search for: shaveiseldagtodag

Thanks again for your help Steve, I’m thinking perhaps my “SelectADDRrr” pattern is inadequate. The sign-extension is at the hardware level, the code generator sees (should see) it as a 16-bit signed register value. My implementation is just: bool SHAVEISelDAGtoDAG::SelectADDRrr(SDValue &Addr, SDValue &Base, SDValue &Offset) { if ((Addr.getOpcode() == ISD::ADD) { Base = Addr.getOperand(0); Offset = Addr.getOperand(1); return true; } return false; } I don’t have any special checks on the offset (or the base for that...

Thanks Steve, I will try this out. I hadn’t realised that TableGen was restricted to matching instructions with more than one output operand. I’m assuming that this is only a limitation for inferring an instruction from the patterns, because it does seem to manage schedules okay. Curiously, my memory Reg32+Reg16 pattern is very similar to yours (the 16-bit offset is sign-extended though):