[PATCH] Use lwsync in PowerPC sync_* builtins

[David Edelsohn]

On Wed, Sep 3, 2008 at 6:53 PM, Anton Blanchard <anton@samba.org> wrote:
> The only thing lwsync wont order is a store followed by a load. Since
> the lwsync will always be paired with a store (the stwcx), we will order
> all accesses before it and provide a release barrier.

Anton,

My one other concern is developers using the builtins for applications on
embedded PowerPC processors.  lwsync will not order accesses to device
memory space, AFAICT.  I do not know if developers would rely on GCC builtins
in that context and assume it implements the correct semantics.  Otherwise,
I agree that the memory barrier operations probably can use lwsync.

David