Author: Gerd Isenberg
Date: 10:57:06 07/09/03
Go up one level in this thread
On July 09, 2003 at 12:54:49, Vincent Diepeveen wrote: >On July 09, 2003 at 07:02:01, Gerd Isenberg wrote: > >> >>Current Opterons use so called "DirectPath Double" decode type for most SSE/SSE2 >>128-bit instructions, internally they do two 64-byte macroops. But AMD already >>mentioned "Future" Processors with 128-bit "DirectPath" SSE/SSE2 instructions: >>(Software Optimization Guide for AMD Athlon™ 64 and AMD Opteron™, Chapter 9 >>Optimizing with SIMD Instructions). >> >>That's a boost to floating point and also SIMD integer algorithms like >>KoggeStone. But when will it be? >> >>Like Athlon, Bitscan (bsf, bsr) and Bittest (btx) instructions are still Vector >>path pipe-blockers (but of course 64-bit). Same for moving data between gp- and >>xmm- or mmx- registers. >> >>Still no popcount and instructions for "reverse" arithmetics (radd, rsub, rneg), >>where the overflow passes from high to low :-( >> >>Cheers, >>Gerd > >And already 1562 in specint with crafty using 64 bits crafty. No idea what it means - i guess it's fast. What's the specint for 32-bit crafty on Opteron or Athlon? Do you have any site where i can read the current specints? > >Please compare what the opteron can do for crafty with the itanium2 and you'll >know which is the better CPU in the future. My Sympathy is with AMD. I currently write KoggeStone-routines for hammer with mmx0-7 for propagators and xmm0-15 for white/black generators. I'm a bit disappointed, that there are these double directpath instructions for 128-bit xmm registers. > >Itanium2 doesn't have bsf/bsr even if i understand well. You need to do it >indirectly at the itanium2!!!! I don't know the itanium2 instructions set - may be there is some "leading" zero count or some fast int to float conversion, where you can pass a single isolated bit as int and get the position from the float exponent. Anyway there is still Walter Faxon's magic c-routine. Regards, Gerd
This page took 0.01 seconds to execute
Last modified: Thu, 15 Apr 21 08:11:13 -0700
Current Computer Chess Club Forums at Talkchess. This site by Sean Mintz.