diff options
Diffstat (limited to 'llvm/lib/CodeGen/SelectionDAG')
| -rw-r--r-- | llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp | 23 |
1 files changed, 23 insertions, 0 deletions
diff --git a/llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp b/llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp index df38ef423fa..306fd6f4984 100644 --- a/llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp +++ b/llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp @@ -15157,6 +15157,29 @@ SDValue DAGCombiner::visitEXTRACT_SUBVECTOR(SDNode* N) { // Skip bitcasting V = peekThroughBitcast(V); + // If the input is a build vector. Try to make a smaller build vector. + if (V->getOpcode() == ISD::BUILD_VECTOR) { + if (auto *Idx = dyn_cast<ConstantSDNode>(N->getOperand(1))) { + EVT InVT = V->getValueType(0); + unsigned NumElems = NVT.getSizeInBits() / InVT.getScalarSizeInBits(); + if (NumElems > 0) { + EVT ExtractVT = EVT::getVectorVT(*DAG.getContext(), + InVT.getVectorElementType(), NumElems); + if (!LegalOperations || + TLI.isOperationLegal(ISD::BUILD_VECTOR, ExtractVT)) { + unsigned IdxVal = Idx->getZExtValue() * NVT.getScalarSizeInBits() / + InVT.getScalarSizeInBits(); + + // Extract the pieces from the original build_vector. + SDValue BuildVec = DAG.getBuildVector(ExtractVT, SDLoc(N), + makeArrayRef(V->op_begin() + IdxVal, + NumElems)); + return DAG.getBitcast(NVT, BuildVec); + } + } + } + } + if (V->getOpcode() == ISD::INSERT_SUBVECTOR) { // Handle only simple case where vector being inserted and vector // being extracted are of same size. |
