tree 70fb2f459b7a55ad711e303463d2218a6ba75cdd
parent b4b2a951c8b4c1315c06cb4d58dbc787949daa4c
author Nicolai Hähnle <nicolai.haehnle@amd.com> 1509718797 +0100
committer Nicolai Hähnle <nicolai.haehnle@amd.com> 1510223850 +0100

util/u_atomic: add p_atomic_xchg

The closest to it in the old-style gcc builtins is __sync_lock_test_and_set,
however, that is only guaranteed to work with values 0 and 1 and only
provides an acquire barrier. I also don't know about other OSes, so we
provide a simple & stupid emulation via p_atomic_cmpxchg.

Reviewed-by: Marek Olšák <marek.olsak@amd.com>