libstdc++: Update backtrace-rename.h

  Hi!

When writing the r13-4629 commit log I've realized that libsanitizer
isn't the only place which nowadays renames libbacktrace symbols,
libstdc++ does that too.

Ok for trunk if this passes bootstrap/regtest?

2022-12-13  Jakub Jelinek  <jakub@redhat.com>

	* src/libbacktrace/backtrace-rename.h (backtrace_uncompress_zstd):
	Define.


	Jakub
  

On Tue, 13 Dec 2022 at 09:44, Jakub Jelinek <jakub@redhat.com> wrote:
>
> Hi!
>
> When writing the r13-4629 commit log I've realized that libsanitizer
> isn't the only place which nowadays renames libbacktrace symbols,
> libstdc++ does that too.
>
> Ok for trunk if this passes bootstrap/regtest?

OK, thanks.

When we move the backtrace symbols from libstdc++_libbacktrace.a into
libstdc++.so we probably want to look into removing the symbols we
don't actually use. Renaming them to our private namespace is good,
but not including them in the library at all would be better.


> 2022-12-13  Jakub Jelinek  <jakub@redhat.com>
>
>         * src/libbacktrace/backtrace-rename.h (backtrace_uncompress_zstd):
>         Define.
>
> --- libstdc++-v3/src/libbacktrace/backtrace-rename.h.jj 2022-09-01 09:37:58.452624676 +0200
> +++ libstdc++-v3/src/libbacktrace/backtrace-rename.h    2022-12-13 10:41:14.551699599 +0100
> @@ -16,6 +16,7 @@
>  #define backtrace_syminfo __glibcxx_backtrace_syminfo
>  #define backtrace_uncompress_lzma __glibcxx_backtrace_uncompress_lzma
>  #define backtrace_uncompress_zdebug __glibcxx_backtrace_uncompress_zdebug
> +#define backtrace_uncompress_zstd __glibcxx_backtrace_uncompress_zstd
>  #define backtrace_vector_finish __glibcxx_backtrace_vector_finish
>  #define backtrace_vector_grow __glibcxx_backtrace_vector_grow
>  #define backtrace_vector_release __glibcxx_backtrace_vector_release
>
>         Jakub
>
  

On Tue, Dec 13, 2022 at 09:50:23AM +0000, Jonathan Wakely via Gcc-patches wrote:
> On Tue, 13 Dec 2022 at 09:44, Jakub Jelinek <jakub@redhat.com> wrote:
> >
> > Hi!
> >
> > When writing the r13-4629 commit log I've realized that libsanitizer
> > isn't the only place which nowadays renames libbacktrace symbols,
> > libstdc++ does that too.
> >
> > Ok for trunk if this passes bootstrap/regtest?
> 
> OK, thanks.
> 
> When we move the backtrace symbols from libstdc++_libbacktrace.a into
> libstdc++.so we probably want to look into removing the symbols we
> don't actually use. Renaming them to our private namespace is good,
> but not including them in the library at all would be better.

Most of them I assume are actually used, the reason they aren't static
is that libbacktrace contains multiple TUs and some APIs are used to
interface between the TUs.  __attribute__((visibility ("hidden"))) would
work for shared libraries and targets where it actually works, but
we still have the *.a libraries where such symbols are visible, so I think
some renaming is needed.

Though, my understanding of backtrace_uncompress_{lzma,zdebug,zstd} is that
those are there just as small wrappers for make check purposes only,
so I bet those symbols could be easily removed (say by not defining them
at all if their names are macros, then we could keep them in
backtrace-rename.h as is).

> > 2022-12-13  Jakub Jelinek  <jakub@redhat.com>
> >
> >         * src/libbacktrace/backtrace-rename.h (backtrace_uncompress_zstd):
> >         Define.
> >
> > --- libstdc++-v3/src/libbacktrace/backtrace-rename.h.jj 2022-09-01 09:37:58.452624676 +0200
> > +++ libstdc++-v3/src/libbacktrace/backtrace-rename.h    2022-12-13 10:41:14.551699599 +0100
> > @@ -16,6 +16,7 @@
> >  #define backtrace_syminfo __glibcxx_backtrace_syminfo
> >  #define backtrace_uncompress_lzma __glibcxx_backtrace_uncompress_lzma
> >  #define backtrace_uncompress_zdebug __glibcxx_backtrace_uncompress_zdebug
> > +#define backtrace_uncompress_zstd __glibcxx_backtrace_uncompress_zstd
> >  #define backtrace_vector_finish __glibcxx_backtrace_vector_finish
> >  #define backtrace_vector_grow __glibcxx_backtrace_vector_grow
> >  #define backtrace_vector_release __glibcxx_backtrace_vector_release

	Jakub