Date: Thu, 27 Aug 2015 20:57:13 +0300 From: Aleksey Cherepanov <lyosha@...nwall.com> To: john-dev@...ts.openwall.com Subject: optimization of constants in first rounds of raw formats For raw-sha512, raw-md5 and similar formats, it is possible to reduce first round to constant+w. Next rounds can be reduced a bit too. I played with it in john-devkit. I tried sse code for sha512 with gcc 5.1: gcc optimizes most of things, but not all. I think it does not optimize rotates (right rotate). I replaced 23 instructions in my intermediate representation. Number of lines in disassembler dropped from 5030 to 4996. But it does not seem to affect speed. Maybe there is 1% speed up, but fluctuations does not allow me to say reliably. I don't know if gcc optimizes it in john at all, because there are 'if's for multiblock computation IIRC. Such optimization needs unrolling of main loop. I think it is not the case in bitslice versions, so they might be improved this way. Thanks! -- Regards, Aleksey Cherepanov
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