From: Richard Guenther <richard.guenther@gmail.com>
To: Richard Guenther <richard.guenther@gmail.com>,
Ira Rosen <ira.rosen@linaro.org>,
gcc-patches@gcc.gnu.org, Patch Tracking <patches@linaro.org>,
richard.sandiford@linaro.org
Subject: Re: [patch] Improve detection of widening multiplication in the vectorizer
Date: Mon, 06 Jun 2011 14:28:00 -0000 [thread overview]
Message-ID: <BANLkTikwdrKoOPxPBNcyOHv+OO9m6hdVHg@mail.gmail.com> (raw)
In-Reply-To: <g4tyc3dsbd.fsf@linaro.org>
On Mon, Jun 6, 2011 at 3:04 PM, Richard Sandiford
<richard.sandiford@linaro.org> wrote:
> Richard Guenther <richard.guenther@gmail.com> writes:
>> Thanks. I would hope that we eventually can get rid of the
>> pattern recognizer ... at least for SSE there is also always
>> a scalar variant instruction for each vectorized one.
>
> AFAIK, that isn't true for ARM and NEON. E.g. I don't know of a single
> instruction that does the scalar equivalent of things like VADDHN
> (add values and narrow to high half), VSUBL.U32 (subtract two values
> and extend the result), etc.
>
> FWIW, I think MIPS only has minimum and maximum operations for paired
> floats, not for single floats or doubles. I don't have the manuals to
> hand to check though.
>
> It's probably OK for the particular case of widening multiplications.
> It sounded like you were making a more general statement though.
> If so, I think we should try to avoid assuming that every vectorisable
> operation has an equivalent scalar machine instruction.
Hmm, too bad ;) Yes, I was suggesting that we assume that. I guess
for now we can go with the vectorizer pattern matching enhancement
and re-visit re-ordering the passes later (I don't have time right now to
look into the reported issue).
Thanks,
Richard.
> Richard
>
next prev parent reply other threads:[~2011-06-06 14:28 UTC|newest]
Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-06-01 9:23 Ira Rosen
2011-06-01 9:42 ` Richard Guenther
2011-06-01 11:37 ` Ira Rosen
2011-06-01 12:15 ` Richard Guenther
2011-06-02 8:46 ` Ira Rosen
2011-06-02 9:59 ` Richard Guenther
2011-06-02 11:08 ` Ira Rosen
2011-06-02 15:35 ` Richard Guenther
2011-06-06 13:05 ` Richard Sandiford
2011-06-06 14:28 ` Richard Guenther [this message]
2011-06-07 21:08 ` H.J. Lu
2011-06-21 0:40 ` H.J. Lu
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=BANLkTikwdrKoOPxPBNcyOHv+OO9m6hdVHg@mail.gmail.com \
--to=richard.guenther@gmail.com \
--cc=gcc-patches@gcc.gnu.org \
--cc=ira.rosen@linaro.org \
--cc=patches@linaro.org \
--cc=richard.sandiford@linaro.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;
as well as URLs for read-only IMAP folder(s) and NNTP newsgroup(s).