Remove context switching in favour of accessing thread_info fields

directly.

	* infrun.c (stepping_over_breakpoint, step_resume_breakpoint):
	Delete.
	(struct thread_stepping_state): Delete.
	(gtss, tss): Delete.
	(follow_inferior_reset_breakpoints, follow_exec)
	(resume, clear_proceed_status): Adjust.
	(prev_pc): Delete.
	(proceed, start_remote, init_wait_for_inferior): Adjust.
	(struct execution_control_state): Add event_thread member.
	(delete_step_resume_breakpoint_callback)
	(delete_step_thread_step_resume_breakpoint)
	(delete_step_thread_step_resume_breakpoint_cleanup)
	(delete_step_thread_step_resume_breakpoint): New.
	(wait_for_inferior, init_execution_control_state): Use
	delete_step_thread_step_resume_breakpoint_cleanup.
	(wait_for_inferior): Set the event_thread.
	(fetch_inferior_event): Ditto.  Delete the step-resume breakpoint
	with delete_step_thread_step_resume_breakpoint.
	(init_thread_stepping_state): Change parameter type to
	thread_info.  Adjust.
	(context_switch): Don't context switch prev_pc,
	stepping_over_breakpoint, step_resume_breakpoint,
	step_range_start, step_range_end, step_frame_id,
	tss->stepping_over_breakpoint,
	tss->stepping_through_solib_after_catch,
	tss->stepping_through_solib_catchpoints, tss->current_line, or
	tss->current_symtab.
	(adjust_pc_after_break, handle_inferior_event)
	(currently_stepping, step_into_function)
	(insert_step_resume_breakpoint_at_sal)
	(insert_longjmp_resume_breakpoint, keep_going): Adjust.
	(clear_stepping_state): New.
	(normal_stop): Adjust.
	(save_inferior_status, restore_inferior_status): Adjust.

	* gdbthread.h (struct thread_info): Comments describing the
	members moved here.  Add step_after_step_resume_breakpoint.
	(delete_step_resume_breakpoint): Add thread_info argument.
	(save_infrun_state, load_infrun_state): Remove prev_pc,
	trap_expected, step_resume_breakpoint, step_range_start,
	step_range_end, step_frame_id, another_trap,
	stepping_through_solib_after_catch,
	stepping_through_solib_catchpoints, current_line and
	current_symtab function arguments.
	(inferior_thread): Declare.

	* thread.c (inferior_thread): New.
	(delete_step_resume_breakpoint): Add a thread_info parameter and
	rewrite.
	(load_infrun_state, save_infrun_state): Remove prev_pc,
	trap_expected, step_resume_breakpoint, step_range_start,
	step_range_end, step_frame_id, stepping_over_breakpoint,
	stepping_through_solib_after_catch,
	stepping_through_solib_catchpoints, current_line and
	current_symtab args.  Remove code referencing them.

	* infcmd.c (step_range_start, step_range_end, step_frame_id):
	Delete.
	(step_1, step_once, until_next_command): Adjust.

	* inferior.h (step_range_start, step_range_end, step_frame_id):
	Delete.

	* linux-nat.c (linux_child_follow_fork): If following the child,
	move the step state to it.  Adjust.
	* inf-ptrace.c (inf_ptrace_follow_fork): Ditto.
	* inf-ttrace.c (inf_ttrace_follow_fork): Ditto.

gdb/thread.c

@@ -74,20 +74,21 @@ enum thread_state
 static enum thread_state main_thread_state = THREAD_STOPPED;
 static int main_thread_executing = 0;
 
-void
-delete_step_resume_breakpoint (void *arg)
+extern struct thread_info*
+inferior_thread (void)
 {
-  struct breakpoint **breakpointp = (struct breakpoint **) arg;
-  struct thread_info *tp;
+  struct thread_info *tp = find_thread_pid (inferior_ptid);
+  gdb_assert (tp);
+  return tp;
+}
 
-  if (*breakpointp != NULL)
+void
+delete_step_resume_breakpoint (struct thread_info *tp)
+{
+  if (tp && tp->step_resume_breakpoint)
     {
-      delete_breakpoint (*breakpointp);
-      for (tp = thread_list; tp; tp = tp->next)
-	if (tp->step_resume_breakpoint == *breakpointp)
-	  tp->step_resume_breakpoint = NULL;
-
-      *breakpointp = NULL;
+      delete_breakpoint (tp->step_resume_breakpoint);
+      tp->step_resume_breakpoint = NULL;
     }
 }
 
@@ -442,17 +443,6 @@ gdb_list_thread_ids (struct ui_out *uiout, char **error_message)
 
 void
 load_infrun_state (ptid_t ptid,
-		   CORE_ADDR *prev_pc,
-		   int *trap_expected,
-		   struct breakpoint **step_resume_breakpoint,
-		   CORE_ADDR *step_range_start,
-		   CORE_ADDR *step_range_end,
-		   struct frame_id *step_frame_id,
-		   int *stepping_over_breakpoint,
-		   int *stepping_through_solib_after_catch,
-		   bpstat *stepping_through_solib_catchpoints,
-		   int *current_line,
-		   struct symtab **current_symtab,
 		   struct continuation **continuations,
 		   struct continuation **intermediate_continuations,
 		   int *proceed_to_finish,
@@ -470,20 +460,6 @@ load_infrun_state (ptid_t ptid,
   if (tp == NULL)
     return;
 
-  *prev_pc = tp->prev_pc;
-  *trap_expected = tp->trap_expected;
-  *step_resume_breakpoint = tp->step_resume_breakpoint;
-  *step_range_start = tp->step_range_start;
-  *step_range_end = tp->step_range_end;
-  *step_frame_id = tp->step_frame_id;
-  *stepping_over_breakpoint = tp->stepping_over_breakpoint;
-  *stepping_through_solib_after_catch =
-    tp->stepping_through_solib_after_catch;
-  *stepping_through_solib_catchpoints =
-    tp->stepping_through_solib_catchpoints;
-  *current_line = tp->current_line;
-  *current_symtab = tp->current_symtab;
-
   /* In all-stop mode, these are global state, while in non-stop mode,
      they are per thread.  */
   if (non_stop)
@@ -509,17 +485,6 @@ load_infrun_state (ptid_t ptid,
 
 void
 save_infrun_state (ptid_t ptid,
-		   CORE_ADDR prev_pc,
-		   int trap_expected,
-		   struct breakpoint *step_resume_breakpoint,
-		   CORE_ADDR step_range_start,
-		   CORE_ADDR step_range_end,
-		   const struct frame_id *step_frame_id,
-		   int stepping_over_breakpoint,
-		   int stepping_through_solib_after_catch,
-		   bpstat stepping_through_solib_catchpoints,
-		   int current_line,
-		   struct symtab *current_symtab,
 		   struct continuation *continuations,
 		   struct continuation *intermediate_continuations,
 		   int proceed_to_finish,
@@ -537,18 +502,6 @@ save_infrun_state (ptid_t ptid,
   if (tp == NULL)
     return;
 
-  tp->prev_pc = prev_pc;
-  tp->trap_expected = trap_expected;
-  tp->step_resume_breakpoint = step_resume_breakpoint;
-  tp->step_range_start = step_range_start;
-  tp->step_range_end = step_range_end;
-  tp->step_frame_id = (*step_frame_id);
-  tp->stepping_over_breakpoint = stepping_over_breakpoint;
-  tp->stepping_through_solib_after_catch = stepping_through_solib_after_catch;
-  tp->stepping_through_solib_catchpoints = stepping_through_solib_catchpoints;
-  tp->current_line = current_line;
-  tp->current_symtab = current_symtab;
-
   /* In all-stop mode, these are global state, while in non-stop mode,
      they are per thread.  */
   if (non_stop)