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From: "matz at gcc dot gnu dot org" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug middle-end/39976] [4.5 Regression] Big sixtrack degradation on powerpc 32/64 after revision r146817
Date: Tue, 12 May 2009 13:38:00 -0000	[thread overview]
Message-ID: <20090512133724.7590.qmail@sourceware.org> (raw)
In-Reply-To: <bug-39976-16550@http.gcc.gnu.org/bugzilla/>



------- Comment #12 from matz at gcc dot gnu dot org  2009-05-12 13:37 -------
The problem is that for PHI node expansion something has to be inserted on
the backedge of a single BB loop, splitting it into two BBs (where one just
contains one instruction).  Something in the RTL passes then moves stuff
into that first BB somehow limiting the scheduler then.

I'm working on a fix.  Earlier compilers contained a hack for this (because
swing modulo scheduling can only deal with single BB loops), which I removed
as part of SSA expand, see PR34263 and PR19038.  I'm working on an alternative
solution that places the copy somewhere more intelligently than now.


-- 

matz at gcc dot gnu dot org changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
         AssignedTo|unassigned at gcc dot gnu   |matz at gcc dot gnu dot org
                   |dot org                     |
             Status|UNCONFIRMED                 |ASSIGNED
     Ever Confirmed|0                           |1
   Last reconfirmed|0000-00-00 00:00:00         |2009-05-12 13:37:22
               date|                            |


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=39976


  parent reply	other threads:[~2009-05-12 13:38 UTC|newest]

Thread overview: 34+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2009-04-30 16:25 [Bug regression/39976] New: " luisgpm at linux dot vnet dot ibm dot com
2009-04-30 16:57 ` [Bug middle-end/39976] " pinskia at gcc dot gnu dot org
2009-04-30 19:30 ` luisgpm at linux dot vnet dot ibm dot com
2009-04-30 19:39 ` luisgpm at linux dot vnet dot ibm dot com
2009-04-30 19:52 ` pinskia at gcc dot gnu dot org
2009-04-30 20:17 ` hjl dot tools at gmail dot com
2009-05-01 20:07 ` rguenth at gcc dot gnu dot org
2009-05-04 13:51 ` luisgpm at linux dot vnet dot ibm dot com
2009-05-04 14:37 ` matz at gcc dot gnu dot org
2009-05-04 15:41 ` luisgpm at linux dot vnet dot ibm dot com
2009-05-04 15:50 ` luisgpm at linux dot vnet dot ibm dot com
2009-05-04 16:10 ` matz at gcc dot gnu dot org
2009-05-05 15:52 ` mmitchel at gcc dot gnu dot org
2009-05-12 12:56 ` luisgpm at linux dot vnet dot ibm dot com
2009-05-12 13:38 ` matz at gcc dot gnu dot org [this message]
2009-05-12 15:29 ` pinskia at gcc dot gnu dot org
2009-05-13 18:17 ` matz at gcc dot gnu dot org
2009-05-13 20:15 ` matz at gcc dot gnu dot org
2009-05-14  4:12 ` luisgpm at linux dot vnet dot ibm dot com
2009-05-15  2:16 ` luisgpm at linux dot vnet dot ibm dot com
2009-05-15  2:19 ` luisgpm at linux dot vnet dot ibm dot com
2009-05-18 18:09 ` pthaugen at gcc dot gnu dot org
2009-05-21 10:40 ` rguenth at gcc dot gnu dot org
2009-06-03  3:01 ` luisgpm at linux dot vnet dot ibm dot com
2009-07-08 21:53 ` pthaugen at gcc dot gnu dot org
2009-07-09 10:43 ` matz at gcc dot gnu dot org
2009-07-14 21:15 ` pthaugen at gcc dot gnu dot org
2009-07-23 23:49 ` pthaugen at gcc dot gnu dot org
2009-11-30 13:14 ` rguenth at gcc dot gnu dot org
2009-11-30 21:29 ` pthaugen at gcc dot gnu dot org
2010-03-28 15:51 ` rguenth at gcc dot gnu dot org
2010-03-31 11:56 ` rguenth at gcc dot gnu dot org
2010-04-06 11:38 ` rguenth at gcc dot gnu dot org
2010-07-31  9:33 ` [Bug middle-end/39976] [4.5/4.6 " rguenth at gcc dot gnu dot org

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