More architectures that do not support __sync_fetch_and_add_4

[Steven Robbins <smr@…>]

Hi,

As noted in #2263, Boost makes the incorrect assumption that if the following condition is true:

defined( GNUC ) && ( GNUC * 100 + GNUC_MINOR >= 401 )

then GCC sync primitives (e.g. sync_lock_test_and_set, sync_fetch_and_add) are available.

Currently, hppa and arm are listed as exceptions. However, building Boost on Debian's 14 architectures suggests that some more exceptions are needed: armel (ARM in little endian mode), m68k and sparc. I'm attaching a patch to atomic_count.hpp to this effect.

When using GNU C++ however, that patch means that all those machines fall through to atomic_count_gcc.hpp, which is known to be broken for GCC > 4.1 (c.f. #1084, never applied). I'm attaching a patch for this problem, too.

Note that these patches are only for the problems I noticed while building Boost, and only because we also build "tools/bcp", which happens to use shared_ptr. From grepping the sources it appears that there are a few others.

[smr@…]

Added sp_counted_base.patch to address another manifestation in sp_counted_base.hpp.

[Peter Dimov]

(In [51517]) Refs #2525 (fixed in trunk.)

[Peter Dimov]

(In [51538]) Merge [51517] to release. Closes #2525.

[Peter Dimov]

Reopening due to the claim in

​http://lists.boost.org/Archives/boost/2007/11/130479.php

that g++ 4.2 has __sync operations on __sparc__. Steven, can you please confirm or deny it?

[smr@…]

On the sparc to which I have access (a sparc64 running Debian Linux), I can attest that g++ 4.2 does *not* have all the __sync primitives used in Boost. I created a test program using all the primitives I could find with "rgrep __sync_ *" in the Boost root source directory (SVN head).

Here is the transcript.

(sid)smr@smetana:~$ uname -a
Linux smetana 2.6.26-1-sparc64-smp #1 SMP Sat Jan 10 18:53:17 UTC 2009 sparc64 GNU/Linux

(sid)smr@smetana:~$ cat sync-primitives.cc
/* Test that uses all the __sync primitives found
   by grepping the boost sources.
*/

int main( int ac, char* av[] )
{
    long value = 0;

    __sync_lock_release( &value );

    return __sync_fetch_and_add( &value, 1 )
        +  __sync_val_compare_and_swap( &value, 1, 2 )
        +  __sync_add_and_fetch( &value, 1 )
        +  __sync_lock_test_and_set( &value, 1 );
}

(sid)smr@smetana:~$ g++-4.1 sync-primitives.cc
/tmp/ccGOFRyI.o: In function `main':
sync-primitives.cc:(.text+0x24): undefined reference to `__sync_fetch_and_add_4'
sync-primitives.cc:(.text+0x44): undefined reference to `__sync_val_compare_and_swap_4'
sync-primitives.cc:(.text+0x60): undefined reference to `__sync_add_and_fetch_4'
sync-primitives.cc:(.text+0x7c): undefined reference to `__sync_lock_test_and_set_4'
collect2: ld returned 1 exit status

(sid)smr@smetana:~$ g++-4.2 sync-primitives.cc
/tmp/ccQg4NKe.o: In function `main':
sync-primitives.cc:(.text+0x28): undefined reference to `__sync_fetch_and_add_4'
sync-primitives.cc:(.text+0x48): undefined reference to `__sync_val_compare_and_swap_4'
sync-primitives.cc:(.text+0x64): undefined reference to `__sync_add_and_fetch_4'
collect2: ld returned 1 exit status

(sid)smr@smetana:~$ g++-4.3 sync-primitives.cc
/tmp/cc8anhqk.o: In function `main':
sync-primitives.cc:(.text+0x28): undefined reference to `__sync_fetch_and_add_4'
sync-primitives.cc:(.text+0x48): undefined reference to `__sync_val_compare_and_swap_4'
sync-primitives.cc:(.text+0x64): undefined reference to `__sync_add_and_fetch_4'
collect2: ld returned 1 exit status

[Peter Dimov]

OK, closing as fixed, thanks.