Description:
------------
If I enable opcache on cli environment (opcache.enable_cli) and run my test.php script I get: "[1]    19066 segmentation fault (core dumped)  php test.php"

This happens only if while (or do-while) condition is variable and content (between curly braces) is empty or contains only comments.

Actually the code makes no sense, but I had to debug few hours and found this exact code with only comment "// TODO: .." in do-while braces. Commenting out whole loop block fixed issue, but it's still a bug I think.

Reproduced on php 5.5.27 and 5.6.11

Test script:
---------------
<?php

if ((int) ini_get('opcache.enable_cli') !== 1) {
    throw new Exception('Opcode cache must be enabled on CLI environment');
}

function neverUsed() {
    $bool = false;
    while ($bool) { };
    // Same with: do { } while ($bool);
}

echo "OK";

Expected result:
----------------
Expected to see OK printed

Actual result:
--------------
[1]    19066 segmentation fault (core dumped)  php test.php