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.

4 files changed, 33 insertions, 37 deletions

diff --git a/gdb/gdbserver/ChangeLog b/gdb/gdbserver/ChangeLog
index 96dc83c..43fa090 100644
--- a/gdb/gdbserver/ChangeLog
+++ b/gdb/gdbserver/ChangeLog
@@ -1,5 +1,14 @@
 2018-04-18  Alan Hayward  <alan.hayward@arm.com>
 
+	* 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.
+
+2018-04-18  Alan Hayward  <alan.hayward@arm.com>
+
 	* tdesc.c (tdesc_architecture_name): Add new function.
 	(tdesc_osabi_name): Likewise.
 	(tdesc_get_features_xml): Use new functions.
diff --git a/gdb/gdbserver/server.c b/gdb/gdbserver/server.c
index 64c72bd..5027df5 100644
--- a/gdb/gdbserver/server.c
+++ b/gdb/gdbserver/server.c
@@ -940,7 +940,7 @@ get_features_xml (const char *annex)
 
   if (strcmp (annex, "target.xml") == 0)
     {
-      const char *ret = tdesc_get_features_xml ((target_desc*) desc);
+      const char *ret = tdesc_get_features_xml (desc);
 
       if (*ret == '@')
 	return ret + 1;
diff --git a/gdb/gdbserver/tdesc.c b/gdb/gdbserver/tdesc.c
index 7603a90..126589f 100644
--- a/gdb/gdbserver/tdesc.c
+++ b/gdb/gdbserver/tdesc.c
@@ -47,6 +47,18 @@ bool target_desc::operator== (const target_desc &other) const
 
 #endif
 
+void target_desc::accept (tdesc_element_visitor &v) const
+{
+#ifndef IN_PROCESS_AGENT
+  v.visit_pre (this);
+
+  for (const tdesc_feature_up &feature : features)
+    feature->accept (v);
+
+  v.visit_post (this);
+#endif
+}
+
 void
 init_target_desc (struct target_desc *tdesc)
 {
@@ -138,11 +150,10 @@ set_tdesc_osabi (struct target_desc *target_desc, const char *name)
   target_desc->osabi = xstrdup (name);
 }
 
-/* Return a string which is of XML format, including XML target
-   description to be sent to GDB.  */
+/* See common/tdesc.h.  */
 
 const char *
-tdesc_get_features_xml (target_desc *tdesc)
+tdesc_get_features_xml (const target_desc *tdesc)
 {
   /* Either .xmltarget or .features is not NULL.  */
   gdb_assert (tdesc->xmltarget != NULL
@@ -151,31 +162,9 @@ tdesc_get_features_xml (target_desc *tdesc)
 
   if (tdesc->xmltarget == NULL)
     {
-      std::string buffer ("@<?xml version=\"1.0\"?>");
-
-      buffer += "<!DOCTYPE target SYSTEM \"gdb-target.dtd\">";
-      buffer += "<target>";
-      buffer += "<architecture>";
-      buffer += tdesc_architecture_name (tdesc);
-      buffer += "</architecture>";
-
-      const char *osabi = tdesc_osabi_name (tdesc);
-      if (osabi != nullptr)
-	{
-	  buffer += "<osabi>";
-	  buffer += osabi;
-	  buffer += "</osabi>";
-	}
-
-      for (const tdesc_feature_up &feature : tdesc->features)
-	{
-	  buffer += "<xi:include href=\"";
-	  buffer += feature->name;
-	  buffer += "\"/>";
-	}
-
-      buffer += "</target>";
-
+      std::string buffer ("@");
+      print_xml_feature v (&buffer);
+      tdesc->accept (v);
       tdesc->xmltarget = xstrdup (buffer.c_str ());
     }
 
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 */