From: Richard Earnshaw <rearnsha@arm.com>
To: Kazu Hirata <kazu@codesourcery.com>
Cc: gcc-patches@gcc.gnu.org, nickc@redhat.com, paul@codesourcery.com
Subject: Re: An unreviewed ARM patch
Date: Tue, 08 Jun 2010 08:55:00 -0000 [thread overview]
Message-ID: <1275987337.6195.7.camel@e102346-lin.cambridge.arm.com> (raw)
In-Reply-To: <4C0DA4E8.1090502@codesourcery.com>
On Mon, 2010-06-07 at 22:03 -0400, Kazu Hirata wrote:
> Hi Richard,
>
> >> Could someone please review the following patch?
> >>
> >> [patch] arm: Improve arm_rtx_costs_1 for Thumb2.
> >> http://gcc.gnu.org/ml/gcc-patches/2009-12/msg00958.html
> >>
> >
> > Hmm, I agree that there's probably some code in the rest of the MINUS
> > case that should be shared. I'm not convinced, however, that we should
> > fall through into the PLUS case: most of the code from that point on
> > will only apply if we have RSB (and we don't in Thumb-2).
>
> Err, which form of RSB are you talking about? IIRC, ARM has:
>
> RSB <Rd>, <Rn>, <shifter_operand>
>
> Thumb-2 has:
>
> RSB <Rd>,<Rn>,#0
> RSB.W <Rd>,<Rn>,#<const>
> RSB <Rd>,<Rn>,<Rm>{,<shift>}
>
> So, Thumb-2's RSB supports most of ARM's RSB, except somewhat exotic
> operands like variable shifts and rotations in <shifter_operand>.
>
> Did you mean to say Thumb-1 above?
>
Possibly :-) But it's more likely I was thinking about the lack of RSC
in Thumb2.
In which case, the patch is OK.
R.
prev parent reply other threads:[~2010-06-08 8:55 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2010-06-04 13:16 Kazu Hirata
2010-06-04 15:53 ` Richard Earnshaw
2010-06-04 17:05 ` Kazu Hirata
2010-06-08 2:03 ` Kazu Hirata
2010-06-08 8:55 ` Richard Earnshaw [this message]
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=1275987337.6195.7.camel@e102346-lin.cambridge.arm.com \
--to=rearnsha@arm.com \
--cc=gcc-patches@gcc.gnu.org \
--cc=kazu@codesourcery.com \
--cc=nickc@redhat.com \
--cc=paul@codesourcery.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 read-only IMAP folder(s) and NNTP newsgroup(s).