initial commit, 4.5 stable

thirdparty/harfbuzz/src/graph/classdef-graph.hh

@@ -0,0 +1,257 @@
+/*
+ * Copyright © 2022  Google, Inc.
+ *
+ *  This is part of HarfBuzz, a text shaping library.
+ *
+ * Permission is hereby granted, without written agreement and without
+ * license or royalty fees, to use, copy, modify, and distribute this
+ * software and its documentation for any purpose, provided that the
+ * above copyright notice and the following two paragraphs appear in
+ * all copies of this software.
+ *
+ * IN NO EVENT SHALL THE COPYRIGHT HOLDER BE LIABLE TO ANY PARTY FOR
+ * DIRECT, INDIRECT, SPECIAL, INCIDENTAL, OR CONSEQUENTIAL DAMAGES
+ * ARISING OUT OF THE USE OF THIS SOFTWARE AND ITS DOCUMENTATION, EVEN
+ * IF THE COPYRIGHT HOLDER HAS BEEN ADVISED OF THE POSSIBILITY OF SUCH
+ * DAMAGE.
+ *
+ * THE COPYRIGHT HOLDER SPECIFICALLY DISCLAIMS ANY WARRANTIES, INCLUDING,
+ * BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND
+ * FITNESS FOR A PARTICULAR PURPOSE.  THE SOFTWARE PROVIDED HEREUNDER IS
+ * ON AN "AS IS" BASIS, AND THE COPYRIGHT HOLDER HAS NO OBLIGATION TO
+ * PROVIDE MAINTENANCE, SUPPORT, UPDATES, ENHANCEMENTS, OR MODIFICATIONS.
+ *
+ * Google Author(s): Garret Rieger
+ */
+
+#include "graph.hh"
+#include "../hb-ot-layout-common.hh"
+
+#ifndef GRAPH_CLASSDEF_GRAPH_HH
+#define GRAPH_CLASSDEF_GRAPH_HH
+
+namespace graph {
+
+struct ClassDefFormat1 : public OT::ClassDefFormat1_3<SmallTypes>
+{
+  bool sanitize (graph_t::vertex_t& vertex) const
+  {
+    int64_t vertex_len = vertex.obj.tail - vertex.obj.head;
+    constexpr unsigned min_size = OT::ClassDefFormat1_3<SmallTypes>::min_size;
+    if (vertex_len < min_size) return false;
+    hb_barrier ();
+    return vertex_len >= min_size + classValue.get_size () - classValue.len.get_size ();
+  }
+};
+
+struct ClassDefFormat2 : public OT::ClassDefFormat2_4<SmallTypes>
+{
+  bool sanitize (graph_t::vertex_t& vertex) const
+  {
+    int64_t vertex_len = vertex.obj.tail - vertex.obj.head;
+    constexpr unsigned min_size = OT::ClassDefFormat2_4<SmallTypes>::min_size;
+    if (vertex_len < min_size) return false;
+    hb_barrier ();
+    return vertex_len >= min_size + rangeRecord.get_size () - rangeRecord.len.get_size ();
+  }
+};
+
+struct ClassDef : public OT::ClassDef
+{
+  template<typename It>
+  static bool add_class_def (gsubgpos_graph_context_t& c,
+                             unsigned parent_id,
+                             unsigned link_position,
+                             It glyph_and_class,
+                             unsigned max_size)
+  {
+    unsigned class_def_prime_id = c.graph.new_node (nullptr, nullptr);
+    auto& class_def_prime_vertex = c.graph.vertices_[class_def_prime_id];
+    if (!make_class_def (c, glyph_and_class, class_def_prime_id, max_size))
+      return false;
+
+    auto* class_def_link = c.graph.vertices_[parent_id].obj.real_links.push ();
+    class_def_link->width = SmallTypes::size;
+    class_def_link->objidx = class_def_prime_id;
+    class_def_link->position = link_position;
+    class_def_prime_vertex.add_parent (parent_id, false);
+
+    return true;
+  }
+
+  template<typename It>
+  static bool make_class_def (gsubgpos_graph_context_t& c,
+                              It glyph_and_class,
+                              unsigned dest_obj,
+                              unsigned max_size)
+  {
+    char* buffer = (char*) hb_calloc (1, max_size);
+    hb_serialize_context_t serializer (buffer, max_size);
+    OT::ClassDef_serialize (&serializer, glyph_and_class);
+    serializer.end_serialize ();
+    if (serializer.in_error ())
+    {
+      hb_free (buffer);
+      return false;
+    }
+
+    hb_bytes_t class_def_copy = serializer.copy_bytes ();
+    if (!class_def_copy.arrayZ) return false;
+    // Give ownership to the context, it will cleanup the buffer.
+    if (!c.add_buffer ((char *) class_def_copy.arrayZ))
+    {
+      hb_free ((char *) class_def_copy.arrayZ);
+      return false;
+    }
+
+    auto& obj = c.graph.vertices_[dest_obj].obj;
+    obj.head = (char *) class_def_copy.arrayZ;
+    obj.tail = obj.head + class_def_copy.length;
+
+    hb_free (buffer);
+    return true;
+  }
+
+  bool sanitize (graph_t::vertex_t& vertex) const
+  {
+    int64_t vertex_len = vertex.obj.tail - vertex.obj.head;
+    if (vertex_len < OT::ClassDef::min_size) return false;
+    hb_barrier ();
+    switch (u.format)
+    {
+    case 1: return ((ClassDefFormat1*)this)->sanitize (vertex);
+    case 2: return ((ClassDefFormat2*)this)->sanitize (vertex);
+#ifndef HB_NO_BEYOND_64K
+    // Not currently supported
+    case 3:
+    case 4:
+#endif
+    default: return false;
+    }
+  }
+};
+
+
+struct class_def_size_estimator_t
+{
+  // TODO(garretrieger): update to support beyond64k coverage/classdef tables.
+  constexpr static unsigned class_def_format1_base_size = 6;
+  constexpr static unsigned class_def_format2_base_size = 4;
+  constexpr static unsigned coverage_base_size = 4;
+  constexpr static unsigned bytes_per_range = 6;
+  constexpr static unsigned bytes_per_glyph = 2;
+
+  template<typename It>
+  class_def_size_estimator_t (It glyph_and_class)
+      : num_ranges_per_class (), glyphs_per_class ()
+  {
+    reset();
+    for (auto p : + glyph_and_class)
+    {
+      unsigned gid = p.first;
+      unsigned klass = p.second;
+
+      hb_set_t* glyphs;
+      if (glyphs_per_class.has (klass, &glyphs) && glyphs) {
+        glyphs->add (gid);
+        continue;
+      }
+
+      hb_set_t new_glyphs;
+      new_glyphs.add (gid);
+      glyphs_per_class.set (klass, std::move (new_glyphs));
+    }
+
+    if (in_error ()) return;
+
+    for (unsigned klass : glyphs_per_class.keys ())
+    {
+      if (!klass) continue; // class 0 doesn't get encoded.
+
+      const hb_set_t& glyphs = glyphs_per_class.get (klass);
+      hb_codepoint_t start = HB_SET_VALUE_INVALID;
+      hb_codepoint_t end = HB_SET_VALUE_INVALID;
+
+      unsigned count = 0;
+      while (glyphs.next_range (&start, &end))
+        count++;
+
+      num_ranges_per_class.set (klass, count);
+    }
+  }
+
+  void reset() {
+    class_def_1_size = class_def_format1_base_size;
+    class_def_2_size = class_def_format2_base_size;
+    included_glyphs.clear();
+    included_classes.clear();
+  }
+
+  // Compute the size of coverage for all glyphs added via 'add_class_def_size'.
+  unsigned coverage_size () const
+  {
+    unsigned format1_size = coverage_base_size + bytes_per_glyph * included_glyphs.get_population();
+    unsigned format2_size = coverage_base_size + bytes_per_range * num_glyph_ranges();
+    return hb_min(format1_size, format2_size);
+  }
+
+  // Compute the new size of the ClassDef table if all glyphs associated with 'klass' were added.
+  unsigned add_class_def_size (unsigned klass)
+  {
+    if (!included_classes.has(klass)) {
+      hb_set_t* glyphs = nullptr;
+      if (glyphs_per_class.has(klass, &glyphs)) {
+        included_glyphs.union_(*glyphs);
+      }
+
+      class_def_1_size = class_def_format1_base_size;
+      if (!included_glyphs.is_empty()) {
+        unsigned min_glyph = included_glyphs.get_min();
+        unsigned max_glyph = included_glyphs.get_max();
+        class_def_1_size += bytes_per_glyph * (max_glyph - min_glyph + 1);
+      }
+
+      class_def_2_size += bytes_per_range * num_ranges_per_class.get (klass);
+
+      included_classes.add(klass);
+    }
+
+    return hb_min (class_def_1_size, class_def_2_size);
+  }
+
+  unsigned num_glyph_ranges() const {
+    hb_codepoint_t start = HB_SET_VALUE_INVALID;
+    hb_codepoint_t end = HB_SET_VALUE_INVALID;
+
+    unsigned count = 0;
+    while (included_glyphs.next_range (&start, &end)) {
+        count++;
+    }
+    return count;
+  }
+
+  bool in_error ()
+  {
+    if (num_ranges_per_class.in_error ()) return true;
+    if (glyphs_per_class.in_error ()) return true;
+
+    for (const hb_set_t& s : glyphs_per_class.values ())
+    {
+      if (s.in_error ()) return true;
+    }
+    return false;
+  }
+
+ private:
+  hb_hashmap_t<unsigned, unsigned> num_ranges_per_class;
+  hb_hashmap_t<unsigned, hb_set_t> glyphs_per_class;
+  hb_set_t included_classes;
+  hb_set_t included_glyphs;
+  unsigned class_def_1_size;
+  unsigned class_def_2_size;
+};
+
+
+}
+
+#endif  // GRAPH_CLASSDEF_GRAPH_HH

thirdparty/harfbuzz/src/graph/coverage-graph.hh

@@ -0,0 +1,183 @@
+/*
+ * Copyright © 2022  Google, Inc.
+ *
+ *  This is part of HarfBuzz, a text shaping library.
+ *
+ * Permission is hereby granted, without written agreement and without
+ * license or royalty fees, to use, copy, modify, and distribute this
+ * software and its documentation for any purpose, provided that the
+ * above copyright notice and the following two paragraphs appear in
+ * all copies of this software.
+ *
+ * IN NO EVENT SHALL THE COPYRIGHT HOLDER BE LIABLE TO ANY PARTY FOR
+ * DIRECT, INDIRECT, SPECIAL, INCIDENTAL, OR CONSEQUENTIAL DAMAGES
+ * ARISING OUT OF THE USE OF THIS SOFTWARE AND ITS DOCUMENTATION, EVEN
+ * IF THE COPYRIGHT HOLDER HAS BEEN ADVISED OF THE POSSIBILITY OF SUCH
+ * DAMAGE.
+ *
+ * THE COPYRIGHT HOLDER SPECIFICALLY DISCLAIMS ANY WARRANTIES, INCLUDING,
+ * BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND
+ * FITNESS FOR A PARTICULAR PURPOSE.  THE SOFTWARE PROVIDED HEREUNDER IS
+ * ON AN "AS IS" BASIS, AND THE COPYRIGHT HOLDER HAS NO OBLIGATION TO
+ * PROVIDE MAINTENANCE, SUPPORT, UPDATES, ENHANCEMENTS, OR MODIFICATIONS.
+ *
+ * Google Author(s): Garret Rieger
+ */
+
+#include "graph.hh"
+#include "../OT/Layout/Common/Coverage.hh"
+
+#ifndef GRAPH_COVERAGE_GRAPH_HH
+#define GRAPH_COVERAGE_GRAPH_HH
+
+namespace graph {
+
+struct CoverageFormat1 : public OT::Layout::Common::CoverageFormat1_3<SmallTypes>
+{
+  bool sanitize (graph_t::vertex_t& vertex) const
+  {
+    int64_t vertex_len = vertex.obj.tail - vertex.obj.head;
+    constexpr unsigned min_size = OT::Layout::Common::CoverageFormat1_3<SmallTypes>::min_size;
+    if (vertex_len < min_size) return false;
+    hb_barrier ();
+    return vertex_len >= min_size + glyphArray.get_size () - glyphArray.len.get_size ();
+  }
+};
+
+struct CoverageFormat2 : public OT::Layout::Common::CoverageFormat2_4<SmallTypes>
+{
+  bool sanitize (graph_t::vertex_t& vertex) const
+  {
+    int64_t vertex_len = vertex.obj.tail - vertex.obj.head;
+    constexpr unsigned min_size = OT::Layout::Common::CoverageFormat2_4<SmallTypes>::min_size;
+    if (vertex_len < min_size) return false;
+    hb_barrier ();
+    return vertex_len >= min_size + rangeRecord.get_size () - rangeRecord.len.get_size ();
+  }
+};
+
+struct Coverage : public OT::Layout::Common::Coverage
+{
+  static Coverage* clone_coverage (gsubgpos_graph_context_t& c,
+                                   unsigned coverage_id,
+                                   unsigned new_parent_id,
+                                   unsigned link_position,
+                                   unsigned start, unsigned end)
+
+  {
+    unsigned coverage_size = c.graph.vertices_[coverage_id].table_size ();
+    auto& coverage_v = c.graph.vertices_[coverage_id];
+    Coverage* coverage_table = (Coverage*) coverage_v.obj.head;
+    if (!coverage_table || !coverage_table->sanitize (coverage_v))
+      return nullptr;
+
+    auto new_coverage =
+        + hb_zip (coverage_table->iter (), hb_range ())
+        | hb_filter ([&] (hb_pair_t<unsigned, unsigned> p) {
+          return p.second >= start && p.second < end;
+        })
+        | hb_map_retains_sorting (hb_first)
+        ;
+
+    return add_coverage (c, new_parent_id, link_position, new_coverage, coverage_size);
+  }
+
+  template<typename It>
+  static Coverage* add_coverage (gsubgpos_graph_context_t& c,
+                                 unsigned parent_id,
+                                 unsigned link_position,
+                                 It glyphs,
+                                 unsigned max_size)
+  {
+    unsigned coverage_prime_id = c.graph.new_node (nullptr, nullptr);
+    auto& coverage_prime_vertex = c.graph.vertices_[coverage_prime_id];
+    if (!make_coverage (c, glyphs, coverage_prime_id, max_size))
+      return nullptr;
+
+    auto* coverage_link = c.graph.vertices_[parent_id].obj.real_links.push ();
+    coverage_link->width = SmallTypes::size;
+    coverage_link->objidx = coverage_prime_id;
+    coverage_link->position = link_position;
+    coverage_prime_vertex.add_parent (parent_id, false);
+
+    return (Coverage*) coverage_prime_vertex.obj.head;
+  }
+
+  // Filter an existing coverage table to glyphs at indices [start, end) and replace it with the filtered version.
+  static bool filter_coverage (gsubgpos_graph_context_t& c,
+                               unsigned existing_coverage,
+                               unsigned start, unsigned end) {
+    unsigned coverage_size = c.graph.vertices_[existing_coverage].table_size ();
+    auto& coverage_v = c.graph.vertices_[existing_coverage];
+    Coverage* coverage_table = (Coverage*) coverage_v.obj.head;
+    if (!coverage_table || !coverage_table->sanitize (coverage_v))
+      return false;
+
+    auto new_coverage =
+        + hb_zip (coverage_table->iter (), hb_range ())
+        | hb_filter ([&] (hb_pair_t<unsigned, unsigned> p) {
+          return p.second >= start && p.second < end;
+        })
+        | hb_map_retains_sorting (hb_first)
+        ;
+
+    return make_coverage (c, new_coverage, existing_coverage, coverage_size * 2 + 100);
+  }
+
+  // Replace the coverage table at dest obj with one covering 'glyphs'.
+  template<typename It>
+  static bool make_coverage (gsubgpos_graph_context_t& c,
+                             It glyphs,
+                             unsigned dest_obj,
+                             unsigned max_size)
+  {
+    char* buffer = (char*) hb_calloc (1, max_size);
+    hb_serialize_context_t serializer (buffer, max_size);
+    OT::Layout::Common::Coverage_serialize (&serializer, glyphs);
+    serializer.end_serialize ();
+    if (serializer.in_error ())
+    {
+      hb_free (buffer);
+      return false;
+    }
+
+    hb_bytes_t coverage_copy = serializer.copy_bytes ();
+    if (!coverage_copy.arrayZ) return false;
+    // Give ownership to the context, it will cleanup the buffer.
+    if (!c.add_buffer ((char *) coverage_copy.arrayZ))
+    {
+      hb_free ((char *) coverage_copy.arrayZ);
+      return false;
+    }
+
+    auto& obj = c.graph.vertices_[dest_obj].obj;
+    obj.head = (char *) coverage_copy.arrayZ;
+    obj.tail = obj.head + coverage_copy.length;
+
+    hb_free (buffer);
+    return true;
+  }
+
+  bool sanitize (graph_t::vertex_t& vertex) const
+  {
+    int64_t vertex_len = vertex.obj.tail - vertex.obj.head;
+    if (vertex_len < OT::Layout::Common::Coverage::min_size) return false;
+    hb_barrier ();
+    switch (u.format)
+    {
+    case 1: return ((CoverageFormat1*)this)->sanitize (vertex);
+    case 2: return ((CoverageFormat2*)this)->sanitize (vertex);
+#ifndef HB_NO_BEYOND_64K
+    // Not currently supported
+    case 3:
+    case 4:
+#endif
+    default: return false;
+    }
+  }
+};
+
+
+}
+
+#endif  // GRAPH_COVERAGE_GRAPH_HH

thirdparty/harfbuzz/src/graph/gsubgpos-context.cc

@@ -0,0 +1,74 @@
+/*
+ * Copyright © 2022  Google, Inc.
+ *
+ *  This is part of HarfBuzz, a text shaping library.
+ *
+ * Permission is hereby granted, without written agreement and without
+ * license or royalty fees, to use, copy, modify, and distribute this
+ * software and its documentation for any purpose, provided that the
+ * above copyright notice and the following two paragraphs appear in
+ * all copies of this software.
+ *
+ * IN NO EVENT SHALL THE COPYRIGHT HOLDER BE LIABLE TO ANY PARTY FOR
+ * DIRECT, INDIRECT, SPECIAL, INCIDENTAL, OR CONSEQUENTIAL DAMAGES
+ * ARISING OUT OF THE USE OF THIS SOFTWARE AND ITS DOCUMENTATION, EVEN
+ * IF THE COPYRIGHT HOLDER HAS BEEN ADVISED OF THE POSSIBILITY OF SUCH
+ * DAMAGE.
+ *
+ * THE COPYRIGHT HOLDER SPECIFICALLY DISCLAIMS ANY WARRANTIES, INCLUDING,
+ * BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND
+ * FITNESS FOR A PARTICULAR PURPOSE.  THE SOFTWARE PROVIDED HEREUNDER IS
+ * ON AN "AS IS" BASIS, AND THE COPYRIGHT HOLDER HAS NO OBLIGATION TO
+ * PROVIDE MAINTENANCE, SUPPORT, UPDATES, ENHANCEMENTS, OR MODIFICATIONS.
+ *
+ * Google Author(s): Garret Rieger
+ */
+
+#include "gsubgpos-graph.hh"
+
+namespace graph {
+
+gsubgpos_graph_context_t::gsubgpos_graph_context_t (hb_tag_t table_tag_,
+                                                    graph_t& graph_)
+    : table_tag (table_tag_),
+      graph (graph_),
+      lookup_list_index (0),
+      lookups ()
+{
+  if (table_tag_ != HB_OT_TAG_GPOS
+      &&  table_tag_ != HB_OT_TAG_GSUB)
+    return;
+
+  GSTAR* gstar = graph::GSTAR::graph_to_gstar (graph_);
+  if (gstar) {
+    gstar->find_lookups (graph, lookups);
+    lookup_list_index = gstar->get_lookup_list_index (graph_);
+  }
+}
+
+unsigned gsubgpos_graph_context_t::create_node (unsigned size)
+{
+  char* buffer = (char*) hb_calloc (1, size);
+  if (!buffer)
+    return -1;
+
+  if (!add_buffer (buffer)) {
+    // Allocation did not get stored for freeing later.
+    hb_free (buffer);
+    return -1;
+  }
+
+  return graph.new_node (buffer, buffer + size);
+}
+
+unsigned gsubgpos_graph_context_t::num_non_ext_subtables ()  {
+  unsigned count = 0;
+  for (auto l : lookups.values ())
+  {
+    if (l->is_extension (table_tag)) continue;
+    count += l->number_of_subtables ();
+  }
+  return count;
+}
+
+}

thirdparty/harfbuzz/src/graph/gsubgpos-context.hh

@@ -0,0 +1,61 @@
+/*
+ * Copyright © 2022  Google, Inc.
+ *
+ *  This is part of HarfBuzz, a text shaping library.
+ *
+ * Permission is hereby granted, without written agreement and without
+ * license or royalty fees, to use, copy, modify, and distribute this
+ * software and its documentation for any purpose, provided that the
+ * above copyright notice and the following two paragraphs appear in
+ * all copies of this software.
+ *
+ * IN NO EVENT SHALL THE COPYRIGHT HOLDER BE LIABLE TO ANY PARTY FOR
+ * DIRECT, INDIRECT, SPECIAL, INCIDENTAL, OR CONSEQUENTIAL DAMAGES
+ * ARISING OUT OF THE USE OF THIS SOFTWARE AND ITS DOCUMENTATION, EVEN
+ * IF THE COPYRIGHT HOLDER HAS BEEN ADVISED OF THE POSSIBILITY OF SUCH
+ * DAMAGE.
+ *
+ * THE COPYRIGHT HOLDER SPECIFICALLY DISCLAIMS ANY WARRANTIES, INCLUDING,
+ * BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND
+ * FITNESS FOR A PARTICULAR PURPOSE.  THE SOFTWARE PROVIDED HEREUNDER IS
+ * ON AN "AS IS" BASIS, AND THE COPYRIGHT HOLDER HAS NO OBLIGATION TO
+ * PROVIDE MAINTENANCE, SUPPORT, UPDATES, ENHANCEMENTS, OR MODIFICATIONS.
+ *
+ * Google Author(s): Garret Rieger
+ */
+
+#include "graph.hh"
+#include "../hb-ot-layout-gsubgpos.hh"
+
+#ifndef GRAPH_GSUBGPOS_CONTEXT_HH
+#define GRAPH_GSUBGPOS_CONTEXT_HH
+
+namespace graph {
+
+struct Lookup;
+
+struct gsubgpos_graph_context_t
+{
+  hb_tag_t table_tag;
+  graph_t& graph;
+  unsigned lookup_list_index;
+  hb_hashmap_t<unsigned, graph::Lookup*> lookups;
+  hb_hashmap_t<unsigned, unsigned> subtable_to_extension;
+
+  HB_INTERNAL gsubgpos_graph_context_t (hb_tag_t table_tag_,
+                                        graph_t& graph_);
+
+  HB_INTERNAL unsigned create_node (unsigned size);
+
+  bool add_buffer (char* buffer)
+  {
+    return graph.add_buffer (buffer);
+  }
+
+ private:
+  HB_INTERNAL unsigned num_non_ext_subtables ();
+};
+
+}
+
+#endif  // GRAPH_GSUBGPOS_CONTEXT

thirdparty/harfbuzz/src/graph/gsubgpos-graph.hh

@@ -0,0 +1,461 @@
+/*
+ * Copyright © 2022  Google, Inc.
+ *
+ *  This is part of HarfBuzz, a text shaping library.
+ *
+ * Permission is hereby granted, without written agreement and without
+ * license or royalty fees, to use, copy, modify, and distribute this
+ * software and its documentation for any purpose, provided that the
+ * above copyright notice and the following two paragraphs appear in
+ * all copies of this software.
+ *
+ * IN NO EVENT SHALL THE COPYRIGHT HOLDER BE LIABLE TO ANY PARTY FOR
+ * DIRECT, INDIRECT, SPECIAL, INCIDENTAL, OR CONSEQUENTIAL DAMAGES
+ * ARISING OUT OF THE USE OF THIS SOFTWARE AND ITS DOCUMENTATION, EVEN
+ * IF THE COPYRIGHT HOLDER HAS BEEN ADVISED OF THE POSSIBILITY OF SUCH
+ * DAMAGE.
+ *
+ * THE COPYRIGHT HOLDER SPECIFICALLY DISCLAIMS ANY WARRANTIES, INCLUDING,
+ * BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND
+ * FITNESS FOR A PARTICULAR PURPOSE.  THE SOFTWARE PROVIDED HEREUNDER IS
+ * ON AN "AS IS" BASIS, AND THE COPYRIGHT HOLDER HAS NO OBLIGATION TO
+ * PROVIDE MAINTENANCE, SUPPORT, UPDATES, ENHANCEMENTS, OR MODIFICATIONS.
+ *
+ * Google Author(s): Garret Rieger
+ */
+
+#include "graph.hh"
+#include "../hb-ot-layout-gsubgpos.hh"
+#include "../OT/Layout/GSUB/ExtensionSubst.hh"
+#include "../OT/Layout/GSUB/SubstLookupSubTable.hh"
+#include "gsubgpos-context.hh"
+#include "pairpos-graph.hh"
+#include "markbasepos-graph.hh"
+#include "ligature-graph.hh"
+
+#ifndef GRAPH_GSUBGPOS_GRAPH_HH
+#define GRAPH_GSUBGPOS_GRAPH_HH
+
+namespace graph {
+
+struct Lookup;
+
+template<typename T>
+struct ExtensionFormat1 : public OT::ExtensionFormat1<T>
+{
+  void reset(unsigned type)
+  {
+    this->format = 1;
+    this->extensionLookupType = type;
+    this->extensionOffset = 0;
+  }
+
+  bool sanitize (graph_t::vertex_t& vertex) const
+  {
+    int64_t vertex_len = vertex.obj.tail - vertex.obj.head;
+    return vertex_len >= OT::ExtensionFormat1<T>::static_size;
+  }
+
+  unsigned get_lookup_type () const
+  {
+    return this->extensionLookupType;
+  }
+
+  unsigned get_subtable_index (graph_t& graph, unsigned this_index) const
+  {
+    return graph.index_for_offset (this_index, &this->extensionOffset);
+  }
+};
+
+struct Lookup : public OT::Lookup
+{
+  unsigned number_of_subtables () const
+  {
+    return subTable.len;
+  }
+
+  bool sanitize (graph_t::vertex_t& vertex) const
+  {
+    int64_t vertex_len = vertex.obj.tail - vertex.obj.head;
+    if (vertex_len < OT::Lookup::min_size) return false;
+    hb_barrier ();
+    return vertex_len >= this->get_size ();
+  }
+
+  bool is_extension (hb_tag_t table_tag) const
+  {
+    return lookupType == extension_type (table_tag);
+  }
+
+  bool make_extension (gsubgpos_graph_context_t& c,
+                       unsigned this_index)
+  {
+    unsigned type = lookupType;
+    unsigned ext_type = extension_type (c.table_tag);
+    if (!ext_type || is_extension (c.table_tag))
+    {
+      // NOOP
+      return true;
+    }
+
+    DEBUG_MSG (SUBSET_REPACK, nullptr,
+               "Promoting lookup type %u (obj %u) to extension.",
+               type,
+               this_index);
+
+    for (unsigned i = 0; i < subTable.len; i++)
+    {
+      unsigned subtable_index = c.graph.index_for_offset (this_index, &subTable[i]);
+      if (!make_subtable_extension (c,
+                                    this_index,
+                                    subtable_index))
+        return false;
+    }
+
+    lookupType = ext_type;
+    return true;
+  }
+
+  bool split_subtables_if_needed (gsubgpos_graph_context_t& c,
+                                  unsigned this_index)
+  {
+    unsigned type = lookupType;
+    bool is_ext = is_extension (c.table_tag);
+
+    if (c.table_tag != HB_OT_TAG_GPOS && c.table_tag != HB_OT_TAG_GSUB)
+      return true;
+
+    if (!is_ext && !is_supported_gpos_type(type, c) && !is_supported_gsub_type(type, c))
+      return true;
+
+    hb_vector_t<hb_pair_t<unsigned, hb_vector_t<unsigned>>> all_new_subtables;
+    for (unsigned i = 0; i < subTable.len; i++)
+    {
+      unsigned subtable_index = c.graph.index_for_offset (this_index, &subTable[i]);
+      unsigned parent_index = this_index;
+      if (is_ext) {
+        unsigned ext_subtable_index = subtable_index;
+        parent_index = ext_subtable_index;
+        ExtensionFormat1<OT::Layout::GSUB_impl::ExtensionSubst>* extension =
+            (ExtensionFormat1<OT::Layout::GSUB_impl::ExtensionSubst>*)
+            c.graph.object (ext_subtable_index).head;
+        if (!extension || !extension->sanitize (c.graph.vertices_[ext_subtable_index]))
+          continue;
+
+        subtable_index = extension->get_subtable_index (c.graph, ext_subtable_index);
+        type = extension->get_lookup_type ();
+        if (!is_supported_gpos_type(type, c) && !is_supported_gsub_type(type, c))
+          continue;
+      }
+
+      hb_vector_t<unsigned> new_sub_tables;
+
+      if (c.table_tag == HB_OT_TAG_GPOS) {
+        switch (type)
+        {
+        case 2:
+          new_sub_tables = split_subtable<PairPos> (c, parent_index, subtable_index); break;
+        case 4:
+          new_sub_tables = split_subtable<MarkBasePos> (c, parent_index, subtable_index); break;
+        default:
+          break;
+        }
+      } else if (c.table_tag == HB_OT_TAG_GSUB) {
+        switch (type)
+        {
+        case 4:
+          new_sub_tables = split_subtable<graph::LigatureSubst> (c, parent_index, subtable_index); break;
+        default:
+          break;
+        }
+      }
+
+      if (new_sub_tables.in_error ()) return false;
+      if (!new_sub_tables) continue;
+      hb_pair_t<unsigned, hb_vector_t<unsigned>>* entry = all_new_subtables.push ();
+      entry->first = i;
+      entry->second = std::move (new_sub_tables);
+    }
+
+    if (all_new_subtables) {
+      return add_sub_tables (c, this_index, type, all_new_subtables);
+    }
+
+    return true;
+  }
+
+  template<typename T>
+  hb_vector_t<unsigned> split_subtable (gsubgpos_graph_context_t& c,
+                                        unsigned parent_idx,
+                                        unsigned objidx)
+  {
+    T* sub_table = (T*) c.graph.object (objidx).head;
+    if (!sub_table || !sub_table->sanitize (c.graph.vertices_[objidx]))
+      return hb_vector_t<unsigned> ();
+
+    return sub_table->split_subtables (c, parent_idx, objidx);
+  }
+
+  bool add_sub_tables (gsubgpos_graph_context_t& c,
+                       unsigned this_index,
+                       unsigned type,
+                       hb_vector_t<hb_pair_t<unsigned, hb_vector_t<unsigned>>>& subtable_ids)
+  {
+    bool is_ext = is_extension (c.table_tag);
+    auto* v = &c.graph.vertices_[this_index];
+    fix_existing_subtable_links (c, this_index, subtable_ids);
+
+    unsigned new_subtable_count = 0;
+    for (const auto& p : subtable_ids)
+      new_subtable_count += p.second.length;
+
+    size_t new_size = v->table_size ()
+                      + new_subtable_count * OT::Offset16::static_size;
+    char* buffer = (char*) hb_calloc (1, new_size);
+    if (!buffer) return false;
+    if (!c.add_buffer (buffer))
+    {
+      hb_free (buffer);
+     return false;
+    }
+    hb_memcpy (buffer, v->obj.head, v->table_size());
+
+    v->obj.head = buffer;
+    v->obj.tail = buffer + new_size;
+
+    Lookup* new_lookup = (Lookup*) buffer;
+
+    unsigned shift = 0;
+    new_lookup->subTable.len = subTable.len + new_subtable_count;
+    for (const auto& p : subtable_ids)
+    {
+      unsigned offset_index = p.first + shift + 1;
+      shift += p.second.length;
+
+      for (unsigned subtable_id : p.second)
+      {
+        if (is_ext)
+        {
+          unsigned ext_id = create_extension_subtable (c, subtable_id, type);
+          c.graph.vertices_[subtable_id].add_parent (ext_id, false);
+          subtable_id = ext_id;
+          // the reference to v may have changed on adding a node, so reassign it.
+          v = &c.graph.vertices_[this_index];
+        }
+
+        auto* link = v->obj.real_links.push ();
+        link->width = 2;
+        link->objidx = subtable_id;
+        link->position = (char*) &new_lookup->subTable[offset_index++] -
+                         (char*) new_lookup;
+        c.graph.vertices_[subtable_id].add_parent (this_index, false);
+      }
+    }
+
+    // Repacker sort order depends on link order, which we've messed up so resort it.
+    v->obj.real_links.qsort ();
+
+    // The head location of the lookup has changed, invalidating the lookups map entry
+    // in the context. Update the map.
+    c.lookups.set (this_index, new_lookup);
+    return true;
+  }
+
+  void fix_existing_subtable_links (gsubgpos_graph_context_t& c,
+                                    unsigned this_index,
+                                    hb_vector_t<hb_pair_t<unsigned, hb_vector_t<unsigned>>>& subtable_ids)
+  {
+    auto& v = c.graph.vertices_[this_index];
+    Lookup* lookup = (Lookup*) v.obj.head;
+
+    unsigned shift = 0;
+    for (const auto& p : subtable_ids)
+    {
+      unsigned insert_index = p.first + shift;
+      unsigned pos_offset = p.second.length * OT::Offset16::static_size;
+      unsigned insert_offset = (char*) &lookup->subTable[insert_index] - (char*) lookup;
+      shift += p.second.length;
+
+      for (auto& l : v.obj.all_links_writer ())
+      {
+        if (l.position > insert_offset) l.position += pos_offset;
+      }
+    }
+  }
+
+  unsigned create_extension_subtable (gsubgpos_graph_context_t& c,
+                                      unsigned subtable_index,
+                                      unsigned type)
+  {
+    unsigned extension_size = OT::ExtensionFormat1<OT::Layout::GSUB_impl::ExtensionSubst>::static_size;
+
+    unsigned ext_index = c.create_node (extension_size);
+    if (ext_index == (unsigned) -1)
+      return -1;
+
+    auto& ext_vertex = c.graph.vertices_[ext_index];
+    ExtensionFormat1<OT::Layout::GSUB_impl::ExtensionSubst>* extension =
+        (ExtensionFormat1<OT::Layout::GSUB_impl::ExtensionSubst>*) ext_vertex.obj.head;
+    extension->reset (type);
+
+    // Make extension point at the subtable.
+    auto* l = ext_vertex.obj.real_links.push ();
+
+    l->width = 4;
+    l->objidx = subtable_index;
+    l->position = 4;
+
+    return ext_index;
+  }
+
+  bool make_subtable_extension (gsubgpos_graph_context_t& c,
+                                unsigned lookup_index,
+                                unsigned subtable_index)
+  {
+    unsigned type = lookupType;
+    unsigned ext_index = -1;
+    unsigned* existing_ext_index = nullptr;
+    if (c.subtable_to_extension.has(subtable_index, &existing_ext_index)) {
+      ext_index = *existing_ext_index;
+    } else {    
+      ext_index = create_extension_subtable(c, subtable_index, type);
+      c.subtable_to_extension.set(subtable_index, ext_index);
+    }
+
+    if (ext_index == (unsigned) -1)
+      return false;
+
+    auto& subtable_vertex = c.graph.vertices_[subtable_index];
+    auto& lookup_vertex = c.graph.vertices_[lookup_index];
+    for (auto& l : lookup_vertex.obj.real_links.writer ())
+    {
+      if (l.objidx == subtable_index) {
+        // Change lookup to point at the extension.
+        l.objidx = ext_index;
+        if (existing_ext_index)
+          subtable_vertex.remove_parent(lookup_index);
+      }
+    }
+
+    // Make extension point at the subtable.
+    auto& ext_vertex = c.graph.vertices_[ext_index];
+    ext_vertex.add_parent (lookup_index, false);
+    if (!existing_ext_index)
+      subtable_vertex.remap_parent (lookup_index, ext_index);
+
+    return true;
+  }
+
+ private:
+  bool is_supported_gsub_type(unsigned type, gsubgpos_graph_context_t& c) const {
+    return (c.table_tag == HB_OT_TAG_GSUB) && (
+      type == OT::Layout::GSUB_impl::SubstLookupSubTable::Type::Ligature
+    );
+  }
+
+  bool is_supported_gpos_type(unsigned type, gsubgpos_graph_context_t& c) const {
+   return (c.table_tag == HB_OT_TAG_GPOS) && (
+      type == OT::Layout::GPOS_impl::PosLookupSubTable::Type::Pair ||
+      type == OT::Layout::GPOS_impl::PosLookupSubTable::Type::MarkBase
+    );
+  }
+
+  unsigned extension_type (hb_tag_t table_tag) const
+  {
+    switch (table_tag)
+    {
+    case HB_OT_TAG_GPOS: return 9;
+    case HB_OT_TAG_GSUB: return 7;
+    default: return 0;
+    }
+  }
+};
+
+template <typename T>
+struct LookupList : public OT::LookupList<T>
+{
+  bool sanitize (const graph_t::vertex_t& vertex) const
+  {
+    int64_t vertex_len = vertex.obj.tail - vertex.obj.head;
+    if (vertex_len < OT::LookupList<T>::min_size) return false;
+    hb_barrier ();
+    return vertex_len >= OT::LookupList<T>::item_size * this->len;
+  }
+};
+
+struct GSTAR : public OT::GSUBGPOS
+{
+  static GSTAR* graph_to_gstar (graph_t& graph)
+  {
+    const auto& r = graph.root ();
+
+    GSTAR* gstar = (GSTAR*) r.obj.head;
+    if (!gstar || !gstar->sanitize (r))
+      return nullptr;
+    hb_barrier ();
+
+    return gstar;
+  }
+
+  const void* get_lookup_list_field_offset () const
+  {
+    switch (u.version.major) {
+    case 1: return u.version1.get_lookup_list_offset ();
+#ifndef HB_NO_BEYOND_64K
+    case 2: return u.version2.get_lookup_list_offset ();
+#endif
+    default: return 0;
+    }
+  }
+
+  bool sanitize (const graph_t::vertex_t& vertex)
+  {
+    int64_t len = vertex.obj.tail - vertex.obj.head;
+    if (len < OT::GSUBGPOS::min_size) return false;
+    hb_barrier ();
+    return len >= get_size ();
+  }
+
+  void find_lookups (graph_t& graph,
+                     hb_hashmap_t<unsigned, Lookup*>& lookups /* OUT */)
+  {
+    switch (u.version.major) {
+      case 1: find_lookups<SmallTypes> (graph, lookups); break;
+#ifndef HB_NO_BEYOND_64K
+      case 2: find_lookups<MediumTypes> (graph, lookups); break;
+#endif
+    }
+  }
+
+  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 = get_lookup_list_index (graph);
+    const LookupList<Types>* lookupList =
+        (const LookupList<Types>*) graph.object (lookup_list_idx).head;
+    if (!lookupList || !lookupList->sanitize (graph.vertices_[lookup_list_idx]))
+      return;
+
+    for (unsigned i = 0; i < lookupList->len; i++)
+    {
+      unsigned lookup_idx = graph.index_for_offset (lookup_list_idx, &(lookupList->arrayZ[i]));
+      Lookup* lookup = (Lookup*) graph.object (lookup_idx).head;
+      if (!lookup || !lookup->sanitize (graph.vertices_[lookup_idx])) continue;
+      lookups.set (lookup_idx, lookup);
+    }
+  }
+};
+
+
+
+
+}
+
+#endif  /* GRAPH_GSUBGPOS_GRAPH_HH */

thirdparty/harfbuzz/src/graph/ligature-graph.hh

@@ -0,0 +1,480 @@
+/*
+ * Copyright © 2025  Google, Inc.
+ *
+ *  This is part of HarfBuzz, a text shaping library.
+ *
+ * Permission is hereby granted, without written agreement and without
+ * license or royalty fees, to use, copy, modify, and distribute this
+ * software and its documentation for any purpose, provided that the
+ * above copyright notice and the following two paragraphs appear in
+ * all copies of this software.
+ *
+ * IN NO EVENT SHALL THE COPYRIGHT HOLDER BE LIABLE TO ANY PARTY FOR
+ * DIRECT, INDIRECT, SPECIAL, INCIDENTAL, OR CONSEQUENTIAL DAMAGES
+ * ARISING OUT OF THE USE OF THIS SOFTWARE AND ITS DOCUMENTATION, EVEN
+ * IF THE COPYRIGHT HOLDER HAS BEEN ADVISED OF THE POSSIBILITY OF SUCH
+ * DAMAGE.
+ *
+ * THE COPYRIGHT HOLDER SPECIFICALLY DISCLAIMS ANY WARRANTIES, INCLUDING,
+ * BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND
+ * FITNESS FOR A PARTICULAR PURPOSE.  THE SOFTWARE PROVIDED HEREUNDER IS
+ * ON AN "AS IS" BASIS, AND THE COPYRIGHT HOLDER HAS NO OBLIGATION TO
+ * PROVIDE MAINTENANCE, SUPPORT, UPDATES, ENHANCEMENTS, OR MODIFICATIONS.
+ *
+ * Google Author(s): Garret Rieger
+ */
+
+#ifndef GRAPH_LIGATURE_GRAPH_HH
+#define GRAPH_LIGATURE_GRAPH_HH
+
+#include "graph.hh"
+#include "../OT/Layout/GSUB/LigatureSubst.hh"
+#include "../OT/Layout/GSUB/LigatureSubstFormat1.hh"
+#include "../OT/Layout/GSUB/LigatureSet.hh"
+#include "../OT/Layout/types.hh"
+#include <algorithm>
+#include <utility>
+
+namespace graph {
+
+struct LigatureSet : public OT::Layout::GSUB_impl::LigatureSet<SmallTypes>
+{
+  bool sanitize (graph_t::vertex_t& vertex) const
+  {
+    int64_t vertex_len = vertex.obj.tail - vertex.obj.head;
+    if (vertex_len < OT::Layout::GSUB_impl::LigatureSet<SmallTypes>::min_size) return false;
+    hb_barrier ();
+
+    int64_t total_len = ligature.get_size() + OT::Layout::GSUB_impl::LigatureSet<SmallTypes>::min_size - ligature.len.get_size();
+    if (vertex_len < total_len) {
+      return false;
+    }
+    return true;
+  }
+};
+
+struct LigatureSubstFormat1 : public OT::Layout::GSUB_impl::LigatureSubstFormat1_2<SmallTypes>
+{
+  bool sanitize (graph_t::vertex_t& vertex) const
+  {
+    int64_t vertex_len = vertex.obj.tail - vertex.obj.head;
+    unsigned min_size = OT::Layout::GSUB_impl::LigatureSubstFormat1_2<SmallTypes>::min_size;
+    if (vertex_len < min_size) return false;
+    hb_barrier ();
+
+    return vertex_len >=
+        min_size + ligatureSet.get_size() - ligatureSet.len.get_size();
+  }
+
+  hb_vector_t<unsigned> split_subtables (gsubgpos_graph_context_t& c,
+                                         unsigned parent_index,
+                                         unsigned this_index)
+  {
+    auto split_points = compute_split_points(c, parent_index, this_index);
+    split_context_t split_context {
+      c,
+      this,
+      c.graph.duplicate_if_shared (parent_index, this_index),
+      total_number_ligas(c, this_index),
+      liga_counts(c, this_index),
+    };
+    return actuate_subtable_split<split_context_t> (split_context, split_points);
+  }
+
+ private:
+  unsigned total_number_ligas(gsubgpos_graph_context_t& c, unsigned this_index) const {
+    unsigned total = 0;
+    for (unsigned i = 0; i < ligatureSet.len; i++)
+    {
+      auto liga_set = c.graph.as_table<LigatureSet>(this_index, &ligatureSet[i]);
+      if (!liga_set.table) {
+        return 0;
+      }
+      total += liga_set.table->ligature.len;
+    }
+    return total;
+  }
+
+  hb_vector_t<unsigned> liga_counts(gsubgpos_graph_context_t& c, unsigned this_index) const {
+    hb_vector_t<unsigned> result;
+    for (unsigned i = 0; i < ligatureSet.len; i++)
+    {
+      auto liga_set = c.graph.as_table<LigatureSet>(this_index, &ligatureSet[i]);
+      result.push(!liga_set.table ? 0 : liga_set.table->ligature.len);
+    }
+    return result;
+  }
+
+  hb_vector_t<unsigned> compute_split_points(gsubgpos_graph_context_t& c,
+                                             unsigned parent_index,
+                                             unsigned this_index) const
+  {
+    // For ligature subst coverage is always packed last, and as a result is where an overflow
+    // will happen if there is one, so we can check the estimate length of the
+    // LigatureSubstFormat1 -> Coverage offset length which is the sum of all data in the
+    // retained sub graph except for the coverage table itself.
+    const unsigned base_size = OT::Layout::GSUB_impl::LigatureSubstFormat1_2<SmallTypes>::min_size;
+    unsigned accumulated = base_size;
+
+    unsigned ligature_index = 0;
+    hb_vector_t<unsigned> split_points;
+    for (unsigned i = 0; i < ligatureSet.len; i++)
+    {
+      accumulated += OT::HBUINT16::static_size; // for ligature set offset
+      accumulated += OT::Layout::GSUB_impl::LigatureSet<SmallTypes>::min_size; // for ligature set table
+
+      auto liga_set = c.graph.as_table<LigatureSet>(this_index, &ligatureSet[i]);
+      if (!liga_set.table) {
+        return hb_vector_t<unsigned> {};
+      }
+
+      for (unsigned j = 0; j < liga_set.table->ligature.len; j++)
+      {
+        const unsigned liga_id = c.graph.index_for_offset (liga_set.index, &liga_set.table->ligature[j]);
+        const unsigned liga_size = c.graph.vertices_[liga_id].table_size ();
+
+        accumulated += OT::HBUINT16::static_size; // for ligature offset
+        accumulated += liga_size; // for the ligature table
+
+        if (accumulated >= (1 << 16))
+        {
+          split_points.push(ligature_index);
+          // We're going to split such that the current ligature will be in the new sub table.
+          // That means we'll have one ligature subst (base_base), one ligature set, and one liga table
+          accumulated = base_size + // for liga subst subtable
+            (OT::HBUINT16::static_size * 2) + // for liga set and liga offset
+            OT::Layout::GSUB_impl::LigatureSet<SmallTypes>::min_size + // for liga set subtable
+            liga_size; // for liga sub table
+        }
+
+        ligature_index++;
+      }
+    }
+
+    return split_points;
+  }
+
+
+  struct split_context_t
+  {
+    gsubgpos_graph_context_t& c;
+    LigatureSubstFormat1* thiz;
+    unsigned this_index;
+    unsigned original_count_;
+    hb_vector_t<unsigned> liga_counts;
+
+    unsigned original_count ()
+    {
+      return original_count_;
+    }
+
+    unsigned clone_range (unsigned start, unsigned end)
+    {
+      return thiz->clone_range (c, this_index, liga_counts, start, end);
+    }
+
+    bool shrink (unsigned count)
+    {
+      return thiz->shrink (c, this_index, original_count(), liga_counts, count);
+    }
+  };
+
+  hb_pair_t<unsigned, LigatureSet*> new_liga_set(gsubgpos_graph_context_t& c, unsigned count) const {
+    unsigned prime_size = OT::Layout::GSUB_impl::LigatureSet<SmallTypes>::min_size
+                          + count * SmallTypes::size;
+
+    unsigned prime_id = c.create_node (prime_size);
+    if (prime_id == (unsigned) -1) return hb_pair(-1, nullptr);
+
+    LigatureSet* prime = (LigatureSet*) c.graph.object (prime_id).head;
+    prime->ligature.len = count;
+    return hb_pair(prime_id, prime);
+  }
+
+  void clear_virtual_links (gsubgpos_graph_context_t& c, unsigned node_index) const
+  {
+    auto& obj = c.graph.vertices_[node_index].obj;
+    for (const auto& l : obj.virtual_links)
+    {
+      auto& child = c.graph.vertices_[l.objidx];
+      child.remove_parent(node_index);
+    }
+    obj.virtual_links.clear();
+  }
+
+  void add_virtual_link(gsubgpos_graph_context_t& c, unsigned from, unsigned to) const {
+    auto& from_obj = c.graph.vertices_[from].obj;
+    c.graph.vertices_[to].add_parent(from, true);
+    auto& link = *from_obj.virtual_links.push ();
+    link.objidx = to;
+  }
+
+  hb_pair_t<unsigned, unsigned> current_liga_set_bounds (gsubgpos_graph_context_t& c,
+                                                         unsigned liga_set_index,
+                                                         const hb_serialize_context_t::object_t& liga_set) const
+  {
+    // Finds the actual liga indices present in the liga set currently. Takes
+    // into account those that have been removed by processing.
+    unsigned min_index = (unsigned) -1;
+    unsigned max_index = 0;
+    for (const auto& l : liga_set.real_links) {
+      if (l.position < 2) continue;
+
+      unsigned liga_index = (l.position - 2) / 2;
+      min_index = hb_min(min_index, liga_index);
+      max_index = hb_max(max_index, liga_index);
+    }
+    return hb_pair(min_index, max_index + 1);
+  }
+
+  void compact_liga_set (gsubgpos_graph_context_t& c, LigatureSet* table, hb_serialize_context_t::object_t& obj) const
+  {
+    if (table->ligature.len <= obj.real_links.length) return;
+
+    // compact the remaining linked liga offsets into a continous array and shrink the node as needed.
+    unsigned to_remove = table->ligature.len - obj.real_links.length;
+    unsigned new_position = SmallTypes::size;
+    obj.real_links.qsort(); // for this to work we need to process links in order of position.
+    for (auto& l : obj.real_links)
+    {
+      l.position = new_position;
+      new_position += SmallTypes::size;
+    }
+
+    table->ligature.len = obj.real_links.length;
+    obj.tail -= to_remove * SmallTypes::size;
+  }
+
+  unsigned clone_range (gsubgpos_graph_context_t& c,
+                        unsigned this_index,
+                        hb_vector_t<unsigned> liga_counts,
+                        unsigned start, unsigned end) const
+  {
+    DEBUG_MSG (SUBSET_REPACK, nullptr,
+               "  Cloning LigatureSubstFormat1 (%u) range [%u, %u).", this_index, start, end);
+
+    // Create an oversized new liga subst, we'll adjust the size down later. We don't know
+    // the final size until we process it but we also need it to exist while we're processing
+    // so that nodes can be moved to it as needed.
+    unsigned prime_size = OT::Layout::GSUB_impl::LigatureSubstFormat1_2<SmallTypes>::min_size
+                          + ligatureSet.get_size() - ligatureSet.len.get_size();
+
+    unsigned liga_subst_prime_id = c.create_node (prime_size);
+    if (liga_subst_prime_id == (unsigned) -1) return -1;
+
+    LigatureSubstFormat1* liga_subst_prime = (LigatureSubstFormat1*) c.graph.object (liga_subst_prime_id).head;
+    liga_subst_prime->format = this->format;
+    liga_subst_prime->ligatureSet.len = this->ligatureSet.len;
+
+    // Create a place holder coverage prime id since we need to add virtual links to it while
+    // generating liga and liga sets. Afterwards it will be updated to have the correct coverage.
+    unsigned coverage_id = c.graph.index_for_offset (this_index, &coverage);
+    unsigned coverage_prime_id = c.graph.duplicate(coverage_id);
+    auto& coverage_prime_vertex = c.graph.vertices_[coverage_prime_id];
+    auto* coverage_prime_link = c.graph.vertices_[liga_subst_prime_id].obj.real_links.push ();
+    coverage_prime_link->width = SmallTypes::size;
+    coverage_prime_link->objidx = coverage_prime_id;
+    coverage_prime_link->position = 2;
+    coverage_prime_vertex.add_parent (liga_subst_prime_id, false);
+
+    // Locate all liga sets with ligas between start and end.
+    // Clone or move them as needed.
+    unsigned count = 0;
+    unsigned liga_set_count = 0;
+    unsigned liga_set_start = -1;
+    unsigned liga_set_end = 0; // inclusive
+    for (unsigned i = 0; i < liga_counts.length; i++)
+    {
+      unsigned num_ligas = liga_counts[i];
+
+      unsigned current_start = count;
+      unsigned current_end = count + num_ligas;
+
+      if (current_start >= end || start >= current_end) {
+        // No intersection, so just skip
+        count += num_ligas;
+        continue;
+      }
+
+      auto liga_set_index = c.graph.index_for_offset(this_index, &ligatureSet[i]);
+      auto liga_set = c.graph.as_table<LigatureSet>(this_index, &ligatureSet[i]);
+      if (!liga_set.table) {
+        return -1;
+      }
+
+      // Bounds may need to be adjusted if some ligas have been previously removed.
+      hb_pair_t<unsigned, unsigned> liga_bounds = current_liga_set_bounds(c, liga_set_index, liga_set.vertex->obj);
+      current_start = hb_max(count + liga_bounds.first, current_start);
+      current_end = hb_min(count + liga_bounds.second, current_end);
+
+      unsigned liga_set_prime_id;
+      if (current_start >= start && current_end <= end) {
+        // This liga set is fully contined within [start, end)
+        // We can move the entire ligaset to the new liga subset object.
+        liga_set_end = i;
+        if (i < liga_set_start) liga_set_start = i;
+        liga_set_prime_id = c.graph.move_child<> (this_index,
+                              &ligatureSet[i],
+                              liga_subst_prime_id,
+                              &liga_subst_prime->ligatureSet[liga_set_count++]);
+        compact_liga_set(c, liga_set.table, liga_set.vertex->obj);
+      }
+      else
+      {
+        // This liga set partially overlaps [start, end). We'll need to create
+        // a new liga set sub table and move the intersecting ligas to it.
+        unsigned liga_count = hb_min(end, current_end) - hb_max(start, current_start);
+        auto result = new_liga_set(c, liga_count);
+        liga_set_prime_id = result.first;
+        LigatureSet* prime = result.second;
+        if (liga_set_prime_id == (unsigned) -1) return -1;
+
+        unsigned new_index = 0;
+        for (unsigned j = hb_max(start, current_start) - count; j < hb_min(end, current_end) - count; j++) {
+          c.graph.move_child<> (liga_set_index,
+                                &liga_set.table->ligature[j],
+                                liga_set_prime_id,
+                                &prime->ligature[new_index++]);
+        }
+
+        liga_set_end = i;
+        if (i < liga_set_start) liga_set_start = i;
+        c.graph.add_link(&liga_subst_prime->ligatureSet[liga_set_count++], liga_subst_prime_id, liga_set_prime_id);
+      }
+
+      // The new liga and all children set needs to have a virtual link to the new coverage table:
+      auto& liga_set_prime = c.graph.vertices_[liga_set_prime_id].obj;
+      clear_virtual_links(c, liga_set_prime_id);
+      add_virtual_link(c, liga_set_prime_id, coverage_prime_id);
+      for (const auto& l : liga_set_prime.real_links) {
+        clear_virtual_links(c, l.objidx);
+        add_virtual_link(c, l.objidx, coverage_prime_id);
+      }
+
+      count += num_ligas;
+    }
+
+    c.graph.vertices_[liga_subst_prime_id].obj.tail -= (liga_subst_prime->ligatureSet.len - liga_set_count) * SmallTypes::size;
+    liga_subst_prime->ligatureSet.len = liga_set_count;
+
+    if (!Coverage::filter_coverage (c,
+                                    coverage_prime_id,
+                                    liga_set_start, liga_set_end + 1))
+      return -1;
+
+    return liga_subst_prime_id;
+  }
+
+  bool shrink (gsubgpos_graph_context_t& c,
+               unsigned this_index,
+               unsigned old_count,
+               hb_vector_t<unsigned> liga_counts,
+               unsigned count)
+  {
+    DEBUG_MSG (SUBSET_REPACK, nullptr,
+               "  Shrinking LigatureSubstFormat1 (%u) to [0, %u).",
+               this_index,
+               count);
+    if (count >= old_count)
+      return true;
+
+    hb_set_t retained_indices;
+    unsigned new_liga_set_count = 0;
+    for (unsigned i = 0; i < liga_counts.length; i++)
+    {
+      auto liga_set = c.graph.as_table<LigatureSet>(this_index, &ligatureSet[i]);
+      if (!liga_set.table) {
+        return false;
+      }
+
+      // We need the virtual links to coverage removed from all descendants on this liga subst.
+      // If any are left when we try to mutate the coverage table later it will be unnessecarily
+      // duplicated. Code later on will re-add the virtual links as needed (via retained_indices).
+      clear_virtual_links(c, liga_set.index);
+      retained_indices.add(liga_set.index);
+      for (const auto& liga_offset : liga_set.table->ligature) {
+        unsigned liga_index = c.graph.index_for_offset(liga_set.index, &liga_offset);
+        if (liga_index != (unsigned) -1) {
+          clear_virtual_links(c, liga_index);
+          retained_indices.add(liga_index);
+        }
+      }
+
+      unsigned num_ligas = liga_counts[i];
+      if (num_ligas >= count) {
+        // drop the trailing liga's from this set and all subsequent liga sets
+        unsigned num_ligas_to_remove = num_ligas - count;
+        new_liga_set_count = i + 1;
+        c.graph.vertices_[liga_set.index].obj.tail -= num_ligas_to_remove * SmallTypes::size;
+        liga_set.table->ligature.len = count;
+        break;
+      } else {
+        count -= num_ligas;
+      }
+    }
+
+    // Adjust liga set array
+    c.graph.vertices_[this_index].obj.tail -= (ligatureSet.len - new_liga_set_count) * SmallTypes::size;
+    ligatureSet.len = new_liga_set_count;
+
+    // Coverage matches the number of liga sets so rebuild as needed
+    auto coverage = c.graph.as_mutable_table<Coverage> (this_index, &this->coverage);
+    if (!coverage) return false;
+
+    for (unsigned i : retained_indices.iter())
+      add_virtual_link(c, i, coverage.index);
+
+    unsigned coverage_size = coverage.vertex->table_size ();
+    auto new_coverage =
+        + hb_zip (coverage.table->iter (), hb_range ())
+        | hb_filter ([&] (hb_pair_t<unsigned, unsigned> p) {
+          return p.second < new_liga_set_count;
+        })
+        | hb_map_retains_sorting (hb_first)
+        ;
+
+    return Coverage::make_coverage (c, new_coverage, coverage.index, coverage_size);
+  }
+};
+
+struct LigatureSubst : public OT::Layout::GSUB_impl::LigatureSubst
+{
+
+  hb_vector_t<unsigned> split_subtables (gsubgpos_graph_context_t& c,
+                                         unsigned parent_index,
+                                         unsigned this_index)
+  {
+    switch (u.format) {
+    case 1:
+      return ((LigatureSubstFormat1*)(&u.format1))->split_subtables (c, parent_index, this_index);
+#ifndef HB_NO_BEYOND_64K
+    case 2: HB_FALLTHROUGH;
+      // Don't split 24bit Ligature Subs
+#endif
+    default:
+      return hb_vector_t<unsigned> ();
+    }
+  }
+
+  bool sanitize (graph_t::vertex_t& vertex) const
+  {
+    int64_t vertex_len = vertex.obj.tail - vertex.obj.head;
+    if (vertex_len < u.format.get_size ()) return false;
+    hb_barrier ();
+
+    switch (u.format) {
+    case 1:
+      return ((LigatureSubstFormat1*)(&u.format1))->sanitize (vertex);
+#ifndef HB_NO_BEYOND_64K
+    case 2:  HB_FALLTHROUGH;
+#endif
+    default:
+      // We don't handle format 2 here.
+      return false;
+    }
+  }
+};
+
+}
+
+#endif  // GRAPH_LIGATURE_GRAPH_HH

thirdparty/harfbuzz/src/graph/markbasepos-graph.hh

@@ -0,0 +1,518 @@
+/*
+ * Copyright © 2022  Google, Inc.
+ *
+ *  This is part of HarfBuzz, a text shaping library.
+ *
+ * Permission is hereby granted, without written agreement and without
+ * license or royalty fees, to use, copy, modify, and distribute this
+ * software and its documentation for any purpose, provided that the
+ * above copyright notice and the following two paragraphs appear in
+ * all copies of this software.
+ *
+ * IN NO EVENT SHALL THE COPYRIGHT HOLDER BE LIABLE TO ANY PARTY FOR
+ * DIRECT, INDIRECT, SPECIAL, INCIDENTAL, OR CONSEQUENTIAL DAMAGES
+ * ARISING OUT OF THE USE OF THIS SOFTWARE AND ITS DOCUMENTATION, EVEN
+ * IF THE COPYRIGHT HOLDER HAS BEEN ADVISED OF THE POSSIBILITY OF SUCH
+ * DAMAGE.
+ *
+ * THE COPYRIGHT HOLDER SPECIFICALLY DISCLAIMS ANY WARRANTIES, INCLUDING,
+ * BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND
+ * FITNESS FOR A PARTICULAR PURPOSE.  THE SOFTWARE PROVIDED HEREUNDER IS
+ * ON AN "AS IS" BASIS, AND THE COPYRIGHT HOLDER HAS NO OBLIGATION TO
+ * PROVIDE MAINTENANCE, SUPPORT, UPDATES, ENHANCEMENTS, OR MODIFICATIONS.
+ *
+ * Google Author(s): Garret Rieger
+ */
+
+#ifndef GRAPH_MARKBASEPOS_GRAPH_HH
+#define GRAPH_MARKBASEPOS_GRAPH_HH
+
+#include "split-helpers.hh"
+#include "coverage-graph.hh"
+#include "../OT/Layout/GPOS/MarkBasePos.hh"
+#include "../OT/Layout/GPOS/PosLookupSubTable.hh"
+
+namespace graph {
+
+struct AnchorMatrix : public OT::Layout::GPOS_impl::AnchorMatrix
+{
+  bool sanitize (graph_t::vertex_t& vertex, unsigned class_count) const
+  {
+    int64_t vertex_len = vertex.obj.tail - vertex.obj.head;
+    if (vertex_len < AnchorMatrix::min_size) return false;
+    hb_barrier ();
+
+    return vertex_len >= AnchorMatrix::min_size +
+        OT::Offset16::static_size * class_count * this->rows;
+  }
+
+  bool shrink (gsubgpos_graph_context_t& c,
+               unsigned this_index,
+               unsigned old_class_count,
+               unsigned new_class_count)
+  {
+    if (new_class_count >= old_class_count) return false;
+    auto& o = c.graph.vertices_[this_index].obj;
+    unsigned base_count = rows;
+    o.tail = o.head +
+             AnchorMatrix::min_size +
+             OT::Offset16::static_size * base_count * new_class_count;
+
+    // Reposition links into the new indexing scheme.
+    for (auto& link : o.real_links.writer ())
+    {
+      unsigned index = (link.position - 2) / 2;
+      unsigned base = index / old_class_count;
+      unsigned klass = index % old_class_count;
+      if (klass >= new_class_count)
+        // should have already been removed
+        return false;
+
+      unsigned new_index = base * new_class_count + klass;
+
+      link.position = (char*) &(this->matrixZ[new_index]) - (char*) this;
+    }
+
+    return true;
+  }
+
+  unsigned clone (gsubgpos_graph_context_t& c,
+                  unsigned this_index,
+                  unsigned start,
+                  unsigned end,
+                  unsigned class_count)
+  {
+    unsigned base_count = rows;
+    unsigned new_class_count = end - start;
+    unsigned size = AnchorMatrix::min_size +
+                    OT::Offset16::static_size * new_class_count * rows;
+    unsigned prime_id = c.create_node (size);
+    if (prime_id == (unsigned) -1) return -1;
+    AnchorMatrix* prime = (AnchorMatrix*) c.graph.object (prime_id).head;
+    prime->rows = base_count;
+
+    auto& o = c.graph.vertices_[this_index].obj;
+    int num_links = o.real_links.length;
+    for (int i = 0; i < num_links; i++)
+    {
+      const auto& link = o.real_links[i];
+      unsigned old_index = (link.position - 2) / OT::Offset16::static_size;
+      unsigned klass = old_index % class_count;
+      if (klass < start || klass >= end) continue;
+
+      unsigned base = old_index / class_count;
+      unsigned new_klass = klass - start;
+      unsigned new_index = base * new_class_count + new_klass;
+
+
+      unsigned child_idx = link.objidx;
+      c.graph.add_link (&(prime->matrixZ[new_index]),
+                        prime_id,
+                        child_idx);
+
+      auto& child = c.graph.vertices_[child_idx];
+      child.remove_parent (this_index);
+
+      o.real_links.remove_unordered (i);
+      num_links--;
+      i--;
+    }
+
+    return prime_id;
+  }
+};
+
+struct MarkArray : public OT::Layout::GPOS_impl::MarkArray
+{
+  bool sanitize (graph_t::vertex_t& vertex) const
+  {
+    int64_t vertex_len = vertex.obj.tail - vertex.obj.head;
+    unsigned min_size = MarkArray::min_size;
+    if (vertex_len < min_size) return false;
+    hb_barrier ();
+
+    return vertex_len >= get_size ();
+  }
+
+  bool shrink (gsubgpos_graph_context_t& c,
+               const hb_hashmap_t<unsigned, unsigned>& mark_array_links,
+               unsigned this_index,
+               unsigned new_class_count)
+  {
+    auto& o = c.graph.vertices_[this_index].obj;
+    for (const auto& link : o.real_links)
+      c.graph.vertices_[link.objidx].remove_parent (this_index);
+    o.real_links.reset ();
+
+    unsigned new_index = 0;
+    for (const auto& record : this->iter ())
+    {
+      unsigned klass = record.klass;
+      if (klass >= new_class_count) continue;
+
+      (*this)[new_index].klass = klass;
+      unsigned position = (char*) &record.markAnchor - (char*) this;
+      unsigned* objidx;
+      if (!mark_array_links.has (position, &objidx))
+      {
+        new_index++;
+        continue;
+      }
+
+      c.graph.add_link (&(*this)[new_index].markAnchor, this_index, *objidx);
+      new_index++;
+    }
+
+    this->len = new_index;
+    o.tail = o.head + MarkArray::min_size +
+             OT::Layout::GPOS_impl::MarkRecord::static_size * new_index;
+    return true;
+  }
+
+  unsigned clone (gsubgpos_graph_context_t& c,
+                  unsigned this_index,
+                  const hb_hashmap_t<unsigned, unsigned>& pos_to_index,
+                  hb_set_t& marks,
+                  unsigned start_class)
+  {
+    unsigned size = MarkArray::min_size +
+                    OT::Layout::GPOS_impl::MarkRecord::static_size *
+                    marks.get_population ();
+    unsigned prime_id = c.create_node (size);
+    if (prime_id == (unsigned) -1) return -1;
+    MarkArray* prime = (MarkArray*) c.graph.object (prime_id).head;
+    prime->len = marks.get_population ();
+
+
+    unsigned i = 0;
+    for (hb_codepoint_t mark : marks)
+    {
+      (*prime)[i].klass = (*this)[mark].klass - start_class;
+      unsigned offset_pos = (char*) &((*this)[mark].markAnchor) - (char*) this;
+      unsigned* anchor_index;
+      if (pos_to_index.has (offset_pos, &anchor_index))
+        c.graph.move_child (this_index,
+                            &((*this)[mark].markAnchor),
+                            prime_id,
+                            &((*prime)[i].markAnchor));
+
+      i++;
+    }
+
+    return prime_id;
+  }
+};
+
+struct MarkBasePosFormat1 : public OT::Layout::GPOS_impl::MarkBasePosFormat1_2<SmallTypes>
+{
+  bool sanitize (graph_t::vertex_t& vertex) const
+  {
+    int64_t vertex_len = vertex.obj.tail - vertex.obj.head;
+    return vertex_len >= MarkBasePosFormat1::static_size;
+  }
+
+  hb_vector_t<unsigned> split_subtables (gsubgpos_graph_context_t& c,
+                                         unsigned parent_index,
+                                         unsigned this_index)
+  {
+    hb_set_t visited;
+
+    const unsigned base_coverage_id = c.graph.index_for_offset (this_index, &baseCoverage);
+    const unsigned base_size =
+        OT::Layout::GPOS_impl::MarkBasePosFormat1_2<SmallTypes>::min_size +
+        MarkArray::min_size +
+        AnchorMatrix::min_size +
+        c.graph.vertices_[base_coverage_id].table_size ();
+
+    hb_vector_t<class_info_t> class_to_info = get_class_info (c, this_index);
+
+    unsigned class_count = classCount;
+    auto base_array = c.graph.as_table<AnchorMatrix> (this_index,
+                                                      &baseArray,
+                                                      class_count);
+    if (!base_array) return hb_vector_t<unsigned> ();
+    unsigned base_count = base_array.table->rows;
+
+    unsigned partial_coverage_size = 4;
+    unsigned accumulated = base_size;
+    hb_vector_t<unsigned> split_points;
+
+    for (unsigned klass = 0; klass < class_count; klass++)
+    {
+      class_info_t& info = class_to_info[klass];
+      partial_coverage_size += OT::HBUINT16::static_size * info.marks.get_population ();
+      unsigned accumulated_delta =
+          OT::Layout::GPOS_impl::MarkRecord::static_size * info.marks.get_population () +
+          OT::Offset16::static_size * base_count;
+
+      for (unsigned objidx : info.child_indices)
+        accumulated_delta += c.graph.find_subgraph_size (objidx, visited);
+
+      accumulated += accumulated_delta;
+      unsigned total = accumulated + partial_coverage_size;
+
+      if (total >= (1 << 16))
+      {
+        split_points.push (klass);
+        accumulated = base_size + accumulated_delta;
+        partial_coverage_size = 4 + OT::HBUINT16::static_size * info.marks.get_population ();
+        visited.clear (); // node sharing isn't allowed between splits.
+      }
+    }
+
+
+    const unsigned mark_array_id = c.graph.index_for_offset (this_index, &markArray);
+    split_context_t split_context {
+      c,
+      this,
+      c.graph.duplicate_if_shared (parent_index, this_index),
+      std::move (class_to_info),
+      c.graph.vertices_[mark_array_id].position_to_index_map (),
+    };
+
+    return actuate_subtable_split<split_context_t> (split_context, split_points);
+  }
+
+ private:
+
+  struct class_info_t {
+    hb_set_t marks;
+    hb_vector_t<unsigned> child_indices;
+  };
+
+  struct split_context_t {
+    gsubgpos_graph_context_t& c;
+    MarkBasePosFormat1* thiz;
+    unsigned this_index;
+    hb_vector_t<class_info_t> class_to_info;
+    hb_hashmap_t<unsigned, unsigned> mark_array_links;
+
+    hb_set_t marks_for (unsigned start, unsigned end)
+    {
+      hb_set_t marks;
+      for (unsigned klass = start; klass < end; klass++)
+      {
+        + class_to_info[klass].marks.iter ()
+        | hb_sink (marks)
+        ;
+      }
+      return marks;
+    }
+
+    unsigned original_count ()
+    {
+      return thiz->classCount;
+    }
+
+    unsigned clone_range (unsigned start, unsigned end)
+    {
+      return thiz->clone_range (*this, this->this_index, start, end);
+    }
+
+    bool shrink (unsigned count)
+    {
+      return thiz->shrink (*this, this->this_index, count);
+    }
+  };
+
+  hb_vector_t<class_info_t> get_class_info (gsubgpos_graph_context_t& c,
+                                            unsigned this_index)
+  {
+    hb_vector_t<class_info_t> class_to_info;
+
+    unsigned class_count = classCount;
+    if (!class_count) return class_to_info;
+
+    if (!class_to_info.resize (class_count))
+      return hb_vector_t<class_info_t>();
+
+    auto mark_array = c.graph.as_table<MarkArray> (this_index, &markArray);
+    if (!mark_array) return hb_vector_t<class_info_t> ();
+    unsigned mark_count = mark_array.table->len;
+    for (unsigned mark = 0; mark < mark_count; mark++)
+    {
+      unsigned klass = (*mark_array.table)[mark].get_class ();
+      if (klass >= class_count) continue;
+      class_to_info[klass].marks.add (mark);
+    }
+
+    for (const auto& link : mark_array.vertex->obj.real_links)
+    {
+      unsigned mark = (link.position - 2) /
+                     OT::Layout::GPOS_impl::MarkRecord::static_size;
+      unsigned klass = (*mark_array.table)[mark].get_class ();
+      if (klass >= class_count) continue;
+      class_to_info[klass].child_indices.push (link.objidx);
+    }
+
+    unsigned base_array_id =
+        c.graph.index_for_offset (this_index, &baseArray);
+    auto& base_array_v = c.graph.vertices_[base_array_id];
+
+    for (const auto& link : base_array_v.obj.real_links)
+    {
+      unsigned index = (link.position - 2) / OT::Offset16::static_size;
+      unsigned klass = index % class_count;
+      class_to_info[klass].child_indices.push (link.objidx);
+    }
+
+    return class_to_info;
+  }
+
+  bool shrink (split_context_t& sc,
+               unsigned this_index,
+               unsigned count)
+  {
+    DEBUG_MSG (SUBSET_REPACK, nullptr,
+               "  Shrinking MarkBasePosFormat1 (%u) to [0, %u).",
+               this_index,
+               count);
+
+    unsigned old_count = classCount;
+    if (count >= old_count)
+      return true;
+
+    classCount = count;
+
+    auto mark_coverage = sc.c.graph.as_mutable_table<Coverage> (this_index,
+                                                                &markCoverage);
+    if (!mark_coverage) return false;
+    hb_set_t marks = sc.marks_for (0, count);
+    auto new_coverage =
+        + hb_enumerate (mark_coverage.table->iter ())
+        | hb_filter (marks, hb_first)
+        | hb_map_retains_sorting (hb_second)
+        ;
+    if (!Coverage::make_coverage (sc.c, + new_coverage,
+                                  mark_coverage.index,
+                                  4 + 2 * marks.get_population ()))
+      return false;
+
+
+    auto base_array = sc.c.graph.as_mutable_table<AnchorMatrix> (this_index,
+                                                                 &baseArray,
+                                                                 old_count);
+    if (!base_array || !base_array.table->shrink (sc.c,
+                                                  base_array.index,
+                                                  old_count,
+                                                  count))
+      return false;
+
+    auto mark_array = sc.c.graph.as_mutable_table<MarkArray> (this_index,
+                                                              &markArray);
+    if (!mark_array || !mark_array.table->shrink (sc.c,
+                                                  sc.mark_array_links,
+                                                  mark_array.index,
+                                                  count))
+      return false;
+
+    return true;
+  }
+
+  // Create a new MarkBasePos that has all of the data for classes from [start, end).
+  unsigned clone_range (split_context_t& sc,
+                        unsigned this_index,
+                        unsigned start, unsigned end) const
+  {
+    DEBUG_MSG (SUBSET_REPACK, nullptr,
+               "  Cloning MarkBasePosFormat1 (%u) range [%u, %u).", this_index, start, end);
+
+    graph_t& graph = sc.c.graph;
+    unsigned prime_size = OT::Layout::GPOS_impl::MarkBasePosFormat1_2<SmallTypes>::static_size;
+
+    unsigned prime_id = sc.c.create_node (prime_size);
+    if (prime_id == (unsigned) -1) return -1;
+
+    MarkBasePosFormat1* prime = (MarkBasePosFormat1*) graph.object (prime_id).head;
+    prime->format = this->format;
+    unsigned new_class_count = end - start;
+    prime->classCount = new_class_count;
+
+    unsigned base_coverage_id =
+        graph.index_for_offset (sc.this_index, &baseCoverage);
+    graph.add_link (&(prime->baseCoverage), prime_id, base_coverage_id);
+    graph.duplicate (prime_id, base_coverage_id);
+
+    auto mark_coverage = sc.c.graph.as_table<Coverage> (this_index,
+                                                        &markCoverage);
+    if (!mark_coverage) return false;
+    hb_set_t marks = sc.marks_for (start, end);
+    auto new_coverage =
+        + hb_enumerate (mark_coverage.table->iter ())
+        | hb_filter (marks, hb_first)
+        | hb_map_retains_sorting (hb_second)
+        ;
+    if (!Coverage::add_coverage (sc.c,
+                                 prime_id,
+                                 2,
+                                 + new_coverage,
+                                 marks.get_population () * 2 + 4))
+      return -1;
+
+    auto mark_array =
+        graph.as_table <MarkArray> (sc.this_index, &markArray);
+    if (!mark_array) return -1;
+    unsigned new_mark_array =
+        mark_array.table->clone (sc.c,
+                                 mark_array.index,
+                                 sc.mark_array_links,
+                                 marks,
+                                 start);
+    graph.add_link (&(prime->markArray), prime_id, new_mark_array);
+
+    unsigned class_count = classCount;
+    auto base_array =
+        graph.as_table<AnchorMatrix> (sc.this_index, &baseArray, class_count);
+    if (!base_array) return -1;
+    unsigned new_base_array =
+        base_array.table->clone (sc.c,
+                                 base_array.index,
+                                 start, end, this->classCount);
+    graph.add_link (&(prime->baseArray), prime_id, new_base_array);
+
+    return prime_id;
+  }
+};
+
+
+struct MarkBasePos : public OT::Layout::GPOS_impl::MarkBasePos
+{
+  hb_vector_t<unsigned> split_subtables (gsubgpos_graph_context_t& c,
+                                         unsigned parent_index,
+                                         unsigned this_index)
+  {
+    switch (u.format) {
+    case 1:
+      return ((MarkBasePosFormat1*)(&u.format1))->split_subtables (c, parent_index, this_index);
+#ifndef HB_NO_BEYOND_64K
+    case 2: HB_FALLTHROUGH;
+      // Don't split 24bit MarkBasePos's.
+#endif
+    default:
+      return hb_vector_t<unsigned> ();
+    }
+  }
+
+  bool sanitize (graph_t::vertex_t& vertex) const
+  {
+    int64_t vertex_len = vertex.obj.tail - vertex.obj.head;
+    if (vertex_len < u.format.get_size ()) return false;
+    hb_barrier ();
+
+    switch (u.format) {
+    case 1:
+      return ((MarkBasePosFormat1*)(&u.format1))->sanitize (vertex);
+#ifndef HB_NO_BEYOND_64K
+    case 2: HB_FALLTHROUGH;
+#endif
+    default:
+      // We don't handle format 3 and 4 here.
+      return false;
+    }
+  }
+};
+
+
+}
+
+#endif  // GRAPH_MARKBASEPOS_GRAPH_HH

thirdparty/harfbuzz/src/graph/pairpos-graph.hh

@@ -0,0 +1,652 @@
+/*
+ * Copyright © 2022  Google, Inc.
+ *
+ *  This is part of HarfBuzz, a text shaping library.
+ *
+ * Permission is hereby granted, without written agreement and without
+ * license or royalty fees, to use, copy, modify, and distribute this
+ * software and its documentation for any purpose, provided that the
+ * above copyright notice and the following two paragraphs appear in
+ * all copies of this software.
+ *
+ * IN NO EVENT SHALL THE COPYRIGHT HOLDER BE LIABLE TO ANY PARTY FOR
+ * DIRECT, INDIRECT, SPECIAL, INCIDENTAL, OR CONSEQUENTIAL DAMAGES
+ * ARISING OUT OF THE USE OF THIS SOFTWARE AND ITS DOCUMENTATION, EVEN
+ * IF THE COPYRIGHT HOLDER HAS BEEN ADVISED OF THE POSSIBILITY OF SUCH
+ * DAMAGE.
+ *
+ * THE COPYRIGHT HOLDER SPECIFICALLY DISCLAIMS ANY WARRANTIES, INCLUDING,
+ * BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND
+ * FITNESS FOR A PARTICULAR PURPOSE.  THE SOFTWARE PROVIDED HEREUNDER IS
+ * ON AN "AS IS" BASIS, AND THE COPYRIGHT HOLDER HAS NO OBLIGATION TO
+ * PROVIDE MAINTENANCE, SUPPORT, UPDATES, ENHANCEMENTS, OR MODIFICATIONS.
+ *
+ * Google Author(s): Garret Rieger
+ */
+
+#ifndef GRAPH_PAIRPOS_GRAPH_HH
+#define GRAPH_PAIRPOS_GRAPH_HH
+
+#include "split-helpers.hh"
+#include "coverage-graph.hh"
+#include "classdef-graph.hh"
+#include "../OT/Layout/GPOS/PairPos.hh"
+#include "../OT/Layout/GPOS/PosLookupSubTable.hh"
+
+namespace graph {
+
+struct PairPosFormat1 : public OT::Layout::GPOS_impl::PairPosFormat1_3<SmallTypes>
+{
+  bool sanitize (graph_t::vertex_t& vertex) const
+  {
+    int64_t vertex_len = vertex.obj.tail - vertex.obj.head;
+    unsigned min_size = OT::Layout::GPOS_impl::PairPosFormat1_3<SmallTypes>::min_size;
+    if (vertex_len < min_size) return false;
+    hb_barrier ();
+
+    return vertex_len >=
+        min_size + pairSet.get_size () - pairSet.len.get_size();
+  }
+
+  hb_vector_t<unsigned> split_subtables (gsubgpos_graph_context_t& c,
+                                         unsigned parent_index,
+                                         unsigned this_index)
+  {
+    hb_set_t visited;
+
+    const unsigned coverage_id = c.graph.index_for_offset (this_index, &coverage);
+    const unsigned coverage_size = c.graph.vertices_[coverage_id].table_size ();
+    const unsigned base_size = OT::Layout::GPOS_impl::PairPosFormat1_3<SmallTypes>::min_size;
+
+    unsigned partial_coverage_size = 4;
+    unsigned accumulated = base_size;
+    hb_vector_t<unsigned> split_points;
+    for (unsigned i = 0; i < pairSet.len; i++)
+    {
+      unsigned pair_set_index = pair_set_graph_index (c, this_index, i);
+      unsigned accumulated_delta =
+          c.graph.find_subgraph_size (pair_set_index, visited) +
+          SmallTypes::size; // for PairSet offset.
+      partial_coverage_size += OT::HBUINT16::static_size;
+
+      accumulated += accumulated_delta;
+      unsigned total = accumulated + hb_min (partial_coverage_size, coverage_size);
+
+      if (total >= (1 << 16))
+      {
+        split_points.push (i);
+        accumulated = base_size + accumulated_delta;
+        partial_coverage_size = 6;
+        visited.clear (); // node sharing isn't allowed between splits.
+      }
+    }
+
+    split_context_t split_context {
+      c,
+      this,
+      c.graph.duplicate_if_shared (parent_index, this_index),
+    };
+
+    return actuate_subtable_split<split_context_t> (split_context, split_points);
+  }
+
+ private:
+
+  struct split_context_t {
+    gsubgpos_graph_context_t& c;
+    PairPosFormat1* thiz;
+    unsigned this_index;
+
+    unsigned original_count ()
+    {
+      return thiz->pairSet.len;
+    }
+
+    unsigned clone_range (unsigned start, unsigned end)
+    {
+      return thiz->clone_range (this->c, this->this_index, start, end);
+    }
+
+    bool shrink (unsigned count)
+    {
+      return thiz->shrink (this->c, this->this_index, count);
+    }
+  };
+
+  bool shrink (gsubgpos_graph_context_t& c,
+               unsigned this_index,
+               unsigned count)
+  {
+    DEBUG_MSG (SUBSET_REPACK, nullptr,
+               "  Shrinking PairPosFormat1 (%u) to [0, %u).",
+               this_index,
+               count);
+    unsigned old_count = pairSet.len;
+    if (count >= old_count)
+      return true;
+
+    pairSet.len = count;
+    c.graph.vertices_[this_index].obj.tail -= (old_count - count) * SmallTypes::size;
+
+    auto coverage = c.graph.as_mutable_table<Coverage> (this_index, &this->coverage);
+    if (!coverage) return false;
+
+    unsigned coverage_size = coverage.vertex->table_size ();
+    auto new_coverage =
+        + hb_zip (coverage.table->iter (), hb_range ())
+        | hb_filter ([&] (hb_pair_t<unsigned, unsigned> p) {
+          return p.second < count;
+        })
+        | hb_map_retains_sorting (hb_first)
+        ;
+
+    return Coverage::make_coverage (c, new_coverage, coverage.index, coverage_size);
+  }
+
+  // Create a new PairPos including PairSet's from start (inclusive) to end (exclusive).
+  // Returns object id of the new object.
+  unsigned clone_range (gsubgpos_graph_context_t& c,
+                        unsigned this_index,
+                        unsigned start, unsigned end) const
+  {
+    DEBUG_MSG (SUBSET_REPACK, nullptr,
+               "  Cloning PairPosFormat1 (%u) range [%u, %u).", this_index, start, end);
+
+    unsigned num_pair_sets = end - start;
+    unsigned prime_size = OT::Layout::GPOS_impl::PairPosFormat1_3<SmallTypes>::min_size
+                          + num_pair_sets * SmallTypes::size;
+
+    unsigned pair_pos_prime_id = c.create_node (prime_size);
+    if (pair_pos_prime_id == (unsigned) -1) return -1;
+
+    PairPosFormat1* pair_pos_prime = (PairPosFormat1*) c.graph.object (pair_pos_prime_id).head;
+    pair_pos_prime->format = this->format;
+    pair_pos_prime->valueFormat[0] = this->valueFormat[0];
+    pair_pos_prime->valueFormat[1] = this->valueFormat[1];
+    pair_pos_prime->pairSet.len = num_pair_sets;
+
+    for (unsigned i = start; i < end; i++)
+    {
+      c.graph.move_child<> (this_index,
+                            &pairSet[i],
+                            pair_pos_prime_id,
+                            &pair_pos_prime->pairSet[i - start]);
+    }
+
+    unsigned coverage_id = c.graph.index_for_offset (this_index, &coverage);
+    if (!Coverage::clone_coverage (c,
+                                   coverage_id,
+                                   pair_pos_prime_id,
+                                   2,
+                                   start, end))
+      return -1;
+
+    return pair_pos_prime_id;
+  }
+
+
+
+  unsigned pair_set_graph_index (gsubgpos_graph_context_t& c, unsigned this_index, unsigned i) const
+  {
+    return c.graph.index_for_offset (this_index, &pairSet[i]);
+  }
+};
+
+struct PairPosFormat2 : public OT::Layout::GPOS_impl::PairPosFormat2_4<SmallTypes>
+{
+  bool sanitize (graph_t::vertex_t& vertex) const
+  {
+    size_t vertex_len = vertex.table_size ();
+    unsigned min_size = OT::Layout::GPOS_impl::PairPosFormat2_4<SmallTypes>::min_size;
+    if (vertex_len < min_size) return false;
+    hb_barrier ();
+
+    const unsigned class1_count = class1Count;
+    return vertex_len >=
+        min_size + class1_count * get_class1_record_size ();
+  }
+
+  hb_vector_t<unsigned> split_subtables (gsubgpos_graph_context_t& c,
+                                         unsigned parent_index,
+                                         unsigned this_index)
+  {
+    const unsigned base_size = OT::Layout::GPOS_impl::PairPosFormat2_4<SmallTypes>::min_size;
+    const unsigned class_def_2_size = size_of (c, this_index, &classDef2);
+    const Coverage* coverage = get_coverage (c, this_index);
+    const ClassDef* class_def_1 = get_class_def_1 (c, this_index);
+    auto gid_and_class =
+        + coverage->iter ()
+        | hb_map_retains_sorting ([&] (hb_codepoint_t gid) {
+          return hb_codepoint_pair_t (gid, class_def_1->get_class (gid));
+        })
+        ;
+    class_def_size_estimator_t estimator (gid_and_class);
+
+    const unsigned class1_count = class1Count;
+    const unsigned class2_count = class2Count;
+    const unsigned class1_record_size = get_class1_record_size ();
+
+    const unsigned value_1_len = valueFormat1.get_len ();
+    const unsigned value_2_len = valueFormat2.get_len ();
+    const unsigned total_value_len = value_1_len + value_2_len;
+
+    unsigned accumulated = base_size;
+    unsigned coverage_size = 4;
+    unsigned class_def_1_size = 4;
+    unsigned max_coverage_size = coverage_size;
+    unsigned max_class_def_1_size = class_def_1_size;
+
+    hb_vector_t<unsigned> split_points;
+
+    hb_hashmap_t<unsigned, unsigned> device_tables = get_all_device_tables (c, this_index);
+    hb_vector_t<unsigned> format1_device_table_indices = valueFormat1.get_device_table_indices ();
+    hb_vector_t<unsigned> format2_device_table_indices = valueFormat2.get_device_table_indices ();
+    bool has_device_tables = bool(format1_device_table_indices) || bool(format2_device_table_indices);
+
+    hb_set_t visited;
+    for (unsigned i = 0; i < class1_count; i++)
+    {
+      unsigned accumulated_delta = class1_record_size;
+      class_def_1_size = estimator.add_class_def_size (i);
+      coverage_size = estimator.coverage_size ();
+      max_coverage_size = hb_max (max_coverage_size, coverage_size);
+      max_class_def_1_size = hb_max (max_class_def_1_size, class_def_1_size);
+
+      if (has_device_tables) {
+        for (unsigned j = 0; j < class2_count; j++)
+        {
+          unsigned value1_index = total_value_len * (class2_count * i + j);
+          unsigned value2_index = value1_index + value_1_len;
+          accumulated_delta += size_of_value_record_children (c,
+                                                        device_tables,
+                                                        format1_device_table_indices,
+                                                        value1_index,
+                                                        visited);
+          accumulated_delta += size_of_value_record_children (c,
+                                                        device_tables,
+                                                        format2_device_table_indices,
+                                                        value2_index,
+                                                        visited);
+        }
+      }
+
+      accumulated += accumulated_delta;
+      unsigned total = accumulated
+                       + coverage_size + class_def_1_size + class_def_2_size
+                       // The largest object will pack last and can exceed the size limit.
+                       - hb_max (hb_max (coverage_size, class_def_1_size), class_def_2_size);
+      if (total >= (1 << 16))
+      {
+        split_points.push (i);
+        // split does not include i, so add the size for i when we reset the size counters.
+        accumulated = base_size + accumulated_delta;
+
+        estimator.reset();
+        class_def_1_size = estimator.add_class_def_size(i);
+        coverage_size = estimator.coverage_size();
+        visited.clear (); // node sharing isn't allowed between splits.
+      }
+    }
+
+    split_context_t split_context {
+      c,
+      this,
+      c.graph.duplicate_if_shared (parent_index, this_index),
+      class1_record_size,
+      total_value_len,
+      value_1_len,
+      value_2_len,
+      max_coverage_size,
+      max_class_def_1_size,
+      device_tables,
+      format1_device_table_indices,
+      format2_device_table_indices
+    };
+
+    return actuate_subtable_split<split_context_t> (split_context, split_points);
+  }
+ private:
+
+  struct split_context_t
+  {
+    gsubgpos_graph_context_t& c;
+    PairPosFormat2* thiz;
+    unsigned this_index;
+    unsigned class1_record_size;
+    unsigned value_record_len;
+    unsigned value1_record_len;
+    unsigned value2_record_len;
+    unsigned max_coverage_size;
+    unsigned max_class_def_size;
+
+    const hb_hashmap_t<unsigned, unsigned>& device_tables;
+    const hb_vector_t<unsigned>& format1_device_table_indices;
+    const hb_vector_t<unsigned>& format2_device_table_indices;
+
+    unsigned original_count ()
+    {
+      return thiz->class1Count;
+    }
+
+    unsigned clone_range (unsigned start, unsigned end)
+    {
+      return thiz->clone_range (*this, start, end);
+    }
+
+    bool shrink (unsigned count)
+    {
+      return thiz->shrink (*this, count);
+    }
+  };
+
+  size_t get_class1_record_size () const
+  {
+    const size_t class2_count = class2Count;
+    return
+        class2_count * (valueFormat1.get_size () + valueFormat2.get_size ());
+  }
+
+  unsigned clone_range (split_context_t& split_context,
+                        unsigned start, unsigned end) const
+  {
+    DEBUG_MSG (SUBSET_REPACK, nullptr,
+               "  Cloning PairPosFormat2 (%u) range [%u, %u).", split_context.this_index, start, end);
+
+    graph_t& graph = split_context.c.graph;
+
+    unsigned num_records = end - start;
+    unsigned prime_size = OT::Layout::GPOS_impl::PairPosFormat2_4<SmallTypes>::min_size
+                          + num_records * split_context.class1_record_size;
+
+    unsigned pair_pos_prime_id = split_context.c.create_node (prime_size);
+    if (pair_pos_prime_id == (unsigned) -1) return -1;
+
+    PairPosFormat2* pair_pos_prime =
+        (PairPosFormat2*) graph.object (pair_pos_prime_id).head;
+    pair_pos_prime->format = this->format;
+    pair_pos_prime->valueFormat1 = this->valueFormat1;
+    pair_pos_prime->valueFormat2 = this->valueFormat2;
+    pair_pos_prime->class1Count = num_records;
+    pair_pos_prime->class2Count = this->class2Count;
+    clone_class1_records (split_context,
+                          pair_pos_prime_id,
+                          start,
+                          end);
+
+    unsigned coverage_id =
+        graph.index_for_offset (split_context.this_index, &coverage);
+    unsigned class_def_1_id =
+        graph.index_for_offset (split_context.this_index, &classDef1);
+    auto& coverage_v = graph.vertices_[coverage_id];
+    auto& class_def_1_v = graph.vertices_[class_def_1_id];
+    Coverage* coverage_table = (Coverage*) coverage_v.obj.head;
+    ClassDef* class_def_1_table = (ClassDef*) class_def_1_v.obj.head;
+    if (!coverage_table
+        || !coverage_table->sanitize (coverage_v)
+        || !class_def_1_table
+        || !class_def_1_table->sanitize (class_def_1_v))
+      return -1;
+
+    auto klass_map =
+    + coverage_table->iter ()
+    | hb_map_retains_sorting ([&] (hb_codepoint_t gid) {
+      return hb_codepoint_pair_t (gid, class_def_1_table->get_class (gid));
+    })
+    | hb_filter ([&] (hb_codepoint_t klass) {
+      return klass >= start && klass < end;
+    }, hb_second)
+    | hb_map_retains_sorting ([&] (hb_codepoint_pair_t gid_and_class) {
+      // Classes must be from 0...N so subtract start
+      return hb_codepoint_pair_t (gid_and_class.first, gid_and_class.second - start);
+    })
+    ;
+
+    if (!Coverage::add_coverage (split_context.c,
+                                 pair_pos_prime_id,
+                                 2,
+                                 + klass_map | hb_map_retains_sorting (hb_first),
+                                 split_context.max_coverage_size))
+      return -1;
+
+    // classDef1
+    if (!ClassDef::add_class_def (split_context.c,
+                                  pair_pos_prime_id,
+                                  8,
+                                  + klass_map,
+                                  split_context.max_class_def_size))
+      return -1;
+
+    // classDef2
+    unsigned class_def_2_id =
+        graph.index_for_offset (split_context.this_index, &classDef2);
+    auto* class_def_link = graph.vertices_[pair_pos_prime_id].obj.real_links.push ();
+    class_def_link->width = SmallTypes::size;
+    class_def_link->objidx = class_def_2_id;
+    class_def_link->position = 10;
+    graph.vertices_[class_def_2_id].add_parent (pair_pos_prime_id, false);
+    graph.duplicate (pair_pos_prime_id, class_def_2_id);
+
+    return pair_pos_prime_id;
+  }
+
+  void clone_class1_records (split_context_t& split_context,
+                             unsigned pair_pos_prime_id,
+                             unsigned start, unsigned end) const
+  {
+    PairPosFormat2* pair_pos_prime =
+        (PairPosFormat2*) split_context.c.graph.object (pair_pos_prime_id).head;
+
+    char* start_addr = ((char*)&values[0]) + start * split_context.class1_record_size;
+    unsigned num_records = end - start;
+    hb_memcpy (&pair_pos_prime->values[0],
+            start_addr,
+            num_records * split_context.class1_record_size);
+
+    if (!split_context.format1_device_table_indices
+        && !split_context.format2_device_table_indices)
+      // No device tables to move over.
+      return;
+
+    unsigned class2_count = class2Count;
+    for (unsigned i = start; i < end; i++)
+    {
+      for (unsigned j = 0; j < class2_count; j++)
+      {
+        unsigned value1_index = split_context.value_record_len * (class2_count * i + j);
+        unsigned value2_index = value1_index + split_context.value1_record_len;
+
+        unsigned new_value1_index = split_context.value_record_len * (class2_count * (i - start) + j);
+        unsigned new_value2_index = new_value1_index + split_context.value1_record_len;
+
+        transfer_device_tables (split_context,
+                                pair_pos_prime_id,
+                                split_context.format1_device_table_indices,
+                                value1_index,
+                                new_value1_index);
+
+        transfer_device_tables (split_context,
+                                pair_pos_prime_id,
+                                split_context.format2_device_table_indices,
+                                value2_index,
+                                new_value2_index);
+      }
+    }
+  }
+
+  void transfer_device_tables (split_context_t& split_context,
+                               unsigned pair_pos_prime_id,
+                               const hb_vector_t<unsigned>& device_table_indices,
+                               unsigned old_value_record_index,
+                               unsigned new_value_record_index) const
+  {
+    PairPosFormat2* pair_pos_prime =
+        (PairPosFormat2*) split_context.c.graph.object (pair_pos_prime_id).head;
+
+    for (unsigned i : device_table_indices)
+    {
+      OT::Offset16* record = (OT::Offset16*) &values[old_value_record_index + i];
+      unsigned record_position = ((char*) record) - ((char*) this);
+      if (!split_context.device_tables.has (record_position)) continue;
+
+      split_context.c.graph.move_child (
+          split_context.this_index,
+          record,
+          pair_pos_prime_id,
+          (OT::Offset16*) &pair_pos_prime->values[new_value_record_index + i]);
+    }
+  }
+
+  bool shrink (split_context_t& split_context,
+               unsigned count)
+  {
+    DEBUG_MSG (SUBSET_REPACK, nullptr,
+               "  Shrinking PairPosFormat2 (%u) to [0, %u).",
+               split_context.this_index,
+               count);
+    unsigned old_count = class1Count;
+    if (count >= old_count)
+      return true;
+
+    graph_t& graph = split_context.c.graph;
+    class1Count = count;
+    graph.vertices_[split_context.this_index].obj.tail -=
+        (old_count - count) * split_context.class1_record_size;
+
+    auto coverage =
+        graph.as_mutable_table<Coverage> (split_context.this_index, &this->coverage);
+    if (!coverage) return false;
+
+    auto class_def_1 =
+        graph.as_mutable_table<ClassDef> (split_context.this_index, &classDef1);
+    if (!class_def_1) return false;
+
+    auto klass_map =
+    + coverage.table->iter ()
+    | hb_map_retains_sorting ([&] (hb_codepoint_t gid) {
+      return hb_codepoint_pair_t (gid, class_def_1.table->get_class (gid));
+    })
+    | hb_filter ([&] (hb_codepoint_t klass) {
+      return klass < count;
+    }, hb_second)
+    ;
+
+    auto new_coverage = + klass_map | hb_map_retains_sorting (hb_first);
+    if (!Coverage::make_coverage (split_context.c,
+                                  + new_coverage,
+                                  coverage.index,
+                                  // existing ranges my not be kept, worst case size is a format 1
+                                  // coverage table.
+                                  4 + new_coverage.len() * 2))
+      return false;
+
+    return ClassDef::make_class_def (split_context.c,
+                                     + klass_map,
+                                     class_def_1.index,
+                                     class_def_1.vertex->table_size ());
+  }
+
+  hb_hashmap_t<unsigned, unsigned>
+  get_all_device_tables (gsubgpos_graph_context_t& c,
+                         unsigned this_index) const
+  {
+    const auto& v = c.graph.vertices_[this_index];
+    return v.position_to_index_map ();
+  }
+
+  const Coverage* get_coverage (gsubgpos_graph_context_t& c,
+                          unsigned this_index) const
+  {
+    unsigned coverage_id = c.graph.index_for_offset (this_index, &coverage);
+    auto& coverage_v = c.graph.vertices_[coverage_id];
+
+    Coverage* coverage_table = (Coverage*) coverage_v.obj.head;
+    if (!coverage_table || !coverage_table->sanitize (coverage_v))
+      return &Null(Coverage);
+    return coverage_table;
+  }
+
+  const ClassDef* get_class_def_1 (gsubgpos_graph_context_t& c,
+                                   unsigned this_index) const
+  {
+    unsigned class_def_1_id = c.graph.index_for_offset (this_index, &classDef1);
+    auto& class_def_1_v = c.graph.vertices_[class_def_1_id];
+
+    ClassDef* class_def_1_table = (ClassDef*) class_def_1_v.obj.head;
+    if (!class_def_1_table || !class_def_1_table->sanitize (class_def_1_v))
+      return &Null(ClassDef);
+    return class_def_1_table;
+  }
+
+  unsigned size_of_value_record_children (gsubgpos_graph_context_t& c,
+                                          const hb_hashmap_t<unsigned, unsigned>& device_tables,
+                                          const hb_vector_t<unsigned> device_table_indices,
+                                          unsigned value_record_index,
+                                          hb_set_t& visited)
+  {
+    unsigned size = 0;
+    for (unsigned i : device_table_indices)
+    {
+      OT::Layout::GPOS_impl::Value* record = &values[value_record_index + i];
+      unsigned record_position = ((char*) record) - ((char*) this);
+      unsigned* obj_idx;
+      if (!device_tables.has (record_position, &obj_idx)) continue;
+      size += c.graph.find_subgraph_size (*obj_idx, visited);
+    }
+    return size;
+  }
+
+  unsigned size_of (gsubgpos_graph_context_t& c,
+                    unsigned this_index,
+                    const void* offset) const
+  {
+    const unsigned id = c.graph.index_for_offset (this_index, offset);
+    return c.graph.vertices_[id].table_size ();
+  }
+};
+
+struct PairPos : public OT::Layout::GPOS_impl::PairPos
+{
+  hb_vector_t<unsigned> split_subtables (gsubgpos_graph_context_t& c,
+                                         unsigned parent_index,
+                                         unsigned this_index)
+  {
+    switch (u.format) {
+    case 1:
+      return ((PairPosFormat1*)(&u.format1))->split_subtables (c, parent_index, this_index);
+    case 2:
+      return ((PairPosFormat2*)(&u.format2))->split_subtables (c, parent_index, this_index);
+#ifndef HB_NO_BEYOND_64K
+    case 3: HB_FALLTHROUGH;
+    case 4: HB_FALLTHROUGH;
+      // Don't split 24bit PairPos's.
+#endif
+    default:
+      return hb_vector_t<unsigned> ();
+    }
+  }
+
+  bool sanitize (graph_t::vertex_t& vertex) const
+  {
+    int64_t vertex_len = vertex.obj.tail - vertex.obj.head;
+    if (vertex_len < u.format.get_size ()) return false;
+    hb_barrier ();
+
+    switch (u.format) {
+    case 1:
+      return ((PairPosFormat1*)(&u.format1))->sanitize (vertex);
+    case 2:
+      return ((PairPosFormat2*)(&u.format2))->sanitize (vertex);
+#ifndef HB_NO_BEYOND_64K
+    case 3: HB_FALLTHROUGH;
+    case 4: HB_FALLTHROUGH;
+#endif
+    default:
+      // We don't handle format 3 and 4 here.
+      return false;
+    }
+  }
+};
+
+}
+
+#endif  // GRAPH_PAIRPOS_GRAPH_HH

thirdparty/harfbuzz/src/graph/serialize.hh

@@ -0,0 +1,277 @@
+/*
+ * Copyright © 2022  Google, Inc.
+ *
+ *  This is part of HarfBuzz, a text shaping library.
+ *
+ * Permission is hereby granted, without written agreement and without
+ * license or royalty fees, to use, copy, modify, and distribute this
+ * software and its documentation for any purpose, provided that the
+ * above copyright notice and the following two paragraphs appear in
+ * all copies of this software.
+ *
+ * IN NO EVENT SHALL THE COPYRIGHT HOLDER BE LIABLE TO ANY PARTY FOR
+ * DIRECT, INDIRECT, SPECIAL, INCIDENTAL, OR CONSEQUENTIAL DAMAGES
+ * ARISING OUT OF THE USE OF THIS SOFTWARE AND ITS DOCUMENTATION, EVEN
+ * IF THE COPYRIGHT HOLDER HAS BEEN ADVISED OF THE POSSIBILITY OF SUCH
+ * DAMAGE.
+ *
+ * THE COPYRIGHT HOLDER SPECIFICALLY DISCLAIMS ANY WARRANTIES, INCLUDING,
+ * BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND
+ * FITNESS FOR A PARTICULAR PURPOSE.  THE SOFTWARE PROVIDED HEREUNDER IS
+ * ON AN "AS IS" BASIS, AND THE COPYRIGHT HOLDER HAS NO OBLIGATION TO
+ * PROVIDE MAINTENANCE, SUPPORT, UPDATES, ENHANCEMENTS, OR MODIFICATIONS.
+ *
+ * Google Author(s): Garret Rieger
+ */
+
+#ifndef GRAPH_SERIALIZE_HH
+#define GRAPH_SERIALIZE_HH
+
+namespace graph {
+
+struct overflow_record_t
+{
+  unsigned parent;
+  unsigned child;
+
+  bool operator != (const overflow_record_t o) const
+  { return !(*this == o); }
+
+  inline bool operator == (const overflow_record_t& o) const
+  {
+    return parent == o.parent &&
+        child == o.child;
+  }
+
+  inline uint32_t hash () const
+  {
+    uint32_t current = 0;
+    current = current * 31 + hb_hash (parent);
+    current = current * 31 + hb_hash (child);
+    return current;
+  }
+};
+
+inline
+int64_t compute_offset (
+    const graph_t& graph,
+    unsigned parent_idx,
+    const hb_serialize_context_t::object_t::link_t& link)
+{
+  const auto& parent = graph.vertices_[parent_idx];
+  const auto& child = graph.vertices_[link.objidx];
+  int64_t offset = 0;
+  switch ((hb_serialize_context_t::whence_t) link.whence) {
+    case hb_serialize_context_t::whence_t::Head:
+      offset = child.start - parent.start; break;
+    case hb_serialize_context_t::whence_t::Tail:
+      offset = child.start - parent.end; break;
+    case hb_serialize_context_t::whence_t::Absolute:
+      offset = child.start; break;
+  }
+
+  assert (offset >= link.bias);
+  offset -= link.bias;
+  return offset;
+}
+
+inline
+bool is_valid_offset (int64_t offset,
+                      const hb_serialize_context_t::object_t::link_t& link)
+{
+  if (unlikely (!link.width))
+    // Virtual links can't overflow.
+    return link.is_signed || offset >= 0;
+
+  if (link.is_signed)
+  {
+    if (link.width == 4)
+      return offset >= -((int64_t) 1 << 31) && offset < ((int64_t) 1 << 31);
+    else
+      return offset >= -(1 << 15) && offset < (1 << 15);
+  }
+  else
+  {
+    if (link.width == 4)
+      return offset >= 0 && offset < ((int64_t) 1 << 32);
+    else if (link.width == 3)
+      return offset >= 0 && offset < ((int32_t) 1 << 24);
+    else
+      return offset >= 0 && offset < (1 << 16);
+  }
+}
+
+/*
+ * Will any offsets overflow on graph when it's serialized?
+ */
+inline bool
+will_overflow (graph_t& graph,
+               hb_vector_t<overflow_record_t>* overflows = nullptr)
+{
+  if (overflows) overflows->resize (0);
+  graph.update_positions ();
+
+  hb_hashmap_t<overflow_record_t*, bool> record_set;
+  const auto& vertices = graph.vertices_;
+  for (int parent_idx = vertices.length - 1; parent_idx >= 0; parent_idx--)
+  {
+    // Don't need to check virtual links for overflow
+    for (const auto& link : vertices.arrayZ[parent_idx].obj.real_links)
+    {
+      int64_t offset = compute_offset (graph, parent_idx, link);
+      if (likely (is_valid_offset (offset, link)))
+        continue;
+
+      if (!overflows) return true;
+
+      overflow_record_t r;
+      r.parent = parent_idx;
+      r.child = link.objidx;
+      if (record_set.has(&r)) continue; // don't keep duplicate overflows.
+
+      overflows->push (r);
+      record_set.set(&r, true);
+    }
+  }
+
+  if (!overflows) return false;
+  return overflows->length;
+}
+
+inline
+void print_overflows (graph_t& graph,
+                      const hb_vector_t<overflow_record_t>& overflows)
+{
+  if (!DEBUG_ENABLED(SUBSET_REPACK)) return;
+
+  graph.update_parents ();
+  int limit = 10;
+  for (const auto& o : overflows)
+  {
+    if (!limit--) break;
+    const auto& parent = graph.vertices_[o.parent];
+    const auto& child = graph.vertices_[o.child];
+    DEBUG_MSG (SUBSET_REPACK, nullptr,
+               "  overflow from "
+               "%4u (%4u in, %4u out, space %2u) => "
+               "%4u (%4u in, %4u out, space %2u)",
+               o.parent,
+               parent.incoming_edges (),
+               parent.obj.real_links.length + parent.obj.virtual_links.length,
+               graph.space_for (o.parent),
+               o.child,
+               child.incoming_edges (),
+               child.obj.real_links.length + child.obj.virtual_links.length,
+               graph.space_for (o.child));
+  }
+  if (overflows.length > 10) {
+    DEBUG_MSG (SUBSET_REPACK, nullptr, "  ... plus %u more overflows.", overflows.length - 10);
+  }
+}
+
+template <typename O> inline void
+serialize_link_of_type (const hb_serialize_context_t::object_t::link_t& link,
+                        char* head,
+                        unsigned size,
+                        hb_serialize_context_t* c)
+{
+  assert(link.position + link.width <= size);
+
+  OT::Offset<O>* offset = reinterpret_cast<OT::Offset<O>*> (head + link.position);
+  *offset = 0;
+  c->add_link (*offset,
+               // serializer has an extra nil object at the start of the
+               // object array. So all id's are +1 of what our id's are.
+               link.objidx + 1,
+               (hb_serialize_context_t::whence_t) link.whence,
+               link.bias);
+}
+
+inline
+void serialize_link (const hb_serialize_context_t::object_t::link_t& link,
+                     char* head,
+                     unsigned size,
+                     hb_serialize_context_t* c)
+{
+  switch (link.width)
+  {
+    case 0:
+      // Virtual links aren't serialized.
+      return;
+    case 4:
+      if (link.is_signed)
+      {
+        serialize_link_of_type<OT::HBINT32> (link, head, size, c);
+      } else {
+        serialize_link_of_type<OT::HBUINT32> (link, head, size, c);
+      }
+      return;
+    case 2:
+      if (link.is_signed)
+      {
+        serialize_link_of_type<OT::HBINT16> (link, head, size, c);
+      } else {
+        serialize_link_of_type<OT::HBUINT16> (link, head, size, c);
+      }
+      return;
+    case 3:
+      serialize_link_of_type<OT::HBUINT24> (link, head, size, c);
+      return;
+    default:
+      // Unexpected link width.
+      assert (0);
+  }
+}
+
+/*
+ * serialize graph into the provided serialization buffer.
+ */
+inline hb_blob_t* serialize (const graph_t& graph)
+{
+  hb_vector_t<char> buffer;
+  size_t size = graph.total_size_in_bytes ();
+
+  if (!size) return hb_blob_get_empty ();
+
+  if (!buffer.alloc (size)) {
+    DEBUG_MSG (SUBSET_REPACK, nullptr, "Unable to allocate output buffer.");
+    return nullptr;
+  }
+  hb_serialize_context_t c((void *) buffer, size);
+
+  c.start_serialize<void> ();
+  const auto& vertices = graph.vertices_;
+  for (unsigned i = 0; i < vertices.length; i++) {
+    c.push ();
+
+    size_t size = vertices[i].obj.tail - vertices[i].obj.head;
+    char* start = c.allocate_size <char> (size);
+    if (!start) {
+      DEBUG_MSG (SUBSET_REPACK, nullptr, "Buffer out of space.");
+      return nullptr;
+    }
+
+    hb_memcpy (start, vertices[i].obj.head, size);
+
+    // Only real links needs to be serialized.
+    for (const auto& link : vertices[i].obj.real_links)
+      serialize_link (link, start, size, &c);
+
+    // All duplications are already encoded in the graph, so don't
+    // enable sharing during packing.
+    c.pop_pack (false);
+  }
+  c.end_serialize ();
+
+  if (c.in_error ()) {
+    DEBUG_MSG (SUBSET_REPACK, nullptr, "Error during serialization. Err flag: %d",
+               c.errors);
+    return nullptr;
+  }
+
+  return c.copy_blob ();
+}
+
+} // namespace graph
+
+#endif // GRAPH_SERIALIZE_HH

thirdparty/harfbuzz/src/graph/split-helpers.hh

@@ -0,0 +1,69 @@
+/*
+ * Copyright © 2022  Google, Inc.
+ *
+ *  This is part of HarfBuzz, a text shaping library.
+ *
+ * Permission is hereby granted, without written agreement and without
+ * license or royalty fees, to use, copy, modify, and distribute this
+ * software and its documentation for any purpose, provided that the
+ * above copyright notice and the following two paragraphs appear in
+ * all copies of this software.
+ *
+ * IN NO EVENT SHALL THE COPYRIGHT HOLDER BE LIABLE TO ANY PARTY FOR
+ * DIRECT, INDIRECT, SPECIAL, INCIDENTAL, OR CONSEQUENTIAL DAMAGES
+ * ARISING OUT OF THE USE OF THIS SOFTWARE AND ITS DOCUMENTATION, EVEN
+ * IF THE COPYRIGHT HOLDER HAS BEEN ADVISED OF THE POSSIBILITY OF SUCH
+ * DAMAGE.
+ *
+ * THE COPYRIGHT HOLDER SPECIFICALLY DISCLAIMS ANY WARRANTIES, INCLUDING,
+ * BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND
+ * FITNESS FOR A PARTICULAR PURPOSE.  THE SOFTWARE PROVIDED HEREUNDER IS
+ * ON AN "AS IS" BASIS, AND THE COPYRIGHT HOLDER HAS NO OBLIGATION TO
+ * PROVIDE MAINTENANCE, SUPPORT, UPDATES, ENHANCEMENTS, OR MODIFICATIONS.
+ *
+ * Google Author(s): Garret Rieger
+ */
+
+#ifndef GRAPH_SPLIT_HELPERS_HH
+#define GRAPH_SPLIT_HELPERS_HH
+
+namespace graph {
+
+template<typename Context>
+HB_INTERNAL
+hb_vector_t<unsigned> actuate_subtable_split (Context& split_context,
+                                              const hb_vector_t<unsigned>& split_points)
+{
+  hb_vector_t<unsigned> new_objects;
+  if (!split_points)
+    return new_objects;
+
+  for (unsigned i = 0; i < split_points.length; i++)
+  {
+    unsigned start = split_points[i];
+    unsigned end = (i < split_points.length - 1)
+                   ? split_points[i + 1]
+                   : split_context.original_count ();
+    unsigned id = split_context.clone_range (start, end);
+
+    if (id == (unsigned) -1)
+    {
+      new_objects.reset ();
+      new_objects.allocated = -1; // mark error
+      return new_objects;
+    }
+    new_objects.push (id);
+  }
+
+  if (!split_context.shrink (split_points[0]))
+  {
+    new_objects.reset ();
+    new_objects.allocated = -1; // mark error
+  }
+
+  return new_objects;
+}
+
+}
+
+#endif  // GRAPH_SPLIT_HELPERS_HH