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From: Richard Henderson <rth@redhat.com>
To: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: "Jeremy Fitzhardinge" <jeremy@goop.org>,
	"Ingo Molnar" <mingo@elte.hu>,
	linux-kernel@vger.kernel.org, "H. Peter Anvin" <hpa@zytor.com>,
	"Thomas Gleixner" <tglx@linutronix.de>,
	"Frédéric Weisbecker" <fweisbec@gmail.com>,
	"Linus Torvalds" <torvalds@linux-foundation.org>,
	"Andrew Morton" <akpm@linux-foundation.org>,
	"Jan Beulich" <JBeulich@suse.com>,
	"Arjan van de Ven" <arjan@infradead.org>,
	"Alexander van Heukelum" <heukelum@fastmail.fm>,
	"Konrad Rzeszutek Wilk" <konrad.wilk@oracle.com>
Subject: Re: [PATCH] x86: Use -m-omit-leaf-frame-pointer to shrink text size
Date: Fri, 16 Dec 2011 08:27:09 -0800	[thread overview]
Message-ID: <4EEB715D.30301@redhat.com> (raw)
In-Reply-To: <1324030817.18942.76.camel@twins>

On 12/16/2011 02:20 AM, Peter Zijlstra wrote:
>> How can we tell gcc the asm contains a call, or otherwise suppress the
>> "leaf function" classification?

You can't at present.

> I only found the function __attribute__((leaf)) to explicitly mark a
> function as being a leaf function, but the documentation doesn't list
> the inverse of that to explicitly mark it as _not_ being one.

In any case, "leaf" doesn't do what you think it does -- see the docs.
I told Honza at the time that he was overloading existing terminology
without  purpose, but no one came up with a better name before the
release, so it stayed that way.  AFAIK, no one uses it because no one
understands it.

Do you have a proposal for what you'd like the extension to look like?
The only thing that comes to mind atm is "call" in the clobber section.
This is not likely to get written before gcc 4.8 though...


r~

  reply	other threads:[~2011-12-16 16:27 UTC|newest]

Thread overview: 12+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2011-12-16  8:19 [PATCH] x86: Use -m-omit-leaf-frame-pointer to shrink text size Ingo Molnar
2011-12-16  8:48 ` Andrew Morton
2011-12-16  8:54   ` Ingo Molnar
2011-12-16  8:53 ` Ingo Molnar
2011-12-16  9:23   ` Jeremy Fitzhardinge
2011-12-16 10:20     ` Peter Zijlstra
2011-12-16 16:27       ` Richard Henderson [this message]
2011-12-16 11:46     ` Jan Beulich
2011-12-16 12:00       ` Ingo Molnar
2011-12-16 15:32         ` H. Peter Anvin
2011-12-16 14:01 ` Frederic Weisbecker
2011-12-16 14:06 ` Frederic Weisbecker

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