reggroups: Add reggroup_gdbarch_new, reggroup_find for dynamic reggroups

Traditionally reggroups have been created via reggroup_new() during
initialization code and never freed.  Now, if we want to initialize
reggroups dynamically (i.e. in target description) we should be able to
free them.  Create this function reggroup_gdbarch_new() which will
allocate the reggroup memory onto the passed gdbarch obstack.

Also creating reggroup_find() as a utility to find a gdbarch registered
reggroup object by name.

gdb/ChangeLog:

yyyy-mm-dd  Stafford Horne  <shorne@gmail.com>

	* reggroups.c (reggroup_gdbarch_new): New function.
	(reggroup_find): New function.
	* reggroups.h (reggroup_gdbarch_new): New function.
	(reggroup_find): New function.

3 files changed, 44 insertions, 0 deletions

diff --git a/gdb/ChangeLog b/gdb/ChangeLog
index 79f5357..e3ef0fe 100644
--- a/gdb/ChangeLog
+++ b/gdb/ChangeLog
@@ -1,5 +1,12 @@
 2017-12-27  Stafford Horne  <shorne@gmail.com>
 
+	* reggroups.c (reggroup_gdbarch_new): New function.
+	(reggroup_find): New function.
+	* reggroups.h (reggroup_gdbarch_new): New function.
+	(reggroup_find): New function.
+
+2017-12-27  Stafford Horne  <shorne@gmail.com>
+
 	* reggroups.c (reggroups_init): Change to depend only on
 	obstack rather than gdbarch.
 	(reggroup_add): Remove logic for forcing premature init.
diff --git a/gdb/reggroups.c b/gdb/reggroups.c
index 5d5e33f..61657e6 100644
--- a/gdb/reggroups.c
+++ b/gdb/reggroups.c
@@ -46,6 +46,20 @@ reggroup_new (const char *name, enum reggroup_type type)
   return group;
 }
 
+/* See reggroups.h.  */
+
+struct reggroup *
+reggroup_gdbarch_new (struct gdbarch *gdbarch, const char *name,
+		      enum reggroup_type type)
+{
+  struct reggroup *group = GDBARCH_OBSTACK_ZALLOC (gdbarch,
+						   struct reggroup);
+
+  group->name = gdbarch_obstack_strdup (gdbarch, name);
+  group->type = type;
+  return group;
+}
+
 /* Register group attributes.  */
 
 const char *
@@ -201,6 +215,23 @@ default_register_reggroup_p (struct gdbarch *gdbarch, int regnum,
   return 0;   
 }
 
+/* See reggroups.h.  */
+
+reggroup *
+reggroup_find (struct gdbarch *gdbarch, const char *name)
+{
+  struct reggroup *group;
+
+  for (group = reggroup_next (gdbarch, NULL);
+       group != NULL;
+       group = reggroup_next (gdbarch, group))
+    {
+      if (strcmp (name, reggroup_name (group)) == 0)
+	return group;
+    }
+  return NULL;
+}
+
 /* Dump out a table of register groups for the current architecture.  */
 
 static void
diff --git a/gdb/reggroups.h b/gdb/reggroups.h
index 18fc1bf..8af77c3 100644
--- a/gdb/reggroups.h
+++ b/gdb/reggroups.h
@@ -41,6 +41,10 @@ extern struct reggroup *const restore_reggroup;
 /* Create a new local register group.  */
 extern struct reggroup *reggroup_new (const char *name,
 				      enum reggroup_type type);
+/* Create a new register group allocated onto the gdbarch obstack.  */
+extern struct reggroup *reggroup_gdbarch_new (struct gdbarch *gdbarch,
+					      const char *name,
+					      enum reggroup_type type);
 
 /* Add a register group (with attribute values) to the pre-defined list.  */
 extern void reggroup_add (struct gdbarch *gdbarch, struct reggroup *group);
@@ -57,6 +61,8 @@ extern struct reggroup *reggroup_next (struct gdbarch *gdbarch,
 				       struct reggroup *last);
 extern struct reggroup *reggroup_prev (struct gdbarch *gdbarch,
 				       struct reggroup *curr);
+/* Find a reggroup by name.  */
+extern reggroup *reggroup_find (struct gdbarch *gdbarch, const char *name);
 
 /* Is REGNUM a member of REGGROUP?  */
 extern int default_register_reggroup_p (struct gdbarch *gdbarch, int regnum,