gdb/

        * frame.c (get_frame_id): Default to outer_frame_id if the this_id
        method does not supply an ID.  Assert that the result is not
        null_frame_id.
        (outer_frame_id): New.
        (frame_id_p): Accept outer_frame_id.
        (frame_id_eq): Allow outer_frame_id to be equal to itself.
        (frame_find_by_id): Revert previous local workarounds.
        (get_prev_frame_1): Adjust end-of-stack check to test outer_frame_id.
        * frame.h (null_frame_id, frame_id_p): Update comments.
        (outer_frame_id): Declare.
        * infrun.c (handle_inferior_event): Do not treat all steps from the
        outermost frame as subroutine calls.

        * libunwind-frame.c (libunwind_frame_this_id): Do not clear THIS_ID.
        * hppa-tdep.c (hppa_stub_frame_this_id): Likewise.
        * ia64-tdep.c (ia64_frame_this_id): Likewise.
        (ia64_libunwind_frame_this_id, ia64_libunwind_sigtramp_frame_this_id):
        Use outer_frame_id instead of null_frame_id.
        * amd64obsd-tdep.c (amd64obsd_trapframe_cache): Use outer_frame_id.
        * i386obsd-tdep.c (i386obsd_trapframe_cache): Likewise.
        * inline-frame.c (inline_frame_this_id): Refuse outer_frame_id.
        * thread.c (restore_selected_frame): Update comment and remove
        frame_id_p check.

        gdb/doc/
        * gdbint.texinfo (Unwinding the Frame ID): Reference outer_frame_id.

1 files changed, 14 insertions, 2 deletions

diff --git a/gdb/infrun.c b/gdb/infrun.c
index c907635..a6ca2e3 100644
--- a/gdb/infrun.c
+++ b/gdb/infrun.c
@@ -3796,10 +3796,22 @@ infrun: not switching back to stepped thread, it has vanished\n");
      NOTE: frame_id_eq will never report two invalid frame IDs as
      being equal, so to get into this block, both the current and
      previous frame must have valid frame IDs.  */
+  /* The outer_frame_id check is a heuristic to detect stepping
+     through startup code.  If we step over an instruction which
+     sets the stack pointer from an invalid value to a valid value,
+     we may detect that as a subroutine call from the mythical
+     "outermost" function.  This could be fixed by marking
+     outermost frames as !stack_p,code_p,special_p.  Then the
+     initial outermost frame, before sp was valid, would
+     have code_addr == &_start.  See the commend in frame_id_eq
+     for more.  */
   if (!frame_id_eq (get_stack_frame_id (frame),
 		    ecs->event_thread->step_stack_frame_id)
-      && frame_id_eq (frame_unwind_caller_id (frame),
-		      ecs->event_thread->step_stack_frame_id))
+      && (frame_id_eq (frame_unwind_caller_id (get_current_frame ()),
+		       ecs->event_thread->step_stack_frame_id)
+	  && (!frame_id_eq (ecs->event_thread->step_stack_frame_id,
+			    outer_frame_id)
+	      || step_start_function != find_pc_function (stop_pc))))
     {
       CORE_ADDR real_stop_pc;