Use is_stopped, instead of !is_running

Pedro Alves
2008-07-29T13:59:37Z

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This patches fixes a couple of left over instances of !is_running to use
is_stopped instead, and adds a missing check for is_exited in
get_selected_block, which I tripped on while development the yet
unsubmitted non-stop remote target.

I'm adding more comments to gdbthread.h to describe why. Basically,
the thread state is not a boolean anymore.

I'll soon post a description of these states in the internal manual
under the currently empty section 3.5 - Thread Handling. Let me
know if it should be placed somewhere else.

Tested on x86_64-unknown-linux-gnu sync and async.

OK?

--
Pedro Alves

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2008-07-29 Pedro Alves <pedro@codesourcery.com>

* gdbthread.h: Add comments.
* stack.c (get_selected_block): Return 0 on an exited thread.
* top.c (execute_command): Check for is_stopped, not !is_running.
* event-top.c (command_handler): Likewise.

---
gdb/event-top.c | 2 +-
gdb/gdbthread.h | 33 ++++++++++++++++++++++++++-------
gdb/stack.c | 3 +++
gdb/top.c | 2 +-
4 files changed, 31 insertions(+), 9 deletions(-)

Index: src/gdb/gdbthread.h
===================================================================
--- src.orig/gdb/gdbthread.h 2008-07-29 13:25:21.000000000 +0100
+++ src/gdb/gdbthread.h 2008-07-29 13:25:42.000000000 +0100
@@ -210,21 +210,40 @@ extern void switch_to_thread (ptid_t pti
If PIDGET (PTID) is -1, marks all threads. */
extern void set_running (ptid_t ptid, int running);

-/* Reports if thread PTID is known to be running right now. */
-extern int is_running (ptid_t ptid);
+/* NOTE: Since the thread state is not a boolean, most times, you do
+ not want to check it with negation. If you really want to check if
+ the thread is stopped,

-/* Reports if any thread is known to be running right now. */
-extern int any_running (void);
+ use (good):
+
+ if (is_stopped (ptid))
+
+ instead of (bad):
+
+ if (!is_running (ptid))
+
+ The latter also returns true on exited threads, most likelly not
+ what you want. */
+
+/* Reports if in the frontend's perpective, thread PTID is running. */
+extern int is_running (ptid_t ptid);

/* Is this thread listed, but known to have exited? We keep it listed
(but not visible) until it's safe to delete. */
extern int is_exited (ptid_t ptid);

-/* Is this thread stopped? */
+/* In the frontend's perpective, is this thread stopped? */
extern int is_stopped (ptid_t ptid);

-/* Marks thread PTID as executing, or as stopped.
- If PIDGET (PTID) is -1, marks all threads. */
+/* In the frontend's perpective is there any thread running? */
+extern int any_running (void);
+
+/* Marks thread PTID as executing, or not. If PIDGET (PTID) is -1,
+ marks all threads.
+
+ Note that this is different from the running state. See the
+ description of state_ and executing_ fields of struct
+ thread_info. */
extern void set_executing (ptid_t ptid, int executing);

/* Reports if thread PTID is executing. */
Index: src/gdb/stack.c
===================================================================
--- src.orig/gdb/stack.c 2008-07-29 13:25:21.000000000 +0100
+++ src/gdb/stack.c 2008-07-29 13:25:42.000000000 +0100
@@ -1644,6 +1644,9 @@ get_selected_block (CORE_ADDR *addr_in_b
if (!target_has_stack)
return 0;

+ if (is_exited (inferior_ptid))
+ return 0;
+
if (is_executing (inferior_ptid))
return 0;

Index: src/gdb/top.c
===================================================================
--- src.orig/gdb/top.c 2008-07-29 13:25:21.000000000 +0100
+++ src/gdb/top.c 2008-07-29 13:25:42.000000000 +0100
@@ -484,7 +484,7 @@ Cannot execute this command without a li
/* FIXME: This should be cacheing the frame and only running when
the frame changes. */

- if (target_has_stack && !is_running (inferior_ptid))
+ if (target_has_stack && is_stopped (inferior_ptid))
{
flang = get_frame_language ();
if (!warned
Index: src/gdb/event-top.c
===================================================================
--- src.orig/gdb/event-top.c 2008-07-29 13:25:21.000000000 +0100
+++ src/gdb/event-top.c 2008-07-29 13:25:42.000000000 +0100
@@ -518,7 +518,7 @@ command_handler (char *command)
/* Do any commands attached to breakpoint we stopped at. Only if we
are always running synchronously. Or if we have just executed a
command that doesn't start the target. */
- if (!target_can_async_p () || !is_running (inferior_ptid))
+ if (!target_can_async_p () || is_stopped (inferior_ptid))
{
bpstat_do_actions (&stop_bpstat);
do_cleanups (old_chain);