[Bug libstdc++/94268] std::filebuf is extremely (at least 10x) slow on windows compared to Linux. Even much slower MSVC STL with terrible ABI.

[cvs-commit at gcc dot gnu.org via Gcc-bugs]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=94268

--- Comment #11 from CVS Commits <cvs-commit at gcc dot gnu.org> ---
The master branch has been updated by Jonathan Wakely <r...@gcc.gnu.org>:

https://gcc.gnu.org/g:0bc199fc5d4eef5a20ced20df892e5e3b8821b60

commit r11-4479-g0bc199fc5d4eef5a20ced20df892e5e3b8821b60
Author: Jonathan Wakely <jwak...@redhat.com>
Date:   Wed Oct 28 13:19:21 2020 +0000

    libstdc++: Override BUFSIZ for Windows targets [PR 94268]

    This replaces uses of BUFSIZ with a new _GLIBCXX_BUFSIZ macro that can
    be overridden in target-specific config headers.

    That allows the mingw and mingw-w64 targets to override it, because
    BUFSIZ is apparently defined to 512, resulting in poor performance. The
    MSVCRT stdio apparently uses 4096, so we use that too.

    libstdc++-v3/ChangeLog:

            PR libstdc++/94268
            * config/os/mingw32-w64/os_defines.h (_GLIBCXX_BUFSIZ):
            Define.
            * config/os/mingw32/os_defines.h (_GLIBCXX_BUFSIZ):
            Define.
            * include/bits/fstream.tcc: Use _GLIBCXX_BUFSIZ instead
            of BUFSIZ.
            * include/ext/stdio_filebuf.h: Likewise.
            * include/std/fstream (_GLIBCXX_BUFSIZ): Define.