diff options
Diffstat (limited to 'llvm/lib/Analysis')
| -rw-r--r-- | llvm/lib/Analysis/DemandedBits.cpp | 21 |
1 files changed, 21 insertions, 0 deletions
diff --git a/llvm/lib/Analysis/DemandedBits.cpp b/llvm/lib/Analysis/DemandedBits.cpp index 35af4be485f..6bef77176cb 100644 --- a/llvm/lib/Analysis/DemandedBits.cpp +++ b/llvm/lib/Analysis/DemandedBits.cpp @@ -142,6 +142,27 @@ void DemandedBits::determineLiveOperandBits( std::min(BitWidth, Known.countMaxTrailingZeros()+1)); } break; + case Intrinsic::fshl: + case Intrinsic::fshr: + if (OperandNo == 2) { + // Shift amount is modulo the bitwidth. For powers of two we have + // SA % BW == SA & (BW - 1). + if (isPowerOf2_32(BitWidth)) + AB = BitWidth - 1; + } else if (auto *SA = dyn_cast<ConstantInt>(II->getOperand(2))) { + // TODO: Support vectors. + // Normalize to funnel shift left. APInt shifts of BitWidth are well- + // defined, so no need to special-case zero shifts here. + uint64_t ShiftAmt = SA->getValue().urem(BitWidth); + if (II->getIntrinsicID() == Intrinsic::fshr) + ShiftAmt = BitWidth - ShiftAmt; + + if (OperandNo == 0) + AB = AOut.lshr(ShiftAmt); + else if (OperandNo == 1) + AB = AOut.shl(BitWidth - ShiftAmt); + } + break; } break; case Instruction::Add: |
