[PATCH] libstdc++: Hide TLS variables in `std::call_once`

[Jonathan Wakely]

On Fri, 29 Nov 2024 at 15:58, LIU Hao wrote:
>
> 在 2024-11-29 23:50, Jonathan Wakely 写道:
> >> It looks like your patch is against gcc-14 not trunk, the
> >> GLIBCXX_15.1.0 version is already there.
> >
> > Sorry, I mean GLIBCXX_3.4.34 for 15.1.0
>
> Oops that's what I used to test the patch. Reapplied to master now.

I've finally had another look at this patch, and I'm more concerned
now about something I noticed earlier.

This adds yet another level of indirection to std::call_once. On trunk
today we call call_once, which calls pthread_once, which calls
__once_proxy, which calls etc. etc.

But after this, there's yet another indirection. And for most targets,
that's just unnecessary overhead.