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Subject: Re: 65 bits!

Author: Robert Hyatt

Date: 17:36:45 10/24/03

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On October 24, 2003 at 13:59:07, Vincent Diepeveen wrote:

>On October 24, 2003 at 13:38:13, Robert Hyatt wrote:
>
>>On October 23, 2003 at 22:29:39, Vincent Diepeveen wrote:
>>
>>>On October 22, 2003 at 11:28:09, Gerd Isenberg wrote:
>>>
>>>>On October 22, 2003 at 03:33:05, Daniel Clausen wrote:
>>>>
>>>>>On October 21, 2003 at 15:29:19, Eugene Nalimov wrote:
>>>>>
>>>>>>On Itanium integer registers are actually 65 bits wide. 64 bits for data and one
>>>>>>NAT (not a thing) bit.
>>>>>>
>>>>>>:-)
>>>>>>
>>>>>>Thanks,
>>>>>>Eugene
>>>>>
>>>>>If there is a way to use this bit for yourself too, I'm sure Gerd will come up
>>>>>with another cool new algorithm! :)
>>>>>
>>>>>Sargon
>>>>
>>>>;-)
>>>>
>>>>I'm really not familar with this very interesting processor architecture. It has
>>>>an integer register file of 128! * 64+NaT. It seems well designed to do a lot of
>>>>parallel fill cycles.
>>>>I guess a set NaT-bit may trigger some exceptions/interrupts if you do some
>>>>operations with uninitialited registers, allowing some lowlevel try-catch like
>>>>control structures (including stack rewind?).
>>>>
>>>>Gerd
>>>
>>>Itanium2 is especially known for executing many NOP instructions :)
>>>
>>>Nah it isn't that bad. It's a cool cpu in fact. Too bad it can't be clocked very
>>>high.
>>>
>>>It's horror & co for bitboards though. Forget writing in assembly for that
>>>processor :)
>>
>>Why do you make such uninformed statements?  It is _not_ "horror and co for
>>bitboards".  It works _great_ for bitboards.
>>
>>And _you_ might forget writing in asm, but I have written asm for VLIW
>>architectures in the past.  It is not that difficult.  But then again,
>>I am very flexible.  Rigidity always has problems bending into a new
>>"shape".
>
>Diep, which is a 32 bits program and doesn't fit in 16KB instruction cache,
>is profitting more from itanium2 than crafty does.
>
>Crafty as you might know is a 64 bits program which is fitting a whole lot
>easier in that 16KB instruction cache than diep is.
>
>End of proof.

Crafty comes _nowhere_ near fitting into a 16kb instruction cache.  Crafty
profits from the 64 bit stuff on Itanium, which is why the itanium is always
faster when I have tested it.





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