Marius Bakke <mbakke@fastmail.com> writes:

> Leo Famulari <leo@famulari.name> writes:
>
>> On Sun, Nov 27, 2016 at 10:02:35PM +0100, Tobias Geerinckx-Rice wrote:
>>> Leo,
>>> 
>>> On 27/11/16 21:56, Leo Famulari wrote:
>>> > Will this work on nachines that don't support SSE? My understanding is
>>> > that we don't wish to require it.
>>> 
>>> Why wouldn't it?
>>> 
>>> I don't often use Icecat, but when I do... I don't see why it would
>>> require SSE by default. ;-) And it's not like we ever patched it to use
>>> IJG's libjpeg to begin with.
>>
>> I'm not sure, but the comment seems to indicate that we don't want to
>> use it:
>>
>> ;; According to
>> ;; http://sourceforge.net/projects/libjpeg-turbo/ ,
>> ;; "libjpeg-turbo is a derivative of libjpeg that
>> ;; uses MMX, SSE, SSE2, and NEON SIMD instructions
>> ;; to accelerate baseline JPEG compression/
>> ;; decompression", so we had better not use it
>
> SSE is pentium III, and SSE2 was introduced in Pentium IV. MMX is even
> older. Are we really committed to supporting 15+ year old hardware?

Digging a bit further, SSE2 is actually part of the AMD64
specification[0]. Perhaps we could make it conditional on architecture?

0: https://en.wikipedia.org/wiki/SSE2#CPU_support