[Bug tree-optimization/24001] Simple redundancy not eliminated

[Bug tree-optimization/24001] Simple redundancy not eliminated

[pinskia at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=24001

Andrew Pinski <pinskia at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|NEW                         |RESOLVED
         Resolution|                            |FIXED

--- Comment #8 from Andrew Pinski <pinskia at gcc dot gnu.org> 2012-02-07 21:10:52 UTC ---
Tail merge (on the tree level) is able to optimize this one on the trunk

[Bug tree-optimization/24001] Simple redundancy not eliminated

[steven at gcc dot gnu dot org]

------- Comment #7 from steven at gcc dot gnu dot org  2007-10-16 13:32 -------
I would expect that tail merging (cross-jumping in gcc jargon) would merge the
two paths.

Better yet would be to optimize this earlier, and for that we need code
hoisting (re. comment #1, I think it is eliminated because we run code hoisting
at -Os).


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http://gcc.gnu.org/bugzilla/show_bug.cgi?id=24001

[Bug tree-optimization/24001] Simple redundancy not eliminated

[dberlin at gcc dot gnu dot org]

------- Comment #6 from dberlin at gcc dot gnu dot org  2006-01-03 18:39 -------
You are confused about what load PRE does.  It will not lift these load because
it is not partially redundant.
You are looking for some sort of generic code hoister.


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http://gcc.gnu.org/bugzilla/show_bug.cgi?id=24001

[Bug tree-optimization/24001] Simple redundancy not eliminated

[pinskia at gcc dot gnu dot org]

------- Comment #5 from pinskia at gcc dot gnu dot org  2005-12-30 22:31 -------
(In reply to comment #2)
> load-pre should sink the load and fix the problem at the tree level.

Lift the load above as it is fully redundant.


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pinskia at gcc dot gnu dot org changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
   Last reconfirmed|2005-09-25 04:31:17         |2005-12-30 22:31:57
               date|                            |


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=24001

[Bug tree-optimization/24001] Simple redundancy not eliminated

[pinskia at gcc dot gnu dot org]

------- Additional Comments From pinskia at gcc dot gnu dot org  2005-09-25 04:31 -------
Confirmed, on most targets (ppc and x86 at least) this is done at the rtl level, I don't know why it is not 
done for alpha.

-- 
           What    |Removed                     |Added
----------------------------------------------------------------------------
           Severity|normal                      |minor
             Status|UNCONFIRMED                 |NEW
     Ever Confirmed|                            |1
  GCC build triplet|alpha-linux-gnu             |
   GCC host triplet|alpha-linux-gnu             |
           Keywords|                            |TREE
   Last reconfirmed|0000-00-00 00:00:00         |2005-09-25 04:31:17
               date|                            |


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=24001

[Bug tree-optimization/24001] Simple redundancy not eliminated

[dberlin at dberlin dot org]

------- Additional Comments From dberlin at gcc dot gnu dot org  2005-09-22 18:40 -------
Subject: Re:  Simple redundancy not eliminated

On Thu, 2005-09-22 at 08:31 +0000, rguenth at gcc dot gnu dot org wrote:
> ------- Additional Comments From rguenth at gcc dot gnu dot org  2005-09-22 08:31 -------
> load-pre should sink the load and fix the problem at the tree level.

Uh, load PRE doesn't sink loads, it would lift it.






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http://gcc.gnu.org/bugzilla/show_bug.cgi?id=24001

Re: [Bug tree-optimization/24001] Simple redundancy not eliminated

[Daniel Berlin]

On Thu, 2005-09-22 at 08:31 +0000, rguenth at gcc dot gnu dot org wrote:
> ------- Additional Comments From rguenth at gcc dot gnu dot org  2005-09-22 08:31 -------
> load-pre should sink the load and fix the problem at the tree level.

Uh, load PRE doesn't sink loads, it would lift it.

[Bug tree-optimization/24001] Simple redundancy not eliminated

[rguenth at gcc dot gnu dot org]

------- Additional Comments From rguenth at gcc dot gnu dot org  2005-09-22 08:31 -------
load-pre should sink the load and fix the problem at the tree level.

GCSE does it at rtl level for both -O2 and -Os on i686, so maybe costs on
alpha are weird enough to prevent it from doing its work at -O2?

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http://gcc.gnu.org/bugzilla/show_bug.cgi?id=24001

[Bug tree-optimization/24001] Simple redundancy not eliminated

[pinskia at gcc dot gnu dot org]

------- Additional Comments From pinskia at gcc dot gnu dot org  2005-09-21 16:32 -------
Try with -Os and you will see it is eliminated.

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http://gcc.gnu.org/bugzilla/show_bug.cgi?id=24001