diff options
Diffstat (limited to 'llvm/lib/Transforms/InstCombine/InstCombineVectorOps.cpp')
| -rw-r--r-- | llvm/lib/Transforms/InstCombine/InstCombineVectorOps.cpp | 115 |
1 files changed, 56 insertions, 59 deletions
diff --git a/llvm/lib/Transforms/InstCombine/InstCombineVectorOps.cpp b/llvm/lib/Transforms/InstCombine/InstCombineVectorOps.cpp index 0c8d64bff43..75f77779ab7 100644 --- a/llvm/lib/Transforms/InstCombine/InstCombineVectorOps.cpp +++ b/llvm/lib/Transforms/InstCombine/InstCombineVectorOps.cpp @@ -876,65 +876,62 @@ Instruction *InstCombiner::visitInsertElementInst(InsertElementInst &IE) { if (isa<UndefValue>(ScalarOp) || isa<UndefValue>(IdxOp)) replaceInstUsesWith(IE, VecOp); - // If the inserted element was extracted from some other vector, and if the - // indexes are constant, try to turn this into a shufflevector operation. - if (ExtractElementInst *EI = dyn_cast<ExtractElementInst>(ScalarOp)) { - if (isa<ConstantInt>(EI->getOperand(1)) && isa<ConstantInt>(IdxOp)) { - unsigned NumInsertVectorElts = IE.getType()->getNumElements(); - unsigned NumExtractVectorElts = - EI->getOperand(0)->getType()->getVectorNumElements(); - unsigned ExtractedIdx = - cast<ConstantInt>(EI->getOperand(1))->getZExtValue(); - unsigned InsertedIdx = cast<ConstantInt>(IdxOp)->getZExtValue(); - - if (ExtractedIdx >= NumExtractVectorElts) // Out of range extract. - return replaceInstUsesWith(IE, VecOp); - - if (InsertedIdx >= NumInsertVectorElts) // Out of range insert. - return replaceInstUsesWith(IE, UndefValue::get(IE.getType())); - - // If we are extracting a value from a vector, then inserting it right - // back into the same place, just use the input vector. - if (EI->getOperand(0) == VecOp && ExtractedIdx == InsertedIdx) - return replaceInstUsesWith(IE, VecOp); - - // TODO: Looking at the user(s) to determine if this insert is a - // fold-to-shuffle opportunity does not match the usual instcombine - // constraints. We should decide if the transform is worthy based only - // on this instruction and its operands, but that may not work currently. - // - // Here, we are trying to avoid creating shuffles before reaching - // the end of a chain of extract-insert pairs. This is complicated because - // we do not generally form arbitrary shuffle masks in instcombine - // (because those may codegen poorly), but collectShuffleElements() does - // exactly that. - // - // The rules for determining what is an acceptable target-independent - // shuffle mask are fuzzy because they evolve based on the backend's - // capabilities and real-world impact. - auto isShuffleRootCandidate = [](InsertElementInst &Insert) { - if (!Insert.hasOneUse()) - return true; - auto *InsertUser = dyn_cast<InsertElementInst>(Insert.user_back()); - if (!InsertUser) - return true; - return false; - }; - - // Try to form a shuffle from a chain of extract-insert ops. - if (isShuffleRootCandidate(IE)) { - SmallVector<Constant*, 16> Mask; - ShuffleOps LR = collectShuffleElements(&IE, Mask, nullptr, *this); - - // The proposed shuffle may be trivial, in which case we shouldn't - // perform the combine. - if (LR.first != &IE && LR.second != &IE) { - // We now have a shuffle of LHS, RHS, Mask. - if (LR.second == nullptr) - LR.second = UndefValue::get(LR.first->getType()); - return new ShuffleVectorInst(LR.first, LR.second, - ConstantVector::get(Mask)); - } + // If the inserted element was extracted from some other vector and both + // indexes are constant, try to turn this into a shuffle. + uint64_t InsertedIdx, ExtractedIdx; + Value *ExtVecOp; + if (match(IdxOp, m_ConstantInt(InsertedIdx)) && + match(ScalarOp, m_ExtractElement(m_Value(ExtVecOp), + m_ConstantInt(ExtractedIdx)))) { + unsigned NumInsertVectorElts = IE.getType()->getNumElements(); + unsigned NumExtractVectorElts = ExtVecOp->getType()->getVectorNumElements(); + if (ExtractedIdx >= NumExtractVectorElts) // Out of range extract. + return replaceInstUsesWith(IE, VecOp); + + if (InsertedIdx >= NumInsertVectorElts) // Out of range insert. + return replaceInstUsesWith(IE, UndefValue::get(IE.getType())); + + // If we are extracting a value from a vector, then inserting it right + // back into the same place, just use the input vector. + if (ExtVecOp == VecOp && ExtractedIdx == InsertedIdx) + return replaceInstUsesWith(IE, VecOp); + + // TODO: Looking at the user(s) to determine if this insert is a + // fold-to-shuffle opportunity does not match the usual instcombine + // constraints. We should decide if the transform is worthy based only + // on this instruction and its operands, but that may not work currently. + // + // Here, we are trying to avoid creating shuffles before reaching + // the end of a chain of extract-insert pairs. This is complicated because + // we do not generally form arbitrary shuffle masks in instcombine + // (because those may codegen poorly), but collectShuffleElements() does + // exactly that. + // + // The rules for determining what is an acceptable target-independent + // shuffle mask are fuzzy because they evolve based on the backend's + // capabilities and real-world impact. + auto isShuffleRootCandidate = [](InsertElementInst &Insert) { + if (!Insert.hasOneUse()) + return true; + auto *InsertUser = dyn_cast<InsertElementInst>(Insert.user_back()); + if (!InsertUser) + return true; + return false; + }; + + // Try to form a shuffle from a chain of extract-insert ops. + if (isShuffleRootCandidate(IE)) { + SmallVector<Constant*, 16> Mask; + ShuffleOps LR = collectShuffleElements(&IE, Mask, nullptr, *this); + + // The proposed shuffle may be trivial, in which case we shouldn't + // perform the combine. + if (LR.first != &IE && LR.second != &IE) { + // We now have a shuffle of LHS, RHS, Mask. + if (LR.second == nullptr) + LR.second = UndefValue::get(LR.first->getType()); + return new ShuffleVectorInst(LR.first, LR.second, + ConstantVector::get(Mask)); } } } |
