PHP_Dyn is PHP Extension to help debugging a PHP script.
You can get execution trace of scripts not to need change them.
HTTP request parameter can be printed.
Argument value of the function call and return value can be printed.
PHP Profiler is both a Zend extension and module capable of generating profiling information (function call statistics) for PHP applications on the server side. No PHP code has to be changed, although the profiler data is available to your scripts.