Home Backend Development PHP Tutorial PHP principle execution cycle example analysis

PHP principle execution cycle example analysis

Jun 02, 2018 am 09:27 AM
php cycle Case Analysis

This article mainly introduces the in-depth understanding of the execution cycle of PHP principles, and briefly analyzes the relevant principles of the PHP program from editing to lexical analysis, syntax analysis and interpretation execution. Friends in need can refer to the following

PHP execution cycle, from the initial PHP script we wrote -> to the final script being executed -> getting the execution result, this process can actually be divided into the following stages:

First , Zend Engine (ZE), calls the lexical analyzer (generated by Lex, the source file is in Zend/zend_language_sanner.l), removes spaces and comments from the PHP source file we want to execute, and divides it into tokens one by one.

Then, ZE will forward the obtained token to the syntax analyzer (generated by yacc, the source file is in Zend/zend_language_parser.y), and generate opcodes one by one. The opcodes generally exist in the form of op array. It is the intermediate language for PHP execution.

Finally, ZE calls zend_executor to execute op array and output the results. (That is, convert the source file into machine language and then run it on a virtual machine.)

ZE is a virtual machine. It is precisely because of its existence that we can write PHP scripts without any need for Consider the type of operating system you are running on, this is why PHP is portable. ZE is a CISC (Complex Instruction Processor), which supports 150 instructions (specific instructions are in Zend/zend_vm_opcodes.h), including the simplest ZEND_ECHO (echo) to the complex ZEND_INCLUDE_OR_EVAL (include, require), All the PHP we write will eventually be processed into a sequence of these 150 instructions (op code), and will eventually be executed.

PHP is a scripting language, that is to say, the PHP code written by the user will eventually be interpreted and executed by the PHP interpreter. All PHP codes written will be translated into the PHP virtual machine ZE virtual instructions (OPCODES) to execute.

So what will our PHP script be "translated" into in the end? In other words, what does the op code look like? Opcode is an intermediate language compiled from PHP scripts.

There is already such a module in PECL, using the VLD (Vulcan Logic Dissassembler) module developed by Derick Rethans. You only need to download this module and load it into PHP, and you can get the result of script translation through simple settings.

Installation and application of VLD module:

[root@localhost software]# tar zxvf vld-0.9.1.tgz.gz
[root@localhost vld-0.9.1]# /usr/local/php/bin/phpize
[root@localhost vld-0.9.1]# ./configure --with-php-config=/usr/local/php/bin/php-config
[root@localhost vld-0.9.1]# make install //不需要make
Copy after login

Edit the php.ini file and activate the vld extension.

Example:

Create a file, such as: hello.php

<?php
  echo &#39;hello, world.&#39;;
?>
Copy after login

Execute:

[root@localhost html]# /usr/local/php/bin/php -dvld.active=1 hello.php
Branch analysis from position: 0
Return found
filename:    /var/www/html/hello.php
function name: (null)
number of ops: 3
compiled vars: none
line   # op              fetch     ext return operands
-------------------------------------------------------------------------------
  2   0 ECHO                           &#39;hello%2C+world.&#39;
  4   1 RETURN                          1
     2* ZEND_HANDLE_EXCEPTION
hello, world.
Copy after login

Watch another:

[root@localhost html]# vi vld.php
<?php
  $i = "This is a string";
  //I am comments
  echo $i. &#39; that has been echoed on screen&#39;;
?>
Copy after login

Execute:

[root@localhost html]# /usr/local/php/bin/php -dvld.active=1 vld.php
Branch analysis from position: 0
Return found
filename:    /var/www/html/vld.php
function name: (null)
number of ops: 5
compiled vars: !0 = $i
line   # op              fetch     ext return operands
-------------------------------------------------------------------------------
  3   0 ASSIGN                          !0, &#39;This+is+a+string&#39;
  7   1 CONCAT                      ~1  !0, &#39;+that+has+been+echoed+on+screen&#39;
     2 ECHO                           ~1
 10  3 RETURN                          1
     4* ZEND_HANDLE_EXCEPTION
This is a string that has been echoed on screen
Copy after login

Note: ZEND_HANDLE_EXCEPTION is the 149th instruction in Zend/zend_vm_opcodes.h

compiled vars: !0 = $i Here is the variable name "i" The variable is at !0 (*zval).
#0 Assign the string "this is a string" (ASSIGN) to !0
#1 String connection
#2 Display

These intermediate codes will be used by Zend VM (Zend virtual machine) is executed directly. The function actually responsible for execution is: zend_execute (zend_execute.h).

Summary: The above is the entire content of this article, I hope it will be helpful to everyone's study.

Related recommendations:

How to use PHP to implement regular capture of the URL in the page

Identity card verification based on PHP Code verification calculation method

Based on PHP using locking to realize the code grabbing function under concurrent circumstances

The above is the detailed content of PHP principle execution cycle example analysis. For more information, please follow other related articles on the PHP Chinese website!

Statement of this Website
The content of this article is voluntarily contributed by netizens, and the copyright belongs to the original author. This site does not assume corresponding legal responsibility. If you find any content suspected of plagiarism or infringement, please contact admin@php.cn

Hot AI Tools

Undresser.AI Undress

Undresser.AI Undress

AI-powered app for creating realistic nude photos

AI Clothes Remover

AI Clothes Remover

Online AI tool for removing clothes from photos.

Undress AI Tool

Undress AI Tool

Undress images for free

Clothoff.io

Clothoff.io

AI clothes remover

Video Face Swap

Video Face Swap

Swap faces in any video effortlessly with our completely free AI face swap tool!

Hot Tools

Notepad++7.3.1

Notepad++7.3.1

Easy-to-use and free code editor

SublimeText3 Chinese version

SublimeText3 Chinese version

Chinese version, very easy to use

Zend Studio 13.0.1

Zend Studio 13.0.1

Powerful PHP integrated development environment

Dreamweaver CS6

Dreamweaver CS6

Visual web development tools

SublimeText3 Mac version

SublimeText3 Mac version

God-level code editing software (SublimeText3)

PHP 8.4 Installation and Upgrade guide for Ubuntu and Debian PHP 8.4 Installation and Upgrade guide for Ubuntu and Debian Dec 24, 2024 pm 04:42 PM

PHP 8.4 brings several new features, security improvements, and performance improvements with healthy amounts of feature deprecations and removals. This guide explains how to install PHP 8.4 or upgrade to PHP 8.4 on Ubuntu, Debian, or their derivati

7 PHP Functions I Regret I Didn't Know Before 7 PHP Functions I Regret I Didn't Know Before Nov 13, 2024 am 09:42 AM

If you are an experienced PHP developer, you might have the feeling that you’ve been there and done that already.You have developed a significant number of applications, debugged millions of lines of code, and tweaked a bunch of scripts to achieve op

How To Set Up Visual Studio Code (VS Code) for PHP Development How To Set Up Visual Studio Code (VS Code) for PHP Development Dec 20, 2024 am 11:31 AM

Visual Studio Code, also known as VS Code, is a free source code editor — or integrated development environment (IDE) — available for all major operating systems. With a large collection of extensions for many programming languages, VS Code can be c

Explain JSON Web Tokens (JWT) and their use case in PHP APIs. Explain JSON Web Tokens (JWT) and their use case in PHP APIs. Apr 05, 2025 am 12:04 AM

JWT is an open standard based on JSON, used to securely transmit information between parties, mainly for identity authentication and information exchange. 1. JWT consists of three parts: Header, Payload and Signature. 2. The working principle of JWT includes three steps: generating JWT, verifying JWT and parsing Payload. 3. When using JWT for authentication in PHP, JWT can be generated and verified, and user role and permission information can be included in advanced usage. 4. Common errors include signature verification failure, token expiration, and payload oversized. Debugging skills include using debugging tools and logging. 5. Performance optimization and best practices include using appropriate signature algorithms, setting validity periods reasonably,

How do you parse and process HTML/XML in PHP? How do you parse and process HTML/XML in PHP? Feb 07, 2025 am 11:57 AM

This tutorial demonstrates how to efficiently process XML documents using PHP. XML (eXtensible Markup Language) is a versatile text-based markup language designed for both human readability and machine parsing. It's commonly used for data storage an

PHP Program to Count Vowels in a String PHP Program to Count Vowels in a String Feb 07, 2025 pm 12:12 PM

A string is a sequence of characters, including letters, numbers, and symbols. This tutorial will learn how to calculate the number of vowels in a given string in PHP using different methods. The vowels in English are a, e, i, o, u, and they can be uppercase or lowercase. What is a vowel? Vowels are alphabetic characters that represent a specific pronunciation. There are five vowels in English, including uppercase and lowercase: a, e, i, o, u Example 1 Input: String = "Tutorialspoint" Output: 6 explain The vowels in the string "Tutorialspoint" are u, o, i, a, o, i. There are 6 yuan in total

Explain late static binding in PHP (static::). Explain late static binding in PHP (static::). Apr 03, 2025 am 12:04 AM

Static binding (static::) implements late static binding (LSB) in PHP, allowing calling classes to be referenced in static contexts rather than defining classes. 1) The parsing process is performed at runtime, 2) Look up the call class in the inheritance relationship, 3) It may bring performance overhead.

What are PHP magic methods (__construct, __destruct, __call, __get, __set, etc.) and provide use cases? What are PHP magic methods (__construct, __destruct, __call, __get, __set, etc.) and provide use cases? Apr 03, 2025 am 12:03 AM

What are the magic methods of PHP? PHP's magic methods include: 1.\_\_construct, used to initialize objects; 2.\_\_destruct, used to clean up resources; 3.\_\_call, handle non-existent method calls; 4.\_\_get, implement dynamic attribute access; 5.\_\_set, implement dynamic attribute settings. These methods are automatically called in certain situations, improving code flexibility and efficiency.

See all articles