Create xml from target descriptions

Add a print_xml_feature visitor class which turns a
target description into xml. Both gdb and gdbserver can do this.

gdb/
	* common/tdesc.c (print_xml_feature::visit_pre): Add xml parsing.
	(print_xml_feature::visit_post): Likewise.
	(print_xml_feature::visit): Likewise.
	* common/tdesc.h (tdesc_get_features_xml): Use const tdesc.
	(print_xml_feature): Add new class.
	* regformats/regdat.sh: Null xmltarget on feature targets.
	* target-descriptions.c (struct target_desc): Add xmltarget.
	(maintenance_check_tdesc_xml_convert): Add unittest function.
	(tdesc_get_features_xml): Add function to get xml.
	(maintenance_check_xml_descriptions): Test xml generation.
	* xml-tdesc.c (string_read_description_xml): Add function.
	* xml-tdesc.h (string_read_description_xml): Add declaration.

gdbserver/
	* gdb/gdbserver/server.c (get_features_xml): Remove cast.
	* tdesc.c (void target_desc::accept): Fill in function.
	(tdesc_get_features_xml): Remove old xml creation.
	(print_xml_feature::visit_pre): Add xml vistor.
	* tdesc.h (struct target_desc): Make xmltarget mutable.
	(tdesc_get_features_xml): Remove declaration.

1 files changed, 6 insertions, 8 deletions

diff --git a/gdb/gdbserver/tdesc.h b/gdb/gdbserver/tdesc.h
index 197fb59..61a3e4e 100644
--- a/gdb/gdbserver/tdesc.h
+++ b/gdb/gdbserver/tdesc.h
@@ -27,7 +27,7 @@
 /* A target description.  Inherit from tdesc_feature so that target_desc
    can be used as tdesc_feature.  */
 
-struct target_desc
+struct target_desc : tdesc_element
 {
   /* A vector of elements of register definitions that
      describe the inferior's register set.  */
@@ -49,9 +49,9 @@ struct target_desc
      verbatim XML code (prefixed with a '@') or else the name of the
      actual XML file to be used in place of "target.xml".
 
-     It can be NULL, then, its content is got from the following three
-     fields features, arch, and osabi in tdesc_get_features_xml.  */
-  const char *xmltarget = NULL;
+     If NULL then its content will be generated by parsing the target
+     description into xml.  */
+  mutable const char *xmltarget = NULL;
 
   /* The value of <architecture> element in the XML, replying GDB.  */
   const char *arch = NULL;
@@ -73,6 +73,8 @@ public:
     return !(*this == other);
   }
 #endif
+
+  void accept (tdesc_element_visitor &v) const override;
 };
 
 /* Copy target description SRC to DEST.  */
@@ -89,8 +91,4 @@ void init_target_desc (struct target_desc *tdesc);
 
 const struct target_desc *current_target_desc (void);
 
-#ifndef IN_PROCESS_AGENT
-const char *tdesc_get_features_xml (struct target_desc *tdesc);
-#endif
-
 #endif /* TDESC_H */