Remove dwarf2_per_cu_data::dwarf2_per_objfile

Nothing references this field anymore, remove it.

gdb/ChangeLog:

	* dwarf2/read.h (struct dwarf2_per_cu_data):
	<dwarf2_per_objfile>: Remove.
	* dwarf2/read.c (create_cu_from_index_list): Don't assign
	dwarf2_per_objfile.
	(create_signatured_type_table_from_index): Likewise.
	(create_signatured_type_table_from_debug_names): Likewise.
	(create_debug_type_hash_table): Likewise.
	(fill_in_sig_entry_from_dwo_entry): Likewise.
	(create_type_unit_group): Likewise.
	(read_comp_units_from_section): Likewise.
	(create_cus_hash_table): Likewise.

gdb/dwarf2/read.c

@@ -2499,7 +2499,6 @@ create_cu_from_index_list (struct dwarf2_per_objfile *dwarf2_per_objfile,
   dwarf2_per_cu_data *the_cu = dwarf2_per_objfile->per_bfd->allocate_per_cu ();
   the_cu->sect_off = sect_off;
   the_cu->length = length;
-  the_cu->dwarf2_per_objfile = dwarf2_per_objfile;
   the_cu->section = section;
   the_cu->v.quick = OBSTACK_ZALLOC (&dwarf2_per_objfile->per_bfd->obstack,
 				    struct dwarf2_per_cu_quick_data);
@@ -2591,7 +2590,6 @@ create_signatured_type_table_from_index
       sig_type->per_cu.is_debug_types = 1;
       sig_type->per_cu.section = section;
       sig_type->per_cu.sect_off = sect_off;
-      sig_type->per_cu.dwarf2_per_objfile = dwarf2_per_objfile;
       sig_type->per_cu.v.quick
 	= OBSTACK_ZALLOC (&dwarf2_per_objfile->per_bfd->obstack,
 			  struct dwarf2_per_cu_quick_data);
@@ -2647,7 +2645,6 @@ create_signatured_type_table_from_debug_names
       sig_type->per_cu.is_debug_types = 1;
       sig_type->per_cu.section = section;
       sig_type->per_cu.sect_off = sect_off;
-      sig_type->per_cu.dwarf2_per_objfile = dwarf2_per_objfile;
       sig_type->per_cu.v.quick
 	= OBSTACK_ZALLOC (&dwarf2_per_objfile->per_bfd->obstack,
 			  struct dwarf2_per_cu_quick_data);
@@ -6299,7 +6296,6 @@ create_debug_type_hash_table (struct dwarf2_per_objfile *dwarf2_per_objfile,
 	  sig_type = dwarf2_per_objfile->per_bfd->allocate_signatured_type ();
 	  sig_type->signature = header.signature;
 	  sig_type->type_offset_in_tu = header.type_cu_offset_in_tu;
-	  sig_type->per_cu.dwarf2_per_objfile = dwarf2_per_objfile;
 	  sig_type->per_cu.is_debug_types = 1;
 	  sig_type->per_cu.section = section;
 	  sig_type->per_cu.sect_off = sect_off;
@@ -6465,7 +6461,6 @@ fill_in_sig_entry_from_dwo_entry (struct dwarf2_per_objfile *dwarf2_per_objfile,
   sig_entry->per_cu.sect_off = dwo_entry->sect_off;
   sig_entry->per_cu.length = dwo_entry->length;
   sig_entry->per_cu.reading_dwo_directly = 1;
-  sig_entry->per_cu.dwarf2_per_objfile = dwarf2_per_objfile;
   sig_entry->per_cu.per_bfd = per_bfd;
   sig_entry->type_offset_in_tu = dwo_entry->type_offset_in_tu;
   sig_entry->dwo_unit = dwo_entry;
@@ -7281,7 +7276,6 @@ create_type_unit_group (struct dwarf2_cu *cu, sect_offset line_offset_struct)
   tu_group = OBSTACK_ZALLOC (&dwarf2_per_objfile->per_bfd->obstack,
 			     struct type_unit_group);
   per_cu = &tu_group->per_cu;
-  per_cu->dwarf2_per_objfile = dwarf2_per_objfile;
   per_cu->per_bfd = per_bfd;
 
   if (per_bfd->using_index)
@@ -8031,7 +8025,6 @@ read_comp_units_from_section (struct dwarf2_per_objfile *dwarf2_per_objfile,
       this_cu->sect_off = sect_off;
       this_cu->length = cu_header.length + cu_header.initial_length_size;
       this_cu->is_dwz = is_dwz;
-      this_cu->dwarf2_per_objfile = dwarf2_per_objfile;
       this_cu->section = section;
 
       dwarf2_per_objfile->per_bfd->all_comp_units.push_back (this_cu);
@@ -11311,7 +11304,6 @@ create_cus_hash_table (struct dwarf2_per_objfile *dwarf2_per_objfile,
       sect_offset sect_off = (sect_offset) (info_ptr - section.buffer);
 
       memset (&per_cu, 0, sizeof (per_cu));
-      per_cu.dwarf2_per_objfile = dwarf2_per_objfile;
       per_cu.per_bfd = per_bfd;
       per_cu.is_debug_types = 0;
       per_cu.sect_off = sect_offset (info_ptr - section.buffer);
@@ -14373,8 +14365,7 @@ handle_data_member_location (struct die_info *die, struct dwarf2_cu *cu,
 	    SET_FIELD_BITPOS (*field, offset * bits_per_byte);
 	  else
 	    {
-	      struct objfile *objfile
-		= cu->per_cu->dwarf2_per_objfile->objfile;
+	      struct objfile *objfile = cu->per_objfile->objfile;
 	      struct dwarf2_locexpr_baton *dlbaton
 		= XOBNEW (&objfile->objfile_obstack,
 			  struct dwarf2_locexpr_baton);
@@ -14820,7 +14811,7 @@ add_variant_property (struct field_info *fip, struct type *type,
   for (int i = 0; i < fip->fields.size (); ++i)
     offset_map[fip->fields[i].offset] = i;
 
-  struct objfile *objfile = cu->per_cu->dwarf2_per_objfile->objfile;
+  struct objfile *objfile = cu->per_objfile->objfile;
   gdb::array_view<variant_part> parts
     = create_variant_parts (&objfile->objfile_obstack, offset_map, fip,
 			    fip->variant_parts);
@@ -15545,7 +15536,7 @@ handle_variant_part (struct die_info *die, struct type *type,
       complaint (_("nested DW_TAG_variant_part seen "
 		   "- DIE at %s [in module %s]"),
 		 sect_offset_str (die->sect_off),
-		 objfile_name (cu->per_cu->dwarf2_per_objfile->objfile));
+		 objfile_name (cu->per_objfile->objfile));
       return;
     }
   else
@@ -15577,7 +15568,7 @@ handle_variant_part (struct die_info *die, struct type *type,
       complaint (_("DW_AT_discr does not have DIE reference form"
 		   " - DIE at %s [in module %s]"),
 		 sect_offset_str (die->sect_off),
-		 objfile_name (cu->per_cu->dwarf2_per_objfile->objfile));
+		 objfile_name (cu->per_objfile->objfile));
     }
 
   for (die_info *child_die = die->child;

gdb/dwarf2/read.h

@@ -419,9 +419,6 @@ struct dwarf2_per_cu_data
   /* The language of this CU.  */
   enum language lang;
 
-  /* The corresponding dwarf2_per_objfile.  */
-  struct dwarf2_per_objfile *dwarf2_per_objfile;
-
   /* Backlink to the owner of this.  */
   dwarf2_per_bfd *per_bfd;