With the OR1KOperand structure defined, the main MatchAndEmitInstruction can be implemented, calling on the MatchInstructionImpl generated by TableGen to do the hard work.

When called, MatchInstructionImpl will use a given MCInst to store details on the instruction if possible, returning an error value. If the instruction was successfully parsed, the value Match_Success is returned and the instruction can be simply emitted via the provided MCStreamer.

If however there is a problem parsing the instruction, the return code will be different and set depending on where the problem occurred. For example Match_MissingFeature is returned if a required target feature is not enabled and Match_MnemonicFail is returned if the instruction mnemonic is not recognized.

These return codes can be used to generate a useful error message, though the simplest case would be just to state than an error occurred and then return. This case is demonstrated below.

bool OR1KAsmParser::
MatchAndEmitInstruction(SMLoc IDLoc,
                        SmallVectorImpl<MCParsedAsmOperand*> &Operands,
                        MCStreamer &Out) {
  MCInst Inst;
  SMLoc ErrorLoc;
  unsigned ErrorInfo;

  if (MatchInstructionImpl(Operands, Inst, ErrorInfo)) {
    Out.EmitInstruction(Inst);
    return false;
  }
  else
    return Error(IDLoc, "Error parsing instruction");
}