[Bug c++/82345] New: low performance (comparing to clang)

["claprix at yandex dot ru" <gcc-bugzilla at gcc dot gnu dot org>]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=82345

            Bug ID: 82345
           Summary: low performance (comparing to clang)
           Product: gcc
           Version: 7.2.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: c++
          Assignee: unassigned at gcc dot gnu.org
          Reporter: claprix at yandex dot ru
  Target Milestone: ---

String search is slow for this code.

$ g++ -O2 -DNDEBUG -std=c++14 gcc_perf_buf.cc && time ./a.out shodan/huge01.txt 

real    0m0.470s
user    0m0.367s
sys     0m0.104s
$ clang++ -O2 -DNDEBUG -std=c++14 gcc_perf_buf.cc && time ./a.out
shodan/huge01.txt 

real    0m0.248s
user    0m0.179s
sys     0m0.069s

$ gcc --version
gcc (Ubuntu 7.2.0-7ubuntu1) 7.2.0
Copyright (C) 2017 Free Software Foundation, Inc.
This is free software; see the source for copying conditions.  There is NO
warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. 

$ lsb_release -d
Description:    Ubuntu Artful Aardvark (development branch)