[RFA] 'set step-mode' to control the step command.

[Christopher Faylor <cgf at redhat dot com>]

This patch is from a net contributor (assignment on file) who has added
an interesting new feature.  To quote:

"Set mode of the step operation.  When set, doing a step on a function
without debug line information will stop at the first instruction of
that function.  Otherwise, the function is skipped and the step command
stops at a different source line."

Does this look reasonable?

cgf

Mon Nov  6 14:34:37 2000  Stephane Carrez  <Stephane.Carrez@sun.com>
        
	* inferior.h (step_stop_if_no_debug): New variable.
	* infrun.c (step_stop_if_no_debug): Declare.
	(handle_inferior_event): Stop the step command if we entered
	a function without line info.
	(_initialize_infrun): New command 'set step-mode' to control
	the step command.
	* infcmd.c (step_once): Switch to stepi mode if there is no line
	info (and switching is enabled).


Index: inferior.h
===================================================================
RCS file: /cvs/cvsfiles/devo/gdb/inferior.h,v
retrieving revision 1.86
retrieving revision 1.86.14.2
diff -u -p -r1.86 -r1.86.14.2
--- inferior.h	2000/08/01 17:38:48	1.86
+++ inferior.h	2000/11/02 00:40:20	1.86.14.2
@@ -125,6 +125,11 @@ extern void clear_proceed_status (void);
 
 extern void proceed (CORE_ADDR, enum target_signal, int);
 
+/* When set, stop the 'step' command if we enter a function which has
+   no line number information.  The normal behavior is that we step
+   over such function.  */
+extern int step_stop_if_no_debug;
+
 extern void kill_inferior (void);
 
 extern void generic_mourn_inferior (void);
Index: infrun.c
===================================================================
RCS file: /cvs/cvsfiles/devo/gdb/infrun.c,v
retrieving revision 1.287
retrieving revision 1.287.8.1
diff -u -p -r1.287 -r1.287.8.1
--- infrun.c	2000/09/07 12:34:15	1.287
+++ infrun.c	2000/10/30 23:55:20	1.287.8.1
@@ -84,6 +84,11 @@ void _initialize_infrun (void);
 int inferior_ignoring_startup_exec_events = 0;
 int inferior_ignoring_leading_exec_events = 0;
 
+/* When set, stop the 'step' command if we enter a function which has
+   no line number information.  The normal behavior is that we step
+   over such function.  */
+int step_stop_if_no_debug = 0;
+
 /* In asynchronous mode, but simulating synchronous execution. */
 
 int sync_execution = 0;
@@ -2810,6 +2815,18 @@ handle_inferior_event (struct execution_
 	      return;
 	    }
 	}
+
+	/* If we have no line number and the step-stop-if-no-debug
+	   is set, we stop the step so that the user has a chance to
+	   switch in assembly mode.  */
+	if (step_over_calls < 0 && step_stop_if_no_debug)
+	  {
+	    stop_step = 1;
+	    print_stop_reason (END_STEPPING_RANGE, 0);
+	    stop_stepping (ecs);
+	    return;
+	  }
+
 	step_over_function (ecs);
 	keep_going (ecs);
 	return;
@@ -4308,5 +4325,14 @@ step == scheduler locked during every si
 			&setlist);
 
   c->function.sfunc = set_schedlock_func;	/* traps on target vector */
+  add_show_from_set (c, &showlist);
+
+  c = add_set_cmd ("step-mode", class_run,
+		   var_boolean, (char*) &step_stop_if_no_debug,
+"Set mode of the step operation. When set, doing a step on a\n\
+function without debug line information will stop at the first\n\
+instruction of that function. Otherwise, the function is skipped and\n\
+the step command stops at a different source line.",
+			&setlist);
   add_show_from_set (c, &showlist);
 }
Index: infcmd.c
===================================================================
RCS file: /cvs/cvsfiles/devo/gdb/infcmd.c,v
retrieving revision 1.173
retrieving revision 1.173.8.1
diff -u -p -r1.173 -r1.173.8.1
--- infcmd.c	2000/09/07 12:34:15	1.173
+++ infcmd.c	2000/10/30 23:55:20	1.173.8.1
@@ -607,7 +607,13 @@ step_once (int skip_subroutines, int sin
       if (!single_inst)
 	{
 	  find_pc_line_pc_range (stop_pc, &step_range_start, &step_range_end);
-	  if (step_range_end == 0)
+
+	  /* If we have no line info, switch to stepi mode.  */
+	  if (step_range_end == 0 && step_stop_if_no_debug)
+	    {
+	      step_range_start = step_range_end = 1;
+	    }
+	  else if (step_range_end == 0)
 	    {
 	      char *name;
 	      if (find_pc_partial_function (stop_pc, &name, &step_range_start,