Bug #72685 [NEW]: No support for PCRE2_NO_UTF_CHECK flag

From: ju1ius at laposte dot net Operating system: Debian Sid PHP version: Irrelevant Package: PCRE related Bug Type: Bug Bug description:No support for PCRE2_NO_UTF_CHECK flag Description: ------------ When matching in UTF8 mode ('u' flag), the preg_match function checks the validity of the entire input string on every call. PCRE2 has a flag to disable this behavior: PCRE2_NO_UTF_CHECK, but PHP does not expose it. This means that when matching a lot of times against the same (potentially long) input string (for example for lexical analysis), a lot of unnecessary computations are performed, leading to catastrophic performance (O(n²) instead of expected O(n)). Test script: --------------- // see online at https://3v4l.org/Duv7g $input_size = 1e4; $str = str_repeat('a', $input_size); $start = microtime(true); $pos = 0; while(preg_match('/\G\w/', $str, $m, 0, $pos)) ++$pos; $end = microtime(true); echo '>>> NO u flag: ', number_format(($end - $start)*1000, 6), 'ms', PHP_EOL; $str = str_repeat('e', $input_size); $start = microtime(true); $pos = 0; while(preg_match('/\G\w/u', $str, $m, 0, $pos)) ++$pos; $end = microtime(true); echo '>>> WITH u flag: ', number_format(($end - $start)*1000, 6), 'ms', PHP_EOL; Expected result: ---------------- I expect the two loops to take roughly the same amount of time, with the second one being slower by a very short margin. The performance should be O(n) for the two. Actual result: -------------- With $input_size === 1e4: >>> NO u flag: 9.632111ms >>> WITH u flag: 109.670877ms With $input_size === 1e5: >>> NO u flag: 96.043110ms >>> WITH u flag: 10,151.215076ms With $input_size === 2*1e5: >>> NO u flag: 188.354015ms >>> WITH u flag: 40,387.295008ms Looks like we have the expected O(n) in first case, and O(n²) with the /u flag. -- Edit bug report at https://bugs.php.net/bug.php?id=72685&edit=1 -- Try a snapshot (PHP 5.4): https://bugs.php.net/fix.php?id=72685&r=trysnapshot54 Try a snapshot (PHP 5.5): https://bugs.php.net/fix.php?id=72685&r=trysnapshot55 Try a snapshot (trunk): https://bugs.php.net/fix.php?id=72685&r=trysnapshottrunk Fixed in SVN: https://bugs.php.net/fix.php?id=72685&r=fixed Fixed in release: https://bugs.php.net/fix.php?id=72685&r=alreadyfixed Need backtrace: https://bugs.php.net/fix.php?id=72685&r=needtrace Need Reproduce Script: https://bugs.php.net/fix.php?id=72685&r=needscript Try newer version: https://bugs.php.net/fix.php?id=72685&r=oldversion Not developer issue: https://bugs.php.net/fix.php?id=72685&r=support Expected behavior: https://bugs.php.net/fix.php?id=72685&r=notwrong Not enough info: https://bugs.php.net/fix.php?id=72685&r=notenoughinfo Submitted twice: https://bugs.php.net/fix.php?id=72685&r=submittedtwice register_globals: https://bugs.php.net/fix.php?id=72685&r=globals PHP 4 support discontinued: https://bugs.php.net/fix.php?id=72685&r=php4 Daylight Savings: https://bugs.php.net/fix.php?id=72685&r=dst IIS Stability: https://bugs.php.net/fix.php?id=72685&r=isapi Install GNU Sed: https://bugs.php.net/fix.php?id=72685&r=gnused Floating point limitations: https://bugs.php.net/fix.php?id=72685&r=float No Zend Extensions: https://bugs.php.net/fix.php?id=72685&r=nozend MySQL Configuration Error: https://bugs.php.net/fix.php?id=72685&r=mysqlcfg