[Bug libgcc/56300] New: Add __sync_fetch_and_add_8 and other 8-byte atomic functions to 32-bit MIPS targets

[chaoyingfu at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=56300

             Bug #: 56300
           Summary: Add __sync_fetch_and_add_8 and other 8-byte atomic
                    functions to 32-bit MIPS targets
    Classification: Unclassified
           Product: gcc
           Version: unknown
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: libgcc
        AssignedTo: unassigned@gcc.gnu.org
        ReportedBy: chaoyingfu@gcc.gnu.org


There is no hardware support for 8 bytes atomic operations on 32-bit MIPS
targets.  Unfortunately, programmers still want to use them.  Ex: please check
this webkit bug: https://bugs.webkit.org/show_bug.cgi?id=106739 and the
following example.

Ex:
fu@debian6:~/dev/test$ cat sync.c
long long K;
void main()
{
   __sync_fetch_and_add(&K, 1);
}

fu@debian6:~/dev/test$ gcc -o sync sync.c
/tmp/ccUoSg9M.o: In function `main':
sync.c:(.text+0x28): undefined reference to `__sync_fetch_and_add_8'
collect2: ld returned 1 exit status

That will be great, if we can add missing atomic functions (via pthread
implementation or other methods) to libgcc for 32-bit MIPS targets.

Thanks a lot!