[subset] Cache has_seac in accelerator

Speeds up SourceHanSans-Regular/10000 benchmark by %25.

src/hb-subset-accelerator.hh

@@ -43,10 +43,12 @@ struct hb_subset_accelerator_t
   }
 
   static hb_subset_accelerator_t* create(const hb_map_t& unicode_to_gid_,
-                                         const hb_set_t& unicodes_) {
+                                         const hb_set_t& unicodes_,
+					 bool has_seac_) {
     hb_subset_accelerator_t* accel =
         (hb_subset_accelerator_t*) hb_malloc (sizeof(hb_subset_accelerator_t));
     new (accel) hb_subset_accelerator_t (unicode_to_gid_, unicodes_);
+    accel->has_seac = has_seac_;
     return accel;
   }
 
@@ -64,6 +66,7 @@ struct hb_subset_accelerator_t
 
   const hb_map_t unicode_to_gid;
   const hb_set_t unicodes;
+  bool has_seac;
   // TODO(garretrieger): cumulative glyf checksum map
   // TODO(garretrieger): sanitized table cache.
 

src/hb-subset-plan.cc

@@ -47,7 +47,7 @@ using OT::Layout::GPOS;
 
 typedef hb_hashmap_t<unsigned, hb::unique_ptr<hb_set_t>> script_langsys_map;
 #ifndef HB_NO_SUBSET_CFF
-static inline void
+static inline bool
 _add_cff_seac_components (const OT::cff1::accelerator_t &cff,
 			  hb_codepoint_t gid,
 			  hb_set_t *gids_to_retain)
@@ -57,7 +57,9 @@ _add_cff_seac_components (const OT::cff1::accelerator_t &cff,
   {
     gids_to_retain->add (base_gid);
     gids_to_retain->add (accent_gid);
+    return true;
   }
+  return false;
 }
 #endif
 
@@ -639,9 +641,15 @@ _populate_gids_to_retain (hb_subset_plan_t* plan,
   else
     plan->_glyphset->union_ (cur_glyphset);
 #ifndef HB_NO_SUBSET_CFF
-  if (cff.is_valid ())
-    for (hb_codepoint_t gid : cur_glyphset)
-      _add_cff_seac_components (cff, gid, plan->_glyphset);
+  if (!plan->accelerator || plan->accelerator->has_seac)
+  {
+    bool has_seac = false;
+    if (cff.is_valid ())
+      for (hb_codepoint_t gid : cur_glyphset)
+	if (_add_cff_seac_components (cff, gid, plan->_glyphset))
+	  has_seac = true;
+    plan->has_seac = has_seac;
+  }
 #endif
 
   _remove_invalid_gids (plan->_glyphset, plan->source->get_num_glyphs ());

src/hb-subset-plan.hh

@@ -194,6 +194,7 @@ struct hb_subset_plan_t
   hb_map_t *axes_old_index_tag_map;
   bool all_axes_pinned;
   bool pinned_at_default;
+  bool has_seac;
 
   //hmtx metrics map: new gid->(advance, lsb)
   hb_hashmap_t<unsigned, hb_pair_t<unsigned, int>> *hmtx_map;

src/hb-subset.cc

@@ -504,7 +504,8 @@ static void _attach_accelerator_data (const hb_subset_plan_t* plan,
 {
   hb_subset_accelerator_t* accel =
       hb_subset_accelerator_t::create (*plan->codepoint_to_glyph,
-                                       *plan->unicodes);
+                                       *plan->unicodes,
+				       plan->has_seac);
 
   if (accel->in_error ())
   {