Support for DW_OP_addrx and DW_FORM_addrx tags

DW_OP_addrx is the new name of DW_OP_GNU_addr_index, and DW_FORM_addrx
is the name of DW_FORM_addr_index in the Dwarf 5 standard. This is a small
step towards supporting Dwarf 5 in gdb.

Note: I could not find any tests specifically for *_GNU_addr_index, and
I did not add any new tests, please advise.

gdb/ChangeLog

@@ -1,3 +1,24 @@
+
+2019-03-27  Ali Tamur  <tamur@google.com>
+
+	* dwarf2-frame.c(dwarf_expr_executor::get_addr_index): Update comment
+	* dwarf2expr.c(dwarf_expr_context::execute_stack_op): Add DW_OP_addrx
+	* dwarf2expr.h(dwarf_expr_context::offset): Update comment
+	(dwarf_expr_context::get_addr_index): Likewise
+	* dwarf2loc.c(dwarf_evaluate_loc_desc::get_addr_index): Likewise
+	(symbol_needs_eval_context::get_addr_index): Likewise
+	(disassemble_dwarf_expression): Add DW_OP_addrx
+	* dwarf2read.c(attr_value_as_address): Add DW_FORM_addrx
+	(read_cutu_die_from_dwo): Update comment
+	(skip_one_die): Add DW_FORM_addrx
+	(read_attribute_value): Likewise
+	(var_decode_location): Add DW_OP_addrx
+	(dwarf2_const_value_attr): Add DW_FORM_addrx
+	(dump_die_shallow): Likewise
+	(dwarf2_fetch_constant_bytes): Likewise
+	(decode_locdesc): Add DW_OP_addrx
+	(skip_form_bytes): Add DW_FORM_addrx
+
 2019-04-22  Ali Tamur  <tamur@google.com>
 
 	* MAINTAINERS (Write After Approval): Add self.

gdb/dwarf2-frame.c

@@ -290,7 +290,7 @@ class dwarf_expr_executor : public dwarf_expr_context
 
   CORE_ADDR get_addr_index (unsigned int index) override
   {
-    invalid ("DW_OP_GNU_addr_index");
+    invalid ("DW_OP_addrx or DW_OP_GNU_addr_index");
   }
 
  private:

gdb/dwarf2expr.c

@@ -634,6 +634,7 @@ dwarf_expr_context::execute_stack_op (const gdb_byte *op_ptr,
 	  result_val = value_from_ulongest (address_type, result);
 	  break;
 
+	case DW_OP_addrx:
 	case DW_OP_GNU_addr_index:
 	  op_ptr = safe_read_uleb128 (op_ptr, op_end, &uoffset);
 	  result = this->get_addr_index (uoffset);

gdb/dwarf2expr.h

@@ -139,7 +139,8 @@ struct dwarf_expr_context
      context and operations depending on DW_FORM_ref_addr are not allowed.  */
   int ref_addr_size;
 
-  /* Offset used to relocate DW_OP_addr and DW_OP_GNU_addr_index arguments.  */
+  /* Offset used to relocate DW_OP_addr, DW_OP_addrx, and
+     DW_OP_GNU_addr_index arguments.  */
   CORE_ADDR offset;
 
   /* The current depth of dwarf expression recursion, via DW_OP_call*,
@@ -242,7 +243,7 @@ struct dwarf_expr_context
 					   union call_site_parameter_u kind_u,
 					   int deref_size) = 0;
 
-  /* Return the address indexed by DW_OP_GNU_addr_index.
+  /* Return the address indexed by DW_OP_addrx or DW_OP_GNU_addr_index.
      This can throw an exception if the index is out of range.  */
   virtual CORE_ADDR get_addr_index (unsigned int index) = 0;
 

gdb/dwarf2loc.c

@@ -636,7 +636,7 @@ class dwarf_evaluate_loc_desc : public dwarf_expr_context
   }
 
   /* Callback function for dwarf2_evaluate_loc_desc.
-     Fetch the address indexed by DW_OP_GNU_addr_index.  */
+     Fetch the address indexed by DW_OP_addrx or DW_OP_GNU_addr_index.  */
 
   CORE_ADDR get_addr_index (unsigned int index) override
   {
@@ -2642,7 +2642,7 @@ class symbol_needs_eval_context : public dwarf_expr_context
     push_address (0, 0);
   }
 
-  /* DW_OP_GNU_addr_index doesn't require a frame.  */
+  /* DW_OP_addrx and DW_OP_GNU_addr_index doesn't require a frame.  */
 
    CORE_ADDR get_addr_index (unsigned int index) override
    {
@@ -4086,6 +4086,7 @@ disassemble_dwarf_expression (struct ui_file *stream,
 	  fprintf_filtered (stream, " offset %s", phex_nz (ul, 4));
 	  break;
 
+	case DW_OP_addrx:
 	case DW_OP_GNU_addr_index:
 	  data = safe_read_uleb128 (data, end, &ul);
 	  ul = dwarf2_read_addr_index (per_cu, ul);

gdb/dwarf2read.c

@@ -2134,7 +2134,8 @@ attr_value_as_address (struct attribute *attr)
 {
   CORE_ADDR addr;
 
-  if (attr->form != DW_FORM_addr && attr->form != DW_FORM_GNU_addr_index)
+  if (attr->form != DW_FORM_addr && attr->form != DW_FORM_addrx
+      && attr->form != DW_FORM_GNU_addr_index)
     {
       /* Aside from a few clearly defined exceptions, attributes that
 	 contain an address must always be in DW_FORM_addr form.
@@ -7229,7 +7230,8 @@ read_cutu_die_from_dwo (struct dwarf2_per_cu_data *this_cu,
       comp_dir = dwarf2_attr (stub_comp_unit_die, DW_AT_comp_dir, cu);
 
       /* There should be a DW_AT_addr_base attribute here (if needed).
-	 We need the value before we can process DW_FORM_GNU_addr_index.  */
+	 We need the value before we can process DW_FORM_GNU_addr_index
+         or DW_FORM_addrx.  */
       cu->addr_base = 0;
       attr = dwarf2_attr (stub_comp_unit_die, DW_AT_GNU_addr_base, cu);
       if (attr)
@@ -9366,6 +9368,7 @@ skip_one_die (const struct die_reader_specs *reader, const gdb_byte *info_ptr,
 	case DW_FORM_block4:
 	  info_ptr += 4 + read_4_bytes (abfd, info_ptr);
 	  break;
+	case DW_FORM_addrx:
 	case DW_FORM_sdata:
 	case DW_FORM_udata:
 	case DW_FORM_ref_udata:
@@ -19279,6 +19282,7 @@ read_attribute_value (const struct die_reader_specs *reader,
     case DW_FORM_implicit_const:
       DW_SND (attr) = implicit_const;
       break;
+    case DW_FORM_addrx:
     case DW_FORM_GNU_addr_index:
       if (reader->dwo_file == NULL)
 	{
@@ -21360,13 +21364,14 @@ var_decode_location (struct attribute *attr, struct symbol *sym,
 
   /* Handle one degenerate form of location expression specially, to
      preserve GDB's previous behavior when section offsets are
-     specified.  If this is just a DW_OP_addr or DW_OP_GNU_addr_index
+     specified.  If this is just a DW_OP_addr, DW_OP_addrx, or
-     then mark this symbol as LOC_STATIC.  */
+     DW_OP_GNU_addr_index then mark this symbol as LOC_STATIC.  */
 
   if (attr_form_is_block (attr)
       && ((DW_BLOCK (attr)->data[0] == DW_OP_addr
 	   && DW_BLOCK (attr)->size == 1 + cu_header->addr_size)
-	  || (DW_BLOCK (attr)->data[0] == DW_OP_GNU_addr_index
+	  || ((DW_BLOCK (attr)->data[0] == DW_OP_GNU_addr_index
+               || DW_BLOCK (attr)->data[0] == DW_OP_addrx)
 	      && (DW_BLOCK (attr)->size
 		  == 1 + leb128_size (&DW_BLOCK (attr)->data[1])))))
     {
@@ -21863,6 +21868,7 @@ dwarf2_const_value_attr (const struct attribute *attr, struct type *type,
   switch (attr->form)
     {
     case DW_FORM_addr:
+    case DW_FORM_addrx:
     case DW_FORM_GNU_addr_index:
       {
 	gdb_byte *data;
@@ -22839,6 +22845,7 @@ dump_die_shallow (struct ui_file *f, int indent, struct die_info *die)
       switch (die->attrs[i].form)
 	{
 	case DW_FORM_addr:
+	case DW_FORM_addrx:
 	case DW_FORM_GNU_addr_index:
 	  fprintf_unfiltered (f, "address: ");
 	  fputs_filtered (hex_string (DW_ADDR (&die->attrs[i])), f);
@@ -23308,6 +23315,7 @@ dwarf2_fetch_constant_bytes (sect_offset sect_off,
   switch (attr->form)
     {
     case DW_FORM_addr:
+    case DW_FORM_addrx:
     case DW_FORM_GNU_addr_index:
       {
 	gdb_byte *tem;
@@ -23912,6 +23920,7 @@ decode_locdesc (struct dwarf_block *blk, struct dwarf2_cu *cu)
 	case DW_OP_GNU_uninit:
 	  break;
 
+	case DW_OP_addrx:
 	case DW_OP_GNU_addr_index:
 	case DW_OP_GNU_const_index:
 	  stack[++stacki] = read_addr_index_from_leb128 (cu, &data[i],
@@ -24282,6 +24291,7 @@ skip_form_bytes (bfd *abfd, const gdb_byte *bytes, const gdb_byte *buffer_end,
       bytes += 4 + read_4_bytes (abfd, bytes);
       break;
 
+    case DW_FORM_addrx:
     case DW_FORM_sdata:
     case DW_FORM_udata:
     case DW_FORM_GNU_addr_index: