[PATCH v2 05/14] add dummy frame destructor

[Tom Tromey <tromey at redhat dot com>]

From: Jan Kratochvil <jan.kratochvil@redhat.com>

The compiler code needed a hook into dummy frame destruction, so that
some state could be kept while the inferior call is made and then
destroyed when the inferior call finishes.

This patch adds an optional destructor to dummy frames and a new API
to access it.

2014-06-20  Jan Kratochvil  <jan.kratochvil@redhat.com>

	* dummy-frame.c (struct dummy_frame) <dtor, dtor_data>: New
	fields.
	(pop_dummy_frame): Call the destructor if it exists.
	(register_dummy_frame_dtor, find_dummy_frame_dtor): New
	functions.
	* dummy-frame.h (dummy_frame_dtor_ftype): New typedef.
	(register_dummy_frame_dtor, find_dummy_frame_dtor): Declare.
---
 gdb/ChangeLog     | 10 ++++++++++
 gdb/dummy-frame.c | 39 +++++++++++++++++++++++++++++++++++++++
 gdb/dummy-frame.h | 13 +++++++++++++
 3 files changed, 62 insertions(+)

diff --git a/gdb/dummy-frame.c b/gdb/dummy-frame.c
index 998ca93..b0608a9 100644
--- a/gdb/dummy-frame.c
+++ b/gdb/dummy-frame.c
@@ -43,6 +43,13 @@ struct dummy_frame
   struct frame_id id;
   /* The caller's state prior to the call.  */
   struct infcall_suspend_state *caller_state;
+
+  /* If non-NULL, a destructor that is run when this dummy frame is
+     popped.  */
+  void (*dtor) (void *data);
+
+  /* Arbitrary data that is passed to DTOR.  */
+  void *dtor_data;
 };
 
 static struct dummy_frame *dummy_frame_stack = NULL;
@@ -107,6 +114,9 @@ pop_dummy_frame (struct dummy_frame **dummy_ptr)
 {
   struct dummy_frame *dummy = *dummy_ptr;
 
+  if (dummy->dtor != NULL)
+    dummy->dtor (dummy->dtor_data);
+
   restore_infcall_suspend_state (dummy->caller_state);
 
   iterate_over_breakpoints (pop_dummy_frame_bpt, dummy);
@@ -171,6 +181,35 @@ dummy_frame_discard (struct frame_id dummy_id)
     remove_dummy_frame (dp);
 }
 
+/* See dummy-frame.h.  */
+
+void
+register_dummy_frame_dtor (struct frame_id dummy_id,
+			   dummy_frame_dtor_ftype *dtor, void *dtor_data)
+{
+  struct dummy_frame **dp, *d;
+
+  dp = lookup_dummy_frame (dummy_id);
+  gdb_assert (dp != NULL);
+  d = *dp;
+  gdb_assert (d->dtor == NULL);
+  d->dtor = dtor;
+  d->dtor_data = dtor_data;
+}
+
+/* See dummy-frame.h.  */
+
+int
+find_dummy_frame_dtor (dummy_frame_dtor_ftype *dtor, void *dtor_data)
+{
+  struct dummy_frame *d;
+
+  for (d = dummy_frame_stack; d != NULL; d = d->next)
+    if (d->dtor == dtor && d->dtor_data == dtor_data)
+      return 1;
+  return 0;
+}
+
 /* There may be stale dummy frames, perhaps left over from when an uncaught
    longjmp took us out of a function that was called by the debugger.  Clean
    them up at least once whenever we start a new inferior.  */
diff --git a/gdb/dummy-frame.h b/gdb/dummy-frame.h
index 6db312e..21e7fff 100644
--- a/gdb/dummy-frame.h
+++ b/gdb/dummy-frame.h
@@ -59,4 +59,17 @@ extern void dummy_frame_discard (struct frame_id dummy_id);
 
 extern const struct frame_unwind dummy_frame_unwind;
 
+/* Call DTOR with DTOR_DATA when DUMMY_ID frame gets discarded.
+   Dummy frame with DUMMY_ID must exist.  There must be no other call of
+   register_dummy_frame_dtor for that dummy frame.  */
+typedef void (dummy_frame_dtor_ftype) (void *data);
+extern void register_dummy_frame_dtor (struct frame_id dummy_id,
+				       dummy_frame_dtor_ftype *dtor,
+				       void *dtor_data);
+
+/* Return 1 if there exists dummy frame with registered DTOR and DTOR_DATA.
+   Return 0 otherwise.  */
+extern int find_dummy_frame_dtor (dummy_frame_dtor_ftype *dtor,
+				  void *dtor_data);
+
 #endif /* !defined (DUMMY_FRAME_H)  */
-- 
1.9.3