[PATCH, committed] PowerPC atomic ops (1/n)

[Geoffrey Keating]

David Edelsohn <dje@watson.ibm.com> writes:

> 	The following patch is one in a series to clean up the PowerPC
> atomic ops implementation.  This is based on the Alpha implementation, as
> suggested by Richard Henderson.
> 
> 	All atomic UNSPEC codes are changed to volatile.

I didn't use unspec_volatile in the original implementation because it
is unnecessarily strict; it prevents the compiler from moving any kind
of instruction over these, even instructions that only affect registers.