* frame.c (has_stack_frames): Make public.

	(get_prev_frame): Don't allow a NULL this_frame anymore.
	* frame.h (has_stack_frames): Declare.
	* varobj.c (find_frame_addr_in_frame_chain): Don't ever pass NULL
	to get_prev_frame, instead start at get_current_frame.
	(varobj_create): Check has_stack_frames before getting any frame;
	eliminate one usage of deprecated_safe_get_selected_frame.

4 files changed, 39 insertions, 53 deletions

diff --git a/gdb/ChangeLog b/gdb/ChangeLog
index 97f7044..94adead 100644
--- a/gdb/ChangeLog
+++ b/gdb/ChangeLog
@@ -1,3 +1,13 @@
+2009-02-05  Pedro Alves  <pedro@codesourcery.com>
+
+	* frame.c (has_stack_frames): Make public.
+	(get_prev_frame): Don't allow a NULL this_frame anymore.
+	* frame.h (has_stack_frames): Declare.
+	* varobj.c (find_frame_addr_in_frame_chain): Don't ever pass NULL
+	to get_prev_frame, instead start at get_current_frame.
+	(varobj_create): Check has_stack_frames before getting any frame;
+	eliminate one usage of deprecated_safe_get_selected_frame.
+
 2009-02-05  Tom Tromey  <tromey@redhat.com>
 	    Thiago Jung Bauermann  <bauerman@br.ibm.com>
 
diff --git a/gdb/frame.c b/gdb/frame.c
index 7f67d2e..f0aefb5 100644
--- a/gdb/frame.c
+++ b/gdb/frame.c
@@ -997,7 +997,7 @@ get_current_frame (void)
 
 static struct frame_info *selected_frame;
 
-static int
+int
 has_stack_frames (void)
 {
   if (!target_has_registers || !target_has_stack || !target_has_memory)
@@ -1458,42 +1458,6 @@ get_prev_frame (struct frame_info *this_frame)
 {
   struct frame_info *prev_frame;
 
-  /* Return the inner-most frame, when the caller passes in NULL.  */
-  /* NOTE: cagney/2002-11-09: Not sure how this would happen.  The
-     caller should have previously obtained a valid frame using
-     get_selected_frame() and then called this code - only possibility
-     I can think of is code behaving badly.
-
-     NOTE: cagney/2003-01-10: Talk about code behaving badly.  Check
-     block_innermost_frame().  It does the sequence: frame = NULL;
-     while (1) { frame = get_prev_frame (frame); .... }.  Ulgh!  Why
-     it couldn't be written better, I don't know.
-
-     NOTE: cagney/2003-01-11: I suspect what is happening in
-     block_innermost_frame() is, when the target has no state
-     (registers, memory, ...), it is still calling this function.  The
-     assumption being that this function will return NULL indicating
-     that a frame isn't possible, rather than checking that the target
-     has state and then calling get_current_frame() and
-     get_prev_frame().  This is a guess mind.  */
-  if (this_frame == NULL)
-    {
-      /* NOTE: cagney/2002-11-09: There was a code segment here that
-	 would error out when CURRENT_FRAME was NULL.  The comment
-	 that went with it made the claim ...
-
-	 ``This screws value_of_variable, which just wants a nice
-	 clean NULL return from block_innermost_frame if there are no
-	 frames.  I don't think I've ever seen this message happen
-	 otherwise.  And returning NULL here is a perfectly legitimate
-	 thing to do.''
-
-         Per the above, this code shouldn't even be called with a NULL
-         THIS_FRAME.  */
-      frame_debug_got_null_frame (this_frame, "this_frame NULL");
-      return current_frame;
-    }
-
   /* There is always a frame.  If this assertion fails, suspect that
      something should be calling get_selected_frame() or
      get_current_frame().  */
diff --git a/gdb/frame.h b/gdb/frame.h
index b25ab9c..224aec9 100644
--- a/gdb/frame.h
+++ b/gdb/frame.h
@@ -204,6 +204,11 @@ enum frame_type
    error.  */
 extern struct frame_info *get_current_frame (void);
 
+/* Does the current target interface have enough state to be able to
+   query the current inferior for frame info, and is the inferior in a
+   state where that is possible?  */
+extern int has_stack_frames (void);
+
 /* Invalidates the frame cache (this function should have been called
    invalidate_cached_frames).
 
diff --git a/gdb/varobj.c b/gdb/varobj.c
index 5b2ed9c..2ec6d90 100644
--- a/gdb/varobj.c
+++ b/gdb/varobj.c
@@ -431,14 +431,15 @@ find_frame_addr_in_frame_chain (CORE_ADDR frame_addr)
   if (frame_addr == (CORE_ADDR) 0)
     return NULL;
 
-  while (1)
+  for (frame = get_current_frame ();
+       frame != NULL;
+       frame = get_prev_frame (frame))
     {
-      frame = get_prev_frame (frame);
-      if (frame == NULL)
-	return NULL;
       if (get_frame_base_address (frame) == frame_addr)
 	return frame;
     }
+
+  return NULL;
 }
 
 struct varobj *
@@ -462,20 +463,26 @@ varobj_create (char *objname,
       struct value *value = NULL;
       int expr_len;
 
-      /* Parse and evaluate the expression, filling in as much
-         of the variable's data as possible */
+      /* Parse and evaluate the expression, filling in as much of the
+         variable's data as possible.  */
 
-      /* Allow creator to specify context of variable */
-      if ((type == USE_CURRENT_FRAME) || (type == USE_SELECTED_FRAME))
-	fi = deprecated_safe_get_selected_frame ();
+      if (has_stack_frames ())
+	{
+	  /* Allow creator to specify context of variable */
+	  if ((type == USE_CURRENT_FRAME) || (type == USE_SELECTED_FRAME))
+	    fi = get_selected_frame (NULL);
+	  else
+	    /* FIXME: cagney/2002-11-23: This code should be doing a
+	       lookup using the frame ID and not just the frame's
+	       ``address''.  This, of course, means an interface
+	       change.  However, with out that interface change ISAs,
+	       such as the ia64 with its two stacks, won't work.
+	       Similar goes for the case where there is a frameless
+	       function.  */
+	    fi = find_frame_addr_in_frame_chain (frame);
+	}
       else
-	/* FIXME: cagney/2002-11-23: This code should be doing a
-	   lookup using the frame ID and not just the frame's
-	   ``address''.  This, of course, means an interface change.
-	   However, with out that interface change ISAs, such as the
-	   ia64 with its two stacks, won't work.  Similar goes for the
-	   case where there is a frameless function.  */
-	fi = find_frame_addr_in_frame_chain (frame);
+	fi = NULL;
 
       /* frame = -2 means always use selected frame */
       if (type == USE_SELECTED_FRAME)