[PATCH 4/6] Simplify regcache_dup

[Yao Qi <qiyaoltc@gmail.com>]

regcache_dup, in fact, is to create a readonly regcache from a
non-readonly regcache.  This patch adds an assert that src is not
readonly.

gdb:

2017-04-25  Yao Qi  <yao.qi@linaro.org>

	* regcache.c (regcache_dup): Assert !src->readonly_p and
	call method save instead of regcache_cpy.
	* regcache.h (struct regcache): Make regcache_dup a friend.
---
 gdb/regcache.c | 3 ++-
 gdb/regcache.h | 3 +++
 2 files changed, 5 insertions(+), 1 deletion(-)

diff --git a/gdb/regcache.c b/gdb/regcache.c
index f4fcf65..28163c2 100644
--- a/gdb/regcache.c
+++ b/gdb/regcache.c
@@ -422,8 +422,9 @@ regcache_dup (struct regcache *src)
 {
   struct regcache *newbuf;
 
+  gdb_assert (!src->readonly_p);
   newbuf = regcache_xmalloc (src->get_arch (), get_regcache_aspace (src));
-  regcache_cpy (newbuf, src);
+  newbuf->save (do_cooked_read, src);
   return newbuf;
 }
 
diff --git a/gdb/regcache.h b/gdb/regcache.h
index 8794966..e6494a9 100644
--- a/gdb/regcache.h
+++ b/gdb/regcache.h
@@ -378,6 +378,9 @@ private:
 
   friend void
   regcache_cpy (struct regcache *dst, struct regcache *src);
+
+  friend struct regcache *
+  regcache_dup (struct regcache *src);
 };
 
 /* Copy/duplicate the contents of a register cache.  By default, the
-- 
1.9.1