This is the mail archive of the
gdb-patches@sourceware.org
mailing list for the GDB project.
[rfc] Fix register cache invalidation
- From: "Ulrich Weigand" <uweigand at de dot ibm dot com>
- To: gdb-patches at sourceware dot org
- Cc: pedro at codesourcery dot com
- Date: Tue, 14 Jul 2009 16:59:28 +0200 (CEST)
- Subject: [rfc] Fix register cache invalidation
Hello,
when testing the Cell/B.E. combined debugger patches I ran into a situation
where registers_changed was not called soon enough.
A while ago I proposed a patch to simplify register invalidation (as part of
a infrun cleanup series):
http://sourceware.org/ml/gdb-patches/2008-12/msg00120.html
This cleanup actually fixes the combined debugger problem as well.
At the time, Pedro pointed out that parts of that patch weren't safe in the
non-stop case. The version below omits those parts, and only changes code
to simplify calling registers_changed and resetting waiton_ptid.
Tested on powerpc64-linux with no regressions.
Any comments? I'd like to commit this in a couple of days.
Bye,
Ulrich
ChangeLog:
* infrun.c (wait_for_inferior): Invalidate registers and overlay
cache every time before calling target_wait.
(handle_inferior_event): Make static. Always reset waiton_ptid.
Never call registers_changed.
(prepare_to_wait): Do not invaliate registers or overlay cache
(moved to wait_for_inferior). Do not reset waiton_ptid (moved
to handle_inferior_event).
(fetch_inferior_event): Remove check for always-true condition.
Index: src/gdb/infrun.c
===================================================================
--- src.orig/gdb/infrun.c
+++ src/gdb/infrun.c
@@ -1756,7 +1756,7 @@ struct execution_control_state
static void init_execution_control_state (struct execution_control_state *ecs);
-void handle_inferior_event (struct execution_control_state *ecs);
+static void handle_inferior_event (struct execution_control_state *ecs);
static void handle_step_into_function (struct gdbarch *gdbarch,
struct execution_control_state *ecs);
@@ -1993,23 +1993,22 @@ wait_for_inferior (int treat_exec_as_sig
ecs = &ecss;
memset (ecs, 0, sizeof (*ecs));
- overlay_cache_invalid = 1;
-
/* We'll update this if & when we switch to a new thread. */
previous_inferior_ptid = inferior_ptid;
- /* We have to invalidate the registers BEFORE calling target_wait
- because they can be loaded from the target while in target_wait.
- This makes remote debugging a bit more efficient for those
- targets that provide critical registers as part of their normal
- status mechanism. */
-
- registers_changed ();
-
while (1)
{
struct cleanup *old_chain;
+ /* We have to invalidate the registers BEFORE calling target_wait
+ because they can be loaded from the target while in target_wait.
+ This makes remote debugging a bit more efficient for those
+ targets that provide critical registers as part of their normal
+ status mechanism. */
+
+ overlay_cache_invalid = 1;
+ registers_changed ();
+
if (deprecated_target_wait_hook)
ecs->ptid = deprecated_target_wait_hook (waiton_ptid, &ecs->ws, 0);
else
@@ -2063,14 +2062,8 @@ fetch_inferior_event (void *client_data)
memset (ecs, 0, sizeof (*ecs));
- overlay_cache_invalid = 1;
-
- /* We can only rely on wait_for_more being correct before handling
- the event in all-stop, but previous_inferior_ptid isn't used in
- non-stop. */
- if (!ecs->wait_some_more)
- /* We'll update this if & when we switch to a new thread. */
- previous_inferior_ptid = inferior_ptid;
+ /* We'll update this if & when we switch to a new thread. */
+ previous_inferior_ptid = inferior_ptid;
if (non_stop)
/* In non-stop mode, the user/frontend should not notice a thread
@@ -2085,6 +2078,7 @@ fetch_inferior_event (void *client_data)
targets that provide critical registers as part of their normal
status mechanism. */
+ overlay_cache_invalid = 1;
registers_changed ();
if (deprecated_target_wait_hook)
@@ -2375,7 +2369,7 @@ stepped_in_from (struct frame_info *fram
by an event from the inferior, figure out what it means and take
appropriate action. */
-void
+static void
handle_inferior_event (struct execution_control_state *ecs)
{
struct frame_info *frame;
@@ -2444,8 +2438,6 @@ handle_inferior_event (struct execution_
case infwait_thread_hop_state:
if (debug_infrun)
fprintf_unfiltered (gdb_stdlog, "infrun: infwait_thread_hop_state\n");
- /* Cancel the waiton_ptid. */
- waiton_ptid = pid_to_ptid (-1);
break;
case infwait_normal_state:
@@ -2476,7 +2468,9 @@ handle_inferior_event (struct execution_
default:
internal_error (__FILE__, __LINE__, _("bad switch"));
}
+
infwait_state = infwait_normal_state;
+ waiton_ptid = pid_to_ptid (-1);
switch (ecs->ws.kind)
{
@@ -3001,7 +2995,6 @@ targets should add new threads to the th
ecs->event_thread->stepping_over_breakpoint = 1;
keep_going (ecs);
- registers_changed ();
return;
}
}
@@ -3076,7 +3069,6 @@ targets should add new threads to the th
/* Single step */
hw_step = maybe_software_singlestep (gdbarch, stop_pc);
target_resume (ecs->ptid, hw_step, TARGET_SIGNAL_0);
- registers_changed ();
waiton_ptid = ecs->ptid;
if (target_have_steppable_watchpoint)
infwait_state = infwait_step_watch_state;
@@ -4482,19 +4474,7 @@ prepare_to_wait (struct execution_contro
{
if (debug_infrun)
fprintf_unfiltered (gdb_stdlog, "infrun: prepare_to_wait\n");
- if (infwait_state == infwait_normal_state)
- {
- overlay_cache_invalid = 1;
- /* We have to invalidate the registers BEFORE calling
- target_wait because they can be loaded from the target while
- in target_wait. This makes remote debugging a bit more
- efficient for those targets that provide critical registers
- as part of their normal status mechanism. */
-
- registers_changed ();
- waiton_ptid = pid_to_ptid (-1);
- }
/* This is the old end of the while loop. Let everybody know we
want to wait for the inferior some more and get called again
soon. */
--
Dr. Ulrich Weigand
GNU Toolchain for Linux on System z and Cell BE
Ulrich.Weigand@de.ibm.com