[Dev] SSE2 safe assumption on i686?

Luke Shumaker lukeshu at lukeshu.com
Tue May 29 01:14:58 GMT 2018

Hi all,

I think I'm turning on SSE2 in CFLAGS for the libre/glib2-static
package (CFLAGS+=" -msse2 -mfpmath=sse").

SSE2 was an extension to i686 introduced with the Pentium 4 in 2001
(i686 itself was introduced with the Pentium Pro in 1995, which came
between the Pentium 1 and 2).

SSE2 is guaranteed to be there on all x86_64 processors.

Is this a thing that we're OK doing?  Or do we want to support i686
processors without SSE2?  The decision to continue i686 support was
based largely on the number of i686 devices supported by LibreBoot; I
don't believe LibreBoot supports any devices with pre-SSE2 processors.
I would not be surprised if many packages already require SSE2 on i686
(via inline assembly or intrinsics or somesuch; after ./configure
discovers that SSE2 is supported on the local processor).

Happy hacking,
~ Luke Shumaker

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