diff options
Diffstat (limited to 'lib/CodeGen/SelectionDAG/SelectionDAG.cpp')
| -rw-r--r-- | lib/CodeGen/SelectionDAG/SelectionDAG.cpp | 8 |
1 files changed, 5 insertions, 3 deletions
diff --git a/lib/CodeGen/SelectionDAG/SelectionDAG.cpp b/lib/CodeGen/SelectionDAG/SelectionDAG.cpp index 18bb040008..6b2f54393d 100644 --- a/lib/CodeGen/SelectionDAG/SelectionDAG.cpp +++ b/lib/CodeGen/SelectionDAG/SelectionDAG.cpp @@ -1257,7 +1257,7 @@ void SelectionDAG::ComputeMaskedBits(SDOperand Op, const APInt &Mask, case ISD::UDIV: { // For the purposes of computing leading zeros we can conservatively // treat a udiv as a logical right shift by the power of 2 known to - // be greater than the denominator. + // be less than the denominator. APInt AllOnes = APInt::getAllOnesValue(BitWidth); ComputeMaskedBits(Op.getOperand(0), AllOnes, KnownZero2, KnownOne2, Depth+1); @@ -1267,8 +1267,10 @@ void SelectionDAG::ComputeMaskedBits(SDOperand Op, const APInt &Mask, KnownZero2.clear(); ComputeMaskedBits(Op.getOperand(1), AllOnes, KnownZero2, KnownOne2, Depth+1); - LeadZ = std::min(BitWidth, - LeadZ + BitWidth - KnownOne2.countLeadingZeros()); + unsigned RHSUnknownLeadingOnes = KnownOne2.countLeadingZeros(); + if (RHSUnknownLeadingOnes != BitWidth) + LeadZ = std::min(BitWidth, + LeadZ + BitWidth - RHSUnknownLeadingOnes - 1); KnownZero = APInt::getHighBitsSet(BitWidth, LeadZ) & Mask; return; |