Java: add flag_use_atomic_builtins

[Andrew Haley]

Joseph S. Myers wrote:
> On Wed, 12 Aug 2009, Andrew Haley wrote:
> 
>> Some targets, particularly ARM, don't have instructions for things
>> such as sync_compare_and_swap.  Instead, a routine in libgcc is
>> used.  This patch adds a new gcj option, -fuse-atomic-builtins,
>> which causes gcj to use the routines in libgcc whenever atomic
>> operations are needed.
> 
> Wouldn't a target hook to allow a target to declare which operations it 
> provides in libgcc be better than a command-line option?

Maybe it would.  I'm happy to work with anyone to create such a
thing.  What would such a hook look like, and how would a front-
end use it?

Andrew.