[PATCH] Compile AVX libm functions with -mavx -mprefer-avx128

[Andreas Jaeger]

On Tuesday, October 02, 2012 13:54:11 H.J. Lu wrote:
> On Tue, Oct 2, 2012 at 12:47 PM, Ondřej Bílka <neleai@seznam.cz> 
wrote:
> > On Tue, Oct 02, 2012 at 03:31:50PM -0400, Mike Frysinger wrote:
> >> On Tuesday 02 October 2012 15:20:54 H.J. Lu wrote:
> >> > On Tue, Oct 2, 2012 at 12:02 PM, Mike Frysinger 
<vapier@gentoo.org> wrote:
> >> > > On Tuesday 02 October 2012 09:53:25 H.J. Lu wrote:
> >> > >> This patch compiles AVX libm functions with -mavx.  It reduces
> >> > >> text size>> > > 
> >> > >> of libm.so by about 1%:
> >> > > looks like you're reverting
> >> > > 56f6f6a2403cfa7267cad722597113be35ecf70d.
> >> > > shouldn't you revert all of it and not just change the CFLAGS
> >> > > back ?
> >> > 
> >> > Doesn't this patch:
> >> > 
> >> > http://sourceware.org/ml/libc-alpha/2012-10/msg00055.html
> >> > 
> >> > do that?
> >> 
> >> yes, i missed the follow up
> >> 
> >> > > it'd be useful to know *why* Ulrich moved away from -mavx, but
> >> > > unfortunately his commit message is useless.
> >> > 
> >> > I can only guess:
> >> might be useful to put some notes (like referring to the older
> >> commit) into the commit message when you do commit things
> >> -mike
> > 
> > could it be a 60 cycle penalty when switching between legagy sse and
> > avx state?
> 
> Here is a patch to compile AVX libm functions with -mavx
> -mprefer-avx128.

Let's first get some benchmarks for these changes, please,

Andreas
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