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Date: Sun, 15 Nov 2015 17:36:59 +0200
From: Konstantin Belousov <kostikbel@gmail.com>
To: David Chisnall <theraven@FreeBSD.org>
Cc: Eric van Gyzen <vangyzen@FreeBSD.org>, src-committers@freebsd.org,
 svn-src-all@freebsd.org, svn-src-stable@freebsd.org,
 svn-src-stable-10@freebsd.org
Subject: Re: svn commit: r290014 - in stable/10: lib/libthr/arch/amd64
 lib/libthr/arch/i386 libexec/rtld-elf/amd64 libexec/rtld-elf/i386 share/mk
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On Sat, Nov 14, 2015 at 06:30:13PM +0000, David Chisnall wrote:
> On 26 Oct 2015, at 16:21, Eric van Gyzen <vangyzen@FreeBSD.org> wrote:
> > 
> > One counter-argument to this change is that most applications already
> >  use SIMD, and the number of applications and amount of SIMD usage
> >  are only increasing.
> 
> Note that SSE and SIMD are not the same thing.  The x86-64 ABI uses SSE registers for floating point arguments, so even a purely scalar application that uses floating point will end up faulting in the SSE state.  This is not the case on IA32, where x87 registers are used (though when compiling for i686, SSE is used by default because register allocation for x87 is a huge pain).
> 

Is it ?  If SSE is used on i686 (AKA >= Pentium Pro) by default,
this is a huge bug.