From: linux@arm.linux.org.uk (Russell King - ARM Linux)
To: linux-arm-kernel@lists.infradead.org
Subject: [PATCH] bitops: remove condition code clobber for CLZ
Date: Tue, 11 Jan 2011 18:53:06 +0000 [thread overview]
Message-ID: <20110111185306.GM11039@n2100.arm.linux.org.uk> (raw)
In-Reply-To: <alpine.LFD.2.00.1101111347320.17086@xanadu.home>
On Tue, Jan 11, 2011 at 01:51:19PM -0500, Nicolas Pitre wrote:
> On Tue, 11 Jan 2011, Russell King - ARM Linux wrote:
>
> > On Tue, Jan 11, 2011 at 11:12:05PM +0530, Rabin Vincent wrote:
> > > The CLZ instruction does not alter the condition flags, so remove the
> > > "cc" clobber from the inline asm for fls().
> >
> > Do you have any evidence that this changes anything, or is it just
> > subjective?
>
> This probably doesn't change anything, as gcc has been presuming that
> inline asms do clobber the condition code for years now, in order to
> prevent issues caused by a lack of %? appended to instructions in order
> to conditionally execute them otherwise. So this would only make the
> code self consistent.
So given that Linus complains about churn from ARM, what's the
justification to apply a patch which has no effect what so ever?
next prev parent reply other threads:[~2011-01-11 18:53 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-01-11 17:42 [PATCH] bitops: remove condition code clobber for CLZ Rabin Vincent
2011-01-11 17:48 ` Nicolas Pitre
2011-01-11 18:39 ` Russell King - ARM Linux
2011-01-11 18:51 ` Nicolas Pitre
2011-01-11 18:53 ` Russell King - ARM Linux [this message]
2011-01-11 22:28 ` Nicolas Pitre
2011-01-12 14:18 ` Rabin Vincent
2011-01-12 14:22 ` Russell King - ARM Linux
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=20110111185306.GM11039@n2100.arm.linux.org.uk \
--to=linux@arm.linux.org.uk \
--cc=linux-arm-kernel@lists.infradead.org \
/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