Re: [patch] Provide a can_compare_and_swap_p target hook.

[Andrew Haley <aph@redhat.com>]

On 11/06/2014 05:57 PM, Andrew MacLeod wrote:
> It looks like java is deciding whether or not GCC can inline atomic 
> operations or not, and if it can't, doesn't want the atomic 
> operations...   which presumably means there is no dependency on 
> libatomic at runtime.
> 
> A call to can_compare_and_swap_p(mode) is analogous to a compile time 
> version of folding atomic_always_lock_free(mode) to a constant...   
> Frankly that seems like a reasonable question for some front end to 
> ask...  and elect not to emit atomic calls if so desired. (which is what 
> java is doing I think)
> 
> whether it still needs to do that is a question for some java person.

I did it because some targets did not have library support for some
builtins, so a compile would fail with a (to a Java programmer)
baffling error message.

The Java operations certainly should use the generic builtins.

Andrew.