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Date: Sun, 26 Jul 2015 17:27:29 +0200
From: Agnieszka Bielec <bielecagnieszka8@...il.com>
To: john-dev@...ts.openwall.com
Subject: Re: PHC: Lyra2 vs yescrypt benchmarks 2

2015-07-26 16:11 GMT+02:00 Solar Designer <solar@...nwall.com>:
> Agnieszka,
>
> On Sun, Jul 26, 2015 at 04:02:19PM +0200, Agnieszka Bielec wrote:
>> my undestranding was that when intrinsic are in SSE2 but AVX is
>> avalialbe they are compiled to AVX,
>
> Yes, although that's only part of the story.

sometimes compilers can mix AVX and SSE2 (I am not sure)

>
>> and similarly SSE4 -> AVX2
>
> No.  This indicates that you don't understand what SSE4 is, and what
> AVX2 is.  Please read up on them, then answer my question again.

I read some stuff,

SSE4 is an additional some instructions to SSE and like SSE2 makes
computations on 128-bits registers MMX (4 integers 32-bit)

AVX - 256-bit registers YMM0 -YMM15 (8 x 32-bits or 4 x 64-bits or
even lower) , some on registers MMX, math operations in form c = a + b
(in sse a=a+b)

AVX2 - more instructions in 256-bit registers

> And you really ought to be reading assembly output to get a feeling of
> this stuff.

I will spend some time on it today and tomorrow

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