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Re: Some thoughts about steerring commitee work
- From: Dorit Nuzman <DORIT at il dot ibm dot com>
- To: "H. J. Lu" <hjl at lucon dot org>
- Cc: Eric Botcazou <ebotcazou at libertysurf dot fr>, gcc at gcc dot gnu dot org, Ian Lance Taylor <iant at google dot com>, "Vladimir N. Makarov" <vmakarov at redhat dot com>
- Date: Sat, 16 Jun 2007 18:28:13 +0300
- Subject: Re: Some thoughts about steerring commitee work
> On Fri, Jun 15, 2007 at 06:21:53PM -0700, Ian Lance Taylor wrote:
> >
> > This is hardly a new thought, but I believe that for the i386 gcc is
> > handicapped by reload. No matter how smart we are before reload, it
> > just take one poor decision by reload in an inner loop and we've lost
> > all the gains. Reload has enormous complexities which are mostly
> > irrelevant for the i386. And I think that the idea of doing register
> > allocation separately from spill code generation does not make sense
> > on the i386.
> >
>
> Why don't we turn on vectorizer at -O3 or even -O2, depending on
> ISA?
I think we want to make more progress on the cost model first, so that we
don't greedily vectorize unless we think it's worth while.
> I added -ftree-vectorize to BOOT_CFLAGS on x86-64. According to
> -ftree-vectorizer-verbose=1, there are 82 loops vectorized in
> gcc source. There are no regressions. There are not much changes
> in bootstrap time as well as "make check" time.
>
that's good to know,
dorit
>
> H.J.