[Bug c++/46806] -O3 implies 0 <= 8 <= 7

[rguenth at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=46806

Richard Guenther <rguenth at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
           Keywords|                            |wrong-code
             Status|UNCONFIRMED                 |ASSIGNED
   Last reconfirmed|                            |2010.12.05 22:13:20
         AssignedTo|unassigned at gcc dot       |rguenth at gcc dot gnu.org
                   |gnu.org                     |
     Ever Confirmed|0                           |1

--- Comment #9 from Richard Guenther <rguenth at gcc dot gnu.org> 2010-12-05 
22:13:20 UTC ---
Heh, you are seeing a dup of https://bugzilla.novell.com/show_bug.cgi?id=623386
(sorry, not public).

Which is a copyrename issue and hard to trigger (I couldn't trigger it
with anything other than 4.3).  4.3 testcase:

typedef enum { zero = 0, one = 1, two = 2, ENUM_MAX = 3 } my_enum;
my_enum e;
extern "C" void abort (void);
int __attribute__((noinline)) foo() { return 10; }
int main()
{
  int r;
  r = foo();
  if ((r < 0) || (r >= ENUM_MAX))
    return 0;
  e = (my_enum)r;
  abort ();
}

And I have a patch (maybe I even posted it just didn't apply it),
the problem is we are coalescing a variable of enum type with one
of integer type.

Index: gcc/tree-ssa-copyrename.c
===================================================================
*** gcc/tree-ssa-copyrename.c   (revision 163549)
--- gcc/tree-ssa-copyrename.c   (working copy)
*************** copy_rename_partition_coalesce (var_map
*** 239,245 ****
      }

    /* Don't coalesce if the two variables aren't type compatible.  */
!   if (!types_compatible_p (TREE_TYPE (root1), TREE_TYPE (root2)))
      {
        if (debug)
        fprintf (debug, " : Incompatible types.  No coalesce.\n");
--- 239,246 ----
      }

    /* Don't coalesce if the two variables aren't type compatible.  */
!   if (TYPE_MAIN_VARIANT (TREE_TYPE (root1))
!       != TYPE_MAIN_VARIANT (TREE_TYPE (root2)))
      {
        if (debug)
        fprintf (debug, " : Incompatible types.  No coalesce.\n");


Seems I did post an earlier version for comments:
http://gcc.gnu.org/ml/gcc-patches/2010-08/msg01873.html