Add -funconstrained-commons to work around PR/69368 (and others) in SPEC2006

gcc/:

        * common.opt (funconstrained-commons, flag_unconstrained_commons): New.
        * tree.c (array_at_struct_end_p): Do not limit to size of decl for
        DECL_COMMONS if flag_unconstrained_commons is set.
        * tree-dfa.c (get_ref_base_and_extent): Likewise.
        * doc/invoke.texi (Optimize Options): Add -funconstrained-commons.
        (funconstrained-commons): Document.

gcc/testsuite:

	* gfortran.dg/unconstrained_commons.f: New.


Co-Authored-By: Jakub Jelinek <jakub@redhat.com>

From-SVN: r234106

1 files changed, 4 insertions, 2 deletions

diff --git a/gcc/tree.c b/gcc/tree.c
index b8333d4..7d0cb03 100644
--- a/gcc/tree.c
+++ b/gcc/tree.c
@@ -12952,8 +12952,10 @@ array_at_struct_end_p (tree ref)
     }
 
   /* If the reference is based on a declared entity, the size of the array
-     is constrained by its given domain.  */
-  if (DECL_P (ref))
+     is constrained by its given domain.  (Do not trust commons PR/69368).  */
+  if (DECL_P (ref)
+      && !(flag_unconstrained_commons
+	   && TREE_CODE (ref) == VAR_DECL && DECL_COMMON (ref)))
     return false;
 
   return true;