[PATCH 3/6] register_dummy_frame_dtor: Permit multiple dtors

[Jan Kratochvil <jan.kratochvil@redhat.com>]

Hi,

later patch needs two independent destructors for the same dummy_frame.
Therefore the registrar has been extended to an arbitrary number of
destructors.


Jan


gdb/ChangeLog
2015-05-08  Jan Kratochvil  <jan.kratochvil@redhat.com>

	* dummy-frame.c (struct dummy_frame_dtor_list): New.
	(struct dummy_frame): Replace dtor and dtor_data by dtor_list.
	(remove_dummy_frame): Process dtor_list.
	(pop_dummy_frame): Process dtor_list.
	(register_dummy_frame_dtor): Maintain dtor_list.
	(find_dummy_frame_dtor): Handle dtor_list.
	* dummy-frame.h (register_dummy_frame_dtor, find_dummy_frame_dtor):
	Update comments.
---
 gdb/dummy-frame.c |   60 +++++++++++++++++++++++++++++++++++++++++------------
 gdb/dummy-frame.h |    9 ++++----
 2 files changed, 51 insertions(+), 18 deletions(-)

diff --git a/gdb/dummy-frame.c b/gdb/dummy-frame.c
index 6c4fb4c..f1d3de8 100644
--- a/gdb/dummy-frame.c
+++ b/gdb/dummy-frame.c
@@ -49,6 +49,20 @@ dummy_frame_id_eq (struct dummy_frame_id *id1,
   return frame_id_eq (id1->id, id2->id) && ptid_equal (id1->ptid, id2->ptid);
 }
 
+/* List of dummy_frame destructors.  */
+
+struct dummy_frame_dtor_list
+{
+  /* Next element in the list or NULL if this is the last element.  */
+  struct dummy_frame_dtor_list *next;
+
+  /* If non-NULL, a destructor that is run when this dummy frame is freed.  */
+  dummy_frame_dtor_ftype *dtor;
+
+  /* Arbitrary data that is passed to DTOR.  */
+  void *dtor_data;
+};
+
 /* Dummy frame.  This saves the processor state just prior to setting
    up the inferior function call.  Older targets save the registers
    on the target stack (but that really slows down function calls).  */
@@ -63,11 +77,9 @@ struct dummy_frame
   /* 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 freed.  */
-  dummy_frame_dtor_ftype *dtor;
-
-  /* Arbitrary data that is passed to DTOR.  */
-  void *dtor_data;
+  /* First element of destructors list or NULL if there are no
+     destructors registered for this dummy_frame.  */
+  struct dummy_frame_dtor_list *dtor_list;
 };
 
 static struct dummy_frame *dummy_frame_stack = NULL;
@@ -96,8 +108,14 @@ remove_dummy_frame (struct dummy_frame **dummy_ptr)
 {
   struct dummy_frame *dummy = *dummy_ptr;
 
-  if (dummy->dtor != NULL)
-    dummy->dtor (dummy->dtor_data, 0);
+  while (dummy->dtor_list != NULL)
+    {
+      struct dummy_frame_dtor_list *list = dummy->dtor_list;
+
+      dummy->dtor_list = list->next;
+      list->dtor (list->dtor_data, 0);
+      xfree (list);
+    }
 
   *dummy_ptr = dummy->next;
   discard_infcall_suspend_state (dummy->caller_state);
@@ -138,8 +156,14 @@ pop_dummy_frame (struct dummy_frame **dummy_ptr)
 
   gdb_assert (ptid_equal (dummy->id.ptid, inferior_ptid));
 
-  if (dummy->dtor != NULL)
-    dummy->dtor (dummy->dtor_data, 1);
+  while (dummy->dtor_list != NULL)
+    {
+      struct dummy_frame_dtor_list *list = dummy->dtor_list;
+
+      dummy->dtor_list = list->next;
+      list->dtor (list->dtor_data, 1);
+      xfree (list);
+    }
 
   restore_infcall_suspend_state (dummy->caller_state);
 
@@ -212,13 +236,16 @@ register_dummy_frame_dtor (struct frame_id dummy_id, ptid_t ptid,
 {
   struct dummy_frame_id id = { dummy_id, ptid };
   struct dummy_frame **dp, *d;
+  struct dummy_frame_dtor_list *list;
 
   dp = lookup_dummy_frame (&id);
   gdb_assert (dp != NULL);
   d = *dp;
-  gdb_assert (d->dtor == NULL);
-  d->dtor = dtor;
-  d->dtor_data = dtor_data;
+  list = xmalloc (sizeof (*list));
+  list->next = d->dtor_list;
+  d->dtor_list = list;
+  list->dtor = dtor;
+  list->dtor_data = dtor_data;
 }
 
 /* See dummy-frame.h.  */
@@ -229,8 +256,13 @@ 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;
+    {
+      struct dummy_frame_dtor_list *list;
+
+      for (list = d->dtor_list; list != NULL; list = list->next)
+	if (list->dtor == dtor && list->dtor_data == dtor_data)
+	  return 1;
+    }
   return 0;
 }
 
diff --git a/gdb/dummy-frame.h b/gdb/dummy-frame.h
index c156b81..9b5aff5 100644
--- a/gdb/dummy-frame.h
+++ b/gdb/dummy-frame.h
@@ -59,14 +59,15 @@ extern const struct frame_unwind dummy_frame_unwind;
 typedef void (dummy_frame_dtor_ftype) (void *data, int registers_valid);
 
 /* Call DTOR with DTOR_DATA when DUMMY_ID frame of thread PTID gets discarded.
-   Dummy frame with DUMMY_ID must exist.  There must be no other call of
-   register_dummy_frame_dtor for that dummy frame.  */
+   Dummy frame with DUMMY_ID must exist.  Multiple destructors may be
+   registered, they will be called in the reverse order of registrations
+   (LIFO).  */
 extern void register_dummy_frame_dtor (struct frame_id dummy_id, ptid_t ptid,
 				       dummy_frame_dtor_ftype *dtor,
 				       void *dtor_data);
 
-/* Return 1 if there exists dummy frame with registered DTOR and DTOR_DATA.
-   Return 0 otherwise.  */
+/* Return 1 if there exists any dummy frame with any of its registered
+   destructors equal to both DTOR and DTOR_DATA.  Return 0 otherwise.  */
 extern int find_dummy_frame_dtor (dummy_frame_dtor_ftype *dtor,
 				  void *dtor_data);