[repacker] include LookupList size when calculating size of 16bit space for ext promotion decisions.

src/graph/graph.hh

@@ -111,6 +111,10 @@ struct graph_t
       return priority >= 3;
     }
 
+    size_t table_size () const {
+      return obj.tail - obj.head;
+    }
+
     int64_t modified_distance (unsigned order) const
     {
       // TODO(garretrieger): once priority is high enough, should try

src/graph/gsubgpos-graph.cc

@@ -34,11 +34,14 @@ make_extension_context_t::make_extension_context_t (hb_tag_t table_tag_,
     : table_tag (table_tag_),
       graph (graph_),
       buffer (buffer_),
+      lookup_list_index (0),
       lookups ()
 {
   GSTAR* gstar = graph::GSTAR::graph_to_gstar (graph_);
-  if (gstar)
+  if (gstar) {
     gstar->find_lookups (graph, lookups);
+    lookup_list_index = gstar->get_lookup_list_index (graph_);
+  }
 
   unsigned extension_size = OT::ExtensionFormat1<OT::Layout::GSUB_impl::ExtensionSubst>::static_size;
   buffer.alloc (num_non_ext_subtables () * extension_size);

src/graph/gsubgpos-graph.hh

@@ -40,6 +40,7 @@ struct make_extension_context_t
   hb_tag_t table_tag;
   graph_t& graph;
   hb_vector_t<char>& buffer;
+  unsigned lookup_list_index;
   hb_hashmap_t<unsigned, graph::Lookup*> lookups;
 
   HB_INTERNAL make_extension_context_t (hb_tag_t table_tag_,
@@ -224,12 +225,17 @@ struct GSTAR : public OT::GSUBGPOS
     }
   }
 
+  unsigned get_lookup_list_index (graph_t& graph)
+  {
+    return graph.index_for_offset (graph.root_idx (),
+                                   get_lookup_list_field_offset());
+  }
+
   template<typename Types>
   void find_lookups (graph_t& graph,
                      hb_hashmap_t<unsigned, Lookup*>& lookups /* OUT */)
   {
-    unsigned lookup_list_idx = graph.index_for_offset (graph.root_idx (),
-                                                       get_lookup_list_field_offset());
+    unsigned lookup_list_idx = get_lookup_list_index (graph);
 
     const LookupList<Types>* lookupList =
         (const LookupList<Types>*) graph.object (lookup_list_idx).head;

src/hb-repacker.hh

@@ -74,6 +74,8 @@ bool _promote_extensions_if_needed (graph::make_extension_context_t& ext_context
   // TODO(garretrieger): also support extension promotion during iterative resolution phase, then
   //                     we can use a less conservative threshold here.
 
+  if (!ext_context.lookups) return true;
+
   hb_vector_t<hb_pair_t<unsigned, size_t>> lookup_sizes;
   lookup_sizes.alloc (ext_context.lookups.get_population ());
 
@@ -88,7 +90,9 @@ bool _promote_extensions_if_needed (graph::make_extension_context_t& ext_context
 
   lookup_sizes.qsort (compare_sizes);
 
-  size_t accumlated_bytes = 0;
+  size_t accumlated_bytes =
+      ext_context.graph.vertices_[ext_context.lookup_list_index].table_size ();
+
   for (auto p : lookup_sizes)
   {
     unsigned lookup_index = p.first;