First take on minimizing face-related X calls

Introduce a frame-specific face_change flag, and set only it
when a face change involves a single frame.
Prevent redisplay from skipping a window when its frame's
face_change flag is set.  Ditto for redisplay optimization 1.
Don't free all faces when the frame's screen-gamma parameter is set.
Don't clear face caches (on all frames!) when tty colors are
registered at startup, when the selected frame is a GUI frame.

5 files changed, 50 insertions, 22 deletions

diff --git a/lisp/term/tty-colors.el b/lisp/term/tty-colors.el
index 98108ce6356..3bc1aa0ee48 100644
--- a/lisp/term/tty-colors.el
+++ b/lisp/term/tty-colors.el
@@ -810,9 +810,11 @@ Value is the modified color alist for FRAME."
     (while colors
       (tty-color-define (car color) (cadr color) (cddr color))
       (setq colors (cdr colors) color (car colors)))
-    ;; Modifying color mappings means realized faces don't
-    ;; use the right colors, so clear them.
-    (clear-face-cache)))
+    ;; Modifying color mappings means realized faces don't use the
+    ;; right colors, so clear them, if we modified colors on a TTY
+    ;; frame.
+    (or (display-graphic-p)
+        (clear-face-cache))))
 
 (defun tty-color-canonicalize (color)
   "Return COLOR in canonical form.
diff --git a/src/frame.c b/src/frame.c
index 0e95749a055..a4ebffc443a 100644
--- a/src/frame.c
+++ b/src/frame.c
@@ -3517,7 +3517,7 @@ x_set_line_spacing (struct frame *f, Lisp_Object new_value, Lisp_Object old_valu
 void
 x_set_screen_gamma (struct frame *f, Lisp_Object new_value, Lisp_Object old_value)
 {
-  Lisp_Object bgcolor;
+  Lisp_Object bgcolor, frame;
 
   if (NILP (new_value))
     f->gamma = 0;
@@ -3539,7 +3539,8 @@ x_set_screen_gamma (struct frame *f, Lisp_Object new_value, Lisp_Object old_valu
 	    (f, bgcolor, Qnil);
     }
 
-  Fclear_face_cache (Qnil);
+  clear_face_cache (true);
+  windows_or_buffers_changed = 70;
 }
 
 
diff --git a/src/frame.h b/src/frame.h
index 546bede213d..af0dadb3d99 100644
--- a/src/frame.h
+++ b/src/frame.h
@@ -335,6 +335,9 @@ struct frame
   /* Set to true after this frame was made by `make-frame'.  */
   bool_bf after_make_frame : 1;
 
+  /* Non-zero if this frame's faces need to be recomputed.  */
+  bool_bf face_change : 1;
+
   /* Bitfield area ends here.  */
 
   /* Number of lines (rounded up) of tool bar.  REMOVE THIS  */
diff --git a/src/xdisp.c b/src/xdisp.c
index 3eff61f3716..9845a9a1dbb 100644
--- a/src/xdisp.c
+++ b/src/xdisp.c
@@ -2661,10 +2661,18 @@ init_iterator (struct it *it, struct window *w,
      free realized faces now because they depend on face definitions
      that might have changed.  Don't free faces while there might be
      desired matrices pending which reference these faces.  */
-  if (face_change && !inhibit_free_realized_faces)
+  if (!inhibit_free_realized_faces)
     {
-      face_change = false;
-      free_all_realized_faces (Qnil);
+      if (face_change)
+	{
+	  face_change = false;
+	  free_all_realized_faces (Qnil);
+	}
+      else if (XFRAME (w->frame)->face_change)
+	{
+	  XFRAME (w->frame)->face_change = 0;
+	  free_all_realized_faces (w->frame);
+	}
     }
 
   /* Perhaps remap BASE_FACE_ID to a user-specified alternative.  */
@@ -13531,6 +13539,7 @@ redisplay_internal (void)
       && FRAME_VISIBLE_P (XFRAME (w->frame))
       && !FRAME_OBSCURED_P (XFRAME (w->frame))
       && !XFRAME (w->frame)->cursor_type_changed
+      && !XFRAME (w->frame)->face_change
       /* Make sure recorded data applies to current buffer, etc.  */
       && this_line_buffer == current_buffer
       && match_p
@@ -15877,6 +15886,7 @@ redisplay_window (Lisp_Object window, bool just_this_one_p)
       && REDISPLAY_SOME_P ()
       && !w->redisplay
       && !w->update_mode_line
+      && !f->face_change
       && !f->redisplay
       && !buffer->text->redisplay
       && BUF_PT (buffer) == w->last_point)
diff --git a/src/xfaces.c b/src/xfaces.c
index 94f3c4d67c2..40713f167ff 100644
--- a/src/xfaces.c
+++ b/src/xfaces.c
@@ -687,7 +687,6 @@ clear_face_cache (bool clear_fonts_p)
 #endif /* HAVE_WINDOW_SYSTEM */
 }
 
-
 DEFUN ("clear-face-cache", Fclear_face_cache, Sclear_face_cache, 0, 1, 0,
        doc: /* Clear face caches on all frames.
 Optional THOROUGHLY non-nil means try to free unused fonts, too.  */)
@@ -2528,7 +2527,10 @@ Value is a vector of face attributes.  */)
      free realized faces.  */
   if (NILP (Fget (face, Qface_no_inherit)))
     {
-      face_change = true;
+      if (f)
+	f->face_change = 1;
+      else
+	face_change = true;
       windows_or_buffers_changed = 54;
     }
 
@@ -2576,6 +2578,7 @@ The value is TO.  */)
   (Lisp_Object from, Lisp_Object to, Lisp_Object frame, Lisp_Object new_frame)
 {
   Lisp_Object lface, copy;
+  struct frame *f;
 
   CHECK_SYMBOL (from);
   CHECK_SYMBOL (to);
@@ -2586,6 +2589,7 @@ The value is TO.  */)
 	 strings etc. because 20.2 didn't do it either.  */
       lface = lface_from_face_name (NULL, from, true);
       copy = Finternal_make_lisp_face (to, Qnil);
+      f = NULL;
     }
   else
     {
@@ -2596,6 +2600,7 @@ The value is TO.  */)
       CHECK_LIVE_FRAME (new_frame);
       lface = lface_from_face_name (XFRAME (frame), from, true);
       copy = Finternal_make_lisp_face (to, new_frame);
+      f = XFRAME (new_frame);
     }
 
   vcopy (copy, 0, XVECTOR (lface)->contents, LFACE_VECTOR_SIZE);
@@ -2607,7 +2612,10 @@ The value is TO.  */)
      free realized faces.  */
   if (NILP (Fget (to, Qface_no_inherit)))
     {
-      face_change = true;
+      if (f)
+	f->face_change = 1;
+      else
+	face_change = true;
       windows_or_buffers_changed = 55;
     }
 
@@ -2630,6 +2638,7 @@ FRAME 0 means change the face on all frames, and change the default
   /* Set one of enum font_property_index (> 0) if ATTR is one of
      font-related attributes other than QCfont and QCfontset.  */
   enum font_property_index prop_index = 0;
+  struct frame *f;
 
   CHECK_SYMBOL (face);
   CHECK_SYMBOL (attr);
@@ -2650,6 +2659,7 @@ FRAME 0 means change the face on all frames, and change the default
   /* Set lface to the Lisp attribute vector of FACE.  */
   if (EQ (frame, Qt))
     {
+      f = NULL;
       lface = lface_from_face_name (NULL, face, true);
 
       /* When updating face-new-frame-defaults, we put :ignore-defface
@@ -2665,9 +2675,10 @@ FRAME 0 means change the face on all frames, and change the default
     {
       if (NILP (frame))
 	frame = selected_frame;
+      f = XFRAME (frame);
 
       CHECK_LIVE_FRAME (frame);
-      lface = lface_from_face_name (XFRAME (frame), face, false);
+      lface = lface_from_face_name (f, face, false);
 
       /* If a frame-local face doesn't exist yet, create one.  */
       if (NILP (lface))
@@ -2989,11 +3000,11 @@ FRAME 0 means change the face on all frames, and change the default
   else if (EQ (attr, QCfont))
     {
 #ifdef HAVE_WINDOW_SYSTEM
-      if (EQ (frame, Qt) || FRAME_WINDOW_P (XFRAME (frame)))
+      if (EQ (frame, Qt) || FRAME_WINDOW_P (f))
 	{
 	  if (!UNSPECIFIEDP (value) && !IGNORE_DEFFACE_P (value))
 	    {
-	      struct frame *f;
+	      struct frame *f1;
 
 	      old_value = LFACE_FONT (lface);
 	      if (! FONTP (value))
@@ -3013,28 +3024,29 @@ FRAME 0 means change the face on all frames, and change the default
 		    signal_error ("Invalid font or font-spec", value);
 		}
 	      if (EQ (frame, Qt))
-		f = XFRAME (selected_frame);
+		f1 = XFRAME (selected_frame);
 	      else
-		f = XFRAME (frame);
+		f1 = XFRAME (frame);
 
               /* FIXME:
                  If frame is t, and selected frame is a tty frame, the font
                  can't be realized.  An improvement would be to loop over frames
                  for a non-tty frame and use that.  See discussion in Bug#18573.
                  For a daemon, frame may be an initial frame (Bug#18869).  */
-              if (FRAME_WINDOW_P (f))
+              if (FRAME_WINDOW_P (f1))
                 {
                   if (! FONT_OBJECT_P (value))
                     {
                       Lisp_Object *attrs = XVECTOR (lface)->contents;
                       Lisp_Object font_object;
 
-                      font_object = font_load_for_lface (f, attrs, value);
+                      font_object = font_load_for_lface (f1, attrs, value);
                       if (NILP (font_object))
                         signal_error ("Font not available", value);
                       value = font_object;
                     }
-                  set_lface_from_font (f, lface, value, true);
+                  set_lface_from_font (f1, lface, value, true);
+		  f1->face_change = 1;
                 }
 	    }
 	  else
@@ -3045,7 +3057,7 @@ FRAME 0 means change the face on all frames, and change the default
   else if (EQ (attr, QCfontset))
     {
 #ifdef HAVE_WINDOW_SYSTEM
-      if (EQ (frame, Qt) || FRAME_WINDOW_P (XFRAME (frame)))
+      if (EQ (frame, Qt) || FRAME_WINDOW_P (f))
 	{
 	  Lisp_Object tmp;
 
@@ -3107,7 +3119,7 @@ FRAME 0 means change the face on all frames, and change the default
       && NILP (Fget (face, Qface_no_inherit))
       && NILP (Fequal (old_value, value)))
     {
-      face_change = true;
+      f->face_change = true;
       windows_or_buffers_changed = 56;
     }
 
@@ -3280,7 +3292,7 @@ update_face_from_frame_parameter (struct frame *f, Lisp_Object param,
   if (!NILP (face)
       && NILP (Fget (face, Qface_no_inherit)))
     {
-      face_change = true;
+      f->face_change = true;
       windows_or_buffers_changed = 57;
     }
 }