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, 10 insertions, 1 deletions

diff --git a/src/eval.c b/src/eval.c
index 01e3db44082..734f01d81ae 100644
--- a/src/eval.c
+++ b/src/eval.c
@@ -1450,7 +1450,7 @@ static Lisp_Object find_handler_clause (Lisp_Object, Lisp_Object);
 static bool maybe_call_debugger (Lisp_Object conditions, Lisp_Object sig,
                                  Lisp_Object data);
 
-void
+static void
 process_quit_flag (void)
 {
   Lisp_Object flag = Vquit_flag;
@@ -1462,6 +1462,15 @@ process_quit_flag (void)
   quit ();
 }
 
+void
+maybe_quit (void)
+{
+  if (!NILP (Vquit_flag) && NILP (Vinhibit_quit))
+    process_quit_flag ();
+  else if (pending_signals)
+    process_pending_signals ();
+}
+
 DEFUN ("signal", Fsignal, Ssignal, 2, 2, 0,
        doc: /* Signal an error.  Args are ERROR-SYMBOL and associated DATA.
 This function does not return.