[Bug tree-optimization/23329] New: hack in may_propagate_copy should be able to removed

["pinskia at gcc dot gnu dot org" <gcc-bugzilla at gcc dot gnu dot org>]

The hack in may_propagate_copy:
  /* FIXME.  GIMPLE is allowing pointer assignments and comparisons of
     pointers that have different alias sets.  This means that these
     pointers will have different memory tags associated to them.

     If we allow copy propagation in these cases, statements de-referencing
     the new pointer will now have a reference to a different memory tag
     with potentially incorrect SSA information.

     This was showing up in libjava/java/util/zip/ZipFile.java with code
     like:

        struct java.io.BufferedInputStream *T.660;
        struct java.io.BufferedInputStream *T.647;
        struct java.io.InputStream *is;
        struct java.io.InputStream *is.662;
        [ ... ]
        T.660 = T.647;
        is = T.660;     <-- This ought to be type-casted
        is.662 = is;

     Also, f/name.c exposed a similar problem with a COND_EXPR predicate
     that was causing DOM to generate and equivalence with two pointers of
     alias-incompatible types:

        struct _ffename_space *n;
        struct _ffename *ns; 
        [ ... ]
        if (n == ns)
          goto lab;
        ...
        lab:
        return n;
   
     I think that GIMPLE should emit the appropriate type-casts.  For the
     time being, blocking copy-propagation in these cases is the safe thing
     to do.  */

Should be able to removed now as both the DOM and java front-ends issues have been fixed now.

PR 22368 referenced the bugs which were filed so this hack could be removed.  Even though PR 22368 
references more than what is needed to remove this hack, I am going to mark this new bug as 
depending on that bug.

-- 
           Summary: hack in may_propagate_copy should be able to removed
           Product: gcc
           Version: 4.1.0
            Status: UNCONFIRMED
          Severity: minor
          Priority: P2
         Component: tree-optimization
        AssignedTo: unassigned at gcc dot gnu dot org
        ReportedBy: pinskia at gcc dot gnu dot org
                CC: dnovillo at gcc dot gnu dot org,gcc-bugs at gcc dot gnu
                    dot org
 BugsThisDependsOn: 22368


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=23329