Function codegen_while

blakcomp/codegen.c:413–457

/ * codegen_while: Generate code for a while loop statement. * numlocals should be # of local variables for message excluding temps. * Returns highest # local variable used in code for statement. */

 *   Returns highest # local variable used in code for statement.
 */
int codegen_while(while_stmt_type s, int numlocals)
{
   opcode_type opcode;
   int our_maxlocal = numlocals, numtemps, sourceval;
   long toppos;
   list_type p;

   toppos = FileCurPos(outfile);
   codegen_enter_loop();

   /* First generate code for condition */
   our_maxlocal = simplify_expr(s->condition, numlocals);

   /* Jump over body if condition is false */
   memset(&opcode, 0, sizeof(opcode));  /* Set opcode to all zeros */
   opcode.command = GOTO;
   opcode.dest = GOTO_IF_FALSE;
   sourceval = set_source_id(&opcode, SOURCE1, s->condition);
   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, sourceval);

   /* 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;
   }

   /* Goto top of loop is last statement of while loop */
   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;
}
/************************************************************************/
/*
 * codegen_for: Generate code for a for loop statement.