GCC 4.7.0 and C++ atomics

[Andrew MacLeod]

On 03/07/2012 10:11 AM, Sebastian Huber wrote:
> Hello,
>
> I run the GCC testsuite for GCC 4.7.0 20120307
>
> http://gcc.gnu.org/ml/gcc-testresults/2012-03/msg00782.html
>
> I got a lot of errors like this:
>
> FAIL: g++.dg/simulate-thread/atomics-1.C  -O0 -g  (test for excess 
> errors)
> 148796 Excess errors:
> 148797 
> /home/sh/rtems-testing/gcc/b-arm-gcc/arm-rtemseabi4.11/libstdc++-v3/include/bits/atomic_base.h:458: 
> undefined reference to `__sync_synchronize'
> 148798 
> /home/sh/rtems-testing/gcc/b-arm-gcc/arm-rtemseabi4.11/libstdc++-v3/include/bits/atomic_base.h:458: 
> undefined reference to `__sync_synchronize'
> 148799 
> /home/sh/rtems-testing/gcc/b-arm-gcc/arm-rtemseabi4.11/libstdc++-v3/include/bits/atomic_base.h:458: 
> undefined reference to `__sync_synchronize'
> 148800 
> /home/sh/rtems-testing/gcc/b-arm-gcc/arm-rtemseabi4.11/libstdc++-v3/include/bits/atomic_base.h:458: 
> undefined reference to `__sync_synchronize'
> 148801 
> /home/sh/rtems-testing/gcc/b-arm-gcc/arm-rtemseabi4.11/libstdc++-v3/include/bits/atomic_base.h:438: 
> undefined reference to `__sync_synchronize'
> 148802 
> /tmp/ccgSyPe7.o:/home/sh/rtems-testing/gcc/b-arm-gcc/arm-rtemseabi4.11/libstdc++-v3/include/bits/atomic_base.h:438: 
> more undefined references to `__sync_synchronize' follow
>
> Who is supposed to provide this function? expand_mem_thread_fence
>
Looks like it is defaulting to emitting the synchronize_libfunc call, 
which is suppose to be provided by libgcc I think...

rth, you are familiar with how this part is suppose to hook up properly...

I traced the code in expand_mem_thread_fence, and the sync_synchronize 
is being emiited by:

else if (synchronize_libfunc != NULL_RTX)
         emit_library_call (synchronize_libfunc, LCT_NORMAL, VOIDmode, 0);

presumably something just isn't being linked to the executable?  or 
maybe not being built into libgcc?
Andrew

Andrew