[subset] cache sanitized tables in subset plan to avoid sanitizing tables multiple times.

src/hb-subset-plan.cc

@@ -164,7 +164,7 @@ _closure_glyphs_lookups_features (hb_subset_plan_t   *plan,
 				  hb_map_t	     *features,
 				  script_langsys_map *langsys_map)
 {
-  hb_blob_ptr_t<T> table = hb_sanitize_context_t ().reference_table<T> (plan->source);
+  hb_blob_ptr_t<T> table = plan->source_table<T> ();
   hb_tag_t table_tag = table->tableTag;
   hb_set_t lookup_indices;
   _collect_layout_indices<T> (plan,
@@ -203,14 +203,14 @@ _closure_glyphs_lookups_features (hb_subset_plan_t   *plan,
 
 #ifndef HB_NO_VAR
 static inline void
-  _collect_layout_variation_indices (hb_face_t *face,
+_collect_layout_variation_indices (hb_subset_plan_t* plan,
 				   const hb_set_t *glyphset,
 				   const hb_map_t *gpos_lookups,
 				   hb_set_t  *layout_variation_indices,
 				   hb_map_t  *layout_variation_idx_map)
 {
-  hb_blob_ptr_t<OT::GDEF> gdef = hb_sanitize_context_t ().reference_table<OT::GDEF> (face);
-  hb_blob_ptr_t<GPOS> gpos = hb_sanitize_context_t ().reference_table<GPOS> (face);
+  hb_blob_ptr_t<OT::GDEF> gdef = plan->source_table<OT::GDEF> ();
+  hb_blob_ptr_t<GPOS> gpos = plan->source_table<GPOS> ();
 
   if (!gdef->has_data ())
   {
@@ -221,7 +221,7 @@ static inline void
   OT::hb_collect_variation_indices_context_t c (layout_variation_indices, glyphset, gpos_lookups);
   gdef->collect_variation_indices (&c);
 
-  if (hb_ot_layout_has_positioning (face))
+  if (hb_ot_layout_has_positioning (plan->source))
     gpos->collect_variation_indices (&c);
 
   gdef->remap_layout_variation_indices (layout_variation_indices, layout_variation_idx_map);
@@ -271,10 +271,10 @@ static void _colr_closure (hb_face_t *face,
 }
 
 static inline void
-_math_closure (hb_face_t           *face,
+_math_closure (hb_subset_plan_t *plan,
                hb_set_t         *glyphset)
 {
-  hb_blob_ptr_t<OT::MATH> math = hb_sanitize_context_t ().reference_table<OT::MATH> (face);
+  hb_blob_ptr_t<OT::MATH> math = plan->source_table<OT::MATH> ();
   if (math->has_data ())
     math->closure_glyphs (glyphset);
   math.destroy ();
@@ -418,7 +418,7 @@ _populate_gids_to_retain (hb_subset_plan_t* plan,
   _remove_invalid_gids (plan->_glyphset_gsub, plan->source->get_num_glyphs ());
 
   hb_set_set (plan->_glyphset_mathed, plan->_glyphset_gsub);
-  _math_closure (plan->source, plan->_glyphset_mathed);
+  _math_closure (plan, plan->_glyphset_mathed);
   _remove_invalid_gids (plan->_glyphset_mathed, plan->source->get_num_glyphs ());
 
   hb_set_t cur_glyphset = *plan->_glyphset_mathed;
@@ -446,7 +446,7 @@ _populate_gids_to_retain (hb_subset_plan_t* plan,
 
 #ifndef HB_NO_VAR
   if (close_over_gdef)
-    _collect_layout_variation_indices (plan->source,
+    _collect_layout_variation_indices (plan,
 				       plan->_glyphset_gsub,
 				       plan->gpos_lookups,
 				       plan->layout_variation_indices,
@@ -583,6 +583,11 @@ hb_subset_plan_create_or_fail (hb_face_t	 *face,
   plan->layout_variation_indices = hb_set_create ();
   plan->layout_variation_idx_map = hb_map_create ();
 
+
+  if ((plan->sanitized_table_cache = hb_object_create<hb_hashmap_t<hb_tag_t, hb::unique_ptr<hb_blob_t>>> ())) {
+    plan->sanitized_table_cache->init_shallow ();
+  }
+
   if (unlikely (plan->in_error ())) {
     hb_subset_plan_destroy (plan);
     return nullptr;
@@ -678,6 +683,12 @@ hb_subset_plan_destroy (hb_subset_plan_t *plan)
     hb_free (plan->gpos_langsys);
   }
 
+  if (plan->sanitized_table_cache) {
+    hb_object_destroy (plan->sanitized_table_cache);
+    plan->sanitized_table_cache->fini ();
+    hb_free (plan->sanitized_table_cache);
+  }
+
   hb_free (plan);
 }
 

src/hb-subset-plan.hh

@@ -106,8 +106,29 @@ struct hb_subset_plan_t
   //Old -> New layout item variation store delta set index mapping
   hb_map_t *layout_variation_idx_map;
 
+  hb_hashmap_t<hb_tag_t, hb::unique_ptr<hb_blob_t>>* sanitized_table_cache;
+
  public:
 
+  template<typename T>
+  hb_blob_ptr_t<T> source_table()
+  {
+    if (sanitized_table_cache
+        && !sanitized_table_cache->in_error ()
+        && sanitized_table_cache->has (T::tableTag)) {
+      return hb_blob_reference (sanitized_table_cache->get (T::tableTag).get ());
+    }
+
+    hb::unique_ptr<hb_blob_t> table_blob {hb_sanitize_context_t ().reference_table<T> (source)};
+    hb_blob_t* ret = hb_blob_reference (table_blob.get ());
+
+    if (likely (sanitized_table_cache))
+      sanitized_table_cache->set (T::tableTag,
+                                  std::move (table_blob));
+
+    return ret;
+  }
+
   bool in_error () const { return !successful; }
 
   bool check_success(bool success)

src/hb-subset.cc

@@ -260,15 +260,15 @@ template<typename TableType>
 static bool
 _subset (hb_subset_plan_t *plan, hb_vector_t<char> &buf)
 {
-  hb_blob_t *source_blob = hb_sanitize_context_t ().reference_table<TableType> (plan->source);
-  const TableType *table = source_blob->as<TableType> ();
+  hb_blob_ptr_t<TableType> source_blob = plan->source_table<TableType> ();
+  const TableType *table = source_blob.get ();
 
   hb_tag_t tag = TableType::tableTag;
-  if (!source_blob->data)
+  if (!source_blob.get_blob()->data)
   {
     DEBUG_MSG (SUBSET, nullptr,
                "OT::%c%c%c%c::subset sanitize failed on source table.", HB_UNTAG (tag));
-    hb_blob_destroy (source_blob);
+    source_blob.destroy ();
     return false;
   }
 
@@ -278,23 +278,23 @@ _subset (hb_subset_plan_t *plan, hb_vector_t<char> &buf)
 			 TableType::tableTag == HB_OT_TAG_GPOS ||
 			 TableType::tableTag == HB_OT_TAG_name;
 
-  unsigned buf_size = _plan_estimate_subset_table_size (plan, source_blob->length, same_size_table);
+  unsigned buf_size = _plan_estimate_subset_table_size (plan, source_blob.get_length (), same_size_table);
   DEBUG_MSG (SUBSET, nullptr,
              "OT::%c%c%c%c initial estimated table size: %u bytes.", HB_UNTAG (tag), buf_size);
   if (unlikely (!buf.alloc (buf_size)))
   {
     DEBUG_MSG (SUBSET, nullptr, "OT::%c%c%c%c failed to allocate %u bytes.", HB_UNTAG (tag), buf_size);
-    hb_blob_destroy (source_blob);
+    source_blob.destroy ();
     return false;
   }
 
   bool needed = false;
   hb_serialize_context_t serializer (buf.arrayZ, buf.allocated);
   {
-    hb_subset_context_t c (source_blob, plan, &serializer, tag);
+    hb_subset_context_t c (source_blob.get_blob (), plan, &serializer, tag);
     needed = _try_subset (table, &buf, &c);
   }
-  hb_blob_destroy (source_blob);
+  source_blob.destroy ();
 
   if (serializer.in_error () && !serializer.only_offset_overflow ())
   {