php - PHP 操作码与实际执行的二进制代码有何关系？

Question

纯文本形式的 test.php:

<?php
$x = "a";
echo $x;

test.php 作为操作码:

debian:~ php -d vld.active=1 -d vld.execute=0 -f test.php

Finding entry points
Branch analysis from position: 0
Return found
filename:       /root/test.php
function name:  (null)
number of ops:  5
compiled vars:  !0 = $x
line     # *  op                           fetch          ext  return  operands
---------------------------------------------------------------------------------
   2     0  >   EXT_STMT
         1      ASSIGN                                                   !0, 'a'
   3     2      EXT_STMT
         3      ECHO                                                     !0
   4     4    > RETURN                                                   1

branch: #  0; line:     2-    4; sop:     0; eop:     4
path #1: 0,

test.php 作为二进制表示:

debian:~ php -d apc.stat=0 -r "
  require '/root/test.php'; 
  echo PHP_EOL; 
  echo chunk_split(bin2hex(
    apc_bin_dump(array('/root/test.php'))
  ),64);
"

(跳过 test.php 的回显输出)

    b110000001000000325dedaa64d801bca2f73027abf0d5ab67f3023901000000
    2c0000000a000000871000000300000000000000000000004c0000005b000000
    8a0200008a020000650000002f726f6f742f746573742e7068700002070f9c00
    00000000000000000000000000000000000000000000000000000000000100fa
    000000fe00000005000000050000007c02000001000000100000000100000000
    00000000000000ffffffff0000000000000000000000000000000000000000ff
    ffffffeb00000000000000000000000000000000000000ffffffff0000000000
    00000001000000000000002f726f6f742f746573742e7068700001000000204a
    3308080000000000000000000000000000000000000008000000000000000000
    0000000000000000000008000000000000000000000000000000000000000000
    00000200000065000000204a3308040000000000000001000000000000000000
    00001000000000000000100000000100000006000000010000007a0200000100
    00000100000006000000000000000200000026000000204a3308080000000000
    0000000000000000000000000000080000000000000000000000000000000000
    0000080000000000000000000000000000000000000000000000030000006500
    0000900f34080800000000000000000000000000000000000000100000000000
    0000100000000100000006000000080000000000000000000000000000000000
    0000000000000300000028000000204a33080800000000000000000000000000
    00000000000001000000010000002c70d7b6010000000100d7b6080000000000
    000000000000000000000000000000000000040000003e000000610088020000
    01000000bd795900780000000000000000000000000000000000000000000000
[ ... a lot of lines just containing 0s ... ]
    0000000000000038000000c30000007f0000007a010000830000007c0200008f
    0000003c000000400000004400000008

现在我想了解更多关于操作码如何转换为二进制表示的信息。

经过编辑和澄清的问题:

操作码是如何翻译成二进制版本的？你能看到'a'到 !0 的 ASSIGN 吗？ECHO 语句及其输出的内容在某处吗？

我在二进制版本中发现很少有模式暗示操作码的逐行表示。

(“2f726f6f742f746573742e706870”是“/root/test.php”的十六进制表示)

编辑:

当行长设置为 4 个字节并在不同程序之间进行比较时，十六进制表示会显示模式。

...
00000002  // 2 seems to be something like the "line number"
00000065  // seems to increase by 1 for every subsequent statement.
00000040  // 
06330808  // seems to mark the START of a statement
00000000
00000000
00000000
00000000
00000001  //
00000012  // In a program with three echo statements,
03000007  // this block was present three times. With mild
00000001  // changes that seem to represent the spot where
00000006  // the output-string is located.
00000008  //
00000000
00000000
00000000
00000000
00000000
00000002  // 2 seems to be something like the "line number"
00000028  //
00000020  //
4a330808  // seems to mark the END of a statement
00000000
00000000
00000000
00000000
00000008  // repeating between (echo-)statements
00000000
00000000
00000000
00000000
00000008  // repeating between (echo-)statements
...

但我对虚拟机如何在这种级别上工作的知识太薄弱，无法真正正确地分析它并将其链接到 C 代码。

编辑:

Does PHP have a virtual machine like Java?

Is the Zend engine embeddable outside of PHP?

Answer 1

好问题...

更新:操作码直接由 PHP 虚拟机(Zend 引擎)执行。看起来它们是由 ./Zend/zend_vm_execute.h 中定义的不同处理函数执行的

参见 the architecture of the Zend Engine有关如何执行 Zend 操作码的更多信息。

这些资源可能会有所帮助:

http://php.net/manual/en/internals2.opcodes.list.php

http://www.php.net/manual/en/internals2.opcodes.ops.php

此外，我将检查 PECL VLD 源以获取更多线索...

http://pecl.php.net/package/vld

http://derickrethans.nl/projects.html#vld

另外，给 VLD Pecl 扩展的作者写信可能会有所帮助:Derick Rethans、Andrei Zmievski 或 Marcus Börger

他们的电子邮件地址位于扩展源中 srm_oparray.c 的顶部。

更新:发现了更多线索

在 PHP 5.3.8 中，我找到了执行操作码的三个线索:

./Zend/zend_execute.c:1270 
ZEND_API void execute_internal

./Zend/zend.c:1214:ZEND_API int zend_execute_scripts(int type TSRMLS_DC, zval **retval, int file_count, ...)
./Zend/zend.c:1236:                  zend_execute(EG(active_op_array) TSRMLS_CC);

./Zend/zend_vm_gen.php

我找不到 zend_execute() 的定义，但我猜它可能是用 ./zend_vm_gen.php 生成的

我想我找到了......

./Zend/zend_vm_execute.h:42
ZEND_API void execute(zend_op_array *op_array TSRMLS_DC)

我可能是错的，但看起来所有操作码处理程序也在 ./Zend/zend_vm_execute.h 中定义。

请参阅 ./Zend/zend_vm_execute.h:2413 以获取“整数加法”操作码的示例。