Vincent Snijders wrote: > Florian Klaempfl schreef: >>> >>> >>> Line 17 generates two assembler instructions. Line 22 generates three >>> assembler instructions. As far as I can see both high(d) and @d[high(d)] >>> are constants, because d is a global variable. >>> >>> Is it possible that line 22 will generate 2 assembler instructions in >>> the future? Or is this a limitation of the i386 assembler? Or do I make >>> a mistake in my reasoning? >> >> No, you aren't, however, the problem of this benchmark are the >> inserted fwaits >> which are necessary to get fpu exceptions at correct lines. The best >> would be to >> introduce a switch which prevents the fwaits. > > Aha, that explains why explicit subexpression elimination fails too.
Yes, an fwait patch would help a lot here :) Even more, because C doesn't insert these fwaits neither. > > using comon expression, less calculations: > distance:=sqrt(sqr(dx)+sqr(dy)+sqr(dz)); > mag := dt / (distance*distance*distance); > but this is faster: > distance:=sqrt(sqr(dx)+sqr(dy)+sqr(dz)); > mag := dt / > (sqrt(sqr(dx)+sqr(dy)+sqr(dz))*(sqr(dx)+sqr(dy)+sqr(dz))); > > using comon expression, less calculations: > b1mag := b1^.mass * mag; > b2^.vx := b2^.vx + dx * b1mag; > b2^.vy := b2^.vy + dy * b1mag; > b2^.vz := b2^.vz + dz * b1mag; > but this is faster: > b2^.vx := b2^.vx + dx * b1^.mass * mag; > b2^.vy := b2^.vy + dy * b1^.mass * mag; > b2^.vz := b2^.vz + dz * b1^.mass * mag; > > Vincent > _______________________________________________ > fpc-pascal maillist - fpc-pascal@lists.freepascal.org > http://lists.freepascal.org/mailman/listinfo/fpc-pascal _______________________________________________ fpc-pascal maillist - fpc-pascal@lists.freepascal.org http://lists.freepascal.org/mailman/listinfo/fpc-pascal
