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Subject: Re: Fruit 1.0 64-bit

Author: Fabien Letouzey

Date: 06:13:12 03/26/04

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On March 26, 2004 at 09:07:18, Slater Wold wrote:

>On March 26, 2004 at 08:50:51, Fabien Letouzey wrote:
>
>>>>I find it interesting; do you feel like investigating?
>>>
>>>Yes.  I can, and will.  I started looking last nite, but ran out of time.
>>
>>It's not urgent of course, but I think we've got something to learn.
>>For instance a way not to do things for 64-bit platforms :)
>>
>>>>One drawback of 64-bit ints and pointers is that they could take more space in
>>>>memory, but I thought I carefully avoided that everywhere ...
>>
>>>I am not sure what's slowing it down.  I could clearly see why it might not get
>>>a huge speedup, but the 10% slow down is confusing.
>>
>>I pass many pointers as function arguments (for instance I pass a pointer to the
>>board everyhere instead of using a global variable).  To me an argument is the
>>same as a local variable, and the slow down is very small on 32-bit platforms I
>>am sure.
>
>This was my first guess.  You cannot cast pointers to int, long, ULONG, or DWORD
>in 64-bit.  And there's a whole slew of other things to look at, also.

I don't do any tricks with pointers, I don't even store them in any struct or
array (only local variables, that's registers or stack).  I just pass them as
argument; no pointer arithmetic ...

>It very well maybe a part of it, but I think investigating the pointers,
>arguments, and variables is a better place to start.

Well if profiling reveals a clear difference between the 32-bit and 64-bit
version that would be easy.  Of course I am expecting no such thing.

Alternately, I could read the AMD 64-bit recommendations looking for something
that I do differently.  I didn't bother because Fruit does not use bitboards.

Fabien.




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