A quicker check for quit

On some microbenchmarks this lets Emacs run 60% faster on my
platform (AMD Phenom II X4 910e, Fedora 25 x86-64).
* src/atimer.c: Include keyboard.h, for pending_signals.
* src/editfns.c (Fcompare_buffer_substrings):
* src/fns.c (Fnthcdr, Fmemq, Fmemql, Fassq, Frassq, Fplist_put)
(Fnconc, Fplist_member):
Set and clear immediate_quit before and after loop instead of
executing QUIT each time through the loop.  This is OK for loops
that affect only locals.
* src/eval.c (process_quit_flag): Now static.
(maybe_quit): New function, containing QUIT’s old body.
* src/fns.c (rarely_quit): New function.
(Fmember, Fassoc, Frassoc, Fdelete, Fnreverse, Freverse)
(Flax_plist_get, Flax_plist_put, internal_equal, Fnconc):
Use it instead of QUIT, for
speed in tight loops that might modify non-locals.
* src/keyboard.h (pending_signals, process_pending_signals):
These belong to keyboard.c, so move them here ...
* src/lisp.h: ... from here.
(QUIT): Redefine in terms of the new maybe_quit function, which
contains this macro’s old definiens.  This works well with branch
prediction on processors with return stack buffers, e.g., x86
other than the original Pentium.

1 files changed, 4 insertions, 12 deletions

diff --git a/src/lisp.h b/src/lisp.h
index 7e918249935..01a08a05f20 100644
--- a/src/lisp.h
+++ b/src/lisp.h
@@ -3133,20 +3133,12 @@ extern Lisp_Object memory_signal_data;
    and (in particular) cannot call arbitrary Lisp code.
 
    If quit-flag is set to `kill-emacs' the SIGINT handler has received
-   a request to exit Emacs when it is safe to do.  */
+   a request to exit Emacs when it is safe to do.
 
-extern void process_pending_signals (void);
-extern bool volatile pending_signals;
-
-extern void process_quit_flag (void);
-#define QUIT						\
-  do {							\
-    if (!NILP (Vquit_flag) && NILP (Vinhibit_quit))	\
-      process_quit_flag ();				\
-    else if (pending_signals)				\
-      process_pending_signals ();			\
-  } while (false)
+   When not quitting, process any pending signals.  */
 
+extern void maybe_quit (void);
+#define QUIT maybe_quit ()
 
 /* True if ought to quit now.  */