diff --git a/llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp b/llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp index 879dc5b36f7e..35c981d7f3db 100644 --- a/llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp +++ b/llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp @@ -803,6 +803,20 @@ SDOperand DAGCombiner::visitAND(SDNode *N) { WorkList.push_back(ANDNode.Val); return DAG.getNode(N0.getOpcode(), VT, ANDNode, N0.getOperand(1)); } + // fold (and (sra)) -> (and (srl)) when possible. + if (N0.getOpcode() == ISD::SRA && N0.Val->hasOneUse()) + if (ConstantSDNode *N01C = dyn_cast(N0.getOperand(1))) { + // If the RHS of the AND has zeros where the sign bits of the SRA will + // land, turn the SRA into an SRL. + if (MaskedValueIsZero(N1, (~0ULL << N01C->getValue()) & + (~0ULL>>(64-OpSizeInBits)), TLI)) { + WorkList.push_back(N); + CombineTo(N0.Val, DAG.getNode(ISD::SRL, VT, N0.getOperand(0), + N0.getOperand(1))); + return SDOperand(); + } + } + // fold (zext_inreg (extload x)) -> (zextload x) if (N0.getOpcode() == ISD::EXTLOAD) { MVT::ValueType EVT = cast(N0.getOperand(3))->getVT();