public override Reg CGenValue(CGenState state) {
Env.Entry entry = this.Env.Find(this.Name).Value;
Int32 offset = entry.Offset;
//if (entry.Kind == Env.EntryKind.STACK) {
// offset = -offset;
//}
switch (entry.Kind) {
case Env.EntryKind.ENUM:
// 1. If the variable is an enum constant,
// return the Value in %eax.
state.MOVL(offset, Reg.EAX);
return Reg.EAX;
case Env.EntryKind.FRAME:
case Env.EntryKind.STACK:
// 2. If the variable is a function argument or a local variable,
// the address would be offset(%ebp).
switch (this.Type.Kind) {
case ExprTypeKind.LONG:
case ExprTypeKind.ULONG:
case ExprTypeKind.POINTER:
// %eax = offset(%ebp)
state.MOVL(offset, Reg.EBP, Reg.EAX);
return Reg.EAX;
case ExprTypeKind.FLOAT:
// %st(0) = offset(%ebp)
state.FLDS(offset, Reg.EBP);
return Reg.ST0;
case ExprTypeKind.DOUBLE:
// %st(0) = offset(%ebp)
state.FLDL(offset, Reg.EBP);
return Reg.ST0;
case ExprTypeKind.STRUCT_OR_UNION:
// %eax = address
state.LEA(offset, Reg.EBP, Reg.EAX);
return Reg.EAX;
//state.LEA(offset, Reg.EBP, Reg.ESI); // source address
//state.CGenExpandStackBy(Utils.RoundUp(Type.SizeOf, 4));
//state.LEA(0, Reg.ESP, Reg.EDI); // destination address
//state.MOVL(Type.SizeOf, Reg.ECX); // nbytes
//state.CGenMemCpy();
//return Reg.STACK;
case ExprTypeKind.VOID:
throw new InvalidProgramException("How could a variable be void?");
// %eax = $0
// state.MOVL(0, Reg.EAX);
// return Reg.EAX;
case ExprTypeKind.FUNCTION:
throw new InvalidProgramException("How could a variable be a function designator?");
// %eax = function_name
// state.MOVL(name, Reg.EAX);
// return Reg.EAX;
case ExprTypeKind.CHAR:
// %eax = [char -> long](off(%ebp))
state.MOVSBL(offset, Reg.EBP, Reg.EAX);
return Reg.EAX;
case ExprTypeKind.UCHAR:
// %eax = [uchar -> ulong](off(%ebp))
state.MOVZBL(offset, Reg.EBP, Reg.EAX);
return Reg.EAX;
case ExprTypeKind.SHORT:
// %eax = [short -> long](off(%ebp))
state.MOVSWL(offset, Reg.EBP, Reg.EAX);
return Reg.EAX;
case ExprTypeKind.USHORT:
// %eax = [ushort -> ulong](off(%ebp))
state.MOVZWL(offset, Reg.EBP, Reg.EAX);
return Reg.EAX;
case ExprTypeKind.ARRAY:
// %eax = (off(%ebp))
state.LEA(offset, Reg.EBP, Reg.EAX); // source address
return Reg.EAX;
default:
throw new InvalidOperationException($"Cannot get value of {this.Type.Kind}");
}
case Env.EntryKind.GLOBAL:
switch (this.Type.Kind) {
case ExprTypeKind.CHAR:
state.MOVSBL(this.Name, Reg.EAX);
return Reg.EAX;
case ExprTypeKind.UCHAR:
state.MOVZBL(this.Name, Reg.EAX);
return Reg.EAX;
case ExprTypeKind.SHORT:
state.MOVSWL(this.Name, Reg.EAX);
return Reg.EAX;
case ExprTypeKind.USHORT:
state.MOVZWL(this.Name, Reg.EAX);
return Reg.EAX;
case ExprTypeKind.LONG:
case ExprTypeKind.ULONG:
case ExprTypeKind.POINTER:
state.MOVL(this.Name, Reg.EAX);
return Reg.EAX;
case ExprTypeKind.FUNCTION:
state.MOVL("$" + this.Name, Reg.EAX);
return Reg.EAX;
case ExprTypeKind.FLOAT:
state.FLDS(this.Name);
return Reg.ST0;
case ExprTypeKind.DOUBLE:
state.FLDL(this.Name);
return Reg.ST0;
case ExprTypeKind.STRUCT_OR_UNION:
state.MOVL($"${this.Name}", Reg.EAX);
return Reg.EAX;
//state.LEA(name, Reg.ESI); // source address
//state.CGenExpandStackBy(Utils.RoundUp(Type.SizeOf, 4));
//state.LEA(0, Reg.ESP, Reg.EDI); // destination address
//state.MOVL(Type.SizeOf, Reg.ECX); // nbytes
//state.CGenMemCpy();
//return Reg.STACK;
case ExprTypeKind.VOID:
throw new InvalidProgramException("How could a variable be void?");
//state.MOVL(0, Reg.EAX);
//return Reg.EAX;
case ExprTypeKind.ARRAY:
state.MOVL($"${this.Name}", Reg.EAX);
return Reg.EAX;
default:
throw new InvalidProgramException("cannot get the Value of a " + this.Type.Kind);
}
case Env.EntryKind.TYPEDEF:
default:
throw new InvalidProgramException("cannot get the Value of a " + entry.Kind);
}
}
}
