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From: "oleg.endo@t-online.de" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug target/49468] SH Target: inefficient integer abs code
Date: Sun, 19 Jun 2011 15:30:00 -0000	[thread overview]
Message-ID: <bug-49468-4-XtNlo3GkKt@http.gcc.gnu.org/bugzilla/> (raw)
In-Reply-To: <bug-49468-4@http.gcc.gnu.org/bugzilla/>

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=49468

--- Comment #1 from Oleg Endo <oleg.endo@t-online.de> 2011-06-19 15:29:45 UTC ---
Created attachment 24560
  --> http://gcc.gnu.org/bugzilla/attachment.cgi?id=24560
Proposed patch

The patch adds explicit handling of abs:SI and abs:DI to the machine
description instead of relying on the default abs handling. On SH4 the
zero-offset branch way is definitely faster. It reduces pressure on EX group
instructions and improves parallel instruction execution. On other than SH4
zero-offset branches are not as fast, but the resulting code should still be
faster than the default branch-free abs code, at least it is more compact. 
The patch also handles the case of neg (abs (...)) by simply inverting the
branch condition.

Feedback appreciated.


  reply	other threads:[~2011-06-19 15:30 UTC|newest]

Thread overview: 13+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2011-06-19 15:15 [Bug target/49468] New: " oleg.endo@t-online.de
2011-06-19 15:30 ` oleg.endo@t-online.de [this message]
2011-06-19 15:49 ` [Bug target/49468] " oleg.endo@t-online.de
2011-06-22 22:38 ` kkojima at gcc dot gnu.org
2011-06-26 20:49 ` oleg.endo@t-online.de
2011-06-27  6:40 ` kkojima at gcc dot gnu.org
2011-06-29  1:37 ` oleg.endo@t-online.de
2011-09-25 12:53 ` oleg.endo@t-online.de
2012-02-26 23:38 ` olegendo at gcc dot gnu.org
2012-02-28  8:44 ` olegendo at gcc dot gnu.org
2012-02-29 23:23 ` kkojima at gcc dot gnu.org
2012-03-14 23:10 ` olegendo at gcc dot gnu.org
2013-12-05 19:26 ` olegendo at gcc dot gnu.org

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