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Date: Tue, 13 Oct 2015 10:43:24 +0200
From: magnum <>
Subject: LOP3.LUT (was: Re: nVidia Maxwell support (especially descrypt)?)

Moved here from john-users to spare the normal people.

On 2015-10-07 23:37, Solar Designer wrote:
> On Wed, Oct 07, 2015 at 06:54:20PM +0200, magnum wrote:
>> BTW we now also use LOP3.LUT for many MD4, MD5 and SHA-2 OpenCL formats.
>> Some driver bug prevented me for using it in SHA-1 with nvidia 352.39
>> (the code is there, just disabled) and md5crypt disable it because of
>> performance regression (still to be investigated). Some formats show a
>> fine boost but none as much as DEScrypt.

That "driver bug" was PEBCAK, fixed now. I also added a trivial perl 
script that (now) correctly calculates the truth table. Here's F5 for 

$ ./ '((x) ^ ((y) | ~(z)))'
lut3(x, y, z, 0x2d)  ==  ((x) ^ ((y) | ~(z)))

The result also works as-is for AVX-512 "ternarylogic", which will make 
life simpler for us.

Most formats now has LOP3.LUT alternatives and seem to work fine now. 
Some don't get any boost (just meaning the toolchain did a good job 
already) but I think md5crypt is the only one getting a definite 
performance regression (and still has it disabled). We should get to the 
bottom of that. BTW it would be very nice having CUDA 7.5 on super.


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