[Bug fortran/78611] -march=native makes code 3x slower

[ubizjak at gmail dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=78611

--- Comment #8 from Uroš Bizjak <ubizjak at gmail dot com> ---
(In reply to H.J. Lu from comment #6)
> Which glibc was used?  You may run into:
> 
> https://sourceware.org/bugzilla/show_bug.cgi?id=20495

Fedora 25:

$ /lib/libc.so.6 
GNU C Library (GNU libc) stable release version 2.24, by Roland McGrath et al.
Copyright (C) 2016 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.
Compiled by GNU CC version 6.1.1 20160721 (Red Hat 6.1.1-4).
Available extensions:
        crypt add-on version 2.1 by Michael Glad and others
        GNU Libidn by Simon Josefsson
        Native POSIX Threads Library by Ulrich Drepper et al
        BIND-8.2.3-T5B
libc ABIs: UNIQUE IFUNC
For bug reporting instructions, please see:
<http://www.gnu.org/software/libc/bugs.html>.