cache shape plans even if (global) user features are set

src/hb-shape-plan-private.hh

@@ -45,6 +45,9 @@ struct hb_shape_plan_t
   hb_shape_func_t *shaper_func;
   const char *shaper_name;
 
+  hb_feature_t *user_features;
+  unsigned int num_user_features;
+
   struct hb_shaper_data_t shaper_data;
 };
 

src/hb-shape-plan.cc

@@ -107,18 +107,27 @@ hb_shape_plan_create (hb_face_t                     *face,
   assert (props->direction != HB_DIRECTION_INVALID);
 
   hb_shape_plan_t *shape_plan;
+  hb_feature_t *features = NULL;
 
   if (unlikely (!face))
     face = hb_face_get_empty ();
   if (unlikely (!props || hb_object_is_inert (face)))
     return hb_shape_plan_get_empty ();
-  if (!(shape_plan = hb_object_create<hb_shape_plan_t> ()))
+  if (num_user_features && !(features = (hb_feature_t *) malloc (num_user_features * sizeof (hb_feature_t))))
     return hb_shape_plan_get_empty ();
+  if (!(shape_plan = hb_object_create<hb_shape_plan_t> ())) {
+    free (features);
+    return hb_shape_plan_get_empty ();
+  }
 
   hb_face_make_immutable (face);
   shape_plan->default_shaper_list = shaper_list == NULL;
   shape_plan->face = hb_face_reference (face);
   shape_plan->props = *props;
+  shape_plan->num_user_features = num_user_features;
+  shape_plan->user_features = features;
+  if (num_user_features)
+    memcpy (features, user_features, num_user_features * sizeof (hb_feature_t));
 
   hb_shape_plan_plan (shape_plan, user_features, num_user_features, shaper_list);
 
@@ -147,6 +156,9 @@ hb_shape_plan_get_empty (void)
     NULL, /* shaper_func */
     NULL, /* shaper_name */
 
+    NULL, /* user_features */
+    0,    /* num_user_featurs */
+
     {
 #define HB_SHAPER_IMPLEMENT(shaper) HB_SHAPER_DATA_INVALID,
 #include "hb-shaper-list.hh"
@@ -191,6 +203,7 @@ hb_shape_plan_destroy (hb_shape_plan_t *shape_plan)
 #undef HB_SHAPER_IMPLEMENT
 
   hb_face_destroy (shape_plan->face);
+  free (shape_plan->user_features);
 
   free (shape_plan);
 }
@@ -301,23 +314,55 @@ hb_shape_plan_hash (const hb_shape_plan_t *shape_plan)
 }
 #endif
 
-/* TODO no user-feature caching for now. */
+/* User-feature caching is currently somewhat dumb:
+ * it only finds matches where the feature array is identical,
+ * not cases where the feature lists would be compatible for plan purposes
+ * but have different ranges, for example.
+ */
 struct hb_shape_plan_proposal_t
 {
   const hb_segment_properties_t  props;
   const char * const            *shaper_list;
+  const hb_feature_t            *user_features;
+  unsigned int                   num_user_features;
   hb_shape_func_t               *shaper_func;
 };
 
+static inline hb_bool_t
+hb_shape_plan_user_features_match (const hb_shape_plan_t          *shape_plan,
+				   const hb_shape_plan_proposal_t *proposal)
+{
+  if (proposal->num_user_features != shape_plan->num_user_features) return false;
+  for (unsigned int i = 0, n = proposal->num_user_features; i < n; i++)
+    if (proposal->user_features[i].tag   != shape_plan->user_features[i].tag   ||
+        proposal->user_features[i].value != shape_plan->user_features[i].value ||
+        proposal->user_features[i].start != shape_plan->user_features[i].start ||
+        proposal->user_features[i].end   != shape_plan->user_features[i].end) return false;
+  return true;
+}
+
 static hb_bool_t
 hb_shape_plan_matches (const hb_shape_plan_t          *shape_plan,
 		       const hb_shape_plan_proposal_t *proposal)
 {
   return hb_segment_properties_equal (&shape_plan->props, &proposal->props) &&
+	 hb_shape_plan_user_features_match (shape_plan, proposal) &&
 	 ((shape_plan->default_shaper_list && proposal->shaper_list == NULL) ||
 	  (shape_plan->shaper_func == proposal->shaper_func));
 }
 
+static inline hb_bool_t
+hb_non_global_user_features_present (const hb_feature_t *user_features,
+				     unsigned int        num_user_features)
+{
+  while (num_user_features)
+    if (user_features->start != 0 || user_features->end != (unsigned int) -1)
+      return true;
+    else
+      num_user_features--, user_features++;
+  return false;
+}
+
 /**
  * hb_shape_plan_create_cached:
  * @face: 
@@ -339,12 +384,11 @@ hb_shape_plan_create_cached (hb_face_t                     *face,
 			     unsigned int                   num_user_features,
 			     const char * const            *shaper_list)
 {
-  if (num_user_features)
-    return hb_shape_plan_create (face, props, user_features, num_user_features, shaper_list);
-
   hb_shape_plan_proposal_t proposal = {
     *props,
     shaper_list,
+    user_features,
+    num_user_features,
     NULL
   };
 
@@ -382,6 +426,11 @@ retry:
 
   hb_shape_plan_t *shape_plan = hb_shape_plan_create (face, props, user_features, num_user_features, shaper_list);
 
+  /* Don't add the plan to the cache if there were user features with non-global ranges */
+
+  if (hb_non_global_user_features_present (user_features, num_user_features))
+    return shape_plan;
+
   hb_face_t::plan_node_t *node = (hb_face_t::plan_node_t *) calloc (1, sizeof (hb_face_t::plan_node_t));
   if (unlikely (!node))
     return shape_plan;