+/// tryAliasOpMatch - This is a helper function for the CodeGenInstAlias
+/// constructor. It checks if an argument in an InstAlias pattern matches
+/// the corresponding operand of the instruction. It returns true on a
+/// successful match, with ResOp set to the result operand to be used.
+bool CodeGenInstAlias::tryAliasOpMatch(DagInit *Result, unsigned AliasOpNo,
+ Record *InstOpRec, bool hasSubOps,
+ SMLoc Loc, CodeGenTarget &T,
+ ResultOperand &ResOp) {
+ Init *Arg = Result->getArg(AliasOpNo);
+ DefInit *ADI = dynamic_cast<DefInit*>(Arg);
+
+ if (ADI && ADI->getDef() == InstOpRec) {
+ // If the operand is a record, it must have a name, and the record type
+ // must match up with the instruction's argument type.
+ if (Result->getArgName(AliasOpNo).empty())
+ throw TGError(Loc, "result argument #" + utostr(AliasOpNo) +
+ " must have a name!");
+ ResOp = ResultOperand(Result->getArgName(AliasOpNo), ADI->getDef());
+ return true;
+ }
+
+ // Handle explicit registers.
+ if (ADI && ADI->getDef()->isSubClassOf("Register")) {
+ if (!InstOpRec->isSubClassOf("RegisterClass"))
+ return false;
+
+ if (!T.getRegisterClass(InstOpRec).containsRegister(ADI->getDef()))
+ throw TGError(Loc, "fixed register " +ADI->getDef()->getName()
+ + " is not a member of the " + InstOpRec->getName() +
+ " register class!");
+
+ if (!Result->getArgName(AliasOpNo).empty())
+ throw TGError(Loc, "result fixed register argument must "
+ "not have a name!");
+
+ ResOp = ResultOperand(ADI->getDef());
+ return true;
+ }
+
+ // Handle "zero_reg" for optional def operands.
+ if (ADI && ADI->getDef()->getName() == "zero_reg") {
+
+ // Check if this is an optional def.
+ if (!InstOpRec->isSubClassOf("OptionalDefOperand"))
+ throw TGError(Loc, "reg0 used for result that is not an "
+ "OptionalDefOperand!");
+
+ ResOp = ResultOperand(static_cast<Record*>(0));
+ return true;
+ }
+
+ if (IntInit *II = dynamic_cast<IntInit*>(Arg)) {
+ if (hasSubOps || !InstOpRec->isSubClassOf("Operand"))
+ return false;
+ // Integer arguments can't have names.
+ if (!Result->getArgName(AliasOpNo).empty())
+ throw TGError(Loc, "result argument #" + utostr(AliasOpNo) +
+ " must not have a name!");
+ ResOp = ResultOperand(II->getValue());
+ return true;
+ }
+
+ return false;
+}
+