/Scalar/InstructionCombining.cpp +++ b/lib/Transforms/Scalar/InstructionCombining.cpp @@ -1346,6 +1346,10 @@ bool InstCombiner::SimplifyDemandedBits(Value *V, APInt DemandedMask, // Signed shift right. APInt DemandedMaskIn(DemandedMask.shl(ShiftAmt)); + // If any of the "high bits" are demanded, we should set the sign bit as + // demanded. + if (DemandedMask.countLeadingZeros() <= ShiftAmt) + DemandedMaskIn.set(BitWidth-1); if (SimplifyDemandedBits(I->getOperand(0), DemandedMaskIn, RHSKnownZero, RHSKnownOne, Depth+1)) |