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....
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