From owner-freebsd-current@FreeBSD.ORG  Thu Mar 10 23:28:39 2011
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Date: Thu, 10 Mar 2011 23:28:39 +0000
From: Alexander Best <arundel@freebsd.org>
To: Dimitry Andric <dim@FreeBSD.org>
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Cc: gerald@freebsd.org, Martin Matuska <mm@freebsd.org>, current@freebsd.org
Subject: Re: [TESTING] ssse3 backport from gcc 4.3
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On Thu Mar 10 11, Alexander Best wrote:
> On Thu Mar 10 11, Dimitry Andric wrote:
> > On 2011-03-09 22:18, David Schultz wrote:
> > >The proliferation of -mno-sse -mno-sse2 -mno-sse3 options in the
> > >makefiles is probably not needed: I'm pretty sure -mno-sse implies
> > >the other two, unless -msse3 is specified explicitly.
> > 
> > Indeed, contrib/gcc/config/i386/i386.c has:
> > 
> > static bool
> > ix86_handle_option (size_t code, const char *arg ATTRIBUTE_UNUSED, int 
> > value)
> > {
> > ...
> >     case OPT_msse:
> >       if (!value)
> >         {
> >           target_flags &= ~(MASK_SSE2 | MASK_SSE3);
> >           target_flags_explicit |= MASK_SSE2 | MASK_SSE3;
> >         }
> >       return true;
> > 
> > E.g -mno-sse disables SSE2 and SSE3, unless you explicitly add -msse2 or
> > -msse3 options.  In Martin's patch, this fragment uses MASK_SSSE3 too.
> 
> +1 for removing -mno-sse2, -mno-sse3 and -mno-ssse3 throughout the source
> tree.
> 
> ...also -mfpmath=387 is still present for amd64 and i don't think it's
> necessary. with -mno-sse i don't think -mfpmath=sse remains the default for
> amd64.

i've compiled two kernels. one with the standard -mno-sse* options in kernel.mk
and one without -mno-sse2, -mno-sse3, -mno-ssse3 and -mfpmath=387.

CPUYTE ?= core2.

diffing showed no major differences for gcc and clang as compiler

cheers.
alex

> 
> > 
> > Clang has a similar mechanism, -mno-sse disables all 'higher' SSE
> > variants too.
> 
> -- 
> a13x

-- 
a13x