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Date: Sat, 14 Mar 2015 22:49:30 +0100
From: magnum <>
Subject: Re: interleaved bitslice?

On 2015-03-14 20:01, Solar Designer wrote:
> On Thu, Mar 12, 2015 at 08:37:01AM +0100, magnum wrote:
>> On 2015-03-11 21:55, Solar Designer wrote:
>>> solar@...l:~/md5slice$ gcc md5slice.c -o md5slice -Wall -s -O3 -fomit-frame-pointer -funroll-loops -DVECTOR -march=native
>>> This gave "warning: always_inline function might not be inlinable" about
>>> FF(), I(), H(), F(), add32r(), add32c(), add32() - but then it built
>>> fine.  The speed is:
>> Solar,
>> While experimenting with this I noticed using a vector size of 32 but
>> still compiling for AVX gave a slight boost (~5%). I assume this ends up
>> similar to the interleaving we use in Jumbo, and is faster for the same
>> reasons.
> I've just tested this with gcc 4.9.2 on Linux, and the generated code is
> "floating-point" 256-bit AVX.  So this is not interleaving.

And yet it's faster? I would not have guessed that ever but I suppose
it's not that special. I'm probably the guy least using floating point
in the entire world.


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