On Sat, May 5, 2012 at 10:58 PM, Joel C. Salomon <[email protected]>wrote:
> On 05/05/2012 05:06 PM, Comeau At9Fans wrote:
> > On Sat, May 5, 2012 at 1:48 PM, Charles Forsyth wrote:
> >
> > if it's performance you're worried about, for programs that don't
> > care about width, i'd expect 32 bits at least
> > to match performance with 64 bits (if there's a measurable
> > difference). for one thing, cache lines will contain
> > more values, and several will be fetched at once when cache lines
> > are filled.
> >
> > And for programs that do care about this, C99 provides things such as
> > int_fast64_t (which IIRC 8c et al does not currently support).
>
> <stdint.h> is just a bunch of typedef's, some of which have been
> included, under different names (u{8,16,32,64}int), in <u.h>. Wouldn't
> be hard to provide for APE if anyone wants it.
Yes, the u{...}int names are important. Those "different names" are
normally for other (though obviously related) purposes (conceptually
int_exact_*), and the int_least_* and int_fast_* names, usually are built
from the exact ones. BTW, more generally re the greater issue raised
earlier by an OP, if ones intent is X bits, then int is not expressing that
intent, and even if your assumption happens to be correct, it might also
create a portability faux pas if that is a concern. Also, if int was X
bits underneath, then arrays of int, now in the case of X == 64 effectively
become arrays of long stuff since not only is there now maybe wasted
memory, but cache management and such can be a concern. This all has
architecture dependencies though.
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