(move_it_vertically_backward): At the end of the

function, when moving forward by lines, treat terminal frames
specially.

diff --git a/src/xdisp.c b/src/xdisp.c
index b1b2fd6bc5967ffff49ce6fef598db02ba4c6fc3..4760893d2848968641fbdf5c55694036294e7b5f 100644 (file)
--- a/src/xdisp.c
+++ b/src/xdisp.c
@@ -5404,12 +5404,24 @@ move_it_vertically_backward (it, dy)
       else if (target_y >= it->current_y + line_height
               && IT_CHARPOS (*it) < ZV)
        {
-         /* Should move forward by at least one line, maybe more.  */
-         do
+         /* Should move forward by at least one line, maybe more.
+            
+            Note: Calling move_it_by_lines can be expensive on
+            terminal frames, where compute_motion is used (via
+            vmotion) to do the job, when there are very long lines
+            and truncate-lines is nil.  That's the reason for
+            treating terminal frames specially here.  */
+         
+         if (!FRAME_WINDOW_P (it->f))
+           move_it_vertically (it, target_y - (it->current_y + line_height));
+         else
            {
-             move_it_by_lines (it, 1, 1);
+             do
+               {
+                 move_it_by_lines (it, 1, 1);
+               }
+             while (target_y >= line_bottom_y (it) && IT_CHARPOS (*it) < ZV);
            }
-         while (target_y >= line_bottom_y (it) && IT_CHARPOS (*it) < ZV);
 
          xassert (IT_CHARPOS (*it) >= BEGV);
        }