https://gcc.gnu.org/bugzilla/show_bug.cgi?id=78276
Bug ID: 78276
Summary: regex_search is slow
Product: gcc
Version: 6.2.1
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: libstdc++
Assignee: unassigned at gcc dot gnu.org
Reporter: idrazil at fit dot vutbr.cz
Target Milestone: ---
Created attachment 40006
--> https://gcc.gnu.org/bugzilla/attachment.cgi?id=40006&action=edit
Example with bug
I tried match this string "<aaaaaaaaaaaaa>\r\n" with regexp
"(?:[^\r\n]*)*<?(aaaaaaaaaaaaa)>?". GCC 4.9 can solve it almost instantly but
at 6.2 (I've also tried 6.1) it takes on my computer more than 5 seconds.
I've discovered increasing count of letter "a" also increase (probably
exponentially) solving time of regexp. The problem goes away when I've
alternated regexp to "[^\r\n]*<?(aaaaaaaaaaaaa)>?". (In this case the change is
possible but my original code contains more complex regexp with the same
problem)
Full example is at the attachment.
