[Bug libstdc++/39491] [4.4/4.5 regression] symbol __signbitl@GLIBCXX_3.4 in libstdc++ not exported anymore

[dave at hiauly1 dot hia dot nrc dot ca]

------- Comment #14 from dave at hiauly1 dot hia dot nrc dot ca  2009-04-22 13:45 -------
Subject: Re:  [4.4/4.5 regression] symbol __signbitl@GLIBCXX_3.4 in libstdc++
not exported anymore

> ------- Comment #13 from jakub at gcc dot gnu dot org  2009-04-22 09:12 -------
> If hppa-linux has long double the same as double (which raises the question why
> it hasn't switched over to 128-bit long double together with
> powerpc*/sparc*/s390*/alpha back in 2006), then __NO_LONG_DOUBLE_MATH should be
> defined and therefore no code will ever reference __signbitl from signbit macro
> (and __signbitl isn't a supported API, so nothing should really care).

The conversion was discussed but

1) HP was unwilling to provide their millicode support,
2) Richard Hendersen expressed an opinion that corner cases in the
   double double implementation made this approach problematic, and
3) Carlos was busy writing his master's thesis.

So, we didn't switch over to a 128-bit long double.

> If we really want to change libstdc++ (which I'm not sure about, can you find a
> single shared library or binary that references __signbitl from libstdc++.so?),
> then the patch should actually handle __signbitl by calling __signbit and also
> should be through .symver directive turned into @ symbol instead of @@ to make
> sure nothing newly linked can reference it from libstdc++.so.

I fully agree.

Dave


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http://gcc.gnu.org/bugzilla/show_bug.cgi?id=39491