From: Michael Matz <matz@suse.de>
To: Richard Kenner <kenner@vlsi1.ultra.nyu.edu>
Cc: dnovillo@google.com, davidxl@google.com, ebotcazou@gnat.com,
gcc-patches@gcc.gnu.org, hubicka@ucw.cz, joseph@codesourcery.com,
richard.guenther@gmail.com
Subject: Re: [google]: initialize language field for clone function struct
Date: Wed, 04 May 2011 13:16:00 -0000 [thread overview]
Message-ID: <Pine.LNX.4.64.1105041507160.1989@wotan.suse.de> (raw)
In-Reply-To: <11105041230.AA02337@vlsi1.ultra.nyu.edu>
Hi,
On Wed, 4 May 2011, Richard Kenner wrote:
> > There are pros and cons about early optimization, actually.
> > Generating extremely optimized IL very early can actually tie up
> > subsequent passes. For instance, loop unrolling and vectorization.
> > There are others in the literature.
>
> Sure, in the sorts of examples you mention where there's a level of
> "globality" to it. But I don't see it in the types of things that
> fold does. How could it ever be better to leave "a - a" in the tree
> instead of "0"?
The former is not a constant expression in the C sense, hence folding it
early disables required diagnostics; that's what Joseph means when he says
that the frontends should fold only exactly those things that the language
standard requires, implying not a general catch-all folder. After the
frontend is ready with a construct we can do all kinds of foldings as
early as we like.
Ciao,
Michael.
next prev parent reply other threads:[~2011-05-04 13:10 UTC|newest]
Thread overview: 40+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-04-30 1:34 Xinliang David Li
2011-05-02 22:13 ` Xinliang David Li
2011-05-03 10:55 ` Jan Hubicka
2011-05-03 16:15 ` Xinliang David Li
2011-05-03 16:46 ` Jan Hubicka
2011-05-03 18:55 ` Eric Botcazou
2011-05-03 19:07 ` Joseph S. Myers
2011-05-03 19:16 ` Nathan Froyd
2011-05-03 19:51 ` Joseph S. Myers
2011-05-03 20:05 ` Nathan Froyd
2011-05-03 19:52 ` Eric Botcazou
2011-05-03 20:09 ` Joseph S. Myers
2011-05-03 20:36 ` Eric Botcazou
2011-05-03 21:27 ` Joseph S. Myers
2011-05-04 8:53 ` Eric Botcazou
2011-05-04 17:27 ` Tom Tromey
2011-05-04 9:52 ` Richard Guenther
2011-05-04 10:02 ` Eric Botcazou
2011-05-04 10:30 ` Joseph S. Myers
2011-05-04 11:01 ` Eric Botcazou
2011-05-04 11:50 ` Richard Kenner
2011-05-04 12:23 ` Diego Novillo
2011-05-04 12:27 ` Richard Kenner
2011-05-04 12:31 ` Diego Novillo
2011-05-04 13:16 ` Michael Matz [this message]
2011-05-04 13:22 ` Nathan Froyd
2011-05-04 13:26 ` Diego Novillo
2011-05-04 13:39 ` Richard Kenner
2011-05-04 11:19 ` Richard Guenther
2011-05-04 12:00 ` Michael Matz
2011-05-04 12:08 ` Richard Guenther
2011-05-04 15:33 ` Eric Botcazou
2011-05-04 16:05 ` Richard Guenther
2011-05-04 17:22 ` Eric Botcazou
2011-05-05 9:07 ` Richard Guenther
2011-05-05 9:25 ` Eric Botcazou
2011-05-05 9:44 ` Richard Guenther
2011-05-05 10:22 ` Eric Botcazou
2011-05-05 11:03 ` Richard Guenther
2011-05-05 11:59 ` Eric Botcazou
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