Disable GNAT encodings by default

Given the latest work in the compiler and debugger, we no longer need to use
most GNAT-specific encodings in the debug info generated for an Ada program,
so the attached patch disables them, except with -fgnat-encodings=all.

gcc/
	* dwarf2out.c (add_data_member_location_attribute): Use GNAT
	encodings only when -fgnat-encodings=all is specified.
	(add_bound_info): Likewise.
	(add_byte_size_attribute): Likewise.
	(gen_member_die): Likewise.

diff --git a/gcc/dwarf2out.c b/gcc/dwarf2out.c
index b91a9b5abaac7bb6fbfea82572c7c0a1cf08f5fd..4bcd3313feec53d85e603f8947cc186ba620daab 100644 (file)
--- a/gcc/dwarf2out.c
+++ b/gcc/dwarf2out.c
@@ -19915,22 +19915,23 @@ add_data_member_location_attribute (dw_die_ref die,
     {
       loc_descr = field_byte_offset (decl, ctx, &offset);
 
-      /* If loc_descr is available then we know the field offset is dynamic.
-        However, GDB does not handle dynamic field offsets very well at the
-        moment.  */
-      if (loc_descr != NULL && gnat_encodings != DWARF_GNAT_ENCODINGS_MINIMAL)
+      if (!loc_descr)
+       ;
+
+      /* If loc_descr is available, then we know the offset is dynamic.  */
+      else if (gnat_encodings == DWARF_GNAT_ENCODINGS_ALL)
        {
          loc_descr = NULL;
          offset = 0;
        }
 
-      /* Data member location evalutation starts with the base address on the
+      /* Data member location evaluation starts with the base address on the
         stack.  Compute the field offset and add it to this base address.  */
-      else if (loc_descr != NULL)
+      else
        add_loc_descr (&loc_descr, new_loc_descr (DW_OP_plus, 0, 0));
     }
 
-  if (! loc_descr)
+  if (!loc_descr)
     {
       /* While DW_AT_data_bit_offset has been added already in DWARF4,
         e.g. GDB only added support to it in November 2016.  For DWARF5
@@ -21389,12 +21390,9 @@ add_bound_info (dw_die_ref subrange_die, enum dwarf_attribute bound_attr,
        /* FALLTHRU */
 
       default:
-       /* Because of the complex interaction there can be with other GNAT
-          encodings, GDB isn't ready yet to handle proper DWARF description
-          for self-referencial subrange bounds: let GNAT encodings do the
-          magic in such a case.  */
+       /* Let GNAT encodings do the magic for self-referential bounds.  */
        if (is_ada ()
-           && gnat_encodings != DWARF_GNAT_ENCODINGS_MINIMAL
+           && gnat_encodings == DWARF_GNAT_ENCODINGS_ALL
            && contains_placeholder_p (bound))
          return;
 
@@ -21566,7 +21564,7 @@ add_byte_size_attribute (dw_die_ref die, tree tree_node)
   /* Support for dynamically-sized objects was introduced in DWARF3.  */
   else if (TYPE_P (tree_node)
           && (dwarf_version >= 3 || !dwarf_strict)
-          && gnat_encodings == DWARF_GNAT_ENCODINGS_MINIMAL)
+          && gnat_encodings != DWARF_GNAT_ENCODINGS_ALL)
     {
       struct loc_descr_context ctx = {
        const_cast<tree> (tree_node),   /* context_type */
@@ -25629,11 +25627,11 @@ gen_member_die (tree type, dw_die_ref context_die)
            splice_child_die (context_die, child);
        }
 
-      /* Do not generate standard DWARF for variant parts if we are generating
-        the corresponding GNAT encodings: DIEs generated for both would
-        conflict in our mappings.  */
+      /* Do not generate DWARF for variant parts if we are generating the
+        corresponding GNAT encodings: DIEs generated for the two schemes
+        would conflict in our mappings.  */
       else if (is_variant_part (member)
-              && gnat_encodings == DWARF_GNAT_ENCODINGS_MINIMAL)
+              && gnat_encodings != DWARF_GNAT_ENCODINGS_ALL)
        {
          vlr_ctx.variant_part_offset = byte_position (member);
          gen_variant_part (member, &vlr_ctx, context_die);