Bitfield accessors

[Jarrett Billingsley]

"bearophile" <bearophileHUGS at lycos.com> wrote in message 
news:fi0054$2q9t$1 at digitalmars.com...

> I have compiled them with:
> DMD: v1.023
> dmd -O -inline -release bitfields1.d
>
> gcc: V. 3.4.2 (mingw-special)
> gcc -O3 -s bitfields1.c -o bitfields1
>
> ...
> Just for reference the ASM code of the following C code:
> ...
> I have no good way to see the ASM generated by dmd yet (I may buy Walter's 
> utility). (Maybe some of you can show that asm, but remember to remove the 
> outer j loop as in the C version).

This isn't an entirely unbiased comparison.  If you used dmd and dmc, or gcc 
and gdc, that would take out at least one very large variable: that dmd and 
gcc have two completely different backends and optimizers.  From anecdotal 
evidence I'd say the gcc (and by proxy, gdc) backend is far more mature than 
dmd's when it comes to optimization.

> My obvious conclusion is that I hope to see built-in bitfields in D ;-)
> The D docs say they aren't used often, but now and then I translate C code 
> to D and I don't want to write many (slow) getter and setter properties 
> like that :-)

I agree.  Bitfields are "seldom used" but when you need them for system 
programming (which is what D is supposed to be for!) they're an awful pain 
to have to emulate.