diff options
Diffstat (limited to 'llvm/lib')
| -rw-r--r-- | llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp | 13 |
1 files changed, 13 insertions, 0 deletions
diff --git a/llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp b/llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp index 871c8ddb8f1..9837f5b4497 100644 --- a/llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp +++ b/llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp @@ -17079,6 +17079,19 @@ SDValue DAGCombiner::visitEXTRACT_SUBVECTOR(SDNode* N) { if (SDValue NarrowLoad = narrowExtractedVectorLoad(N, DAG)) return NarrowLoad; + // Combine an extract of an extract into a single extract_subvector. + // ext (ext X, C), 0 --> ext X, C + if (isNullConstant(N->getOperand(1)) && + V.getOpcode() == ISD::EXTRACT_SUBVECTOR && V.hasOneUse() && + isa<ConstantSDNode>(V.getOperand(1))) { + if (TLI.isExtractSubvectorCheap(NVT, V.getOperand(0).getValueType(), + V.getConstantOperandVal(1)) && + TLI.isOperationLegalOrCustom(ISD::EXTRACT_SUBVECTOR, NVT)) { + return DAG.getNode(ISD::EXTRACT_SUBVECTOR, SDLoc(N), NVT, V.getOperand(0), + V.getOperand(1)); + } + } + // Combine: // (extract_subvec (concat V1, V2, ...), i) // Into: |
