本文简要介绍 zend 虚拟机解释执行字节码的基本逻辑以及相关的数据结构，关于 PHP 源代码的下载，编译，调试可以参考之前的系列文章

execute_ex

我们来看看执行一个简单的脚本 test.php 的调用栈

execute_ex @ zend_vm_execute.h : 411
zend_execute @ zend_vm_execute.h : 474
php_execute_script @ zend.c : 1474
do_cli @ php_cli.c : 993 main @ php_cli.c : 1381 

由于是执行脚本文件，所以 do_cli 调用了 php_execute_script 函数，最终调用 execute_ex 函数：

ZEND_API void execute_ex(zend_execute_data *ex)
{DCL_OPLINE#ifdef ZEND_VM_IP_GLOBAL_REG const zend_op *orig_opline = opline; #endif #ifdef ZEND_VM_FP_GLOBAL_REG zend_execute_data *orig_execute_data = execute_data; execute_data = ex; #else zend_execute_data *execute_data = ex; #endif LOAD_OPLINE(); ZEND_VM_LOOP_INTERRUPT_CHECK(); while (1) { #if !defined(ZEND_VM_FP_GLOBAL_REG) || !defined(ZEND_VM_IP_GLOBAL_REG) int ret; #endif #if defined(ZEND_VM_FP_GLOBAL_REG) && defined(ZEND_VM_IP_GLOBAL_REG) ((opcode_handler_t)OPLINE->handler)(ZEND_OPCODE_HANDLER_ARGS_PASSTHRU); if (UNEXPECTED(!OPLINE)) { #else if (UNEXPECTED((ret = ((opcode_handler_t)OPLINE->handler)www.90168.org(ZEND_OPCODE_HANDLER_ARGS_PASSTHRU)) != 0)) { #endif #ifdef ZEND_VM_FP_GLOBAL_REG execute_data = orig_execute_data; # ifdef ZEND_VM_IP_GLOBAL_REG opline = orig_opline; # endif return; #else if (EXPECTED(ret > 0)) { execute_data = EG(current_execute_data); ZEND_VM_LOOP_INTERRUPT_CHECK(); } else { # ifdef ZEND_VM_IP_GLOBAL_REG opline = orig_opline; # endif return; } #endif } } zend_error_noreturn(E_CORE_ERROR, "Arrived at end of main loop which shouldn't happen"); }

和其它 C 语言编写的系统软件类似，函数中使用了大量的宏定义，通过宏定义的名字还是能大概看出其用途

• DCL_OPLINE，变量声明

• LOAD_OPLINE()，加载指令字节码

• ZEND_VM_LOOP_INTERRUPT_CHECK()，interrupt 检测