diff options
Diffstat (limited to 'llvm/lib/CodeGen')
| -rw-r--r-- | llvm/lib/CodeGen/SelectionDAG/SelectionDAG.cpp | 22 |
1 files changed, 12 insertions, 10 deletions
diff --git a/llvm/lib/CodeGen/SelectionDAG/SelectionDAG.cpp b/llvm/lib/CodeGen/SelectionDAG/SelectionDAG.cpp index a0f621ab50a..64d439f5f78 100644 --- a/llvm/lib/CodeGen/SelectionDAG/SelectionDAG.cpp +++ b/llvm/lib/CodeGen/SelectionDAG/SelectionDAG.cpp @@ -2885,23 +2885,25 @@ KnownBits SelectionDAG::computeKnownBits(SDValue Op, const APInt &DemandedElts, } break; case ISD::SRL: + Known = computeKnownBits(Op.getOperand(0), DemandedElts, Depth + 1); + if (const APInt *ShAmt = getValidShiftAmountConstant(Op, DemandedElts)) { - Known = computeKnownBits(Op.getOperand(0), DemandedElts, Depth + 1); unsigned Shift = ShAmt->getZExtValue(); Known.Zero.lshrInPlace(Shift); Known.One.lshrInPlace(Shift); // High bits are known zero. Known.Zero.setHighBits(Shift); - } else if (const APInt *ShMinAmt = - getValidMinimumShiftAmountConstant(Op, DemandedElts)) { - // Minimum shift high bits are known zero. - Known.Zero.setHighBits(ShMinAmt->getZExtValue()); - } else { - // No matter the shift amount, the leading zeros will stay zero. - Known = computeKnownBits(Op.getOperand(0), DemandedElts, Depth + 1); - Known.Zero = APInt::getHighBitsSet(BitWidth, Known.countMinLeadingZeros()); - Known.One.clearAllBits(); + break; } + + // No matter the shift amount, the leading zeros will stay zero. + Known.Zero = APInt::getHighBitsSet(BitWidth, Known.countMinLeadingZeros()); + Known.One.clearAllBits(); + + // Minimum shift high bits are known zero. + if (const APInt *ShMinAmt = + getValidMinimumShiftAmountConstant(Op, DemandedElts)) + Known.Zero.setHighBits(ShMinAmt->getZExtValue()); break; case ISD::SRA: if (const APInt *ShAmt = getValidShiftAmountConstant(Op, DemandedElts)) { |
