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From: "jakub at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug rtl-optimization/47477] [4.6 regression] Sub-optimal mov at end of method
Date: Thu, 27 Jan 2011 17:34:00 -0000	[thread overview]
Message-ID: <bug-47477-4-35tWlwFvmK@http.gcc.gnu.org/bugzilla/> (raw)
In-Reply-To: <bug-47477-4@http.gcc.gnu.org/bugzilla/>

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=47477

--- Comment #3 from Jakub Jelinek <jakub at gcc dot gnu.org> 2011-01-27 17:21:04 UTC ---
Not so easily, addsi3_cc is quite specialized pattern and if we add peepholes
to help with reg1 = reg1 op reg2; reg2 = reg1 [reg1 DEAD];
I think we'd add it only for a couple of most common arithmetics ops.

Wonder whether the splitters couldn't be smarter here, when splitting a
doubleword addition see that we only care about a SImode subreg thereof.

Or, if lower-subreg.c could do something about it, optimize
(insn 10 9 11 2 (parallel [
            (set (reg:DI 74)
                (plus:DI (reg:DI 71)
                    (reg:DI 73)))
            (clobber (reg:CC 17 flags))
        ]) pr47477.c:4 243 {*adddi3_doubleword}
     (nil))

(insn 11 10 12 2 (set (reg:SI 70)
        (subreg:SI (reg:DI 74) 0)) pr47477.c:5 64 {*movsi_internal}
     (nil))
into just SImode addition.


  parent reply	other threads:[~2011-01-27 17:22 UTC|newest]

Thread overview: 29+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2011-01-26 16:54 [Bug rtl-optimization/47477] New: " tony.poppleton at gmail dot com
2011-01-27  7:08 ` [Bug rtl-optimization/47477] " hjl.tools at gmail dot com
2011-01-27 11:51 ` rguenth at gcc dot gnu.org
2011-01-27 17:34 ` jakub at gcc dot gnu.org [this message]
2011-01-27 17:58 ` jakub at gcc dot gnu.org
2011-01-27 19:43 ` tony.poppleton at gmail dot com
2011-01-28 11:31 ` rguenth at gcc dot gnu.org
2011-01-29 20:37 ` jakub at gcc dot gnu.org
2011-02-08 14:40 ` rguenth at gcc dot gnu.org
2011-02-08 14:41 ` rguenth at gcc dot gnu.org
2011-02-21 16:19 ` jakub at gcc dot gnu.org
2012-01-02 11:36 ` [Bug rtl-optimization/47477] [4.6/4.7/4.8 " jakub at gcc dot gnu.org
2012-03-06 12:48 ` jakub at gcc dot gnu.org
2012-11-30 16:27 ` jakub at gcc dot gnu.org
2013-03-22 14:46 ` [Bug rtl-optimization/47477] [4.6/4.7/4.8/4.9 " jakub at gcc dot gnu.org
2013-04-10  1:44 ` tony.poppleton at gmail dot com
2013-05-31 11:03 ` [Bug rtl-optimization/47477] [4.7/4.8/4.9 " jakub at gcc dot gnu.org
2013-10-16  9:49 ` jakub at gcc dot gnu.org
2013-10-22 13:40 ` jakub at gcc dot gnu.org
2013-10-22 14:18 ` ktietz at gcc dot gnu.org
2013-10-22 14:56 ` jakub at gcc dot gnu.org
2014-05-22  9:07 ` [Bug rtl-optimization/47477] [4.7/4.8/4.9/4.10 " rguenth at gcc dot gnu.org
2014-12-19 13:40 ` [Bug rtl-optimization/47477] [4.8/4.9/5 " jakub at gcc dot gnu.org
2015-02-13 20:18 ` law at gcc dot gnu.org
2015-02-13 20:20 ` [Bug rtl-optimization/47477] [4.8/4.9 " law at redhat dot com
2015-02-17  5:22 ` law at redhat dot com
2015-06-23  8:20 ` rguenth at gcc dot gnu.org
2015-06-26 20:13 ` [Bug rtl-optimization/47477] [4.9 " jakub at gcc dot gnu.org
2015-06-26 20:35 ` jakub at gcc dot gnu.org

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