GDC review process.

[Manu]

On 20 June 2012 13:59, Don Clugston <dac at nospam.com> wrote:

> You and I seem to be from different planets. I have almost never written
> as asm function which was suitable for inlining.
>
> Take a look at std.internal.math.biguintX86.d
>
> I do not know how to write that code without inline asm.
>

Interesting.
I wish I could paste some counter-examples, but they're all proprietary >_<

I think they key detail here is where you stated, they _always_ include a
loop. Is this because it's hard to manipulate the compiler into the correct
interaction with the flags register?
I'd be interested to compare the compiled D code, and your hand written asm
code, to see where exactly the optimiser goes wrong. It doesn't look like
you're exploiting too many tricks (at a brief glance), it's just nice tight
hand written code, which the optimiser should theoretically be able to get
right...

I find optimisers are very good at code simplification, assuming that you
massage the code/expressions to neatly match any architectural quirks.
I also appreciate that good x86 code is possibly the hardest architecture
for an optimiser to get right...
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