[PATCH 5/7] Garbage collect dummy_frame_ctx_saver

[Pedro Alves <palves@redhat.com>]

Since the "finish" command and infcall's FSMs are now responsible for
saving the return value, the dummy_frame_ctx_saver is no longer needed
anywhere.

gdb/ChangeLog:
2015-08-12  Pedro Alves  <palves@redhat.com>

	* infcall.c (struct dummy_frame_context_saver): Delete.
	(dummy_frame_context_saver_free, dummy_frame_context_saver_dtor)
	(dummy_frame_context_saver_drop)
	(dummy_frame_context_saver_cleanup)
	(dummy_frame_context_saver_get_regs)
	(dummy_frame_context_saver_setup): Delete.
	* infcall.h (dummy_frame_context_saver_drop)
	(dummy_frame_context_saver_cleanup)
	(dummy_frame_context_saver_get_regs, dummy_frame_context_saver):
	Delete.
	(get_return_value): Remove 'ctx_saver' paremeter.  Adjust.
	* inferior.h (get_return_value): Remove 'ctx_saver' paremeter.
	* python/py-finishbreakpoint.c (bpfinishpy_pre_stop_hook): Adjust.
---
 gdb/infcall.c                    | 92 +---------------------------------------
 gdb/infcall.h                    |  9 ----
 gdb/infcmd.c                     | 19 +++------
 gdb/inferior.h                   |  6 +--
 gdb/python/py-finishbreakpoint.c |  5 +--
 5 files changed, 10 insertions(+), 121 deletions(-)

diff --git a/gdb/infcall.c b/gdb/infcall.c
index 5acdff0..e3df9f7 100644
--- a/gdb/infcall.c
+++ b/gdb/infcall.c
@@ -18,6 +18,7 @@
    along with this program.  If not, see <http://www.gnu.org/licenses/>.  */
 
 #include "defs.h"
+#include "infcall.h"
 #include "breakpoint.h"
 #include "tracepoint.h"
 #include "target.h"
@@ -30,7 +31,6 @@
 #include "objfiles.h"
 #include "gdbcmd.h"
 #include "command.h"
-#include "infcall.h"
 #include "dummy-frame.h"
 #include "ada-lang.h"
 #include "gdbthread.h"
@@ -661,96 +661,6 @@ call_function_by_hand (struct value *function, int nargs, struct value **args)
   return call_function_by_hand_dummy (function, nargs, args, NULL, NULL);
 }
 
-/* Data for dummy_frame_context_saver.  Structure can be freed only
-   after both dummy_frame_context_saver_dtor and
-   dummy_frame_context_saver_drop have been called for it.  */
-
-struct dummy_frame_context_saver
-{
-  /* Inferior registers fetched before associated dummy_frame got freed
-     and before any other destructors of associated dummy_frame got called.
-     It is initialized to NULL.  */
-  struct regcache *retbuf;
-
-  /* It is 1 if this dummy_frame_context_saver_drop has been already
-     called.  */
-  int drop_done;
-};
-
-/* Free struct dummy_frame_context_saver.  */
-
-static void
-dummy_frame_context_saver_free (struct dummy_frame_context_saver *saver)
-{
-  regcache_xfree (saver->retbuf);
-  xfree (saver);
-}
-
-/* Destructor for associated dummy_frame.  */
-
-static void
-dummy_frame_context_saver_dtor (void *data_voidp, int registers_valid)
-{
-  struct dummy_frame_context_saver *data = data_voidp;
-
-  gdb_assert (data->retbuf == NULL);
-
-  if (data->drop_done)
-    dummy_frame_context_saver_free (data);
-  else if (registers_valid)
-    data->retbuf = regcache_dup (get_current_regcache ());
-}
-
-/* Caller is no longer interested in this
-   struct dummy_frame_context_saver.  After its associated dummy_frame
-   gets freed struct dummy_frame_context_saver can be also freed.  */
-
-void
-dummy_frame_context_saver_drop (struct dummy_frame_context_saver *saver)
-{
-  saver->drop_done = 1;
-
-  if (!find_dummy_frame_dtor (dummy_frame_context_saver_dtor, saver))
-    dummy_frame_context_saver_free (saver);
-}
-
-/* Stub dummy_frame_context_saver_drop compatible with make_cleanup.  */
-
-void
-dummy_frame_context_saver_cleanup (void *data)
-{
-  struct dummy_frame_context_saver *saver = data;
-
-  dummy_frame_context_saver_drop (saver);
-}
-
-/* Fetch RETBUF field of possibly opaque DTOR_DATA.
-   RETBUF must not be NULL.  */
-
-struct regcache *
-dummy_frame_context_saver_get_regs (struct dummy_frame_context_saver *saver)
-{
-  gdb_assert (saver->retbuf != NULL);
-  return saver->retbuf;
-}
-
-/* Register provider of inferior registers at the time DUMMY_ID frame of
-   PTID gets freed (before inferior registers get restored to those
-   before dummy_frame).  */
-
-struct dummy_frame_context_saver *
-dummy_frame_context_saver_setup (struct frame_id dummy_id, ptid_t ptid)
-{
-  struct dummy_frame_context_saver *saver;
-
-  saver = xmalloc (sizeof (*saver));
-  saver->retbuf = NULL;
-  saver->drop_done = 0;
-  register_dummy_frame_dtor (dummy_id, inferior_ptid,
-			     dummy_frame_context_saver_dtor, saver);
-  return saver;
-}
-
 /* All this stuff with a dummy frame may seem unnecessarily complicated
    (why not just save registers in GDB?).  The purpose of pushing a dummy
    frame which looks just like a real frame is so that if you call a
diff --git a/gdb/infcall.h b/gdb/infcall.h
index 43b5f66..77c5101 100644
--- a/gdb/infcall.h
+++ b/gdb/infcall.h
@@ -50,13 +50,4 @@ extern struct value *
 			       dummy_frame_dtor_ftype *dummy_dtor,
 			       void *dummy_dtor_data);
 
-struct dummy_frame_context_saver;
-extern void dummy_frame_context_saver_drop
-  (struct dummy_frame_context_saver *data);
-extern void dummy_frame_context_saver_cleanup (void *data_voidp);
-extern struct regcache *dummy_frame_context_saver_get_regs
-  (struct dummy_frame_context_saver *saver);
-extern struct dummy_frame_context_saver *dummy_frame_context_saver_setup
-  (struct frame_id dummy_id, ptid_t ptid);
-
 #endif
diff --git a/gdb/infcmd.c b/gdb/infcmd.c
index e5d01ff..87b28a5 100644
--- a/gdb/infcmd.c
+++ b/gdb/infcmd.c
@@ -1588,22 +1588,15 @@ advance_command (char *arg, int from_tty)
    right after an inferior call has finished.  */
 
 struct value *
-get_return_value (struct value *function, struct type *value_type,
-		  struct dummy_frame_context_saver *ctx_saver)
+get_return_value (struct value *function, struct type *value_type)
 {
-  struct regcache *stop_regs = NULL;
+  struct regcache *stop_regs;
   struct gdbarch *gdbarch;
   struct value *value;
-  struct cleanup *cleanup = make_cleanup (null_cleanup, NULL);
+  struct cleanup *cleanup;
 
-  /* If registers were not saved, use the current registers.  */
-  if (ctx_saver != NULL)
-    stop_regs = dummy_frame_context_saver_get_regs (ctx_saver);
-  else
-    {
-      stop_regs = regcache_dup (get_current_regcache ());
-      make_cleanup_regcache_xfree (stop_regs);
-    }
+  stop_regs = regcache_dup (get_current_regcache ());
+  cleanup = make_cleanup_regcache_xfree (stop_regs);
 
   gdbarch = get_regcache_arch (stop_regs);
 
@@ -1803,7 +1796,7 @@ finish_command_fsm_should_stop (struct thread_fsm *self)
 	  struct value *func;
 
 	  func = read_var_value (f->function, get_current_frame ());
-	  rv->value = get_return_value (func, rv->type, NULL);
+	  rv->value = get_return_value (func, rv->type);
 	  rv->value_history_index = record_latest_value (rv->value);
 	}
     }
diff --git a/gdb/inferior.h b/gdb/inferior.h
index 48cba45..e09cb00 100644
--- a/gdb/inferior.h
+++ b/gdb/inferior.h
@@ -165,10 +165,8 @@ extern void detach_command (char *, int);
 
 extern void notice_new_inferior (ptid_t, int, int);
 
-struct dummy_frame_context_saver;
-extern struct value *get_return_value
-  (struct value *function, struct type *value_type,
-   struct dummy_frame_context_saver *ctx_saver);
+extern struct value *get_return_value (struct value *function,
+				       struct type *value_type);
 
 /* Prepare for execution command.  TARGET is the target that will run
    the command.  BACKGROUND determines whether this is a foreground
diff --git a/gdb/python/py-finishbreakpoint.c b/gdb/python/py-finishbreakpoint.c
index e543bb3..e1629b0 100644
--- a/gdb/python/py-finishbreakpoint.c
+++ b/gdb/python/py-finishbreakpoint.c
@@ -107,10 +107,7 @@ bpfinishpy_pre_stop_hook (struct gdbpy_breakpoint_object *bp_obj)
         value_object_to_value (self_finishbp->function_value);
       struct type *value_type =
         type_object_to_type (self_finishbp->return_type);
-
-      /* bpfinishpy_init cannot finish into DUMMY_FRAME (throws an error
-         in such case) so it is OK to always pass CTX_SAVER as NULL.  */
-      struct value *ret = get_return_value (function, value_type, NULL);
+      struct value *ret = get_return_value (function, value_type);
 
       if (ret)
         {
-- 
1.9.3