Eliminate immediate_quit

This finally gets rid of immediate_quit (and surrounding
infrustruture), as nothing sets it anymore.

gdb_call_async_signal_handler was only necessary in order to handle
immediate_quit.  We can just call mark_async_signal_handler directly
on all hosts now.

In turn, we can clean up mingw-hdep.c's gdb_select a bit, as
sigint_event / sigint_handler is no longer needed.

gdb/ChangeLog:
2016-04-12  Pedro Alves  <palves@redhat.com>

	* defs.h: Update comments on SIGINT handling.
	(immediate_quit): Delete declaration.
	* event-loop.c (call_async_signal_handler): Delete.
	* event-loop.h (call_async_signal_handler): Delete declaration.
	(mark_async_signal_handler): Update comments.
	(gdb_call_async_signal_handler): Delete declaration.
	* event-top.c (handle_sigint): Call mark_async_signal_handler
	instead of gdb_call_async_signal_handler.
	* exceptions.c (prepare_to_throw_exception): Remove reference to
	immediate_quit.
	(exception_fprintf): Remove comments about immediate_quit.
	* mingw-hdep.c (sigint_event, sigint_handler): Delete.
	(gdb_select): Don't wait on sigint_event.
	(gdb_call_async_signal_handler): Delete.
	(_initialize_mingw_hdep): Delete.
	* posix-hdep.c (gdb_call_async_signal_handler): Delete.
	* utils.c (immediate_quit): Delete.

9 files changed, 32 insertions, 131 deletions

diff --git a/gdb/ChangeLog b/gdb/ChangeLog
index 1f6200f..0e8327e 100644
--- a/gdb/ChangeLog
+++ b/gdb/ChangeLog
@@ -1,5 +1,25 @@
 2016-04-12  Pedro Alves  <palves@redhat.com>
 
+	* defs.h: Update comments on SIGINT handling.
+	(immediate_quit): Delete declaration.
+	* event-loop.c (call_async_signal_handler): Delete.
+	* event-loop.h (call_async_signal_handler): Delete declaration.
+	(mark_async_signal_handler): Update comments.
+	(gdb_call_async_signal_handler): Delete declaration.
+	* event-top.c (handle_sigint): Call mark_async_signal_handler
+	instead of gdb_call_async_signal_handler.
+	* exceptions.c (prepare_to_throw_exception): Remove reference to
+	immediate_quit.
+	(exception_fprintf): Remove comments about immediate_quit.
+	* mingw-hdep.c (sigint_event, sigint_handler): Delete.
+	(gdb_select): Don't wait on sigint_event.
+	(gdb_call_async_signal_handler): Delete.
+	(_initialize_mingw_hdep): Delete.
+	* posix-hdep.c (gdb_call_async_signal_handler): Delete.
+	* utils.c (immediate_quit): Delete.
+
+2016-04-12  Pedro Alves  <palves@redhat.com>
+
 	* defs.h (quit_handler_ftype, quit_handler)
 	(make_cleanup_override_quit_handler, default_quit_handler): New.
 	(QUIT): Adjust comments.
diff --git a/gdb/defs.h b/gdb/defs.h
index 83e4e11..482ef1c 100644
--- a/gdb/defs.h
+++ b/gdb/defs.h
@@ -125,11 +125,10 @@ extern char *python_libdir;
 /* * Search path for separate debug files.  */
 extern char *debug_file_directory;
 
-/* GDB has two methods for handling SIGINT.  When immediate_quit is
-   nonzero, a SIGINT results in an immediate longjmp out of the signal
-   handler.  Otherwise, SIGINT simply sets a flag; code that might
-   take a long time, and which ought to be interruptible, checks this
-   flag using the QUIT macro.
+/* GDB's SIGINT handler basically sets a flag; code that might take a
+   long time before it gets back to the event loop, and which ought to
+   be interruptible, checks this flag using the QUIT macro, which, if
+   GDB has the terminal, throws a quit exception.
 
    In addition to setting a flag, the SIGINT handler also marks a
    select/poll-able file descriptor as read-ready.  That is used by
@@ -176,8 +175,6 @@ extern void default_quit_handler (void);
 /* Flag that function quit should call quit_force.  */
 extern volatile int sync_quit_force_run;
 
-extern int immediate_quit;
-
 extern void quit (void);
 
 /* Helper for the QUIT macro.  */
diff --git a/gdb/event-loop.c b/gdb/event-loop.c
index 052d535..60ef2a5 100644
--- a/gdb/event-loop.c
+++ b/gdb/event-loop.c
@@ -911,15 +911,6 @@ create_async_signal_handler (sig_handler_func * proc,
   return async_handler_ptr;
 }
 
-/* Call the handler from HANDLER immediately.  This function runs
-   signal handlers when returning to the event loop would be too
-   slow.  */
-void
-call_async_signal_handler (struct async_signal_handler *handler)
-{
-  (*handler->proc) (handler->client_data);
-}
-
 /* Mark the handler (ASYNC_HANDLER_PTR) as ready.  This information
    will be used when the handlers are invoked, after we have waited
    for some event.  The caller of this function is the interrupt
diff --git a/gdb/event-loop.h b/gdb/event-loop.h
index 155dafa..7159d97 100644
--- a/gdb/event-loop.h
+++ b/gdb/event-loop.h
@@ -91,16 +91,9 @@ extern int create_timer (int milliseconds,
 			 gdb_client_data client_data);
 extern void delete_timer (int id);
 
-/* Call the handler from HANDLER immediately.  This function
-   runs signal handlers when returning to the event loop would be too
-   slow.  Do not call this directly; use gdb_call_async_signal_handler,
-   below, with IMMEDIATE_P == 1.  */
-void call_async_signal_handler (struct async_signal_handler *handler);
-
-/* Call the handler from HANDLER the next time through the event loop.
-   Do not call this directly; use gdb_call_async_signal_handler,
-   below, with IMMEDIATE_P == 0.  */
-void mark_async_signal_handler (struct async_signal_handler *handler);
+/* Call the handler from HANDLER the next time through the event
+   loop.  */
+extern void mark_async_signal_handler (struct async_signal_handler *handler);
 
 /* Returns true if HANDLER is marked ready.  */
 
@@ -111,17 +104,6 @@ extern int
 
 extern void clear_async_signal_handler (struct async_signal_handler *handler);
 
-/* Wrapper for the body of signal handlers.  Call this function from
-   any SIGINT handler which needs to access GDB data structures or
-   escape via longjmp.  If IMMEDIATE_P is set, this triggers either
-   immediately (for POSIX platforms), or from gdb_select (for
-   MinGW).  If IMMEDIATE_P is clear, the handler will run the next
-   time we return to the event loop and any current select calls
-   will be interrupted.  */
-
-void gdb_call_async_signal_handler (struct async_signal_handler *handler,
-				    int immediate_p);
-
 /* Create and register an asynchronous event source in the event loop,
    and set PROC as its callback.  CLIENT_DATA is passed as argument to
    PROC upon its invocation.  Returns a pointer to an opaque structure
diff --git a/gdb/event-top.c b/gdb/event-top.c
index 41d3aac..fc1a6c6 100644
--- a/gdb/event-top.c
+++ b/gdb/event-top.c
@@ -901,18 +901,11 @@ handle_sigint (int sig)
      it may be quite a while before we get back to the event loop.  So
      set quit_flag to 1 here.  Then if QUIT is called before we get to
      the event loop, we will unwind as expected.  */
-
   set_quit_flag ();
 
-  /* If immediate_quit is set, we go ahead and process the SIGINT right
-     away, even if we usually would defer this to the event loop.  The
-     assumption here is that it is safe to process ^C immediately if
-     immediate_quit is set.  If we didn't, SIGINT would be really
-     processed only the next time through the event loop.  To get to
-     that point, though, the command that we want to interrupt needs to
-     finish first, which is unacceptable.  If immediate quit is not set,
-     we process SIGINT the next time through the loop, which is fine.  */
-  gdb_call_async_signal_handler (sigint_token, immediate_quit);
+  /* In case nothing calls QUIT before the event loop is reached, the
+     event loop handles it.  */
+  mark_async_signal_handler (sigint_token);
 }
 
 /* See gdb_select.h.  */
diff --git a/gdb/exceptions.c b/gdb/exceptions.c
index ffdd1f3..7f6599f 100644
--- a/gdb/exceptions.c
+++ b/gdb/exceptions.c
@@ -30,7 +30,6 @@
 void
 prepare_to_throw_exception (void)
 {
-  immediate_quit = 0;
 }
 
 static void
@@ -148,12 +147,7 @@ exception_fprintf (struct ui_file *file, struct gdb_exception e,
    returned by catch_exceptions().  It is an internal_error() for
    FUNC() to return a negative value.
 
-   See exceptions.h for further usage details.
-
-   Must not be called with immediate_quit in effect (bad things might
-   happen, say we got a signal in the middle of a memcpy to quit_return).
-   This is an OK restriction; with very few exceptions immediate_quit can
-   be replaced by judicious use of QUIT.  */
+   See exceptions.h for further usage details.  */
 
 /* MAYBE: cagney/1999-11-05: catch_errors() in conjunction with
    error() et al. could maintain a set of flags that indicate the
diff --git a/gdb/mingw-hdep.c b/gdb/mingw-hdep.c
index 8247a8c..2e010fa 100644
--- a/gdb/mingw-hdep.c
+++ b/gdb/mingw-hdep.c
@@ -27,14 +27,6 @@
 
 #include <windows.h>
 
-/* This event is signalled whenever an asynchronous SIGINT handler
-   needs to perform an action in the main thread.  */
-static HANDLE sigint_event;
-
-/* When SIGINT_EVENT is signalled, gdb_select will call this
-   function.  */
-struct async_signal_handler *sigint_handler;
-
 /* Return an absolute file name of the running GDB, if possible, or
    ARGV0 if not.  The return value is in malloc'ed storage.  */
 
@@ -120,8 +112,7 @@ gdb_select (int n, fd_set *readfds, fd_set *writefds, fd_set *exceptfds,
 	}
     }
 
-  gdb_assert (num_handles < MAXIMUM_WAIT_OBJECTS);
-  handles[num_handles++] = sigint_event;
+  gdb_assert (num_handles <= MAXIMUM_WAIT_OBJECTS);
 
   event = WaitForMultipleObjects (num_handles,
 				  handles,
@@ -184,46 +175,5 @@ gdb_select (int n, fd_set *readfds, fd_set *writefds, fd_set *exceptfds,
   while (RL_ISSTATE (RL_STATE_SIGHANDLER))
     Sleep (1);
 
-  if (h == sigint_event
-      || WaitForSingleObject (sigint_event, 0) == WAIT_OBJECT_0)
-    {
-      if (sigint_handler != NULL)
-	call_async_signal_handler (sigint_handler);
-
-      if (num_ready == 0)
-	{
-	  errno = EINTR;
-	  return -1;
-	}
-    }
-
   return num_ready;
 }
-
-/* Wrapper for the body of signal handlers.  On Windows systems, a
-   SIGINT handler runs in its own thread.  We can't longjmp from
-   there, and we shouldn't even prompt the user.  Delay HANDLER
-   until the main thread is next in gdb_select.  */
-
-void
-gdb_call_async_signal_handler (struct async_signal_handler *handler,
-			       int immediate_p)
-{
-  if (immediate_p)
-    sigint_handler = handler;
-  else
-    {
-      mark_async_signal_handler (handler);
-      sigint_handler = NULL;
-    }
-  SetEvent (sigint_event);
-}
-
-/* -Wmissing-prototypes */
-extern initialize_file_ftype _initialize_mingw_hdep;
-
-void
-_initialize_mingw_hdep (void)
-{
-  sigint_event = CreateEvent (0, FALSE, FALSE, 0);
-}
diff --git a/gdb/posix-hdep.c b/gdb/posix-hdep.c
index 90cab8f..e9db576 100644
--- a/gdb/posix-hdep.c
+++ b/gdb/posix-hdep.c
@@ -30,16 +30,3 @@ gdb_select (int n, fd_set *readfds, fd_set *writefds, fd_set *exceptfds,
 {
   return select (n, readfds, writefds, exceptfds, timeout);
 }
-
-/* Wrapper for the body of signal handlers.  Nothing special needed on
-   POSIX platforms.  */
-
-void
-gdb_call_async_signal_handler (struct async_signal_handler *handler,
-			       int immediate_p)
-{
-  if (immediate_p)
-    call_async_signal_handler (handler);
-  else
-    mark_async_signal_handler (handler);
-}
diff --git a/gdb/utils.c b/gdb/utils.c
index bc62218..db5104d 100644
--- a/gdb/utils.c
+++ b/gdb/utils.c
@@ -109,19 +109,6 @@ static int debug_timestamp = 0;
 
 int job_control;
 
-/* Nonzero means quit immediately if Control-C is typed now, rather
-   than waiting until QUIT is executed.  Be careful in setting this;
-   code which executes with immediate_quit set has to be very careful
-   about being able to deal with being interrupted at any time.  It is
-   almost always better to use QUIT; the only exception I can think of
-   is being able to quit out of a system call (using EINTR loses if
-   the SIGINT happens between the previous QUIT and the system call).
-   To immediately quit in the case in which a SIGINT happens between
-   the previous QUIT and setting immediate_quit (desirable anytime we
-   expect to block), call QUIT after setting immediate_quit.  */
-
-int immediate_quit;
-
 /* Nonzero means that strings with character values >0x7F should be printed
    as octal escapes.  Zero means just print the value (e.g. it's an
    international character, and the terminal or window can cope.)  */