* buffer.c (unchain_overlay): Simplify. Add comment.

* marker.c (unchain_marker): Simplify.  Fix comments.

src/ChangeLog

+2012-07-06  Dmitry Antipov  <dmantipov@yandex.ru>
+
+	* buffer.c (unchain_overlay): Simplify.  Add comment.
+	* marker.c (unchain_marker): Simplify. Fix comments.
+
 2012-07-06  Dmitry Antipov  <dmantipov@yandex.ru>
 
 	Introduce fast path for the widely used marker operation.

src/buffer.c

@@ -3672,18 +3672,17 @@ modify_overlay (struct buffer *buf, ptrdiff_t start, ptrdiff_t end)
   ++BUF_OVERLAY_MODIFF (buf);
 }
 
-
+/* Remove OVERLAY from LIST.  */
+
 static struct Lisp_Overlay *
 unchain_overlay (struct Lisp_Overlay *list, struct Lisp_Overlay *overlay)
 {
-  struct Lisp_Overlay *tmp, *prev;
-  for (tmp = list, prev = NULL; tmp; prev = tmp, tmp = tmp->next)
-    if (tmp == overlay)
+  register struct Lisp_Overlay *tail, **prev = &list;
+
+  for (tail = list; tail; prev = &tail->next, tail = *prev)
+    if (tail == overlay)
       {
-	if (prev)
-	  prev->next = tmp->next;
-	else
-	  list = tmp->next;
+	*prev = overlay->next;
 	overlay->next = NULL;
 	break;
       }

src/marker.c

@@ -672,59 +672,47 @@ set_marker_restricted_both (Lisp_Object marker, Lisp_Object buffer, ptrdiff_t ch
   return marker;
 }
 
-/* Remove MARKER from the chain of whatever buffer it is in.
-   Leave it "in no buffer".
-
-   This is called during garbage collection,
-   so we must be careful to ignore and preserve mark bits,
-   including those in chain fields of markers.  */
+/* Remove MARKER from the chain of whatever buffer it is in,
+   leaving it points to nowhere.  This is called during garbage
+   collection, so we must be careful to ignore and preserve
+   mark bits, including those in chain fields of markers.  */
 
 void
 unchain_marker (register struct Lisp_Marker *marker)
 {
-  register struct Lisp_Marker *tail, *prev, *next;
-  register struct buffer *b;
-
-  b = marker->buffer;
-  if (b == 0)
-    return;
-
-  if (EQ (BVAR (b, name), Qnil))
-    abort ();
+  register struct buffer *b = marker->buffer;
 
-  marker->buffer = 0;
-
-  tail = BUF_MARKERS (b);
-  prev = NULL;
-  while (tail)
+  if (b)
     {
-      next = tail->next;
-
-      if (marker == tail)
-	{
-	  if (!prev)
-	    {
-	      BUF_MARKERS (b) = next;
-	      /* Deleting first marker from the buffer's chain.  Crash
-		 if new first marker in chain does not say it belongs
-		 to the same buffer, or at least that they have the same
-		 base buffer.  */
-	      if (next && b->text != next->buffer->text)
-		abort ();
-	    }
-	  else
-	    prev->next = next;
-	  /* We have removed the marker from the chain;
-	     no need to scan the rest of the chain.  */
-	  return;
-	}
-      else
-	prev = tail;
-      tail = next;
+      register struct Lisp_Marker *tail, **prev;
+
+      /* No dead buffers here.  */
+      eassert (!NILP (BVAR (b, name)));
+
+      marker->buffer = NULL;
+      prev = &BUF_MARKERS (b);
+
+      for (tail = BUF_MARKERS (b); tail; prev = &tail->next, tail = *prev)
+	if (marker == tail)
+	  {
+	    if (*prev == BUF_MARKERS (b))
+	      {
+		/* Deleting first marker from the buffer's chain.  Crash 
+		   if new first marker in chain does not say it belongs
+		   to the same buffer, or at least that they have the same
+		   base buffer.  */
+		if (tail->next && b->text != tail->next->buffer->text)
+		  abort ();
+	      }
+	    *prev = tail->next;
+	    /* We have removed the marker from the chain;
+	       no need to scan the rest of the chain.  */
+	    break;
+	  }
+
+      /* Error if marker was not in it's chain.  */
+      eassert (tail != NULL);
     }
-
-  /* Marker was not in its chain.  */
-  abort ();
 }
 
 /* Return the char position of marker MARKER, as a C integer.  */