public void Visit(Program program)
{
// the init op code sets up the call stack, to read command line arguments
var main = program.Definitions.Single(d => d.Name == "main");
tacs.Add(Tac.Init(main.Formals.Count));
// call main
tacs.Add(Tac.BeginCall(main.Name, main.Formals.Count, "t0"));
for (int i = 0; i < main.Formals.Count; i++)
{
tacs.Add(Tac.Param($"arg{i}"));
}
tacs.Add(Tac.Call("main", "t0"));
// call print
tacs.Add(Tac.BeginCall("print", 1, "t1"));
tacs.Add(Tac.Param("t0"));
tacs.Add(Tac.Call("print", "t1"));
tacs.Add(Tac.Halt());
// declare print function
tacs.Add(Tac.BeginFunc("print", 1));
tacs.Add(Tac.PrintVariable("arg0"));
tacs.Add(Tac.EndFunc("print"));
foreach (var definition in program.Definitions)
{
definition.Accept(this);
}
}
public void Visit(Print print)
{
print.Expr.Accept(this);
var temp = tacs.Last().Result;
var returnVariable = MakeNewTemp();
tacs.Add(Tac.BeginCall("print", 1, returnVariable));
tacs.Add(Tac.Param(temp));
tacs.Add(Tac.Call("print", returnVariable));
}
public void Visit(FunctionCall functionCall)
{
var args = new List <string>();
foreach (var actual in functionCall.Actuals)
{
actual.Expr.Accept(this);
args.Add(tacs.Last().Result);
}
var returnValue = MakeNewTemp();
tacs.Add(Tac.BeginCall(functionCall.Name, functionCall.Actuals.Count, returnValue));
foreach (var arg in args)
{
tacs.Add(Tac.Param(arg));
}
tacs.Add(Tac.Call(functionCall.Name, returnValue));
}