Use PHP extension vld to view PHP opcode operation steps_PHP tutorial

~/public_html/php-5.3.13/ext> ; wget http://pecl.php.net/get/vld-0.11.2.tgz
~/public_html/php-5.3.13/ext> tar zxvf vld-0.11.2.tgz
~/ public_html/php-5.3.13/ext> cd vld-0.11.2/

~/public_html/php-5.3.13/ext/vld-0.11.2> phpize
~/public_html/php-5.3.13/ext/vld -0.11.2> ./configure --with-php-config=/usr/local/services/php/bin/php-config --enable-vld
~/public_html/php-5.3.13/ext/ vld-0.11.2> make
~/public_html/php-5.3.13/ext/vld-0.11.2> sudo make install
Installing shared extensions: /usr/local/services/php/lib/php /extensions/no-debug-non-zts-20090626/

~/public_html/php-5.3.13/ext/vld-0.11.2> cd /usr/local/services/php/lib/php/extensions /no-debug-non-zts-20090626/
/usr/local/services/php/lib/php/extensions/no-debug-non-zts-20090626> sudo cp vld.so /usr/local/services /php/extensions/

extension=vld.so

$a = "hello world";
echo $a . PHP_EOL;

~/public_html> php -dvld.active=1 test.php
Finding entry points
Branch analysis from position: 0
Return found
filename: /home/zhanhailiang/public_html/test.php
function name: (null)
number of ops : 4
compiled vars: !0 = $a
line # * op fetch ext return operands
----------------------- -------------------------------------------------- --------
3 0 > ASSIGN !0, 'hello+world'
5 1 CONCAT ~1 !0, '%0A'
2 ECHO ~1
6 3 > RETURN 1
branch: # 0; line: 3- 6; sop: 0; eop: 3
path #1: 0,
hello world