[Bug tree-optimization/23297] immediate uses hosed after CCP

[Bug tree-optimization/23297] immediate uses hosed after CCP

[rguenth at gcc dot gnu dot org]

------- Comment #5 from rguenth at gcc dot gnu dot org  2005-10-16 10:41 -------
This was "fixed" on improved-aliasing-branch.  It cannot happen on mainline,
closing as fixed (w/o a target milestone).


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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=23297

[Bug tree-optimization/23297] immediate uses hosed after CCP

[rguenth at gcc dot gnu dot org]

------- Additional Comments From rguenth at gcc dot gnu dot org  2005-08-11 08:32 -------
Created an attachment (id=9470)
 --> (http://gcc.gnu.org/bugzilla/attachment.cgi?id=9470&action=view)
patch fixing the problem

This is the patch which fixes the problem.  Whether this situation can happen
with an unpatched mainline is unclear to me.  What to do with bugreports like
this as well ;)  Leaving UNCONFIRMED.

-- 
           What    |Removed                     |Added
----------------------------------------------------------------------------
         AssignedTo|unassigned at gcc dot gnu   |rguenth at gcc dot gnu dot
                   |dot org                     |org
             Status|UNCONFIRMED                 |ASSIGNED


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=23297

[Bug tree-optimization/23297] immediate uses hosed after CCP

[rguenth at gcc dot gnu dot org]

------- Additional Comments From rguenth at gcc dot gnu dot org  2005-08-11 08:30 -------
Now that you describe what is going wrong, I remember having this problem earlier.
And even a fix.  Ugh.  Sorry for bothering you.

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http://gcc.gnu.org/bugzilla/show_bug.cgi?id=23297

[Bug tree-optimization/23297] immediate uses hosed after CCP

[amacleod at redhat dot com]

------- Additional Comments From amacleod at redhat dot com  2005-08-10 15:55 -------
A quick glance shows that parse_ssa_operands() does not expect to receive a tree
that looks like:

b.c[d_5].i

get_expr_operands is called on this, and  when processing COMPONENT_REF:
       ref = okay_component_ref_for_subvars (expr, &offset, &size);
        if (ref)
          {
            subvar_t svars = get_subvars_for_var (ref);
            subvar_t sv;
            for (sv = svars; sv; sv = sv->next)
              {
                bool exact;
                if (overlap_subvar (offset, size, sv, &exact))
                  {
                    int subvar_flags = flags;
                    if (!exact)
                      subvar_flags &= ~opf_kill_def;
                    add_stmt_operand (&sv->var, s_ann, subvar_flags);
                  }
              }
          }
        else
          get_expr_operands (stmt, &TREE_OPERAND (expr, 0),
                             flags & ~opf_kill_def);

if okay_component_ref_for_subvars() is true (which it is in this case), we never
call get_expr_operands on the rest of the expression, which contains the array
ref. Therefore the operand builder never sees the use of d_5 in the expression,
and chaos breaks out as you have observed.

I dont pay much attention to the semantics of gimple, but either b.c[d_5].i is
not valid gimple, or you have to be prepared to explore the component ref deeper
in get_expr_operands.  I would have expected to trip over this earlier if it was
valid, but what do I know :-)

 

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http://gcc.gnu.org/bugzilla/show_bug.cgi?id=23297

[Bug tree-optimization/23297] immediate uses hosed after CCP

[rguenth at gcc dot gnu dot org]

-- 
           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |amacleod at redhat dot com


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=23297

[Bug tree-optimization/23297] immediate uses hosed after CCP

[rguenth at gcc dot gnu dot org]

------- Additional Comments From rguenth at gcc dot gnu dot org  2005-08-09 15:49 -------
Created an attachment (id=9455)
 --> (http://gcc.gnu.org/bugzilla/attachment.cgi?id=9455&action=view)
patch to enable salias for structures which contain arrays

required patch to reproduce the ICE.

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http://gcc.gnu.org/bugzilla/show_bug.cgi?id=23297