public void Visit(NotOperator not)
{
not.Right.Accept(this);
var rightOperand = tacs.Last().Result;
tacs.Add(Tac.Not(rightOperand, MakeNewTemp()));
}
public void Visit(NegateOperator negate)
{
negate.Right.Accept(this);
var rightOperand = tacs.Last().Result;
tacs.Add(Tac.Negate(rightOperand, MakeNewTemp()));
}
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(Body body)
{
foreach (var print in body.Prints)
{
print.Accept(this);
}
body.Expr.Accept(this);
tacs.Add(Tac.Return(tacs.Last().Result));
}
public void Visit(TimesOperator times)
{
times.Left.Accept(this);
var leftOperand = tacs.Last().Result;
times.Right.Accept(this);
var rightOperand = tacs.Last().Result;
tacs.Add(Tac.Times(leftOperand, rightOperand, MakeNewTemp()));
}
public void Visit(MinusOperator minus)
{
minus.Left.Accept(this);
var leftOperand = tacs.Last().Result;
minus.Right.Accept(this);
var rightOperand = tacs.Last().Result;
tacs.Add(Tac.Minus(leftOperand, rightOperand, MakeNewTemp()));
}
public void Visit(DivideOperator divide)
{
divide.Left.Accept(this);
var leftOperand = tacs.Last().Result;
divide.Right.Accept(this);
var rightOperand = tacs.Last().Result;
tacs.Add(Tac.Divide(leftOperand, rightOperand, MakeNewTemp()));
}
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(Definition definition)
{
// temps are local to the function so reset the counter for each func
// (makes it easy to work out where the temp is stored in the stack frame)
tempCounter = 0;
Ast.SymbolTable.CurrentFunction = definition.Name;
tacs.Add(Tac.BeginFunc(definition.Name, definition.Formals.Count));
definition.Body.Accept(this);
tacs.Add(Tac.EndFunc(definition.Name));
}
public void Visit(IfThenElse ifthenelse)
{
var elseLabel = MakeNewLabel();
var endLabel = MakeNewLabel();
var resultVariable = MakeNewTemp();
ifthenelse.IfExpr.Accept(this);
var ifoperand = tacs.Last().Result;
tacs.Add(Tac.IfFalse(ifoperand, elseLabel));
ifthenelse.ThenExpr.Accept(this);
tacs.Add(Tac.Assign(tacs.Last().Result, resultVariable));
tacs.Add(Tac.Goto(endLabel));
tacs.Add(Tac.Label(elseLabel, resultVariable));
ifthenelse.ElseExpr.Accept(this);
tacs.Add(Tac.Assign(tacs.Last().Result, resultVariable));
tacs.Add(Tac.Label(endLabel, resultVariable));
}
public void Visit(EqualsOperator equals)
{
equals.Left.Accept(this);
var leftOperand = tacs.Last().Result;
equals.Right.Accept(this);
var rightOperand = tacs.Last().Result;
var result = MakeNewTemp();
var label1 = MakeNewLabel();
var label2 = MakeNewLabel();
tacs.Add(Tac.IfEqual(leftOperand, rightOperand, label1));
tacs.Add(Tac.Assign("0", result));
tacs.Add(Tac.Goto(label2));
tacs.Add(Tac.Label(label1, result));
tacs.Add(Tac.Assign("1", result));
tacs.Add(Tac.Label(label2, result));
}
public void Visit(LessThanOperator lessThan)
{
lessThan.Left.Accept(this);
var leftOperand = tacs.Last().Result;
lessThan.Right.Accept(this);
var rightOperand = tacs.Last().Result;
var result = MakeNewTemp();
var label1 = MakeNewLabel();
var label2 = MakeNewLabel();
tacs.Add(Tac.IfLessThan(leftOperand, rightOperand, label1));
tacs.Add(Tac.Assign("0", result));
tacs.Add(Tac.Goto(label2));
tacs.Add(Tac.Label(label1, result));
tacs.Add(Tac.Assign("1", result));
tacs.Add(Tac.Label(label2, result));
}
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));
}
public void Visit(OrOperator or)
{
var trueLabel = MakeNewLabel();
var endLabel = MakeNewLabel();
or.Left.Accept(this);
var leftOperand = tacs.Last().Result;
tacs.Add(Tac.IfTrue(leftOperand, trueLabel));
or.Right.Accept(this);
var rightOperand = tacs.Last().Result;
tacs.Add(Tac.IfTrue(rightOperand, trueLabel));
var resultVariable = MakeNewTemp();
tacs.Add(Tac.Assign("0", resultVariable));
tacs.Add(Tac.Goto(endLabel));
tacs.Add(Tac.Label(trueLabel, resultVariable));
tacs.Add(Tac.Assign("1", resultVariable));
tacs.Add(Tac.Label(endLabel, resultVariable));
}
public void Visit(AndOperator and)
{
var falseLabel = MakeNewLabel();
var endLabel = MakeNewLabel();
and.Left.Accept(this);
var leftOperand = tacs.Last().Result;
tacs.Add(Tac.IfFalse(leftOperand, falseLabel));
and.Right.Accept(this);
var rightOperand = tacs.Last().Result;
tacs.Add(Tac.IfFalse(rightOperand, falseLabel));
var resultVariable = MakeNewTemp();
tacs.Add(Tac.Assign("1", resultVariable));
tacs.Add(Tac.Goto(endLabel));
tacs.Add(Tac.Label(falseLabel, resultVariable));
tacs.Add(Tac.Assign("0", resultVariable));
tacs.Add(Tac.Label(endLabel, resultVariable));
}
public void Visit(IntegerLiteral literal)
{
tacs.Add(Tac.Assign(literal.Value.ToString(), MakeNewTemp()));
}
public void Visit(BooleanLiteral booleanLiteral)
{
var booleanValue = booleanLiteral.Value ? "1" : "0";
tacs.Add(Tac.Assign(booleanValue, MakeNewTemp()));
}
public void Visit(Identifier identifier)
{
var arg = $"arg{Ast.SymbolTable.ArgumentNumber(identifier.Value)}";
tacs.Add(Tac.Assign(arg, MakeNewTemp()));
}