diff options
Diffstat (limited to 'llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp')
| -rw-r--r-- | llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp | 25 |
1 files changed, 20 insertions, 5 deletions
diff --git a/llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp b/llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp index 8f745a149ac..a26f378b49a 100644 --- a/llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp +++ b/llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp @@ -11886,7 +11886,24 @@ SDValue DAGCombiner::visitEXTRACT_VECTOR_ELT(SDNode *N) { } SDValue EltNo = N->getOperand(1); - bool ConstEltNo = isa<ConstantSDNode>(EltNo); + ConstantSDNode *ConstEltNo = dyn_cast<ConstantSDNode>(EltNo); + + // extract_vector_elt (build_vector x, y), 1 -> y + if (ConstEltNo && + InVec.getOpcode() == ISD::BUILD_VECTOR && + TLI.isTypeLegal(VT) && + (InVec.hasOneUse() || + TLI.aggressivelyPreferBuildVectorSources(VT))) { + SDValue Elt = InVec.getOperand(ConstEltNo->getZExtValue()); + EVT InEltVT = Elt.getValueType(); + + // Sometimes build_vector's scalar input types do not match result type. + if (NVT == InEltVT) + return Elt; + + // TODO: It may be useful to truncate if free if the build_vector implicitly + // converts. + } // Transform: (EXTRACT_VECTOR_ELT( VECTOR_SHUFFLE )) -> EXTRACT_VECTOR_ELT. // We only perform this optimization before the op legalization phase because @@ -11894,13 +11911,11 @@ SDValue DAGCombiner::visitEXTRACT_VECTOR_ELT(SDNode *N) { // patterns. For example on AVX, extracting elements from a wide vector // without using extract_subvector. However, if we can find an underlying // scalar value, then we can always use that. - if (InVec.getOpcode() == ISD::VECTOR_SHUFFLE - && ConstEltNo) { - int Elt = cast<ConstantSDNode>(EltNo)->getZExtValue(); + if (ConstEltNo && InVec.getOpcode() == ISD::VECTOR_SHUFFLE) { int NumElem = VT.getVectorNumElements(); ShuffleVectorSDNode *SVOp = cast<ShuffleVectorSDNode>(InVec); // Find the new index to extract from. - int OrigElt = SVOp->getMaskElt(Elt); + int OrigElt = SVOp->getMaskElt(ConstEltNo->getZExtValue()); // Extracting an undef index is undef. if (OrigElt == -1) |
