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Re: missing symbols in libstdc++.so.6 built from the 4.9 branch

From: John David Anglin <dave dot anglin at bell dot net>
To: Hans-Peter Nilsson <hp at bitrange dot com>, Jonathan Wakely <jwakely dot gcc at gmail dot com>
Cc: Matthias Klose <doko at ubuntu dot com>, "libstdc++ at gcc dot gnu dot org" <libstdc++ at gcc dot gnu dot org>, gcc Development <gcc at gcc dot gnu dot org>, Ramana Radhakrishnan <ramana dot radhakrishnan at arm dot com>, Richard Earnshaw <Richard dot Earnshaw at arm dot com>, Aurelien Jarno <aurel32 at debian dot org>
Date: Fri, 4 Jul 2014 10:25:27 -0400
Subject: Re: missing symbols in libstdc++.so.6 built from the 4.9 branch
Authentication-results: sourceware.org; auth=none
References: <53B273E6 dot 8040402 at ubuntu dot com> <CAH6eHdRQt13=pQesbAOwOVVYuuQQw=rD-cWC0+Ugv7ndDBJ+3w at mail dot gmail dot com> <BLU436-SMTP48F2A40D90438F0564A7BC97070 at phx dot gbl> <CAH6eHdRCvz+fyz6qcgzQhY9_-R-o7wW6FhvzAczUqCyGDRe38A at mail dot gmail dot com> <alpine dot BSF dot 2 dot 02 dot 1407040002170 dot 7444 at arjuna dot pair dot com>

On 7/4/2014 12:08 AM, Hans-Peter Nilsson wrote:

Currently, c-cppbuiltin.c doesn't provide proper defines for this support.
> >We
> >currently define __GCC_HAVE_SYNC_COMPARE_AND_SWAP_4, etc, in
> >pa-linux.h.

I thought that was cheating!  1/2:)

>  I'll experiment with defining ATOMIC_INT_LOCK_FREE there.
>
>It should already be defined,

Yes, if the proper insn patterns are in place, those macros are
automatically defined.  They aren't if library functions are
called, regardless of lock-freelessness of those functions.

That is the problem.  I added the __GCC_HAVE_SYNC_COMPARE_AND_SWAP
defines when I saw that the library implementation was being detected
by some packages.

Trying an even bigger cheat:

#define HAVE_sync_compare_and_swapqi 1
#define HAVE_sync_compare_and_swaphi 1
#define HAVE_sync_compare_and_swapsi 1

This seems to give __GCC_ATOMIC_INT_LOCK_FREE = 2, etc.

Have to see if this works with our library functions :-

Dave

--
John David Anglin    dave.anglin@bell.net

References:
- missing symbols in libstdc++.so.6 built from the 4.9 branch
  - From: Matthias Klose
- Re: missing symbols in libstdc++.so.6 built from the 4.9 branch
  - From: Jonathan Wakely
- Re: missing symbols in libstdc++.so.6 built from the 4.9 branch
  - From: John David Anglin
- Re: missing symbols in libstdc++.so.6 built from the 4.9 branch
  - From: Jonathan Wakely
- Re: missing symbols in libstdc++.so.6 built from the 4.9 branch
  - From: Hans-Peter Nilsson

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