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* [Bug c/33711]  New: Missed optimization: reduction by subtraction (vectorizer)
@ 2007-10-09 13:20 eres at il dot ibm dot com
  2007-10-09 13:50 ` [Bug tree-optimization/33711] " eres at il dot ibm dot com
  2007-12-08 23:12 ` pinskia at gcc dot gnu dot org
  0 siblings, 2 replies; 3+ messages in thread
From: eres at il dot ibm dot com @ 2007-10-09 13:20 UTC (permalink / raw)
  To: gcc-bugs

For example:

   for (i = 0; i < N; i++) {
     udiff -= (ub[i] * uc[i]);


-- 
           Summary: Missed optimization: reduction by subtraction
                    (vectorizer)
           Product: gcc
           Version: 4.3.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: c
        AssignedTo: unassigned at gcc dot gnu dot org
        ReportedBy: eres at il dot ibm dot com


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=33711


^ permalink raw reply	[flat|nested] 3+ messages in thread
* [Bug tree-optimization/33711] Missed optimization: reduction by subtraction (vectorizer)
  2007-10-09 13:20 [Bug c/33711] New: Missed optimization: reduction by subtraction (vectorizer) eres at il dot ibm dot com
@ 2007-10-09 13:50 ` eres at il dot ibm dot com
  2007-12-08 23:12 ` pinskia at gcc dot gnu dot org
  1 sibling, 0 replies; 3+ messages in thread
From: eres at il dot ibm dot com @ 2007-10-09 13:50 UTC (permalink / raw)
  To: gcc-bugs



------- Comment #1 from eres at il dot ibm dot com  2007-10-09 13:49 -------
The loop in the above example does not get vectorized because of the
subtraction in reduction; which is currently not supported.

Taken from the vectorizer dump:
test.c:19: note: worklist: examine stmt: udiff_7 = udiff_20 - D.2210_6
test.c:19: note: vect_is_simple_use: operand udiff_20
test.c:19: note: def_stmt: udiff_20 = PHI <udiff_7(4), 1.5e+3(2)>
test.c:19: note: Unsupported pattern.
test.c:19: note: not vectorized: unsupported use in stmt.
test.c:19: note: unexpected pattern.


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=33711


^ permalink raw reply	[flat|nested] 3+ messages in thread
* [Bug tree-optimization/33711] Missed optimization: reduction by subtraction (vectorizer)
  2007-10-09 13:20 [Bug c/33711] New: Missed optimization: reduction by subtraction (vectorizer) eres at il dot ibm dot com
  2007-10-09 13:50 ` [Bug tree-optimization/33711] " eres at il dot ibm dot com
@ 2007-12-08 23:12 ` pinskia at gcc dot gnu dot org
  1 sibling, 0 replies; 3+ messages in thread
From: pinskia at gcc dot gnu dot org @ 2007-12-08 23:12 UTC (permalink / raw)
  To: gcc-bugs



------- Comment #2 from pinskia at gcc dot gnu dot org  2007-12-08 23:12 -------
Confirmed.


-- 

pinskia at gcc dot gnu dot org changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
           Severity|normal                      |enhancement
             Status|UNCONFIRMED                 |NEW
     Ever Confirmed|0                           |1
           Keywords|                            |missed-optimization
   Last reconfirmed|0000-00-00 00:00:00         |2007-12-08 23:12:46
               date|                            |


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=33711


^ permalink raw reply	[flat|nested] 3+ messages in thread
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Thread overview: 3+ messages (download: mbox.gz / follow: Atom feed)
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2007-10-09 13:20 [Bug c/33711] New: Missed optimization: reduction by subtraction (vectorizer) eres at il dot ibm dot com
2007-10-09 13:50 ` [Bug tree-optimization/33711] " eres at il dot ibm dot com
2007-12-08 23:12 ` pinskia at gcc dot gnu dot org

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