A couple of va_gc_atomic tweaks

The only current user of va_gc_atomic is Ada's:

    vec<Entity_Id, va_gc_atomic>

It uses the generic gt_pch_nx routines (with gt_pch_nx being the
“note pointers” hooks), such as:

    template<typename T, typename A>
    void
    gt_pch_nx (vec<T, A, vl_embed> *v)
    {
      extern void gt_pch_nx (T &);
      for (unsigned i = 0; i < v->length (); i++)
	gt_pch_nx ((*v)[i]);
    }

It then defines gt_pch_nx routines for Entity_Id &.

The problem is that if we wanted to take the same approach for
an array of unsigned ints, we'd need to define:

    inline void gt_pch_nx (unsigned int &) { }

which would then be ambiguous with:

    inline void gt_pch_nx (unsigned int) { }

The point of va_gc_atomic is that the elements don't need to be GCed,
and so we have:

    template<typename T>
    void
    gt_ggc_mx (vec<T, va_gc_atomic, vl_embed> *v ATTRIBUTE_UNUSED)
    {
      /* Nothing to do.  Vectors of atomic types wrt GC do not need to
	 be traversed.  */
    }

I think it's therefore reasonable to assume that no pointers will
need to be processed for PCH either.

The patch also relaxes the array_slice constructor for vec<T, va_gc> *
so that it handles all embedded vectors.

gcc/
	* vec.h (gt_pch_nx): Add overloads for va_gc_atomic.
	(array_slice): Relax va_gc constructor to handle all vectors
	with a vl_embed layout.

gcc/ada/
	* gcc-interface/decl.cc (gt_pch_nx): Remove overloads for Entity_Id.

1 files changed, 0 insertions, 11 deletions

diff --git a/gcc/ada/gcc-interface/decl.cc b/gcc/ada/gcc-interface/decl.cc
index 494b24e..ee913a0 100644
--- a/gcc/ada/gcc-interface/decl.cc
+++ b/gcc/ada/gcc-interface/decl.cc
@@ -163,17 +163,6 @@ struct GTY((for_user)) tree_entity_vec_map
   vec<Entity_Id, va_gc_atomic> *to;
 };
 
-void
-gt_pch_nx (Entity_Id &)
-{
-}
-
-void
-gt_pch_nx (Entity_Id *x, gt_pointer_operator op, void *cookie)
-{
-  op (x, NULL, cookie);
-}
-
 struct dummy_type_hasher : ggc_cache_ptr_hash<tree_entity_vec_map>
 {
   static inline hashval_t