diff options
Diffstat (limited to 'lib/CodeGen')
| -rw-r--r-- | lib/CodeGen/SelectionDAG/DAGCombiner.cpp | 42 |
1 files changed, 42 insertions, 0 deletions
diff --git a/lib/CodeGen/SelectionDAG/DAGCombiner.cpp b/lib/CodeGen/SelectionDAG/DAGCombiner.cpp index 0c5cd3e6cab..f2d3a8d4fe9 100644 --- a/lib/CodeGen/SelectionDAG/DAGCombiner.cpp +++ b/lib/CodeGen/SelectionDAG/DAGCombiner.cpp @@ -5308,6 +5308,48 @@ SDValue DAGCombiner::visitTRUNCATE(SDNode *N) { if (Reduced.getNode()) return Reduced; } + // fold (trunc (concat ... x ...)) -> (concat ..., (trunc x), ...)), + // where ... are all 'undef'. + if (N0.getOpcode() == ISD::CONCAT_VECTORS && !LegalTypes) { + SmallVector<EVT, 8> VTs; + SDValue V; + unsigned Idx = 0; + unsigned NumDefs = 0; + + for (unsigned i = 0, e = N0.getNumOperands(); i != e; ++i) { + SDValue X = N0.getOperand(i); + if (X.getOpcode() != ISD::UNDEF) { + V = X; + Idx = i; + NumDefs++; + } + // Stop if more than one members are non-undef. + if (NumDefs > 1) + break; + VTs.push_back(EVT::getVectorVT(*DAG.getContext(), + VT.getVectorElementType(), + X.getValueType().getVectorNumElements())); + } + + if (NumDefs == 0) + return DAG.getUNDEF(VT); + + if (NumDefs == 1) { + assert(V.getNode() && "The single defined operand is empty!"); + SmallVector<SDValue, 8> Opnds; + for (unsigned i = 0, e = VTs.size(); i != e; ++i) { + if (i != Idx) { + Opnds.push_back(DAG.getUNDEF(VTs[i])); + continue; + } + SDValue NV = DAG.getNode(ISD::TRUNCATE, V.getDebugLoc(), VTs[i], V); + AddToWorkList(NV.getNode()); + Opnds.push_back(NV); + } + return DAG.getNode(ISD::CONCAT_VECTORS, N->getDebugLoc(), VT, + &Opnds[0], Opnds.size()); + } + } // Simplify the operands using demanded-bits information. if (!VT.isVector() && |