void n_for::code_gen(status& stat, std::ostream& out)
{
if (init != NULL) // initialising expression
init->code_gen(stat, out);
// start of loop: this is a lot like a while loop.
stat.set_continue_label();
out << stat.get_continue_label() << ":\n";
stat.lock_register(out);
stat.set_assign_expr();
// check expression
cond->code_gen(stat, out);
stat.set_break_label();
// exit loop if expression equals zero
out << "\tbeqz\t$t" << stat.get_register() << "," << stat.get_break_label() << "\n";
out << "\tnop\n";
stat.unlock_register(out);
stat.set_assign_expr();
// loop statement
left->code_gen(stat, out);
if (right != NULL) // loop expression (something like i++)
right->code_gen(stat, out);
out << "\tb\t" << stat.get_continue_label() << "\n";
out << "\tnop\n";
out << stat.get_break_label() << ":\n";
stat.reset_labels(true);
return;
}
void n_ifelse::code_gen(status& stat, std::ostream& out)
{
stat.lock_register(out);
stat.set_assign_expr();
// check expression
left->code_gen(stat, out);
// branch over if statement, if the expression equals zero
std::string else_label = stat.label_gen();
out << "\tbeqz\t$t" << stat.get_register() << "," << else_label << "\n";
out << "\tnop\n";
stat.unlock_register(out);
stat.set_assign_expr();
// if statement
right->code_gen(stat, out);
if (else_node != NULL)
{
std::string end_label = stat.label_gen();
// branch over else statement, if if branch was executed
out << "\tb\t" << end_label << "\n";
out << "\tnop\n";
out << else_label << ":\n";
// else statement
else_node->code_gen(stat, out);
out << end_label << ":\n";
}
else
{
out << else_label << ":\n";
}
return;
}
void n_case::code_gen(status& stat, std::ostream& out)
{
if (left != NULL) // case:
{
stat.lock_register(out);
stat.set_assign_expr();
int op2 = stat.get_register();
left->code_gen(stat, out);
stat.unlock_register(out);
stat.set_assign_expr();
std::string next_case_label = stat.label_gen();
// if the expressions are not equal, branch over statement
out << "\tbne\t$t" << stat.get_register() << ",$t" << op2 << "," << next_case_label << "\n";
out << "\tnop\n";
// case body label
if (stat.get_case_label() != "empty")
out << stat.get_case_label() << ":\n";
stat.set_case_label();
if (right != NULL)
right->code_gen(stat, out); // case body
// fall through: need to jump to the next case body.
out << "\tb\t" << stat.get_case_label() << "\n";
out << "\tnop\n";
out << next_case_label << ":\n";
}
else // default:
{
if (right != NULL)
right->code_gen(stat, out);
}
return;
}
void n_init_decl::code_gen(status& stat, std::ostream& out)
{
if (left != NULL)
{
stat.set_decl(false); // let the id node know that a variable is being declared
left->code_gen(stat, out);
stat.set_decl(false);
}
if (right != NULL) // if variable is initialised to value
{
if (stat.global_var())
{
std::stringstream amount;
right->print(amount);
out << "\t" << amount.str() << "\n";
}
else
{
stat.lock_register(out);
stat.set_assign_expr();
// evaluate assign expr
right->code_gen(stat, out);
stat.set_assign_var(); // let the id node know that a variable is being set to a value
left->code_gen(stat, out);
stat.set_assign_var();
stat.unlock_register(out);
stat.set_assign_expr();
}
}
else if (stat.global_var())
out << "\n";
return;
}
void n_jump_stat::code_gen(status& stat, std::ostream& out)
{
if (type == "continue")
{
out << "\tb\t" << stat.get_continue_label() << "\n";
}
else if (type == "break")
{
out << "\tb\t" << stat.get_break_label() << "\n";
}
else if (type == "return")
{
if (left != NULL)
{
stat.lock_register(out);
stat.set_assign_expr();
left->code_gen(stat, out);
out << "\tmove\t$v0,$t" << stat.get_register() << "\n";
stat.set_assign_expr();
stat.unlock_register(out);
out << "\tb\tr" << stat.get_function_name() << "\n";
out << "\tnop\n";
}
}
else // goto
{
out << "\tj\tl_" << type << "\n";
}
return;
}
void n_ternary::code_gen(status& stat, std::ostream& out)
{
bool unlock = false;
if (!stat.get_assign_expr())
{
stat.lock_register(out);
stat.set_assign_expr();
unlock = true;
}
cond->code_gen(stat, out); // the condition
std::string zero_label = stat.label_gen();
out << "\tbeqz\t$t" << stat.get_register() << "," << zero_label << "\n";
out << "\tnop\n";
left->code_gen(stat, out); // the first expression
std::string end_label = stat.label_gen();
out << "\tb\t" << end_label << "\n";
out << zero_label << ":\n";
right->code_gen(stat, out); // the second expression
out << end_label << ":\n";
if (unlock)
{
stat.unlock_register(out);
stat.set_assign_expr();
}
return;
}
void n_arg_list::code_gen(status& stat, std::ostream& out)
{
if (left != NULL)
left->code_gen(stat, out);
int arg_reg = stat.lock_arg_register(out);
stat.lock_register(out);
right->code_gen(stat, out);
if (arg_reg < 4)
out << "\tmove\t$a" << arg_reg << ",$t" << stat.get_register() << "\n";
else
out << "\tsw\t$t" << stat.get_register() << ",($sp)\n";
stat.unlock_register(out);
return;
}
void n_switch::code_gen(status& stat, std::ostream& out)
{
stat.lock_register(out);
stat.set_assign_expr();
// check expression
left->code_gen(stat, out);
stat.set_assign_expr();
stat.set_break_label();
// list of cases
right->code_gen(stat, out);
stat.unlock_register(out);
out << stat.get_break_label() << ":\n";
out << stat.get_case_label() << ":\n";
stat.reset_labels(false);
return;
}
void n_dowhile::code_gen(status& stat, std::ostream& out)
{
// label signifying the start of the loop
stat.set_continue_label();
out << stat.get_continue_label() << ":\n";
// loop statement
stat.set_break_label();
left->code_gen(stat, out);
stat.lock_register(out);
stat.set_assign_expr();
// check expression
right->code_gen(stat, out);
// do another loop if expression is non zero
out << "\tbnez\t$t" << stat.get_register() << "," << stat.get_continue_label() << "\n";
out << "\tnop\n";
out << stat.get_break_label() << ":\n";
stat.unlock_register(out);
stat.set_assign_expr();
stat.reset_labels(true);
return;
}
void n_while::code_gen(status& stat, std::ostream& out)
{
// label signifying the start of the loop
stat.set_continue_label();
out << stat.get_continue_label() << ":\n";
stat.lock_register(out);
stat.set_assign_expr();
// check expression
left->code_gen(stat, out);
stat.set_break_label();
// exit loop if expression equals zero
out << "\tbeqz\t$t" << stat.get_register() << "," << stat.get_break_label() << "\n";
out << "\tnop\n";
stat.unlock_register(out);
stat.set_assign_expr();
// loop statement
right->code_gen(stat, out);
// return to top of loop
out << "\tb\t" << stat.get_continue_label() << "\n";
out << "\tnop\n";
out << stat.get_break_label() << ":\n";
stat.reset_labels(true);
return;
}
void n_expression::code_gen(status& stat, std::ostream& out)
{
// left OP right : result_reg = t0 OP t1
bool unlock = false;
if (!stat.get_assign_expr())
{
stat.lock_register(out);
stat.set_assign_expr();
unlock = true;
}
if (opstr == "+")
{
if (left != NULL)
{
left->code_gen(stat, out);
stat.lock_register(out);
right->code_gen(stat, out);
int op2 = stat.get_register();
int op2f = stat.get_f_register();
stat.unlock_register(out);
if (stat.is_float())
out << "\tadd.s\t$f" << stat.get_f_register() << ",$f" << stat.get_f_register() << ",$f" << op2f << "\n";
else
out << "\tadd\t$t" << stat.get_register() << ",$t" << stat.get_register() << ",$t" << op2 << "\n";
}
else
{
right->code_gen(stat, out);
}
}
else if (opstr == "-")
{
if (left != NULL)
{
left->code_gen(stat, out);
stat.lock_register(out);
right->code_gen(stat, out);
int op2 = stat.get_register();
int op2f = stat.get_f_register();
stat.unlock_register(out);
if (stat.is_float())
out << "\tsub.s\t$f" << stat.get_f_register() << ",$f" << stat.get_f_register() << ",$f" << op2f << "\n";
else
out << "\tsub\t$t" << stat.get_register() << ",$t" << stat.get_register() << ",$t" << op2 << "\n";
}
else
{
stat.lock_register(out);
right->code_gen(stat, out);
int op2 = stat.get_register();
stat.unlock_register(out);
out << "\tneg\t$t" << stat.get_register() << ",$t" << op2 << "\n";
}
}
else if (opstr == "*")
{
if (left != NULL) // if operation is left MULT right
{
left->code_gen(stat, out);
stat.lock_register(out);
right->code_gen(stat, out);
int op2 = stat.get_register();
int op2f = stat.get_f_register();
stat.unlock_register(out);
if (stat.is_float())
out << "\tmul.s\t$f" << stat.get_f_register() << ",$f" << stat.get_f_register() << ",$f" << op2f << "\n";
else
out << "\tmul\t$t" << stat.get_register() << ",$t" << stat.get_register() << ",$t" << op2 << "\n";
}
else // if operation is dereferencing
{
if (stat.get_assign_var())
stat.lock_register(out);
int op2 = stat.get_register();
stat.set_dereference();
right->code_gen(stat, out);
stat.set_dereference();
if (stat.get_assign_var()) // if variable needs to be saved
stat.unlock_register(out);
out << "\t" << stat.pointer_opcode() << "\t$t" << stat.get_register() << ",($t" << op2 << ")\n";
}
}
else if (opstr == "/")
{
left->code_gen(stat, out);
stat.lock_register(out);
right->code_gen(stat, out);
int op2 = stat.get_register();
int op2f = stat.get_f_register();
stat.unlock_register(out);
if (stat.is_float())
out << "\tdiv.s\t$f" << stat.get_f_register() << ",$f" << stat.get_f_register() << ",$f" << op2f << "\n";
else
out << "\tdiv\t$t" << stat.get_register() << ",$t" << stat.get_register() << ",$t" << op2 << "\n";
}
else if (opstr == "%")
{
left->code_gen(stat, out);
stat.lock_register(out);
right->code_gen(stat, out);
int op2 = stat.get_register();
stat.unlock_register(out);
out << "\trem\t$t" << stat.get_register() << ",$t" << stat.get_register() << ",$t" << op2 << "\n";
}
else if (opstr == "&")
{
if (left != NULL) // if operation is left AND right
{
left->code_gen(stat, out);
stat.lock_register(out);
right->code_gen(stat, out);
int op2 = stat.get_register();
stat.unlock_register(out);
out << "\tand\t$t" << stat.get_register();
out << ",$t" << stat.get_register() << ",$t" << op2 << "\n";
}
else // if operation is referencing
{
stat.set_reference();
right->code_gen(stat, out);
stat.set_reference();
}
}
else if (opstr == "|")
{
left->code_gen(stat, out);
stat.lock_register(out);
right->code_gen(stat, out);
int op2 = stat.get_register();
stat.unlock_register(out);
out << "\tor\t$t" << stat.get_register();
out << ",$t" << stat.get_register() << ",$t" << op2 << "\n";
}
else if (opstr == "^")
{
left->code_gen(stat, out);
stat.lock_register(out);
right->code_gen(stat, out);
int op2 = stat.get_register();
stat.unlock_register(out);
out << "\txor\t$t" << stat.get_register();
out << ",$t" << stat.get_register() << ",$t" << op2 << "\n";
}
else if (opstr == "<<")
{
left->code_gen(stat, out);
stat.lock_register(out);
right->code_gen(stat, out);
int op2 = stat.get_register();
stat.unlock_register(out);
out << "\tsllv\t$t" << stat.get_register();
out << ",$t" << stat.get_register() << ",$t" << op2 << "\n";
}
else if (opstr == ">>")
{
left->code_gen(stat, out);
stat.lock_register(out);
right->code_gen(stat, out);
int op2 = stat.get_register();
stat.unlock_register(out);
out << "\tsrav\t$t" << stat.get_register();
out << ",$t" << stat.get_register() << ",$t" << op2 << "\n";
}
else if (opstr == "==")
{
left->code_gen(stat, out);
stat.lock_register(out);
right->code_gen(stat, out);
int op2 = stat.get_register();
stat.unlock_register(out);
out << "\tseq\t$t" << stat.get_register() << ",$t" << stat.get_register() << ",$t" << op2 << "\n";
}
else if (opstr == "!=")
{
left->code_gen(stat, out);
stat.lock_register(out);
right->code_gen(stat, out);
int op2 = stat.get_register();
stat.unlock_register(out);
out << "\tsne\t$t" << stat.get_register() << ",$t" << stat.get_register() << ",$t" << op2 << "\n";
}
else if (opstr == "<")
{
left->code_gen(stat, out);
stat.lock_register(out);
right->code_gen(stat, out);
int op2 = stat.get_register();
stat.unlock_register(out);
out << "\tslt\t$t" << stat.get_register() << ",$t" << stat.get_register() << ",$t" << op2 << "\n";
}
else if (opstr == ">")
{
left->code_gen(stat, out);
stat.lock_register(out);
right->code_gen(stat, out);
int op2 = stat.get_register();
stat.unlock_register(out);
out << "\tslt\t$t" << stat.get_register() << ",$t" << op2 << ",$t" << stat.get_register() << "\n";
}
else if (opstr == "<=")
{
left->code_gen(stat, out);
stat.lock_register(out);
right->code_gen(stat, out);
int op2 = stat.get_register();
stat.unlock_register(out);
out << "\tsge\t$t" << stat.get_register() << ",$t" << op2 << ",$t" << stat.get_register() << "\n";
}
else if (opstr == ">=")
{
left->code_gen(stat, out);
stat.lock_register(out);
right->code_gen(stat, out);
int op2 = stat.get_register();
stat.unlock_register(out);
out << "\tsge\t$t" << stat.get_register() << ",$t" << stat.get_register() << ",$t" << op2 << "\n";
}
else if (opstr == "++")
{
if (left != NULL) // postfix
{
left->code_gen(stat, out);
int op1 = stat.get_register();
stat.lock_register(out);
out << "\tadd\t$t" << stat.get_register() << ",$t" << op1 << ",1\n";
stat.set_assign_var();
left->code_gen(stat, out);
stat.set_assign_var();
stat.unlock_register(out);
}
else if (right != NULL) // prefix
{
right->code_gen(stat, out);
out << "\tadd\t$t" << stat.get_register() << ",$t" << stat.get_register() << ",1\n";
stat.set_assign_var();
right->code_gen(stat, out);
stat.set_assign_var();
}
}
else if (opstr == "--")
{
if (left != NULL) // postfix
{
left->code_gen(stat, out);
int op1 = stat.get_register();
stat.lock_register(out);
out << "\tsub\t$t" << stat.get_register() << ",$t" << op1 << ",1\n";
stat.set_assign_var();
left->code_gen(stat, out);
stat.set_assign_var();
stat.unlock_register(out);
}
else if (right != NULL) // prefix
{
right->code_gen(stat, out);
out << "\tsub\t$t" << stat.get_register() << ",$t" << stat.get_register() << ",1\n";
stat.set_assign_var();
right->code_gen(stat, out);
stat.set_assign_var();
}
}
else if (opstr == "[]")
{
if (stat.get_assign_var())
stat.lock_register(out);
// get offset of first element
stat.lock_register(out);
int op2 = stat.get_register();
stat.set_reference();
left->code_gen(stat, out);
stat.set_reference();
stat.unlock_register(out);
// evaluate operation
right->code_gen(stat, out);
// shift the operation to get number of bytes for array offset
out << "\tsll\t$t" << stat.get_register() << ",$t" << stat.get_register() << ",2\n";
// subtract array offset from first element offset
out << "\tsubu\t$t" << stat.get_register() << ",$t" << op2 << ",$t" << stat.get_register() << "\n";
// store or load the variable
op2 = stat.get_register();
if (stat.get_assign_var())
stat.unlock_register(out);
out << "\t" << stat.pointer_opcode() << "\t$t" << stat.get_register() << ",($t" << op2 << ")\n";
}
else if (opstr == "!")
{
left->code_gen(stat, out);
out << "\tseq\t$" << stat.get_register() << ",$zero,$t" << stat.get_register();
}
else if (opstr == "~")
{
left->code_gen(stat, out);
out << "\tnot\t$" << stat.get_register() << ",$t" << stat.get_register() << "\n";
}
else if (opstr == "=")
{
right->code_gen(stat, out);
stat.set_assign_var();
left->code_gen(stat, out);
stat.set_assign_var();
}
if (unlock)
{
stat.unlock_register(out);
stat.set_assign_expr();
}
return;
}
