diff options
Diffstat (limited to 'thirdparty/harfbuzz/src/graph')
| -rw-r--r-- | thirdparty/harfbuzz/src/graph/graph.hh | 860 | ||||
| -rw-r--r-- | thirdparty/harfbuzz/src/graph/serialize.hh | 249 |
2 files changed, 1109 insertions, 0 deletions
diff --git a/thirdparty/harfbuzz/src/graph/graph.hh b/thirdparty/harfbuzz/src/graph/graph.hh new file mode 100644 index 0000000000..52ca9dd142 --- /dev/null +++ b/thirdparty/harfbuzz/src/graph/graph.hh @@ -0,0 +1,860 @@ +/* + * 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_GRAPH_HH +#define GRAPH_GRAPH_HH + +namespace graph { + +/** + * Represents a serialized table in the form of a graph. + * Provides methods for modifying and reordering the graph. + */ +struct graph_t +{ + struct vertex_t + { + hb_serialize_context_t::object_t obj; + int64_t distance = 0 ; + int64_t space = 0 ; + hb_vector_t<unsigned> parents; + unsigned start = 0; + unsigned end = 0; + unsigned priority = 0; + + friend void swap (vertex_t& a, vertex_t& b) + { + hb_swap (a.obj, b.obj); + hb_swap (a.distance, b.distance); + hb_swap (a.space, b.space); + hb_swap (a.parents, b.parents); + hb_swap (a.start, b.start); + hb_swap (a.end, b.end); + hb_swap (a.priority, b.priority); + } + + bool is_shared () const + { + return parents.length > 1; + } + + unsigned incoming_edges () const + { + return parents.length; + } + + void remove_parent (unsigned parent_index) + { + for (unsigned i = 0; i < parents.length; i++) + { + if (parents[i] != parent_index) continue; + parents.remove (i); + break; + } + } + + void remap_parents (const hb_vector_t<unsigned>& id_map) + { + for (unsigned i = 0; i < parents.length; i++) + parents[i] = id_map[parents[i]]; + } + + void remap_parent (unsigned old_index, unsigned new_index) + { + for (unsigned i = 0; i < parents.length; i++) + { + if (parents[i] == old_index) + parents[i] = new_index; + } + } + + bool is_leaf () const + { + return !obj.real_links.length && !obj.virtual_links.length; + } + + bool raise_priority () + { + if (has_max_priority ()) return false; + priority++; + return true; + } + + bool has_max_priority () const { + return priority >= 3; + } + + int64_t modified_distance (unsigned order) const + { + // TODO(garretrieger): once priority is high enough, should try + // setting distance = 0 which will force to sort immediately after + // it's parent where possible. + + int64_t modified_distance = + hb_min (hb_max(distance + distance_modifier (), 0), 0x7FFFFFFFFFF); + if (has_max_priority ()) { + modified_distance = 0; + } + return (modified_distance << 18) | (0x003FFFF & order); + } + + int64_t distance_modifier () const + { + if (!priority) return 0; + int64_t table_size = obj.tail - obj.head; + + if (priority == 1) + return -table_size / 2; + + return -table_size; + } + }; + + /* + * A topological sorting of an object graph. Ordered + * in reverse serialization order (first object in the + * serialization is at the end of the list). This matches + * the 'packed' object stack used internally in the + * serializer + */ + template<typename T> + graph_t (const T& objects) + : parents_invalid (true), + distance_invalid (true), + positions_invalid (true), + successful (true) + { + num_roots_for_space_.push (1); + bool removed_nil = false; + vertices_.alloc (objects.length); + vertices_scratch_.alloc (objects.length); + for (unsigned i = 0; i < objects.length; i++) + { + // TODO(grieger): check all links point to valid objects. + + // If this graph came from a serialization buffer object 0 is the + // nil object. We don't need it for our purposes here so drop it. + if (i == 0 && !objects[i]) + { + removed_nil = true; + continue; + } + + vertex_t* v = vertices_.push (); + if (check_success (!vertices_.in_error ())) + v->obj = *objects[i]; + if (!removed_nil) continue; + // Fix indices to account for removed nil object. + for (auto& l : v->obj.all_links_writer ()) { + l.objidx--; + } + } + } + + ~graph_t () + { + vertices_.fini (); + } + + bool in_error () const + { + return !successful || + vertices_.in_error () || + num_roots_for_space_.in_error (); + } + + const vertex_t& root () const + { + return vertices_[root_idx ()]; + } + + unsigned root_idx () const + { + // Object graphs are in reverse order, the first object is at the end + // of the vector. Since the graph is topologically sorted it's safe to + // assume the first object has no incoming edges. + return vertices_.length - 1; + } + + const hb_serialize_context_t::object_t& object(unsigned i) const + { + return vertices_[i].obj; + } + + /* + * Generates a new topological sorting of graph ordered by the shortest + * distance to each node. + */ + void sort_shortest_distance () + { + positions_invalid = true; + + if (vertices_.length <= 1) { + // Graph of 1 or less doesn't need sorting. + return; + } + + update_distances (); + + hb_priority_queue_t queue; + hb_vector_t<vertex_t> &sorted_graph = vertices_scratch_; + if (unlikely (!check_success (sorted_graph.resize (vertices_.length)))) return; + hb_vector_t<unsigned> id_map; + if (unlikely (!check_success (id_map.resize (vertices_.length)))) return; + + hb_vector_t<unsigned> removed_edges; + if (unlikely (!check_success (removed_edges.resize (vertices_.length)))) return; + update_parents (); + + queue.insert (root ().modified_distance (0), root_idx ()); + int new_id = root_idx (); + unsigned order = 1; + while (!queue.in_error () && !queue.is_empty ()) + { + unsigned next_id = queue.pop_minimum().second; + + hb_swap (sorted_graph[new_id], vertices_[next_id]); + const vertex_t& next = sorted_graph[new_id]; + + id_map[next_id] = new_id--; + + for (const auto& link : next.obj.all_links ()) { + removed_edges[link.objidx]++; + if (!(vertices_[link.objidx].incoming_edges () - removed_edges[link.objidx])) + // Add the order that the links were encountered to the priority. + // This ensures that ties between priorities objects are broken in a consistent + // way. More specifically this is set up so that if a set of objects have the same + // distance they'll be added to the topological order in the order that they are + // referenced from the parent object. + queue.insert (vertices_[link.objidx].modified_distance (order++), + link.objidx); + } + } + + check_success (!queue.in_error ()); + check_success (!sorted_graph.in_error ()); + if (!check_success (new_id == -1)) + print_orphaned_nodes (); + + remap_all_obj_indices (id_map, &sorted_graph); + + hb_swap (vertices_, sorted_graph); + } + + /* + * Assign unique space numbers to each connected subgraph of 32 bit offset(s). + */ + bool assign_32bit_spaces () + { + unsigned root_index = root_idx (); + hb_set_t visited; + hb_set_t roots; + for (unsigned i = 0; i <= root_index; i++) + { + // Only real links can form 32 bit spaces + for (auto& l : vertices_[i].obj.real_links) + { + if (l.width == 4 && !l.is_signed) + { + roots.add (l.objidx); + find_subgraph (l.objidx, visited); + } + } + } + + // Mark everything not in the subgraphs of 32 bit roots as visited. + // This prevents 32 bit subgraphs from being connected via nodes not in the 32 bit subgraphs. + visited.invert (); + + if (!roots) return false; + + while (roots) + { + unsigned next = HB_SET_VALUE_INVALID; + if (unlikely (!check_success (!roots.in_error ()))) break; + if (!roots.next (&next)) break; + + hb_set_t connected_roots; + find_connected_nodes (next, roots, visited, connected_roots); + if (unlikely (!check_success (!connected_roots.in_error ()))) break; + + isolate_subgraph (connected_roots); + if (unlikely (!check_success (!connected_roots.in_error ()))) break; + + unsigned next_space = this->next_space (); + num_roots_for_space_.push (0); + for (unsigned root : connected_roots) + { + DEBUG_MSG (SUBSET_REPACK, nullptr, "Subgraph %u gets space %u", root, next_space); + vertices_[root].space = next_space; + num_roots_for_space_[next_space] = num_roots_for_space_[next_space] + 1; + distance_invalid = true; + positions_invalid = true; + } + + // TODO(grieger): special case for GSUB/GPOS use extension promotions to move 16 bit space + // into the 32 bit space as needed, instead of using isolation. + } + + + + return true; + } + + /* + * Isolates the subgraph of nodes reachable from root. Any links to nodes in the subgraph + * that originate from outside of the subgraph will be removed by duplicating the linked to + * object. + * + * Indices stored in roots will be updated if any of the roots are duplicated to new indices. + */ + bool isolate_subgraph (hb_set_t& roots) + { + update_parents (); + hb_map_t subgraph; + + // incoming edges to root_idx should be all 32 bit in length so we don't need to de-dup these + // set the subgraph incoming edge count to match all of root_idx's incoming edges + hb_set_t parents; + for (unsigned root_idx : roots) + { + subgraph.set (root_idx, wide_parents (root_idx, parents)); + find_subgraph (root_idx, subgraph); + } + + unsigned original_root_idx = root_idx (); + hb_map_t index_map; + bool made_changes = false; + for (auto entry : subgraph.iter ()) + { + const auto& node = vertices_[entry.first]; + unsigned subgraph_incoming_edges = entry.second; + + if (subgraph_incoming_edges < node.incoming_edges ()) + { + // Only de-dup objects with incoming links from outside the subgraph. + made_changes = true; + duplicate_subgraph (entry.first, index_map); + } + } + + if (!made_changes) + return false; + + if (original_root_idx != root_idx () + && parents.has (original_root_idx)) + { + // If the root idx has changed since parents was determined, update root idx in parents + parents.add (root_idx ()); + parents.del (original_root_idx); + } + + auto new_subgraph = + + subgraph.keys () + | hb_map([&] (unsigned node_idx) { + const unsigned *v; + if (index_map.has (node_idx, &v)) return *v; + return node_idx; + }) + ; + + remap_obj_indices (index_map, new_subgraph); + remap_obj_indices (index_map, parents.iter (), true); + + // Update roots set with new indices as needed. + unsigned next = HB_SET_VALUE_INVALID; + while (roots.next (&next)) + { + const unsigned *v; + if (index_map.has (next, &v)) + { + roots.del (next); + roots.add (*v); + } + } + + return true; + } + + void find_subgraph (unsigned node_idx, hb_map_t& subgraph) + { + for (const auto& link : vertices_[node_idx].obj.all_links ()) + { + const unsigned *v; + if (subgraph.has (link.objidx, &v)) + { + subgraph.set (link.objidx, *v + 1); + continue; + } + subgraph.set (link.objidx, 1); + find_subgraph (link.objidx, subgraph); + } + } + + void find_subgraph (unsigned node_idx, hb_set_t& subgraph) + { + if (subgraph.has (node_idx)) return; + subgraph.add (node_idx); + for (const auto& link : vertices_[node_idx].obj.all_links ()) + find_subgraph (link.objidx, subgraph); + } + + /* + * duplicates all nodes in the subgraph reachable from node_idx. Does not re-assign + * links. index_map is updated with mappings from old id to new id. If a duplication has already + * been performed for a given index, then it will be skipped. + */ + void duplicate_subgraph (unsigned node_idx, hb_map_t& index_map) + { + if (index_map.has (node_idx)) + return; + + index_map.set (node_idx, duplicate (node_idx)); + for (const auto& l : object (node_idx).all_links ()) { + duplicate_subgraph (l.objidx, index_map); + } + } + + /* + * Creates a copy of node_idx and returns it's new index. + */ + unsigned duplicate (unsigned node_idx) + { + positions_invalid = true; + distance_invalid = true; + + auto* clone = vertices_.push (); + auto& child = vertices_[node_idx]; + if (vertices_.in_error ()) { + return -1; + } + + clone->obj.head = child.obj.head; + clone->obj.tail = child.obj.tail; + clone->distance = child.distance; + clone->space = child.space; + clone->parents.reset (); + + unsigned clone_idx = vertices_.length - 2; + for (const auto& l : child.obj.real_links) + { + clone->obj.real_links.push (l); + vertices_[l.objidx].parents.push (clone_idx); + } + for (const auto& l : child.obj.virtual_links) + { + clone->obj.virtual_links.push (l); + vertices_[l.objidx].parents.push (clone_idx); + } + + check_success (!clone->obj.real_links.in_error ()); + check_success (!clone->obj.virtual_links.in_error ()); + + // The last object is the root of the graph, so swap back the root to the end. + // The root's obj idx does change, however since it's root nothing else refers to it. + // all other obj idx's will be unaffected. + hb_swap (vertices_[vertices_.length - 2], *clone); + + // Since the root moved, update the parents arrays of all children on the root. + for (const auto& l : root ().obj.all_links ()) + vertices_[l.objidx].remap_parent (root_idx () - 1, root_idx ()); + + return clone_idx; + } + + /* + * Creates a copy of child and re-assigns the link from + * parent to the clone. The copy is a shallow copy, objects + * linked from child are not duplicated. + */ + bool duplicate (unsigned parent_idx, unsigned child_idx) + { + update_parents (); + + unsigned links_to_child = 0; + for (const auto& l : vertices_[parent_idx].obj.all_links ()) + { + if (l.objidx == child_idx) links_to_child++; + } + + if (vertices_[child_idx].incoming_edges () <= links_to_child) + { + // Can't duplicate this node, doing so would orphan the original one as all remaining links + // to child are from parent. + DEBUG_MSG (SUBSET_REPACK, nullptr, " Not duplicating %d => %d", + parent_idx, child_idx); + return false; + } + + DEBUG_MSG (SUBSET_REPACK, nullptr, " Duplicating %d => %d", + parent_idx, child_idx); + + unsigned clone_idx = duplicate (child_idx); + if (clone_idx == (unsigned) -1) return false; + // duplicate shifts the root node idx, so if parent_idx was root update it. + if (parent_idx == clone_idx) parent_idx++; + + auto& parent = vertices_[parent_idx]; + for (auto& l : parent.obj.all_links_writer ()) + { + if (l.objidx != child_idx) + continue; + + reassign_link (l, parent_idx, clone_idx); + } + + return true; + } + + /* + * Raises the sorting priority of all children. + */ + bool raise_childrens_priority (unsigned parent_idx) + { + DEBUG_MSG (SUBSET_REPACK, nullptr, " Raising priority of all children of %d", + parent_idx); + // This operation doesn't change ordering until a sort is run, so no need + // to invalidate positions. It does not change graph structure so no need + // to update distances or edge counts. + auto& parent = vertices_[parent_idx].obj; + bool made_change = false; + for (auto& l : parent.all_links_writer ()) + made_change |= vertices_[l.objidx].raise_priority (); + return made_change; + } + + void print_orphaned_nodes () + { + if (!DEBUG_ENABLED(SUBSET_REPACK)) return; + + DEBUG_MSG (SUBSET_REPACK, nullptr, "Graph is not fully connected."); + parents_invalid = true; + update_parents(); + + for (unsigned i = 0; i < root_idx (); i++) + { + const auto& v = vertices_[i]; + if (!v.parents) + DEBUG_MSG (SUBSET_REPACK, nullptr, "Node %u is orphaned.", i); + } + } + + unsigned num_roots_for_space (unsigned space) const + { + return num_roots_for_space_[space]; + } + + unsigned next_space () const + { + return num_roots_for_space_.length; + } + + void move_to_new_space (const hb_set_t& indices) + { + num_roots_for_space_.push (0); + unsigned new_space = num_roots_for_space_.length - 1; + + for (unsigned index : indices) { + auto& node = vertices_[index]; + num_roots_for_space_[node.space] = num_roots_for_space_[node.space] - 1; + num_roots_for_space_[new_space] = num_roots_for_space_[new_space] + 1; + node.space = new_space; + distance_invalid = true; + positions_invalid = true; + } + } + + unsigned space_for (unsigned index, unsigned* root = nullptr) const + { + const auto& node = vertices_[index]; + if (node.space) + { + if (root != nullptr) + *root = index; + return node.space; + } + + if (!node.parents) + { + if (root) + *root = index; + return 0; + } + + return space_for (node.parents[0], root); + } + + void err_other_error () { this->successful = false; } + + size_t total_size_in_bytes () const { + size_t total_size = 0; + for (unsigned i = 0; i < vertices_.length; i++) { + size_t size = vertices_[i].obj.tail - vertices_[i].obj.head; + total_size += size; + } + return total_size; + } + + + private: + + /* + * Returns the numbers of incoming edges that are 32bits wide. + */ + unsigned wide_parents (unsigned node_idx, hb_set_t& parents) const + { + unsigned count = 0; + hb_set_t visited; + for (unsigned p : vertices_[node_idx].parents) + { + if (visited.has (p)) continue; + visited.add (p); + + // Only real links can be wide + for (const auto& l : vertices_[p].obj.real_links) + { + if (l.objidx == node_idx && l.width == 4 && !l.is_signed) + { + count++; + parents.add (p); + } + } + } + return count; + } + + bool check_success (bool success) + { return this->successful && (success || ((void) err_other_error (), false)); } + + public: + /* + * Creates a map from objid to # of incoming edges. + */ + void update_parents () + { + if (!parents_invalid) return; + + for (unsigned i = 0; i < vertices_.length; i++) + vertices_[i].parents.reset (); + + for (unsigned p = 0; p < vertices_.length; p++) + { + for (auto& l : vertices_[p].obj.all_links ()) + { + vertices_[l.objidx].parents.push (p); + } + } + + parents_invalid = false; + } + + /* + * compute the serialized start and end positions for each vertex. + */ + void update_positions () + { + if (!positions_invalid) return; + + unsigned current_pos = 0; + for (int i = root_idx (); i >= 0; i--) + { + auto& v = vertices_[i]; + v.start = current_pos; + current_pos += v.obj.tail - v.obj.head; + v.end = current_pos; + } + + positions_invalid = false; + } + + /* + * Finds the distance to each object in the graph + * from the initial node. + */ + void update_distances () + { + if (!distance_invalid) return; + + // Uses Dijkstra's algorithm to find all of the shortest distances. + // https://en.wikipedia.org/wiki/Dijkstra%27s_algorithm + // + // Implementation Note: + // Since our priority queue doesn't support fast priority decreases + // we instead just add new entries into the queue when a priority changes. + // Redundant ones are filtered out later on by the visited set. + // According to https://www3.cs.stonybrook.edu/~rezaul/papers/TR-07-54.pdf + // for practical performance this is faster then using a more advanced queue + // (such as a fibonacci queue) with a fast decrease priority. + for (unsigned i = 0; i < vertices_.length; i++) + { + if (i == vertices_.length - 1) + vertices_[i].distance = 0; + else + vertices_[i].distance = hb_int_max (int64_t); + } + + hb_priority_queue_t queue; + queue.insert (0, vertices_.length - 1); + + hb_vector_t<bool> visited; + visited.resize (vertices_.length); + + while (!queue.in_error () && !queue.is_empty ()) + { + unsigned next_idx = queue.pop_minimum ().second; + if (visited[next_idx]) continue; + const auto& next = vertices_[next_idx]; + int64_t next_distance = vertices_[next_idx].distance; + visited[next_idx] = true; + + for (const auto& link : next.obj.all_links ()) + { + if (visited[link.objidx]) continue; + + const auto& child = vertices_[link.objidx].obj; + unsigned link_width = link.width ? link.width : 4; // treat virtual offsets as 32 bits wide + int64_t child_weight = (child.tail - child.head) + + ((int64_t) 1 << (link_width * 8)) * (vertices_[link.objidx].space + 1); + int64_t child_distance = next_distance + child_weight; + + if (child_distance < vertices_[link.objidx].distance) + { + vertices_[link.objidx].distance = child_distance; + queue.insert (child_distance, link.objidx); + } + } + } + + check_success (!queue.in_error ()); + if (!check_success (queue.is_empty ())) + { + print_orphaned_nodes (); + return; + } + + distance_invalid = false; + } + + private: + /* + * Updates a link in the graph to point to a different object. Corrects the + * parents vector on the previous and new child nodes. + */ + void reassign_link (hb_serialize_context_t::object_t::link_t& link, + unsigned parent_idx, + unsigned new_idx) + { + unsigned old_idx = link.objidx; + link.objidx = new_idx; + vertices_[old_idx].remove_parent (parent_idx); + vertices_[new_idx].parents.push (parent_idx); + } + + /* + * Updates all objidx's in all links using the provided mapping. Corrects incoming edge counts. + */ + template<typename Iterator, hb_requires (hb_is_iterator (Iterator))> + void remap_obj_indices (const hb_map_t& id_map, + Iterator subgraph, + bool only_wide = false) + { + if (!id_map) return; + for (unsigned i : subgraph) + { + for (auto& link : vertices_[i].obj.all_links_writer ()) + { + const unsigned *v; + if (!id_map.has (link.objidx, &v)) continue; + if (only_wide && !(link.width == 4 && !link.is_signed)) continue; + + reassign_link (link, i, *v); + } + } + } + + /* + * Updates all objidx's in all links using the provided mapping. + */ + void remap_all_obj_indices (const hb_vector_t<unsigned>& id_map, + hb_vector_t<vertex_t>* sorted_graph) const + { + for (unsigned i = 0; i < sorted_graph->length; i++) + { + (*sorted_graph)[i].remap_parents (id_map); + for (auto& link : (*sorted_graph)[i].obj.all_links_writer ()) + { + link.objidx = id_map[link.objidx]; + } + } + } + + /* + * Finds all nodes in targets that are reachable from start_idx, nodes in visited will be skipped. + * For this search the graph is treated as being undirected. + * + * Connected targets will be added to connected and removed from targets. All visited nodes + * will be added to visited. + */ + void find_connected_nodes (unsigned start_idx, + hb_set_t& targets, + hb_set_t& visited, + hb_set_t& connected) + { + if (unlikely (!check_success (!visited.in_error ()))) return; + if (visited.has (start_idx)) return; + visited.add (start_idx); + + if (targets.has (start_idx)) + { + targets.del (start_idx); + connected.add (start_idx); + } + + const auto& v = vertices_[start_idx]; + + // Graph is treated as undirected so search children and parents of start_idx + for (const auto& l : v.obj.all_links ()) + find_connected_nodes (l.objidx, targets, visited, connected); + + for (unsigned p : v.parents) + find_connected_nodes (p, targets, visited, connected); + } + + public: + // TODO(garretrieger): make private, will need to move most of offset overflow code into graph. + hb_vector_t<vertex_t> vertices_; + hb_vector_t<vertex_t> vertices_scratch_; + private: + bool parents_invalid; + bool distance_invalid; + bool positions_invalid; + bool successful; + hb_vector_t<unsigned> num_roots_for_space_; +}; + +} + +#endif // GRAPH_GRAPH_HH diff --git a/thirdparty/harfbuzz/src/graph/serialize.hh b/thirdparty/harfbuzz/src/graph/serialize.hh new file mode 100644 index 0000000000..ecc6cc5aea --- /dev/null +++ b/thirdparty/harfbuzz/src/graph/serialize.hh @@ -0,0 +1,249 @@ +/* + * 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; +}; + +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 (); + + 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[parent_idx].obj.real_links) + { + int64_t offset = compute_offset (graph, parent_idx, link); + if (is_valid_offset (offset, link)) + continue; + + if (!overflows) return true; + + overflow_record_t r; + r.parent = parent_idx; + r.child = link.objidx; + overflows->push (r); + } + } + + 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 " + "%4d (%4d in, %4d out, space %2d) => " + "%4d (%4d in, %4d out, space %2d)", + 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 %d 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, + hb_serialize_context_t* c) +{ + 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, + 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, c); + } else { + serialize_link_of_type<OT::HBUINT32> (link, head, c); + } + return; + case 2: + if (link.is_signed) + { + serialize_link_of_type<OT::HBINT16> (link, head, c); + } else { + serialize_link_of_type<OT::HBUINT16> (link, head, c); + } + return; + case 3: + serialize_link_of_type<OT::HBUINT24> (link, head, 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 (!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; + } + + 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, &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 |