diff options
| -rw-r--r-- | lib/Transforms/InstCombine/InstCombineCalls.cpp | 11 |
1 files changed, 6 insertions, 5 deletions
diff --git a/lib/Transforms/InstCombine/InstCombineCalls.cpp b/lib/Transforms/InstCombine/InstCombineCalls.cpp index b5fd0b9af4..875e9cae58 100644 --- a/lib/Transforms/InstCombine/InstCombineCalls.cpp +++ b/lib/Transforms/InstCombine/InstCombineCalls.cpp @@ -487,14 +487,15 @@ Instruction *InstCombiner::visitCallInst(CallInst &CI) { APInt RHSKnownOne(BitWidth, 0); ComputeMaskedBits(RHS, Mask, RHSKnownZero, RHSKnownOne); - // Get the largest possible values for each operand, extended to be large - // enough so that every possible product of two BitWidth-sized ints fits. - APInt LHSMax = (~LHSKnownZero).zext(BitWidth*2); - APInt RHSMax = (~RHSKnownZero).zext(BitWidth*2); + // Get the largest possible values for each operand. + APInt LHSMax = ~LHSKnownZero; + APInt RHSMax = ~RHSKnownZero; // If multiplying the maximum values does not overflow then we can turn // this into a plain NUW mul. - if ((LHSMax * RHSMax).getActiveBits() <= BitWidth) { + bool Overflow; + LHSMax.umul_ov(RHSMax, Overflow); + if (!Overflow) { Value *Mul = Builder->CreateNUWMul(LHS, RHS, "umul_with_overflow"); Constant *V[] = { UndefValue::get(LHS->getType()), |