1 files changed, 47 insertions, 54 deletions

diff --git a/src/xdisp.c b/src/xdisp.c
index 3b82de9432d..463f4f9ef05 100644
--- a/src/xdisp.c
+++ b/src/xdisp.c
@@ -1392,21 +1392,9 @@ pos_visible_p (struct window *w, ptrdiff_t charpos, int *x, int *y,
 	      Lisp_Object cpos = make_number (charpos);
 	      Lisp_Object spec = Fget_char_property (cpos, Qdisplay, Qnil);
 	      Lisp_Object string = string_from_display_spec (spec);
-	      int newline_in_string = 0;
-
-	      if (STRINGP (string))
-		{
-		  const char *s = SSDATA (string);
-		  const char *e = s + SBYTES (string);
-		  while (s < e)
-		    {
-		      if (*s++ == '\n')
-			{
-			  newline_in_string = 1;
-			  break;
-			}
-		    }
-		}
+	      bool newline_in_string
+		= (STRINGP (string)
+		   && memchr (SDATA (string), '\n', SBYTES (string)));
 	      /* The tricky code below is needed because there's a
 		 discrepancy between move_it_to and how we set cursor
 		 when the display line ends in a newline from a
@@ -14759,7 +14747,7 @@ compute_window_start_on_continuation_line (struct window *w)
 	SET_TEXT_POS (start_pos, ZV, ZV_BYTE);
 
       /* Find the start of the continued line.  This should be fast
-	 because scan_buffer is fast (newline cache).  */
+	 because find_newline is fast (newline cache).  */
       row = w->desired_matrix->rows + (WINDOW_WANTS_HEADER_LINE_P (w) ? 1 : 0);
       init_iterator (&it, w, CHARPOS (start_pos), BYTEPOS (start_pos),
 		     row, DEFAULT_FACE_ID);
@@ -21626,31 +21614,36 @@ display_count_lines (ptrdiff_t start_byte,
 	  ceiling = min (limit_byte - 1, ceiling);
 	  ceiling_addr = BYTE_POS_ADDR (ceiling) + 1;
 	  base = (cursor = BYTE_POS_ADDR (start_byte));
-	  while (1)
+
+	  do
 	    {
 	      if (selective_display)
-		while (*cursor != '\n' && *cursor != 015 && ++cursor != ceiling_addr)
-		  ;
+		{
+		  while (*cursor != '\n' && *cursor != 015
+			 && ++cursor != ceiling_addr)
+		    continue;
+		  if (cursor == ceiling_addr)
+		    break;
+		}
 	      else
-		while (*cursor != '\n' && ++cursor != ceiling_addr)
-		  ;
+		{
+		  cursor = memchr (cursor, '\n', ceiling_addr - cursor);
+		  if (! cursor)
+		    break;
+		}
+
+	      cursor++;
 
-	      if (cursor != ceiling_addr)
+	      if (--count == 0)
 		{
-		  if (--count == 0)
-		    {
-		      start_byte += cursor - base + 1;
-		      *byte_pos_ptr = start_byte;
-		      return orig_count;
-		    }
-		  else
-		    if (++cursor == ceiling_addr)
-		      break;
+		  start_byte += cursor - base;
+		  *byte_pos_ptr = start_byte;
+		  return orig_count;
 		}
-	      else
-		break;
 	    }
-	  start_byte += cursor - base;
+	  while (cursor < ceiling_addr);
+
+	  start_byte += ceiling_addr - base;
 	}
     }
   else
@@ -21659,35 +21652,35 @@ display_count_lines (ptrdiff_t start_byte,
 	{
 	  ceiling = BUFFER_FLOOR_OF (start_byte - 1);
 	  ceiling = max (limit_byte, ceiling);
-	  ceiling_addr = BYTE_POS_ADDR (ceiling) - 1;
+	  ceiling_addr = BYTE_POS_ADDR (ceiling);
 	  base = (cursor = BYTE_POS_ADDR (start_byte - 1) + 1);
 	  while (1)
 	    {
 	      if (selective_display)
-		while (--cursor != ceiling_addr
-		       && *cursor != '\n' && *cursor != 015)
-		  ;
+		{
+		  while (--cursor >= ceiling_addr
+			 && *cursor != '\n' && *cursor != 015)
+		    continue;
+		  if (cursor < ceiling_addr)
+		    break;
+		}
 	      else
-		while (--cursor != ceiling_addr && *cursor != '\n')
-		  ;
+		{
+		  cursor = memrchr (ceiling_addr, '\n', cursor - ceiling_addr);
+		  if (! cursor)
+		    break;
+		}
 
-	      if (cursor != ceiling_addr)
+	      if (++count == 0)
 		{
-		  if (++count == 0)
-		    {
-		      start_byte += cursor - base + 1;
-		      *byte_pos_ptr = start_byte;
-		      /* When scanning backwards, we should
-			 not count the newline posterior to which we stop.  */
-		      return - orig_count - 1;
-		    }
+		  start_byte += cursor - base + 1;
+		  *byte_pos_ptr = start_byte;
+		  /* When scanning backwards, we should
+		     not count the newline posterior to which we stop.  */
+		  return - orig_count - 1;
 		}
-	      else
-		break;
 	    }
-	  /* Here we add 1 to compensate for the last decrement
-	     of CURSOR, which took it past the valid range.  */
-	  start_byte += cursor - base + 1;
+	  start_byte += ceiling_addr - base;
 	}
     }