需要防止php regex segfault

为什么会出现下面的segfault,如何防止它?

<?php

$str = ' <fieldset> <label for="go-to">Go to: </label>  ' 
       . str_repeat(' ', 10000) 
       . '<input type="submit" value="Go" /> </fieldset> </form>';

preg_match_all("@
</?(?![bisa]\b)(?!em\b)[^>]*> # starting tag, must not be one of several inline tags
(?:[^<]|</?(?:(?:[bisau]|em|strong|sup)\b)[^>]*>)* #allow text and some inline tags
[\?\!\.]+
@ix", $str, $matches);

?>

我相信这会导致……等等……堆栈溢出。

编辑:

上面是一个简化的版本——演示问题的模式。更完整的版本:

@
</?(?![bisa]\b)(?!em\b)[^>]*> # starting tag, must not be one of several inline tags
(?:[^<]|</?(?:(?:[bisau]|em|strong|sup)\b)[^>]*>)* # continue, allow text content and some inline tags

# normal sentence ending
[\?\!\.]+ # valid ending characters -- note elipses allowed
(?<!\b[ap]m\.)(?<!\b[ap]\.m\.)(?<!digg this\!)(?<!Stumble This\!) # disallow some  false positives that we don't care about
\s*
(?:&apos;|&\#0*34;|'|&lsquo;)?\s* # closing single quotes, in the unusual case like "he said: 'go away'".
(?:"|&quot;|&\#0*34;|&\#x0*22;|&rdquo;|&\#0*8221;|&\#x0*201D;|''|``|\xe2\x80\x9d|&\#0*148;|&\#x0*94;|\x94|\))?\s* # followed by any kind of close-quote char
(?=\<) # should be followed by a tag.
@ix

目的是找到似乎以有效的英语句子结尾的HTML块。我发现这种方法非常擅长区分“内容”文本(如文章正文)和“布局”文本(如导航元素)之间的区别。然而,有时如果标签之间有大量空白,它就会爆炸。