[Bug tree-optimization/22415] New: ICE in coalesce_abnormal_edges

[Bug tree-optimization/22415] New: ICE in coalesce_abnormal_edges

[jakub at redhat dot com]

struct C
{
  int a;
  int *b;
  int *c1 (int x) { return new int[sizeof (int) * x]; }
  void c2 (int *x, int *y, int z)
  {
    for (int i = 0; i < z; i++)
      y[i] = x[i];
  }
  C (int x = 0) : a (x)
  {
    if (a)
      {
        b = c1 (a);
        for (int i = 0; i < a; i++)
          b[i] = 0;
      }
  }
  C (const C & x) : a (x.a)
  {
    if (a)
      {
        b = c1 (a);
        c2 (x.b, b, a);
      }
  }
  ~C (void) { if (a) delete b; }
  int &operator [] (int x)
  {
    if (a == 0 && x == 0)
      {
        a = 1;
        b = c1 (1);
        b[0] = 0;
      }
    else
      {
        C e (*this);
        a = x + 1;
        b = c1 (a);
        c2 (e.b, b, e.a);
        for (int i = e.a; i < a; i++)
          b[i] = 0;
      }
    return b[x];
  }
  C & operator << (int x) { (*this)[a] = x; return *this; }
};

int
bar (void)
{
  C a;
  int f = 1;
  while (f != -1)
    {
      f = 0;
      a << 1;
    }
  return 0;
}

ICEs at -O2 in coalesce_abnormal_edges.  The bug is not present on HEAD
and 3.4.x compiles it just fine as well.

-- 
           Summary: ICE in coalesce_abnormal_edges
           Product: gcc
           Version: 4.0.2
            Status: UNCONFIRMED
          Severity: normal
          Priority: P2
         Component: tree-optimization
        AssignedTo: unassigned at gcc dot gnu dot org
        ReportedBy: jakub at redhat dot com
                CC: gcc-bugs at gcc dot gnu dot org


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=22415

[Bug tree-optimization/22415] [4.0 Regression] ICE in coalesce_abnormal_edges

[pinskia at gcc dot gnu dot org]

------- Additional Comments From pinskia at gcc dot gnu dot org  2005-07-11 19:56 -------
Confirmed, this might be a latent bug on the mainline.

-- 
           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|UNCONFIRMED                 |NEW
     Ever Confirmed|                            |1
           Keywords|                            |ice-on-valid-code
      Known to fail|                            |4.0.0
      Known to work|                            |3.4.0
   Last reconfirmed|0000-00-00 00:00:00         |2005-07-11 19:56:04
               date|                            |
            Summary|ICE in                      |[4.0 Regression] ICE in
                   |coalesce_abnormal_edges     |coalesce_abnormal_edges
   Target Milestone|---                         |4.0.2


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=22415

[Bug tree-optimization/22415] [4.0 Regression] ICE in coalesce_abnormal_edges

[pinskia at gcc dot gnu dot org]

------- Additional Comments From pinskia at gcc dot gnu dot org  2005-07-11 20:12 -------
Hmm, the reason why we cannot reproduce it on the mainline is because SRA thinks the variable a 
cannot be SRA'd because we still take the address of the variable even though that statement is dead.

-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=22415

[Bug tree-optimization/22415] [4.0 Regression] ICE in coalesce_abnormal_edges

[pinskia at gcc dot gnu dot org]

------- Additional Comments From pinskia at gcc dot gnu dot org  2005-07-11 20:15 -------
I think adding another DCE pass right before SRA and we will be able to reproduce this on the mainline 
also.

Also note turning off PRE "fixes" the ICE.  It might be PRE moving a statement causing the conflict.

-- 
           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |dberlin at gcc dot gnu dot
                   |                            |org


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=22415

[Bug tree-optimization/22415] [4.0 Regression] ICE in coalesce_abnormal_edges

[pinskia at gcc dot gnu dot org]

------- Additional Comments From pinskia at gcc dot gnu dot org  2005-07-13 12:54 -------
(In reply to comment #3)
> I think adding another DCE pass right before SRA and we will be able to reproduce this on the 
mainline 
> also.

Nope, adding both DCE and MAY_ALIAS right before SRA does not cause this to happen on the 
mainline.

-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=22415

[Bug tree-optimization/22415] [4.0 Regression] ICE in coalesce_abnormal_edges

[dberlin at gcc dot gnu dot org]

------- Additional Comments From dberlin at gcc dot gnu dot org  2005-07-13 13:08 -------
PRE checks the SSA_NAME_OCCURS_IN_ABNORMAL_PHI flag everywhere, and we shouldn't
really be doing anything over abnormal edges.
(see compute_avail and compute_antic).



-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=22415

[Bug tree-optimization/22415] [4.0 Regression] ICE in coalesce_abnormal_edges

[mmitchel at gcc dot gnu dot org]

-- 
           What    |Removed                     |Added
----------------------------------------------------------------------------
   Target Milestone|4.0.2                       |4.0.3


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=22415