diff options
Diffstat (limited to 'llvm/lib')
| -rw-r--r-- | llvm/lib/Transforms/InstCombine/InstCombineCalls.cpp | 23 |
1 files changed, 23 insertions, 0 deletions
diff --git a/llvm/lib/Transforms/InstCombine/InstCombineCalls.cpp b/llvm/lib/Transforms/InstCombine/InstCombineCalls.cpp index a99eaf013e6..cbaa0ddaa28 100644 --- a/llvm/lib/Transforms/InstCombine/InstCombineCalls.cpp +++ b/llvm/lib/Transforms/InstCombine/InstCombineCalls.cpp @@ -1992,6 +1992,29 @@ Instruction *InstCombiner::visitCallInst(CallInst &CI) { case Intrinsic::fshl: case Intrinsic::fshr: { + const APInt *SA; + if (match(II->getArgOperand(2), m_APInt(SA))) { + Value *Op0 = II->getArgOperand(0), *Op1 = II->getArgOperand(1); + unsigned BitWidth = SA->getBitWidth(); + uint64_t ShiftAmt = SA->urem(BitWidth); + assert(ShiftAmt != 0 && "SimplifyCall should have handled zero shift"); + // Normalize to funnel shift left. + if (II->getIntrinsicID() == Intrinsic::fshr) + ShiftAmt = BitWidth - ShiftAmt; + + // fshl(X, 0, C) -> shl X, C + // fshl(X, undef, C) -> shl X, C + if (match(Op1, m_Zero()) || match(Op1, m_Undef())) + return BinaryOperator::CreateShl( + Op0, ConstantInt::get(II->getType(), ShiftAmt)); + + // fshl(0, X, C) -> lshr X, (BW-C) + // fshl(undef, X, C) -> lshr X, (BW-C) + if (match(Op0, m_Zero()) || match(Op0, m_Undef())) + return BinaryOperator::CreateLShr( + Op1, ConstantInt::get(II->getType(), BitWidth - ShiftAmt)); + } + // The shift amount (operand 2) of a funnel shift is modulo the bitwidth, // so only the low bits of the shift amount are demanded if the bitwidth is // a power-of-2. |
