Author: Fabien Letouzey
Date: 04:16:03 03/27/04
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On March 26, 2004 at 11:50:04, Robert Hyatt wrote: >On March 26, 2004 at 09:15:12, Fabien Letouzey wrote: > >>On March 26, 2004 at 09:13:12, Fabien Letouzey wrote: >> >>>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. >> >>Would there be a reason why, for instance, 16-bit integers would be slower in >>64-bit mode? >> >>Fabien. > > >Yes. 16/32 bit ints require sign-extension. signed things are a problem... Could this explain an overall 10% slow down (assuming many array accesses)? Fabien.
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