On Wed, Apr 21, 2021 at 08:04:18PM +0200, Martin Liška wrote:
> Hello.
>
> There's a patch attempt for the problem with
> std::thread::hardware_concurrency where
> it's used only if _GLIBCXX_HAS_GTHREADS is set.
>
> Does it help?
> Thanks,
> Martin
>
> gcc/ChangeLog:
>
> PR bootstrap/100186
> * lto-wrapper.c: Use hardware_concurrency only if
> _GLIBCXX_HAS_GTHREADS.
> ---
> gcc/lto-wrapper.c | 6 +++++-
> 1 file changed, 5 insertions(+), 1 deletion(-)
>
> diff --git a/gcc/lto-wrapper.c b/gcc/lto-wrapper.c
> index 6ba401007f6..8a85b3e93a8 100644
> --- a/gcc/lto-wrapper.c
> +++ b/gcc/lto-wrapper.c
> @@ -1285,7 +1285,11 @@ run_gcc (unsigned argc, char *argv[])
> static char current_dir[] = { '.', DIR_SEPARATOR, '\0' };
>
> /* Number of CPUs that can be used for parallel LTRANS phase. */
> - unsigned long nthreads_var = std::thread::hardware_concurrency ();
> + unsigned long nthreads_var = 0;
> +
> +#ifdef _GLIBCXX_HAS_GTHREADS
> + nthreads_var = std::thread::hardware_concurrency ();
> +#endif
_GLIBCXX_HAS_GTHREADS is a libstdc++ internal macro, it shouldn't be used
outside of libstdc++.
And, when using some other compiler or standard C++ library, nthreads_var
will be always 0. That isn't an improvement.
Jakub
