diff options
Diffstat (limited to 'llvm/lib/CodeGen')
| -rw-r--r-- | llvm/lib/CodeGen/SelectionDAG/SelectionDAG.cpp | 19 |
1 files changed, 9 insertions, 10 deletions
diff --git a/llvm/lib/CodeGen/SelectionDAG/SelectionDAG.cpp b/llvm/lib/CodeGen/SelectionDAG/SelectionDAG.cpp index 56945b4bf98..974322aabc1 100644 --- a/llvm/lib/CodeGen/SelectionDAG/SelectionDAG.cpp +++ b/llvm/lib/CodeGen/SelectionDAG/SelectionDAG.cpp @@ -2144,23 +2144,21 @@ void SelectionDAG::computeKnownBits(SDValue Op, APInt &KnownZero, KnownZero |= APInt::getHighBitsSet(BitWidth, BitWidth - 1); break; case ISD::SHL: - // (shl X, C1) & C2 == 0 iff (X & C2 >>u C1) == 0 - if (ConstantSDNode *SA = dyn_cast<ConstantSDNode>(Op.getOperand(1))) { - unsigned ShAmt = SA->getZExtValue(); - + if (ConstantSDNode *SA = isConstOrConstSplat(Op.getOperand(1))) { // If the shift count is an invalid immediate, don't do anything. - if (ShAmt >= BitWidth) + APInt ShAmt = SA->getAPIntValue(); + if (ShAmt.uge(BitWidth)) break; - computeKnownBits(Op.getOperand(0), KnownZero, KnownOne, Depth+1); - KnownZero <<= ShAmt; - KnownOne <<= ShAmt; + computeKnownBits(Op.getOperand(0), KnownZero, KnownOne, Depth + 1); + KnownZero = KnownZero << ShAmt; + KnownOne = KnownOne << ShAmt; // low bits known zero. - KnownZero |= APInt::getLowBitsSet(BitWidth, ShAmt); + KnownZero |= APInt::getLowBitsSet(BitWidth, ShAmt.getZExtValue()); } break; case ISD::SRL: - // (ushr X, C1) & C2 == 0 iff (-1 >> C1) & C2 == 0 + // FIXME: Reuse isConstOrConstSplat + APInt from above. if (ConstantSDNode *SA = dyn_cast<ConstantSDNode>(Op.getOperand(1))) { unsigned ShAmt = SA->getZExtValue(); @@ -2177,6 +2175,7 @@ void SelectionDAG::computeKnownBits(SDValue Op, APInt &KnownZero, } break; case ISD::SRA: + // FIXME: Reuse isConstOrConstSplat + APInt from above. if (ConstantSDNode *SA = dyn_cast<ConstantSDNode>(Op.getOperand(1))) { unsigned ShAmt = SA->getZExtValue(); |
