linux-kernel.vger.kernel.org archive mirror
 help / color / mirror / Atom feed
From: Linus Torvalds <torvalds@osdl.org>
To: Denis Vlasenko <vda.linux@googlemail.com>
Cc: Albert Cahalan <acahalan@gmail.com>,
	Segher Boessenkool <segher@kernel.crashing.org>,
	akpm@osdl.org, linux-kernel@vger.kernel.org,
	s0348365@sms.ed.ac.uk, bunk@stusta.de, mikpe@it.uu.se
Subject: Re: kernel + gcc 4.1 = several problems
Date: Sat, 6 Jan 2007 20:45:49 -0800 (PST)	[thread overview]
Message-ID: <Pine.LNX.4.64.0701062041330.3661@woody.osdl.org> (raw)
In-Reply-To: <200701070525.45974.vda.linux@googlemail.com>



On Sun, 7 Jan 2007, Denis Vlasenko wrote:
> 
> I'd say "care about obvious, safe optimizations which we still not do".
> I want this:
> 
> char v[4];
> ...
> 	memcmp(v, "abcd", 4) == 0
> 
> compile to single cmpl on i386.

Yeah. For a more relevant case, look at the hoops we used to jump through 
to get "memcpy()" to generate ok code for trivial fixed-sized cases.

(That said, I think __builtin_memcpy() does a reasonable job these days 
with gcc, and we might drop the crap one day when we can trust the 
compiler to do ok. It didn't use to, and we continued using our 
ridiculous macro/__builtin_constant_p misuses just because it works with 
_all_ relevant gcc versions).

			Linus

  reply	other threads:[~2007-01-07  4:49 UTC|newest]

Thread overview: 60+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2007-01-04  7:11 kernel + gcc 4.1 = several problems Albert Cahalan
2007-01-04 16:43 ` Segher Boessenkool
2007-01-04 17:04   ` Albert Cahalan
2007-01-04 17:24     ` Segher Boessenkool
2007-01-04 17:47       ` Linus Torvalds
2007-01-04 18:53         ` Segher Boessenkool
2007-01-04 19:10         ` Al Viro
2007-01-05 17:17       ` Pavel Machek
2007-01-06  8:23         ` Segher Boessenkool
2007-01-04 17:37     ` Linus Torvalds
2007-01-04 18:34       ` Segher Boessenkool
2007-01-04 22:02         ` Geert Bosch
2007-01-07  4:25       ` Denis Vlasenko
2007-01-07  4:45         ` Linus Torvalds [this message]
2007-01-07  5:26           ` Jeff Garzik
2007-01-07 15:10         ` Segher Boessenkool
2007-01-26 22:05           ` Michael K. Edwards
2007-01-04 18:08     ` Andreas Schwab
  -- strict thread matches above, loose matches on Subject: below --
2007-01-03  2:12 Mikael Pettersson
2007-01-03  2:20 ` Alistair John Strachan
2007-01-05 15:53   ` Alistair John Strachan
2007-01-05 16:02     ` Linus Torvalds
2007-01-05 16:19       ` Alistair John Strachan
2007-01-05 16:49         ` Linus Torvalds
2007-01-07  0:36           ` Pavel Machek
2007-01-07  0:57             ` Alistair John Strachan
2007-01-03  5:55 ` Willy Tarreau
2007-01-03 10:29 ` Alan
2007-01-03 10:32   ` Grzegorz Kulewski
2007-01-03 11:51     ` Jeff Garzik
2007-01-03 12:44     ` Alan
2007-01-03 13:32       ` Arjan van de Ven
2007-01-03 13:58         ` Jakub Jelinek
2007-01-03 14:28         ` Alan
2007-01-03 16:06           ` Linus Torvalds
2007-01-03 16:03     ` Linus Torvalds
2007-01-03 17:01       ` l.genoni
2007-01-03 17:45         ` Tim Schmielau
2007-01-03 20:24           ` Linus Torvalds
2007-01-03 17:06       ` l.genoni
2007-01-03 17:53       ` Mariusz Kozlowski
2007-01-03 19:47       ` Denis Vlasenko
2007-01-03 20:38         ` Linus Torvalds
2007-01-03 21:48           ` Denis Vlasenko
2007-01-03 22:13             ` Linus Torvalds
2007-01-03 21:44       ` Thomas Sailer
2007-01-03 22:08         ` Linus Torvalds
2007-01-04  3:08       ` Zou, Nanhai
2007-01-04 15:34         ` Linus Torvalds
2006-12-20 14:21 Oops in 2.6.19.1 Alistair John Strachan
2006-12-30 16:59 ` Alistair John Strachan
2006-12-31 16:27   ` Adrian Bunk
2006-12-31 16:55     ` Alistair John Strachan
2007-01-02 21:10       ` kernel + gcc 4.1 = several problems Adrian Bunk
2007-01-02 21:56         ` Alistair John Strachan
2007-01-02 22:06           ` D. Hazelton
2007-01-02 23:24             ` Adrian Bunk
2007-01-02 23:41               ` D. Hazelton
2007-01-03  2:05                 ` Horst H. von Brand
2007-01-02 22:13           ` Linus Torvalds
2007-01-02 23:18             ` Alistair John Strachan
2007-01-03  1:43               ` Linus Torvalds
2007-01-02 22:01         ` Linus Torvalds
2007-01-02 23:09           ` David Rientjes

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=Pine.LNX.4.64.0701062041330.3661@woody.osdl.org \
    --to=torvalds@osdl.org \
    --cc=acahalan@gmail.com \
    --cc=akpm@osdl.org \
    --cc=bunk@stusta.de \
    --cc=linux-kernel@vger.kernel.org \
    --cc=mikpe@it.uu.se \
    --cc=s0348365@sms.ed.ac.uk \
    --cc=segher@kernel.crashing.org \
    --cc=vda.linux@googlemail.com \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line before the message body. 
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).