Re: Compiler for Z80/6510

["Vladimir Olensky" <vladimir_olensky@yahoo.com>]

Robert Dewar wrote in message <81m3a5$blp$1@nnrp1.deja.com>...
>In article <s3rhigaqa4r69@corp.supernews.com>,
>  "Vladimir Olensky" <vladimir_olensky@yahoo.com> wrote:
>> There are of course some special cases when using assembler
>> one can easily outperform GNAT in up to 8 times on  the IA32
>> platform but I think that next GNAT releases will leave no
>> such opportunities. I think it is quite obvious what these
>> cases are :-).
>
>I have no idea what Vladimir is talking about here. There are
>certainly cases where GNAT, like all other compilers I know
>of does not generate optimal code, but
>
>a) I do not know of specific cases that Vladimir is talking of


I thought that  "up to 8 times on  the IA32 platform" is a good hint.

As I mentioned GNAT is very effective when used carefully (much
more effective than for example OA educational version that does not
provide  any optimization options)

I was  talking about  IA32 ++  architecture features that are not
directly supported by GNAT yet. These features are SIMD IA32
extensions (Single Instruction Multiple Data) .
Right now they are accessible only by using assembler
(but may  be I do not know something ???).
Operations on  vectors of bytes are eight times faster as such
operations are done in parallel on eight bytes in a single instruction.
These IA32 SIMD extensions also provide direct  support
for saturated arithmetic  which is very interesting option as well.

I have in my plans to create small Ada package for saturated
arithmetic making use this features in some near future.

>b) No one around here would claim that all such cases will be
>     removed in the next release!

  I just expressed hope that may be in the next release or next
after next or some time in the future GNAT would have direct
IA32++ SIMD support. (I wrote releases but not release).

So I was talking about  adding and not removing.
But may be it is better not to spent time on this but focus
on IA64 architecture that offer much more advanced features.


Regards,
Vladimir Olensky