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 |
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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] | |