[Bug fortran/88364] New: [9 Regression] Wrong-code due to CLOBBER

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

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=88364

            Bug ID: 88364
           Summary: [9 Regression] Wrong-code due to CLOBBER
           Product: gcc
           Version: 9.0
            Status: UNCONFIRMED
          Keywords: ice-on-valid-code
          Severity: normal
          Priority: P3
         Component: fortran
          Assignee: unassigned at gcc dot gnu.org
          Reporter: jakub at gcc dot gnu.org
                CC: anlauf at gmx dot de, jakub at gcc dot gnu.org, rguenth at gcc dot gnu.org,
                    unassigned at gcc dot gnu.org
        Depends on: 88304
  Target Milestone: ---
            Target: x86_64-pc-linux-gnu

+++ This bug was initially created as a clone of Bug #88304 +++

As mentioned in https://gcc.gnu.org/bugzilla/show_bug.cgi?id=88304#c9
I believe the CLOBBERs added in:
      else if (add_clobber)
        {
          tree clobber;
          tree var;
          /* FIXME: This fails if var is passed by reference, see PR
             41453.  */
          var = expr->symtree->n.sym->backend_decl;
          clobber = build_clobber (TREE_TYPE (var));
          gfc_add_modify (&se->pre, var, clobber);
        }
are sometimes IMHO inappropriate, in particular if we are passing by reference
only a part of some variable (when the size of the expression that actually
should be clobbered is smaller than the whole backend_decl).


Referenced Bugs:

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=88304
[Bug 88304] [9 Regression] ICE in use_pointer_in_frame, at tree-nested.c:267