Messages in this thread |  | | | Subject | Re: [PATCH 1/24] make atomic_read() behave consistently on alpha | | From | Valdis.Kletnieks@vt ... | | Date | Sat, 11 Aug 2007 00:38:35 -0400 | |
On Sat, 11 Aug 2007 02:38:40 +0200, Segher Boessenkool said:
> >> That means GCC cannot compile Linux; it already optimises
> >> some accesses to scalars to smaller accesses when it knows
> >> it is allowed to. Not often though, since it hardly ever
> >> helps in the cost model it employs.
> >
> > Please give an example code snippet + gcc version + arch
> > to back this up.
>
> unsigned char f(unsigned long *p)
> {
> return *p & 1;
> }
Not really valid, because it's still able to do one atomic access to
compute the result.
Now, if you had found an example where it converts a 32-bit atomic access into
2 separate 16-bit accesses that weren't atomic as a whole....[unhandled content-type:application/pgp-signature] |  |