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From: "pinskia at gcc dot gnu dot org" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug tree-optimization/16913] [4.0/4.1/4.2/4.3 Regression] restrict does not make a difference
Date: Mon, 11 Jun 2007 00:47:00 -0000	[thread overview]
Message-ID: <20070611004704.10789.qmail@sourceware.org> (raw)
In-Reply-To: <bug-16913-2736@http.gcc.gnu.org/bugzilla/>



------- Comment #10 from pinskia at gcc dot gnu dot org  2007-06-11 00:47 -------
There are a couple of issues here, first pointer_plus improves the aliasing set
issue, but then PRE comes around and messes it up because it does not add
pointer types which have DECL_BASED_ON_RESTRICT_P/DECL_GET_RESTRICT_BASE setup
correctly.  

Disabling PRE on powerpc-linux-gnu (on the pointer_plus branch) is enough to
get the RTL optimizers to optimize away the extra loads and we get for the
inner loop:
.L3:
        stfsx 0,9,3
        addi 9,9,4
        bdnz .L3
Which is almost the best you can do :).



One more issue (for x86) is expand emits code that causes the rtl optimizers
not to optimize well as they only look into loads in sets.  I don't know how to
fix that issue without fixing restrict at the tree level.


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=16913


  parent reply	other threads:[~2007-06-11  0:47 UTC|newest]

Thread overview: 10+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
     [not found] <bug-16913-2736@http.gcc.gnu.org/bugzilla/>
2005-10-22  3:13 ` [Bug tree-optimization/16913] [4.0/4.1 " pinskia at gcc dot gnu dot org
2005-10-30 22:47 ` mmitchel at gcc dot gnu dot org
2006-03-11  3:21 ` [Bug tree-optimization/16913] [4.0/4.1/4.2 " mmitchel at gcc dot gnu dot org
2007-01-18  3:02 ` [Bug tree-optimization/16913] [4.0/4.1/4.2/4.3 " gdr at gcc dot gnu dot org
2007-01-21 21:48 ` pinskia at gcc dot gnu dot org
2007-02-14  9:29 ` mmitchel at gcc dot gnu dot org
2007-06-11  0:47 ` pinskia at gcc dot gnu dot org [this message]
2007-07-04 17:02 ` pinskia at gcc dot gnu dot org
2008-07-04 16:33 ` [Bug tree-optimization/16913] [4.2/4.3/4.4 " jsm28 at gcc dot gnu dot org
2008-10-01 14:34 ` rguenth at gcc dot gnu dot org

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