[Bug tree-optimization/32306] New: Bad Code generation ( Tree optimization )

[Bug tree-optimization/32306] New: Bad Code generation ( Tree optimization )

[pranav dot bhandarkar at gmail dot com]

For the following Code Snippet
void bar ()
{

  b1 = foo(1);
  b2 = foo(1);
  b3 = foo(1);
  b4 = foo(1);
  b5 = foo(1);
  b6 = foo(1);
  b7 = foo(1);
  b8 = foo(1);
  b9 = foo(1);
  b10 = foo(1);
  b11 = foo(1);
  b12 = foo(1);

  array[0] = b1 && b2 && b3 && b4 && b5 && b6 && b7 && b8 && b9 && b10 && b11
&& b12;
  array[1] = b1 && b2 && b3 && b4 && b5 && b6 && b7 && b8 && b9 && b10 && b11
&& b12;
  array[2] = b1 && b2 && b3 && b4 && b5 && b6 && b7 && b8 && b9 && b10 && b11
&& b12;
  array[3] = b1 && b2 && b3 && b4 && b5 && b6 && b7 && b8 && b9 && b10 && b11
&& b12;
  array[4] = b1 && b2 && b3 && b4 && b5 && b6 && b7 && b8 && b9 && b10 && b11
&& b12;
  array[5] = b1 && b2 && b3 && b4 && b5 && b6 && b7 && b8 && b9 && b10 && b11
&& b12;
  array[6] = b1 && b2 && b3 && b4 && b5 && b6 && b7 && b8 && b9 && b10 && b11
&& b12;
  array[7] = b1 && b2 && b3 && b4 && b5 && b6 && b7 && b8 && b9 && b10 && b11
&& b12;
  array[8] = b1 && b2 && b3 && b4 && b5 && b6 && b7 && b8 && b9 && b10 && b11
&& b12;
  array[9] = b1 && b2 && b3 && b4 && b5 && b6 && b7 && b8 && b9 && b10 && b11
&& b12;
  array[10] = b1 && b2 && b3 && b4 && b5 && b6 && b7 && b8 && b9 && b10 && b11
&& b12;

  return;
}

Where b ( from b1 to b12) are all declared static short b1, static short b2
etc.
and array is static short array[11].
This should generate code such as

if (b1 == 0) goto L1 else goto L2
L2:
if (b2 == 0) goto L1 else goto L3
L3:
if (b3 == 0) goto L1 else goto L4
L4:
if (b4 == 0) goto L1 else goto L5
L5:
if (b5 == 0) goto L1 else goto L6
L6:
if (b6 == 0) goto L1 else goto L7
L7:
if (b7 == 0) goto L1 else goto L8
L8:
if (b8 == 0) goto L1 else goto L9
L9:
if (b9 == 0) goto L1 else goto L10
L10:
if (b10 == 0) goto L1 else goto L11
L11:
if (b11 == 0) goto L1 else goto L12
L12:
if (b12 == 0) goto L1 else goto L13
L13:
array[i]=1 (for i from 0 to 10)
return

L1:
array[i]=0 (for i from 0 to 10)
return

This is exactly what 4.1 generates but 4.3 fails to combine the if sequences.
Version Details:
GNU C version 4.3.0 20070316 (experimental) (arm-none-eabi)
        compiled by GNU C version 3.4.6 (Ubuntu 3.4.6-1ubuntu2).
GGC heuristics: --param ggc-min-expand=30 --param ggc-min-heapsize=4096


-- 
           Summary: Bad Code generation ( Tree optimization )
           Product: gcc
           Version: 4.3.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: tree-optimization
        AssignedTo: unassigned at gcc dot gnu dot org
        ReportedBy: pranav dot bhandarkar at gmail dot com
GCC target triplet: arm-none-eabi


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=32306

[Bug tree-optimization/32306] Bad Code generation ( Tree optimization )

[pranav dot bhandarkar at gmail dot com]

------- Comment #1 from pranav dot bhandarkar at gmail dot com  2007-06-12 14:48 -------
Created an attachment (id=13686)
 --> (http://gcc.gnu.org/bugzilla/attachment.cgi?id=13686&action=view)
Tes


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=32306

[Bug tree-optimization/32306] Bad Code generation ( Tree optimization )

[pranav dot bhandarkar at gmail dot com]

------- Comment #3 from pranav dot bhandarkar at gmail dot com  2007-06-12 14:50 -------
Created an attachment (id=13688)
 --> (http://gcc.gnu.org/bugzilla/attachment.cgi?id=13688&action=view)
Code Generated by 4.3


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=32306

[Bug tree-optimization/32306] Bad Code generation ( Tree optimization )

[pranav dot bhandarkar at gmail dot com]

------- Comment #2 from pranav dot bhandarkar at gmail dot com  2007-06-12 14:50 -------
Created an attachment (id=13687)
 --> (http://gcc.gnu.org/bugzilla/attachment.cgi?id=13687&action=view)
Code Generated by 4.1


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=32306

[Bug tree-optimization/32306] [4.2/4.3 Regression] Bad Code generation ( Tree optimization )

[rguenth at gcc dot gnu dot org]

------- Comment #4 from rguenth at gcc dot gnu dot org  2007-06-12 15:06 -------
Try to narrow it down to sth shorter.  (Looks like a jump-threading issue)


-- 

rguenth at gcc dot gnu dot org changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|UNCONFIRMED                 |NEW
     Ever Confirmed|0                           |1
 GCC target triplet|arm-none-eabi               |
           Keywords|                            |missed-optimization
      Known to work|                            |4.1.2
   Last reconfirmed|0000-00-00 00:00:00         |2007-06-12 15:06:52
               date|                            |
            Summary|Bad Code generation ( Tree  |[4.2/4.3 Regression] Bad
                   |optimization )              |Code generation ( Tree
                   |                            |optimization )
   Target Milestone|---                         |4.2.1


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=32306

[Bug tree-optimization/32306] [4.2/4.3 Regression] Bad Code generation ( Tree optimization )

[pranav dot bhandarkar at gmail dot com]

------- Comment #5 from pranav dot bhandarkar at gmail dot com  2007-06-12 21:10 -------
Created an attachment (id=13694)
 --> (http://gcc.gnu.org/bugzilla/attachment.cgi?id=13694&action=view)
A smaller Testcase that displays the said behaviour

Reduced the testcase. Reducing to less than b1 thru b6 results in the compiler
being able to combine the if conditions at the tree level. Therefore couldnt
reduce it to less than b6. array elements written have been reduced to 4.


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=32306

[Bug tree-optimization/32306] [4.2/4.3 Regression] Bad Code generation ( Tree optimization )

[pranav dot bhandarkar at gmail dot com]

------- Comment #6 from pranav dot bhandarkar at gmail dot com  2007-06-12 21:14 -------
dom, in 4.1 is able to combine the if conditions unlike 4.3.


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=32306

[Bug tree-optimization/32306] [4.2/4.3 Regression] DOM chooses bad jump threading targets.

[rguenth at gcc dot gnu dot org]

------- Comment #7 from rguenth at gcc dot gnu dot org  2007-06-12 21:57 -------
The difference is that we iterated jump threading in DOM in 4.1 but do so no
longer.  On the mainline each dom and vrp pass figures more jump threading
opportunities - just not enough.  With 4.1 the third and last DOM pass doesn't
find any more.


-- 

rguenth at gcc dot gnu dot org changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
            Summary|[4.2/4.3 Regression] Bad    |[4.2/4.3 Regression] DOM
                   |Code generation ( Tree      |chooses bad jump threading
                   |optimization )              |targets.


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=32306

[Bug tree-optimization/32306] [4.2/4.3 Regression] DOM jump threading no longer iterates

[pinskia at gcc dot gnu dot org]

------- Comment #8 from pinskia at gcc dot gnu dot org  2007-06-12 22:01 -------
http://gcc.gnu.org/ml/gcc-patches/2006-02/msg00586.html


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=32306

[Bug tree-optimization/32306] [4.2/4.3 Regression] DOM jump threading no longer iterates

[mmitchel at gcc dot gnu dot org]

-- 

mmitchel at gcc dot gnu dot org changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
           Priority|P3                          |P2


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=32306

[Bug tree-optimization/32306] [4.2/4.3 Regression] DOM jump threading no longer iterates

[mmitchel at gcc dot gnu dot org]

-- 

mmitchel at gcc dot gnu dot org changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
   Target Milestone|4.2.1                       |4.2.2


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=32306

[Bug tree-optimization/32306] [4.2/4.3 Regression] DOM jump threading no longer iterates

[mmitchel at gcc dot gnu dot org]

------- Comment #9 from mmitchel at gcc dot gnu dot org  2007-10-09 19:21 -------
Change target milestone to 4.2.3, as 4.2.2 has been released.


-- 

mmitchel at gcc dot gnu dot org changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
   Target Milestone|4.2.2                       |4.2.3


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=32306

[Bug tree-optimization/32306] [4.2/4.3 Regression] DOM jump threading no longer iterates

[steven at gcc dot gnu dot org]

------- Comment #10 from steven at gcc dot gnu dot org  2008-01-09 13:49 -------
This is a code generation difference due to a design choice.  IMHO this should
not be a P2 regression.


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=32306

[Bug tree-optimization/32306] [4.2/4.3 Regression] DOM jump threading no longer iterates

[jsm28 at gcc dot gnu dot org]

------- Comment #11 from jsm28 at gcc dot gnu dot org  2008-02-01 16:54 -------
4.2.3 is being released now, changing milestones of open bugs to 4.2.4.


-- 

jsm28 at gcc dot gnu dot org changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
   Target Milestone|4.2.3                       |4.2.4


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=32306

[Bug tree-optimization/32306] [4.2/4.3/4.4 Regression] DOM jump threading no longer iterates

[jsm28 at gcc dot gnu dot org]

------- Comment #12 from jsm28 at gcc dot gnu dot org  2008-05-19 20:23 -------
4.2.4 is being released, changing milestones to 4.2.5.


-- 

jsm28 at gcc dot gnu dot org changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
   Target Milestone|4.2.4                       |4.2.5


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=32306

[Bug tree-optimization/32306] [4.2/4.3/4.4 Regression] redundant && || not eliminated

[bonzini at gnu dot org]

------- Comment #13 from bonzini at gnu dot org  2008-11-20 08:48 -------
I agree with Steven that the bug title does not make sense.  It is the same as
complaining that IRA has a regression because it disables regmove.

OTOH, this *is* a regression and the bug should stay open.  For example, it
could be fixed by doing some of the tree optimizations with && not lowered to
jumps (just shooting).


-- 

bonzini at gnu dot org changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |bonzini at gnu dot org
            Summary|[4.2/4.3/4.4 Regression] DOM|[4.2/4.3/4.4 Regression]
                   |jump threading no longer    |redundant && || not
                   |iterates                    |eliminated


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=32306

[Bug tree-optimization/32306] [4.2/4.3/4.4 Regression] redundant && || not eliminated

[ramana at icerasemi dot com]

------- Comment #14 from ramana at icerasemi dot com  2009-01-15 10:35 -------
Redo CCs


-- 

ramana at icerasemi dot com changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |ramana dot r at gmail dot
                   |                            |com


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=32306

[Bug tree-optimization/32306] [4.3/4.4/4.5 Regression] redundant && || not eliminated

[jsm28 at gcc dot gnu dot org]

------- Comment #15 from jsm28 at gcc dot gnu dot org  2009-03-31 20:10 -------
Closing 4.2 branch.


-- 

jsm28 at gcc dot gnu dot org changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
            Summary|[4.2/4.3/4.4/4.5 Regression]|[4.3/4.4/4.5 Regression]
                   |redundant && || not         |redundant && || not
                   |eliminated                  |eliminated
   Target Milestone|4.2.5                       |4.3.4


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=32306

[Bug tree-optimization/32306] [4.3/4.4/4.5 Regression] redundant && || not eliminated

[rguenth at gcc dot gnu dot org]

------- Comment #16 from rguenth at gcc dot gnu dot org  2009-08-04 12:28 -------
GCC 4.3.4 is being released, adjusting target milestone.


-- 

rguenth at gcc dot gnu dot org changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
   Target Milestone|4.3.4                       |4.3.5


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=32306

[Bug tree-optimization/32306] [4.3/4.4/4.5/4.6 Regression] redundant && || not eliminated

[rguenth at gcc dot gnu dot org]

------- Comment #17 from rguenth at gcc dot gnu dot org  2010-05-22 18:11 -------
GCC 4.3.5 is being released, adjusting target milestone.


-- 

rguenth at gcc dot gnu dot org changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
   Target Milestone|4.3.5                       |4.3.6


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=32306