expr_type make_expr_from_id(id_type id)
{
expr_type e = (expr_type) SafeMalloc(sizeof(expr_struct));
/* Id must be a parameter, local, property, constant, or resource */
lookup_id(id);
switch(id->type)
{
case I_LOCAL:
case I_PROPERTY:
case I_CLASSVAR:
e->type = E_IDENTIFIER;
e->value.idval = id;
break;
case I_RESOURCE:
{
const_type c = (const_type) SafeMalloc(sizeof(const_struct));
/* Turn resource id reference into the resource # itself */
c->type = C_RESOURCE;
c->value.numval = id->idnum;
e->type = E_CONSTANT;
e->value.constval = c;
return e;
}
case I_CONSTANT:
{
const_type c = (const_type) SafeMalloc(sizeof(const_struct));
id_type temp;
/* Turn constant id reference into the constant itself */
c->type = C_NUMBER;
temp = (id_type) list_find_item(st.constants, id, id_compare);
c->value.numval = temp->source; /* Value is stored in source field */
e->type = E_CONSTANT;
e->value.constval = c;
break;
}
case I_UNDEFINED:
case I_MISSING:
action_error("Unknown identifier %s", id->name);
/* Put in something so that compilation can continue */
e = make_expr_from_constant(make_nil_constant());
break;
default:
action_error("Identifier %s in expression has wrong type", id->name);
/* Put in something so that compilation can continue */
e = make_expr_from_constant(make_nil_constant());
break;
}
e->lineno = lineno;
return e;
}
/*
* codegen_foreach: Generate code for a for loop statement.
* numlocals should be # of local variables for message excluding temps.
* Returns highest # local variable used in code for statement.
* Here is how code is generated for a FOR statement:
* for i in list ===> temp = list 1
* {body} top: if (temp = $) goto end 2
* i = First(temp) 3
* { body }
* temp = Rest(temp) 4
* goto top 5
* end:
*
* Note that continue statements need to jump to statement 4.
*/
int codegen_foreach(foreach_stmt_type s, int numlocals)
{
opcode_type opcode;
int our_maxlocal, numtemps;
stmt_type temp_stmt = (stmt_type) SafeMalloc(sizeof(stmt_struct));
expr_type temp_expr = (expr_type) SafeMalloc(sizeof(expr_struct));
expr_type temp2_expr = (expr_type) SafeMalloc(sizeof(expr_struct));
assign_stmt_type assign_stmt = (assign_stmt_type) SafeMalloc(sizeof(assign_stmt_struct));
call_stmt_type call_stmt = (call_stmt_type) SafeMalloc(sizeof(call_stmt_struct));
arg_type arg = (arg_type) SafeMalloc(sizeof(arg_struct));
id_type temp_id, temp2_id;
long toppos;
list_type p;
/* Make variable "temp" */
temp_id = make_temp_var(numlocals + 1);
/**** Statement #1: temp = list ****/
assign_stmt->lhs = temp_id;
assign_stmt->rhs = s->condition;
temp_stmt->type = S_ASSIGN;
temp_stmt->value.assign_stmt_val = assign_stmt;
temp_stmt->lineno = 0;
numtemps = codegen_statement(temp_stmt, numlocals);
/* Reserve variable "temp" through entire loop by incrementing numlocals */
our_maxlocal = ++numlocals;
if (numtemps > our_maxlocal)
our_maxlocal = numtemps;
toppos = FileCurPos(outfile);
codegen_enter_loop();
/**** Statement #2: if (temp = $) goto end ****/
/* First put result of temp = $ into temp2 */
temp2_id = make_temp_var(numlocals + 1);
if (numlocals + 1 > our_maxlocal)
our_maxlocal = numlocals + 1;
temp2_expr->type = E_IDENTIFIER;
temp2_expr->value.idval = temp_id;
temp_expr->type = E_BINARY_OP;
temp_expr->value.binary_opval.op = EQ_OP;
temp_expr->value.binary_opval.left_exp = temp2_expr;
temp_expr->value.binary_opval.right_exp = make_expr_from_constant(make_nil_constant());
assign_stmt->lhs = temp2_id;
assign_stmt->rhs = temp_expr;
temp_stmt->type = S_ASSIGN;
temp_stmt->value.assign_stmt_val = assign_stmt; /* YECHHH! */
temp_stmt->lineno = 0;
codegen_statement(temp_stmt, numlocals); /* Won't require more temps */
/* Now perform jump if temp = $ is true */
memset(&opcode, 0, sizeof(opcode)); /* Set opcode to all zeros */
opcode.command = GOTO;
opcode.source1 = LOCAL_VAR;
opcode.dest = GOTO_IF_TRUE;
OutputOpcode(outfile, opcode);
/* Make believe goto is a break statement & leave space for backpatching */
current_loop->break_list =
list_add_item(current_loop->break_list, (void *) FileCurPos(outfile));
OutputInt(outfile, 0);
OutputInt(outfile, temp2_id->idnum); /* Jump if temp2 = TRUE */
/**** Statement #3: i = First(temp) ****/
temp_expr->type = E_IDENTIFIER;
temp_expr->value.idval = temp_id;
arg->type = ARG_EXPR;
arg->value.expr_val = temp_expr;
call_stmt->function = FIRST;
call_stmt->args = list_create(arg);
codegen_call(call_stmt, s->id, numlocals); /* Won't require more temps */
/* Write code for loop body */
for (p = s->body; p != NULL; p = p->next)
{
numtemps = codegen_statement( (stmt_type) p->data, numlocals);
if (numtemps > our_maxlocal)
our_maxlocal = numtemps;
}
/* Backpatch continue statements in loop body */
for (p = current_loop->for_continue_list; p != NULL; p = p->next)
BackpatchGoto(outfile, (int) p->data, FileCurPos(outfile));
/**** Statement #4: temp = Rest(temp) ****/
/* Can reuse most of statement #3 above */
call_stmt->function = REST;
codegen_call(call_stmt, temp_id, numlocals); /* Won't require more temps */
/**** Statement #5: goto top ****/
opcode.source1 = 0;
opcode.source2 = GOTO_UNCONDITIONAL;
opcode.dest = 0;
OutputOpcode(outfile, opcode);
OutputGotoOffset(outfile, FileCurPos(outfile), toppos);
codegen_exit_loop(); /* Takes care of break statements */
return our_maxlocal;
}
