Msieve 64 bit optimizations..

Carlo · 2011-09-09, 17:58

Hi,

I was looking at the msieve\trunk\common\mp.c file and I noticed there is 64 bit inline assembly code for GCC (although doesn't seem to use 64 bit wide instructions ?), but not for MSC, since inline assembler is not available for 64 bit targets with that compiler.

Would there be any benefit in looking into compiler intrinsics for MSC (i.e. things like _BitScanForward()) etc.?

-Carlo

jasonp · 2011-09-09, 20:44

The multiple precision library in mp.c does not take up enough of the total runtime in the QS and NFS codes to be worth optimizing.

In any case, I am working on a set of patches (now in testing) to the NFS code that use GMP almost everywhere. Those patches will have to get rolled out in stages, since the NFS code depends on mp.c surprisingly often. The NFS code is pretty much the only part of Msieve that I care about anymore (especially since YAFU and GMP-ECM do everything else so well), so I consider pretty much anything that does not support the NFS code to be obsolete.

2011-09-09, 17:58	#1
Carlo Jul 2010 1000₂ Posts	Msieve 64 bit optimizations.. Hi, I was looking at the msieve\trunk\common\mp.c file and I noticed there is 64 bit inline assembly code for GCC (although doesn't seem to use 64 bit wide instructions ?), but not for MSC, since inline assembler is not available for 64 bit targets with that compiler. Would there be any benefit in looking into compiler intrinsics for MSC (i.e. things like _BitScanForward()) etc.? -Carlo

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2011-09-09, 20:44	#2
jasonp Tribal Bullet Oct 2004 3565₁₀ Posts	The multiple precision library in mp.c does not take up enough of the total runtime in the QS and NFS codes to be worth optimizing. In any case, I am working on a set of patches (now in testing) to the NFS code that use GMP almost everywhere. Those patches will have to get rolled out in stages, since the NFS code depends on mp.c surprisingly often. The NFS code is pretty much the only part of Msieve that I care about anymore (especially since YAFU and GMP-ECM do everything else so well), so I consider pretty much anything that does not support the NFS code to be obsolete.