From: Marc Glisse <marc.glisse@inria.fr>
To: gcc-patches@gcc.gnu.org
Cc: rv@rasmusvillemoes.dk
Subject: Re: [PATCH 2/4] match.pd: Add x & ~(x & y) -> x & ~y pattern
Date: Wed, 21 Jan 2015 21:24:00 -0000 [thread overview]
Message-ID: <alpine.DEB.2.11.1501212001150.28775@stedding.saclay.inria.fr> (raw)
Hello,
(sorry for the broken thread, for some reason I haven't received any email
from gcc since about 10am, I'll investigate later)
+/* x & ~(x & y) -> x & ~y */
+(simplify
+ (bit_and:c @0 (bit_not (bit_and:c@2 @0 @1)))
+ (if (TREE_CODE (@2) != SSA_NAME || has_single_use (@2))
+ (bit_and @0 (bit_not @1))))
Wouldn't it make more sense to put @2 on bit_not? If bit_and is used
multiple times, the transformation is neutral so it should be done as a
canonicalization. On the other hand, if bit_not is used multiple times,
the transformation adds an extra bit_not (which might be free when there
is an andn insn). So I believe the 2 main options are:
- move @2 on the bit_not
- don't test has_single_use at all
--
Marc Glisse
next reply other threads:[~2015-01-21 20:00 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-01-21 21:24 Marc Glisse [this message]
2015-01-22 9:24 ` Richard Biener
2015-01-22 14:24 ` Rasmus Villemoes
-- strict thread matches above, loose matches on Subject: below --
2015-01-14 14:01 RFC: Two minor optimization patterns Richard Biener
2015-01-21 10:50 ` [PATCH 0/4] A few " Rasmus Villemoes
2015-01-21 10:55 ` [PATCH 2/4] match.pd: Add x & ~(x & y) -> x & ~y pattern Rasmus Villemoes
2015-05-01 18:29 ` Jeff Law
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=alpine.DEB.2.11.1501212001150.28775@stedding.saclay.inria.fr \
--to=marc.glisse@inria.fr \
--cc=gcc-patches@gcc.gnu.org \
--cc=rv@rasmusvillemoes.dk \
/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).