From: Paul Eggert <eggert@cs.ucla.edu>
Date: Tue, 11 Sep 2012 20:35:23 +0000 (-0700)
Subject: * alloc.c (discard_killed_buffers): Tune and simplify a bit.
X-Git-Url: http://git.hcoop.net/bpt/emacs.git/commitdiff_plain/5779a1dc62593be8294edaecfecca4359be9ab4e

* alloc.c (discard_killed_buffers): Tune and simplify a bit.

Use pointer-to-a-pointer to simplify and avoid a NILP check each
time an item is removed.  No need to mark this function 'inline';
the compiler knows better than we do.
---

diff --git a/src/ChangeLog b/src/ChangeLog
index 6cb0e65281..2b0686cc49 100644
--- a/src/ChangeLog
+++ b/src/ChangeLog
@@ -1,3 +1,10 @@
+2012-09-11  Paul Eggert  <eggert@cs.ucla.edu>
+
+	* alloc.c (discard_killed_buffers): Tune and simplify a bit.
+	Use pointer-to-a-pointer to simplify and avoid a NILP check each
+	time an item is removed.  No need to mark this function 'inline';
+	the compiler knows better than we do.
+
 2012-09-11  Jan Djärv  <jan.h.d@swipnet.se>
 
 	* nsterm.m (ns_judge_scroll_bars): Pass NO to updateFrameSize.
diff --git a/src/alloc.c b/src/alloc.c
index fb16b7d751..61cb7086c2 100644
--- a/src/alloc.c
+++ b/src/alloc.c
@@ -5868,25 +5868,21 @@ mark_buffer (struct buffer *buffer)
 /* Remove killed buffers or items whose car is a killed buffer
    from LIST and return changed LIST.  Called during GC.  */
 
-static inline Lisp_Object
+static Lisp_Object
 discard_killed_buffers (Lisp_Object list)
 {
-  Lisp_Object tail, prev, tem;
+  Lisp_Object *prev = &list;
+  Lisp_Object tail;
 
-  for (tail = list, prev = Qnil; CONSP (tail); tail = XCDR (tail))
+  for (tail = list; CONSP (tail); tail = XCDR (tail))
     {
-      tem = XCAR (tail);
+      Lisp_Object tem = XCAR (tail);
       if (CONSP (tem))
 	tem = XCAR (tem);
       if (BUFFERP (tem) && !BUFFER_LIVE_P (XBUFFER (tem)))
-	{
-	  if (NILP (prev))
-	    list = XCDR (tail);
-	  else
-	    XSETCDR (prev, XCDR (tail));
-	}
+	*prev = XCDR (tail);
       else
-	prev = tail;
+	prev = &XCDR_AS_LVALUE (tail);
     }
   return list;
 }
@@ -6045,7 +6041,7 @@ mark_object (Lisp_Object arg)
 	    {
 	      struct window *w = (struct window *) ptr;
 	      bool leaf = NILP (w->hchild) && NILP (w->vchild);
-	      
+
 	      /* For live windows, Lisp code filters out killed buffers
 		 from both buffer lists.  For dead windows, we do it here
 		 in attempt to help GC to reclaim killed buffers faster.  */