Description

JIT traces are not invalidated after a class is re-linked. The JIT code may make assumptions that are not true anymore after re-linking.

For example, in

<?php

$a=0;

class A implement Iface {
    public function hello() {
        global $a;
        for ($i = 0; $i < 100; $i++) {
            $a++;
        }
    }
}

we may still enter in the JITed loop after A has been re-linked (A can be re-link due to Iface being recompiled for example). The JITed code may be based on assumptions that are not true anymore (at least the run_time_cache pointer changes during linking, but I suspect that other assumptions can be made based on the parent classes or interfaces, that do not hold true after re-linking).

This is due to op_array.oplines being shared between all linked versions of the same class. oplines has pointers to JITed code.

op_array.oplines is also shared between all sub-classes, but as long as the JIT's asumptions are based on the declaring class it should be ok.

PHP Version

PHP 8.1

Operating System

No response