diff options
| -rw-r--r-- | lib/Transforms/Scalar/InstructionCombining.cpp | 10 |
1 files changed, 10 insertions, 0 deletions
diff --git a/lib/Transforms/Scalar/InstructionCombining.cpp b/lib/Transforms/Scalar/InstructionCombining.cpp index a1d9e97832..9d327c7883 100644 --- a/lib/Transforms/Scalar/InstructionCombining.cpp +++ b/lib/Transforms/Scalar/InstructionCombining.cpp @@ -979,6 +979,16 @@ static bool MaskedValueIsZero(Value *V, uint64_t Mask, unsigned Depth = 0) { return (KnownZero & Mask) == Mask; } +/// MaskedValueIsZero - Return true if 'V & Mask' is known to be zero. We use +/// this predicate to simplify operations downstream. Mask is known to be zero +/// for bits that V cannot have. +static bool MaskedValueIsZero(Value *V, const APInt& Mask, unsigned Depth = 0) { + APInt KnownZero(Mask), KnownOne(Mask); + ComputeMaskedBits(V, Mask, KnownZero, KnownOne, Depth); + assert((KnownZero & KnownOne) == 0 && "Bits known to be one AND zero?"); + return (KnownZero & Mask) == Mask; +} + /// ShrinkDemandedConstant - Check to see if the specified operand of the /// specified instruction is a constant integer. If so, check to see if there /// are any bits set in the constant that are not demanded. If so, shrink the |