"volatile" has nothing to do with reordering. atomic_dec() writes
to memory, so it _does_ have "volatile semantics", implicitly, as
long as the compiler cannot optimise the atomic variable away
completely -- any store counts as a side effect.
Stores can be reordered. Only x86 has (mostly) implicit write ordering.
So no atomic_dec has no volatile semantics
Read again: I said the C "volatile" construct has nothing to do
with CPU memory access reordering.
and may be reordered on a variety
of processors. Writes to memory may not follow code order on several
processors.
The _compiler_ isn't allowed to reorder things here. Yes, of course
you do need stronger barriers for many purposes, volatile isn't all
that useful you know.
Segher
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