gcc源代码分析，end_final()函数把insn转化成汇编代码

  end_final()函数在toplev.c里面被调用。定义在final.c文件里。

end_final (main_input_filename);

final()函数：

void
final (first, file, write_symbols, optimize, prescan)
     rtx first;
     FILE *file;
     enum debugger write_symbols;
     int optimize;
     int prescan;
{
  register rtx insn;

  last_ignored_compare = 0;
  new_block = 1;

  init_recog ();

  CC_STATUS_INIT;

  for (insn = NEXT_INSN (first); insn;)
    insn = final_scan_insn (insn, file, write_symbols, optimize,
                prescan, 0);
}

可以看出这是最后一遍处理。

final_scan_insn ( )函数关键代码：

    /* Try to recognize the instruction.
       If successful, verify that the operands satisfy the
       constraints for the instruction.  Crash if they don't,
       since `reload' should have changed them so that they do.  */

    insn_code_number = recog_memoized (insn);
    insn_extract (insn);
    for (i = 0; i < insn_n_operands[insn_code_number]; i++)
      {
        if (GET_CODE (recog_operand[i]) == SUBREG)
          recog_operand[i] = alter_subreg (recog_operand[i]);
      }

/*insn_n_operands[140]=3，紧接着的insn_template[140]=0*/

    template = insn_template[insn_code_number];
    if (template == 0)
      {
        template = (*insn_outfun[insn_code_number]) (recog_operand, insn);

        /* If the C code returns 0, it means that it is a jump insn
           which follows a deleted test insn, and that test insn
           needs to be reinserted.  */
        if (template == 0)
          {
        if (PREV_INSN (insn) != last_ignored_compare)
          abort ();
        new_block = 0;
        return PREV_INSN (insn);
          }
      }

    if (prescan > 0)
      break;

    /* Output assembler code from the template.  */

    output_asm_insn (template, recog_operand);

    /* Mark this insn as having been output.  */
    INSN_DELETED_P (insn) = 1;
      }
    }
  return NEXT_INSN (insn);
}

/*template = (*insn_outfun[140]) (recog_operand, insn);

/*template = output_140 (recog_operand, insn);

recog_operand[]数组是比较重要的数组，和insn_extract()函数产生，用于output_asm_insn()函数，还有这里的(*insn_outfun[insn_code_number])函数。