diff options
Diffstat (limited to 'llvm/lib')
| -rw-r--r-- | llvm/lib/Transforms/InstCombine/InstCombineCalls.cpp | 19 |
1 files changed, 10 insertions, 9 deletions
diff --git a/llvm/lib/Transforms/InstCombine/InstCombineCalls.cpp b/llvm/lib/Transforms/InstCombine/InstCombineCalls.cpp index bdc235f247d..938517e64c3 100644 --- a/llvm/lib/Transforms/InstCombine/InstCombineCalls.cpp +++ b/llvm/lib/Transforms/InstCombine/InstCombineCalls.cpp @@ -2006,28 +2006,29 @@ Instruction *InstCombiner::visitCallInst(CallInst &CI) { II->setArgOperand(2, ModuloC); return II; } - // Canonicalize rotate right by constant to rotate left. This is not - // entirely arbitrary. For historical reasons, the backend may recognize - // rotate left patterns but miss rotate right patterns. - if (II->getIntrinsicID() == Intrinsic::fshr && Op0 == Op1) { - // fshr X, X, C --> fshl X, X, (BitWidth - C) + // Canonicalize funnel shift right by constant to funnel shift left. This + // is not entirely arbitrary. For historical reasons, the backend may + // recognize rotate left patterns but miss rotate right patterns. + if (II->getIntrinsicID() == Intrinsic::fshr) { + // fshr X, Y, C --> fshl X, Y, (BitWidth - C) assert(ConstantExpr::getICmp(ICmpInst::ICMP_UGT, WidthC, ShAmtC) == ConstantInt::getTrue(CmpInst::makeCmpResultType(Ty)) && "Shift amount expected to be modulo bitwidth"); Constant *LeftShiftC = ConstantExpr::getSub(WidthC, ShAmtC); Module *Mod = II->getModule(); Function *Fshl = Intrinsic::getDeclaration(Mod, Intrinsic::fshl, Ty); - return CallInst::Create(Fshl, { Op0, Op0, LeftShiftC }); + return CallInst::Create(Fshl, { Op0, Op1, LeftShiftC }); } } + // TODO: Pull this into the block above. We can handle semi-arbitrary vector + // shift amount constants as well as splats. const APInt *SA; if (match(II->getArgOperand(2), m_APInt(SA))) { 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; + assert(II->getIntrinsicID() == Intrinsic::fshl && + "All funnel shifts by simple constants should go left"); // fshl(X, 0, C) -> shl X, C // fshl(X, undef, C) -> shl X, C |
