Avoid long futile looping on a TTY under huge values of hscroll.

 src/xdisp.c (display_line): Fix horizontal pixel coordinates when
 hscroll is larger than the line width.  Fixes long and futile
 looping inside extend_face_to_end_of_line (on a TTY) producing
 glyphs that are not needed and thrown away.

2 files changed, 22 insertions, 2 deletions

diff --git a/src/ChangeLog b/src/ChangeLog
index a2cfd3029f3..1fdeee52f7f 100644
--- a/src/ChangeLog
+++ b/src/ChangeLog
@@ -1,3 +1,10 @@
+2012-07-05  Eli Zaretskii  <eliz@gnu.org>
+
+        * xdisp.c (display_line): Fix horizontal pixel coordinates when
+        hscroll is larger than the line width.  Fixes long and futile
+        looping inside extend_face_to_end_of_line (on a TTY) producing
+        glyphs that are not needed and thrown away.
+
 2012-07-05  Dmitry Antipov  <dmantipov@yandex.ru>
 
         * marker.c (set_marker_restricted_both): Simplify by using
diff --git a/src/xdisp.c b/src/xdisp.c
index d24c05172b6..0c210198fc5 100644
--- a/src/xdisp.c
+++ b/src/xdisp.c
@@ -19177,9 +19177,22 @@ display_line (struct it *it)
      if the first glyph is partially visible or if we hit a line end.  */
   if (it->current_x < it->first_visible_x)
     {
+      enum move_it_result move_result;
+
       this_line_min_pos = row->start.pos;
-      move_it_in_display_line_to (it, ZV, it->first_visible_x,
-                                  MOVE_TO_POS | MOVE_TO_X);
+      move_result = move_it_in_display_line_to (it, ZV, it->first_visible_x,
+                                                MOVE_TO_POS | MOVE_TO_X);
+      /* If we are under a large hscroll, move_it_in_display_line_to
+         could hit the end of the line without reaching
+         it->first_visible_x.  Pretend that we did reach it.  This is
+         especially important on a TTY, where we will call
+         extend_face_to_end_of_line, which needs to know how many
+         blank glyphs to produce.  */
+      if (it->current_x < it->first_visible_x
+          && (move_result == MOVE_NEWLINE_OR_CR
+              || move_result == MOVE_POS_MATCH_OR_ZV))
+        it->current_x = it->first_visible_x;
+
       /* Record the smallest positions seen while we moved over
          display elements that are not visible.  This is needed by
          redisplay_internal for optimizing the case where the cursor