From: Marek Polacek <polacek@redhat.com>
To: GCC Patches <gcc-patches@gcc.gnu.org>,
Richard Biener <rguenther@suse.de>
Subject: match.pd: Optimize (x & y) ^ (x | y)
Date: Thu, 11 Jun 2015 11:08:00 -0000 [thread overview]
Message-ID: <20150611110432.GY2756@redhat.com> (raw)
This patch introduces a new pattern for the match-and-simplify
machinery.
I have verified this transformation on a toy testcase (tried x and y
in the range [-1000,1000]) and it does a correct thing for all integers.
The asm diff for fn1 is
- andl %esi, %eax
- orl %edi, %esi
so clearly a win.
Bootstrapped/regtested on x86_64-linux, ok for trunk?
2015-06-11 Marek Polacek <polacek@redhat.com>
* match.pd ((x & y) ^ (x | y) -> x ^ y): New pattern.
* gcc.dg/fold-xor-3.c: New test.
diff --git gcc/match.pd gcc/match.pd
index 48358a8..7a7b201 100644
--- gcc/match.pd
+++ gcc/match.pd
@@ -320,6 +320,12 @@ along with GCC; see the file COPYING3. If not see
(bitop:c (rbitop:c @0 @1) (bit_not@2 @0))
(bitop @1 @2)))
+/* (x & y) ^ (x | y) -> x ^ y */
+(simplify
+ (bit_xor:c (bit_and@2 @0 @1) (bit_ior@3 @0 @1))
+ (if (single_use (@2) && single_use (@3))
+ (bit_xor @0 @1)))
+
(simplify
(abs (negate @0))
(abs @0))
diff --git gcc/testsuite/gcc.dg/fold-xor-3.c gcc/testsuite/gcc.dg/fold-xor-3.c
index e69de29..a66f89d 100644
--- gcc/testsuite/gcc.dg/fold-xor-3.c
+++ gcc/testsuite/gcc.dg/fold-xor-3.c
@@ -0,0 +1,28 @@
+/* { dg-do compile } */
+/* { dg-options "-fdump-tree-original" } */
+
+int
+fn1 (signed int x, signed int y)
+{
+ return (x & y) ^ (x | y);
+}
+
+unsigned int
+fn2 (unsigned int x, unsigned int y)
+{
+ return (x & y) ^ (x | y);
+}
+
+int
+fn3 (signed int x, signed int y)
+{
+ return (x | y) ^ (x & y);
+}
+
+unsigned int
+fn4 (unsigned int x, unsigned int y)
+{
+ return (x | y) ^ (x & y);
+}
+
+/* { dg-final { scan-tree-dump-times "return x \\^ y;" 4 "original" } } */
Marek
next reply other threads:[~2015-06-11 11:04 UTC|newest]
Thread overview: 16+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-06-11 11:08 Marek Polacek [this message]
2015-06-11 11:09 ` Richard Biener
2015-06-11 12:14 ` Marek Polacek
2015-06-11 11:18 ` Jakub Jelinek
2015-06-11 12:07 ` Marek Polacek
2015-06-11 20:12 ` Marc Glisse
2015-06-12 5:59 ` Richard Biener
2015-06-12 7:22 ` Marc Glisse
2015-06-12 9:04 ` Marek Polacek
2015-06-13 10:46 ` Marc Glisse
2015-06-16 13:47 ` Richard Biener
2015-06-11 15:26 ` Marc Glisse
2015-06-11 16:12 ` Richard Biener
2015-06-11 16:14 ` Marek Polacek
2015-06-11 16:34 ` Marc Glisse
2015-06-11 16:58 ` Marek Polacek
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=20150611110432.GY2756@redhat.com \
--to=polacek@redhat.com \
--cc=gcc-patches@gcc.gnu.org \
--cc=rguenther@suse.de \
/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).