=== modified file 'src/buffer.c'
--- src/buffer.c	2012-06-18 07:20:19 +0000
+++ src/buffer.c	2012-06-22 05:34:23 +0000
@@ -1049,14 +1049,7 @@
   register struct buffer *buf;
   register Lisp_Object result;
 
-  if (NILP (buffer))
-    buf = current_buffer;
-  else
-    {
-      CHECK_BUFFER (buffer);
-      buf = XBUFFER (buffer);
-    }
-
+  buf = buffer_or_current (buffer);
   result = buffer_lisp_local_variables (buf);
 
   /* Add on all the variables stored in special slots.  */
@@ -1091,15 +1084,7 @@
 No argument or nil as argument means use current buffer as BUFFER.  */)
   (register Lisp_Object buffer)
 {
-  register struct buffer *buf;
-  if (NILP (buffer))
-    buf = current_buffer;
-  else
-    {
-      CHECK_BUFFER (buffer);
-      buf = XBUFFER (buffer);
-    }
-
+  register struct buffer *buf = buffer_or_current (buffer);
   return BUF_SAVE_MODIFF (buf) < BUF_MODIFF (buf) ? Qt : Qnil;
 }
 
@@ -1208,16 +1193,7 @@
 No argument or nil as argument means use current buffer as BUFFER.  */)
   (register Lisp_Object buffer)
 {
-  register struct buffer *buf;
-  if (NILP (buffer))
-    buf = current_buffer;
-  else
-    {
-      CHECK_BUFFER (buffer);
-      buf = XBUFFER (buffer);
-    }
-
-  return make_number (BUF_MODIFF (buf));
+  return make_number (BUF_MODIFF (buffer_or_current (buffer)));
 }
 
 DEFUN ("buffer-chars-modified-tick", Fbuffer_chars_modified_tick,
@@ -1232,16 +1208,7 @@
 buffer as BUFFER.  */)
   (register Lisp_Object buffer)
 {
-  register struct buffer *buf;
-  if (NILP (buffer))
-    buf = current_buffer;
-  else
-    {
-      CHECK_BUFFER (buffer);
-      buf = XBUFFER (buffer);
-    }
-
-  return make_number (BUF_CHARS_MODIFF (buf));
+  return make_number (BUF_CHARS_MODIFF (buffer_or_current (buffer)));
 }
 
 DEFUN ("rename-buffer", Frename_buffer, Srename_buffer, 1, 2,
@@ -3580,17 +3547,11 @@
   (Lisp_Object beg, Lisp_Object end, Lisp_Object buffer, Lisp_Object front_advance, Lisp_Object rear_advance)
 {
   Lisp_Object overlay;
-  struct buffer *b;
+  struct buffer *b = buffer_or_current (buffer);
 
-  if (NILP (buffer))
-    XSETBUFFER (buffer, current_buffer);
-  else
-    CHECK_BUFFER (buffer);
-  if (MARKERP (beg)
-      && ! EQ (Fmarker_buffer (beg), buffer))
+  if (MARKERP (beg) && XMARKER (beg)->buffer != b)
     error ("Marker points into wrong buffer");
-  if (MARKERP (end)
-      && ! EQ (Fmarker_buffer (end), buffer))
+  if (MARKERP (end) && XMARKER (end)->buffer != b)
     error ("Marker points into wrong buffer");
 
   CHECK_NUMBER_COERCE_MARKER (beg);
@@ -3602,8 +3563,7 @@
       temp = beg; beg = end; end = temp;
     }
 
-  b = XBUFFER (buffer);
-
+  XSETBUFFER (buffer, b);
   beg = Fset_marker (Fmake_marker (), beg, buffer);
   end = Fset_marker (Fmake_marker (), end, buffer);
 
@@ -3705,18 +3665,14 @@
   CHECK_OVERLAY (overlay);
   if (NILP (buffer))
     buffer = Fmarker_buffer (OVERLAY_START (overlay));
-  if (NILP (buffer))
-    XSETBUFFER (buffer, current_buffer);
-  CHECK_BUFFER (buffer);
+  b = buffer_or_current (buffer);
 
-  if (NILP (Fbuffer_live_p (buffer)))
+  if (NILP (BVAR (b, name)))
     error ("Attempt to move overlay to a dead buffer");
 
-  if (MARKERP (beg)
-      && ! EQ (Fmarker_buffer (beg), buffer))
+  if (MARKERP (beg) && XMARKER (beg)->buffer != b)
     error ("Marker points into wrong buffer");
-  if (MARKERP (end)
-      && ! EQ (Fmarker_buffer (end), buffer))
+  if (MARKERP (end) && XMARKER (end)->buffer != b)
     error ("Marker points into wrong buffer");
 
   CHECK_NUMBER_COERCE_MARKER (beg);
@@ -3731,7 +3687,6 @@
   specbind (Qinhibit_quit, Qt);
 
   obuffer = Fmarker_buffer (OVERLAY_START (overlay));
-  b = XBUFFER (buffer);
 
   if (!NILP (obuffer))
     {

=== modified file 'src/buffer.h'
--- src/buffer.h	2012-06-16 12:24:15 +0000
+++ src/buffer.h	2012-06-22 05:37:28 +0000
@@ -886,6 +886,17 @@
 extern void fix_overlays_before (struct buffer *, ptrdiff_t, ptrdiff_t);
 extern void mmap_set_vars (int);
 
+/* Get buffer pointer from BUF, or current buffer pointer if BUF is nil.  */
+
+static inline struct buffer *
+buffer_or_current (Lisp_Object buf)
+{
+  if (NILP (buf))
+    return current_buffer;
+  CHECK_BUFFER (buf);
+  return XBUFFER (buf);
+}
+
 /* Get overlays at POSN into array OVERLAYS with NOVERLAYS elements.
    If NEXTP is non-NULL, return next overlay there.
    See overlay_at arg CHANGE_REQ for meaning of CHRQ arg.  */

=== modified file 'src/data.c'
--- src/data.c	2012-06-19 16:56:28 +0000
+++ src/data.c	2012-06-22 04:55:54 +0000
@@ -1827,14 +1827,7 @@
   register struct buffer *buf;
   struct Lisp_Symbol *sym;
 
-  if (NILP (buffer))
-    buf = current_buffer;
-  else
-    {
-      CHECK_BUFFER (buffer);
-      buf = XBUFFER (buffer);
-    }
-
+  buf = buffer_or_current (buffer);
   CHECK_SYMBOL (variable);
   sym = XSYMBOL (variable);
 

=== modified file 'src/fileio.c'
--- src/fileio.c	2012-06-20 21:20:06 +0000
+++ src/fileio.c	2012-06-22 04:55:59 +0000
@@ -5081,13 +5081,7 @@
   Lisp_Object handler;
   Lisp_Object filename;
 
-  if (NILP (buf))
-    b = current_buffer;
-  else
-    {
-      CHECK_BUFFER (buf);
-      b = XBUFFER (buf);
-    }
+  b = buffer_or_current (buf);
 
   if (!STRINGP (BVAR (b, filename))) return Qt;
   if (b->modtime == 0) return Qt;

=== modified file 'src/xdisp.c'
--- src/xdisp.c	2012-06-19 06:49:50 +0000
+++ src/xdisp.c	2012-06-22 05:09:06 +0000
@@ -19816,15 +19816,9 @@
 See also `bidi-paragraph-direction'.  */)
   (Lisp_Object buffer)
 {
-  struct buffer *buf = current_buffer;
+  struct buffer *buf = buffer_or_current (buffer);
   struct buffer *old = buf;
 
-  if (! NILP (buffer))
-    {
-      CHECK_BUFFER (buffer);
-      buf = XBUFFER (buffer);
-    }
-
   if (NILP (BVAR (buf, bidi_display_reordering))
       || NILP (BVAR (buf, enable_multibyte_characters))
       /* When we are loading loadup.el, the character property tables