Atomic Operations

Hi,

what are the assumptions PostgreSQL normally does about atomic 
operations? I see sig_atomic_t is used in signal handlers. Additionally, 
there is a match for a cmpxchg instruction in some solaris ports code, 
but that's about what I found in the source.

Am I safe assuming that pointer assignments are atomic (on all platforms 
PostgreSQL compiles on, that is)? (This is a 'practical advice' from the 
GNU Libc Manual) How about other integers smaller or equal in size to 
sizeof(sig_atomic_t)?

I'm asking to make sure I rely on the same guarantees in my code.

Regards

Markus