[Bug c++/41728] New: error: SSA name in freelist but still referenced

[Bug c++/41728] New: error: SSA name in freelist but still referenced

[dcb314 at hotmail dot com]

I just tried to compile some C++ code
with the gcc 4.5 mainline snapshot 20091015
and the compiler said

In function 'int s244(defs*)':
cq.cc:562:1: error: SSA name in freelist but still referenced
D.9231_46
cc1plus: note: in statement
lrc_55 = D.9231_46 != D.8194_53;

cq.cc:562:1: internal compiler error: Segmentation fault
Please submit a full bug report,
with preprocessed source if appropriate.
See <http://gcc.gnu.org/bugs.html> for instructions.

Preprocessed C++ source attached. Flags -O3 -ffast-math required.


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           Summary: error: SSA name in freelist but still referenced
           Product: gcc
           Version: 4.5.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: c++
        AssignedTo: unassigned at gcc dot gnu dot org
        ReportedBy: dcb314 at hotmail dot com
  GCC host triplet: x86_64-suse-linux


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=41728

[Bug c++/41728] error: SSA name in freelist but still referenced

[dcb314 at hotmail dot com]

------- Comment #1 from dcb314 at hotmail dot com  2009-10-16 10:08 -------
Created an attachment (id=18808)
 --> (http://gcc.gnu.org/bugzilla/attachment.cgi?id=18808&action=view)
C++ source code


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http://gcc.gnu.org/bugzilla/show_bug.cgi?id=41728

[Bug c++/41728] error: SSA name in freelist but still referenced

[rguenth at gcc dot gnu dot org]

------- Comment #2 from rguenth at gcc dot gnu dot org  2009-10-16 11:32 -------
Confirmed.  Reducing.


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rguenth at gcc dot gnu dot org changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|UNCONFIRMED                 |NEW
     Ever Confirmed|0                           |1
   Last reconfirmed|0000-00-00 00:00:00         |2009-10-16 11:32:16
               date|                            |
            Summary|error: SSA name in freelist |error: SSA name in freelist
                   |but still referenced        |but still referenced


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=41728

[Bug tree-optimization/41728] [4.5 Regression] error: SSA name in freelist but still referenced

[rguenth at gcc dot gnu dot org]

------- Comment #3 from rguenth at gcc dot gnu dot org  2009-10-16 11:39 -------
int a[8];
int s244(void)
{
  int lrc, j;
  lrc = 0;
  for (j=0; j<7; j++)
    if(a[j] != a[j+1])
      lrc = 1;
  if (lrc != 0)
    return 0;
  return 1;
}

-O3 required.  After 126t.cddce2.


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rguenth at gcc dot gnu dot org changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
          Component|c++                         |tree-optimization
            Summary|error: SSA name in freelist |[4.5 Regression] error: SSA
                   |but still referenced        |name in freelist but still
                   |                            |referenced
   Target Milestone|---                         |4.5.0


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=41728

[Bug tree-optimization/41728] [4.5 Regression] error: SSA name in freelist but still referenced

[rguenth at gcc dot gnu dot org]

------- Comment #4 from rguenth at gcc dot gnu dot org  2009-10-16 12:09 -------
After DOM2 we have

<bb 2>:
  D.2725_21 = a[0];
  D.2706_26 = D.2725_21;
  D.2708_28 = a[1];
  a_I_lsm0.4_29 = D.2708_28;
  lrc_30 = D.2725_21 != D.2708_28;
...

but

D.2725_21 : --> single use.
D.2706_26 = D.2725_21;

DOM changes

  lrc_30 = [cond_expr] D.2706_26 == D.2708_28 ? 0 : 1;

to

  lrc_30 = D.2725_21 != D.2708_28;

and likely misses an update_stmt() (again).


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http://gcc.gnu.org/bugzilla/show_bug.cgi?id=41728

[Bug tree-optimization/41728] [4.5 Regression] error: SSA name in freelist but still referenced

[rguenth at gcc dot gnu dot org]

------- Comment #5 from rguenth at gcc dot gnu dot org  2009-10-16 12:18 -------
I have a patch.


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rguenth at gcc dot gnu dot org changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
         AssignedTo|unassigned at gcc dot gnu   |rguenth at gcc dot gnu dot
                   |dot org                     |org
             Status|NEW                         |ASSIGNED
   Last reconfirmed|2009-10-16 11:32:16         |2009-10-16 12:18:21
               date|                            |


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=41728

[Bug tree-optimization/41728] [4.5 Regression] error: SSA name in freelist but still referenced

[rguenth at gcc dot gnu dot org]

------- Comment #6 from rguenth at gcc dot gnu dot org  2009-10-16 16:57 -------
Fixed.


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rguenth at gcc dot gnu dot org changed:

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


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=41728

[Bug tree-optimization/41728] [4.5 Regression] error: SSA name in freelist but still referenced

[rguenth at gcc dot gnu dot org]

------- Comment #7 from rguenth at gcc dot gnu dot org  2009-10-16 16:57 -------
Subject: Bug 41728

Author: rguenth
Date: Fri Oct 16 16:57:31 2009
New Revision: 152910

URL: http://gcc.gnu.org/viewcvs?root=gcc&view=rev&rev=152910
Log:
2009-10-16  Richard Guenther  <rguenther@suse.de>

        PR tree-optimization/41728
        * tree-ssa-dom.c (optimize_stmt): Mark the stmt modified
        if fold_stmt did anything.

        * gcc.c-torture/compile/pr41728.c: New testcase.

Added:
    trunk/gcc/testsuite/gcc.c-torture/compile/pr41728.c
Modified:
    trunk/gcc/ChangeLog
    trunk/gcc/testsuite/ChangeLog
    trunk/gcc/tree-ssa-dom.c


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http://gcc.gnu.org/bugzilla/show_bug.cgi?id=41728

[Bug tree-optimization/41728] [4.5 Regression] error: SSA name in freelist but still referenced

[hjl at gcc dot gnu dot org]

------- Comment #8 from hjl at gcc dot gnu dot org  2009-10-21 16:05 -------
Subject: Bug 41728

Author: hjl
Date: Wed Oct 21 16:05:31 2009
New Revision: 153063

URL: http://gcc.gnu.org/viewcvs?root=gcc&view=rev&rev=153063
Log:
2009-10-21  H.J. Lu  <hongjiu.lu@intel.com>

        2009-10-16  Richard Guenther  <rguenther@suse.de>

        PR tree-optimization/41728
        * gcc.c-torture/compile/pr41728.c: New testcase.

        2009-10-15  Jakub Jelinek  <jakub@redhat.com>

        PR debug/41717
        * gcc.dg/debug/pr41717.c: New test.

Added:
    branches/gcc-4_4-branch/gcc/testsuite/gcc.c-torture/compile/pr41728.c
      - copied unchanged from r153062,
trunk/gcc/testsuite/gcc.c-torture/compile/pr41728.c
    branches/gcc-4_4-branch/gcc/testsuite/gcc.dg/debug/pr41717.c
      - copied unchanged from r153062,
trunk/gcc/testsuite/gcc.dg/debug/pr41717.c
Modified:
    branches/gcc-4_4-branch/gcc/testsuite/ChangeLog


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http://gcc.gnu.org/bugzilla/show_bug.cgi?id=41728