diff options
Diffstat (limited to 'llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp')
| -rw-r--r-- | llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp | 8 |
1 files changed, 8 insertions, 0 deletions
diff --git a/llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp b/llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp index a8a76311225..6e6dfd855f8 100644 --- a/llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp +++ b/llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp @@ -12397,6 +12397,14 @@ SDValue DAGCombiner::visitEXTRACT_VECTOR_ELT(SDNode *N) { return DAG.getNode(ISD::TRUNCATE, SDLoc(N), NVT, BCSrc); } + // extract_vector_elt (insert_vector_elt vec, val, idx), idx) -> val + // + // This only really matters if the index is non-constant since other combines + // on the constant elements already work. + if (InVec.getOpcode() == ISD::INSERT_VECTOR_ELT && + EltNo == InVec.getOperand(2)) + return InVec.getOperand(1); + // Transform: (EXTRACT_VECTOR_ELT( VECTOR_SHUFFLE )) -> EXTRACT_VECTOR_ELT. // We only perform this optimization before the op legalization phase because // we may introduce new vector instructions which are not backed by TD |
