Author: Matt Taylor
Date: 20:39:04 02/09/03
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On February 09, 2003 at 22:56:59, Tom Kerrigan wrote: >On February 09, 2003 at 22:47:01, Robert Hyatt wrote: > >>The claim to fame for the sparc approach is simply "fast procedure calls". >>No register saving or restoring. It was a necessary trade-off since the >>first sparcs didn't have hardware integer multiply/divide which made procedure >>calls very frequent. > >Compilers that inline code and do "fastcalls" negate any benefit that register >windowing gives you. On an architecture like Sparc or IA-64 that gives you enough registers to do so. Let's start counting...I have 8 registers on IA-32...1 used as frame pointer...1 as stack pointer...3 get preserved by convention...hmm. I guess that leaves -3- registers for "fastcall" convention. This is why IA-32 usually doesn't even bother with fastcall. Sparc and other "fastcall" machines have enough registers that the called function actually benefits from receiving parameters in registers. Extremely few functions can make efficient use of fastcall registers on IA-32. You gain nothing by passing parameters in registers when the called function has to turn around and put them on the stack again because it needs registers for computation. >>>Doesn't matter for computer chess. Every program I know about (with the >>>exception of HIARCS) has a working set of < 256k. >>I have one that doesn't fit your working set limit... >>IE my attack lookup tables are 8 byte arrays of size [64][256] which turns > >You don't have to do some sort of thought experiment to try to figure out how >big your working set is. Just run your program on a certain processor and vary >its clock speed. If the program scales [more or less] linearly, your working set >is smaller than the CPU's caches. Not always. Crafty scales with clock speed, and it consistently blows the cache. I can't explain that, but I haven't thought through it yet. -Matt
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