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Diffstat (limited to 'gfx/harfbuzz/src/graph/graph.hh')
| -rw-r--r-- | gfx/harfbuzz/src/graph/graph.hh | 1385 |
1 files changed, 1385 insertions, 0 deletions
diff --git a/gfx/harfbuzz/src/graph/graph.hh b/gfx/harfbuzz/src/graph/graph.hh new file mode 100644 index 0000000000..dc5b6a36fe --- /dev/null +++ b/gfx/harfbuzz/src/graph/graph.hh @@ -0,0 +1,1385 @@ +/* + * 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 "../hb-set.hh" +#include "../hb-priority-queue.hh" +#include "../hb-serialize.hh" + +#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; + + + bool link_positions_valid (unsigned num_objects, bool removed_nil) + { + hb_set_t assigned_bytes; + for (const auto& l : obj.real_links) + { + if (l.objidx >= num_objects + || (removed_nil && !l.objidx)) + { + DEBUG_MSG (SUBSET_REPACK, nullptr, + "Invalid graph. Invalid object index."); + return false; + } + + unsigned start = l.position; + unsigned end = start + l.width - 1; + + if (unlikely (l.width < 2 || l.width > 4)) + { + DEBUG_MSG (SUBSET_REPACK, nullptr, + "Invalid graph. Invalid link width."); + return false; + } + + if (unlikely (end >= table_size ())) + { + DEBUG_MSG (SUBSET_REPACK, nullptr, + "Invalid graph. Link position is out of bounds."); + return false; + } + + if (unlikely (assigned_bytes.intersects (start, end))) + { + DEBUG_MSG (SUBSET_REPACK, nullptr, + "Invalid graph. Found offsets whose positions overlap."); + return false; + } + + assigned_bytes.add_range (start, end); + } + + return !assigned_bytes.in_error (); + } + + void normalize () + { + obj.real_links.qsort (); + for (auto& l : obj.real_links) + { + for (unsigned i = 0; i < l.width; i++) + { + obj.head[l.position + i] = 0; + } + } + } + + bool equals (const vertex_t& other, + const graph_t& graph, + const graph_t& other_graph, + unsigned depth) const + { + if (!(as_bytes () == other.as_bytes ())) + { + DEBUG_MSG (SUBSET_REPACK, nullptr, + "vertex [%lu] bytes != [%lu] bytes, depth = %u", + (unsigned long) table_size (), + (unsigned long) other.table_size (), + depth); + + auto a = as_bytes (); + auto b = other.as_bytes (); + while (a || b) + { + DEBUG_MSG (SUBSET_REPACK, nullptr, + " 0x%x %s 0x%x", *a, (*a == *b) ? "==" : "!=", *b); + a++; + b++; + } + return false; + } + + return links_equal (obj.real_links, other.obj.real_links, graph, other_graph, depth); + } + + hb_bytes_t as_bytes () const + { + return hb_bytes_t (obj.head, table_size ()); + } + + 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); + } + + hb_hashmap_t<unsigned, unsigned> + position_to_index_map () const + { + hb_hashmap_t<unsigned, unsigned> result; + + for (const auto& l : obj.real_links) { + result.set (l.position, l.objidx); + } + + return result; + } + + 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_unordered (i); + break; + } + } + + void remove_real_link (unsigned child_index, const void* offset) + { + for (unsigned i = 0; i < obj.real_links.length; i++) + { + auto& link = obj.real_links.arrayZ[i]; + if (link.objidx != child_index) + continue; + + if ((obj.head + link.position) != offset) + continue; + + obj.real_links.remove_unordered (i); + return; + } + } + + 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; + } + + size_t table_size () const { + return obj.tail - obj.head; + } + + int64_t modified_distance (unsigned order) const + { + // TODO(garretrieger): once priority is high enough, should try + // 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; + } + + private: + bool links_equal (const hb_vector_t<hb_serialize_context_t::object_t::link_t>& this_links, + const hb_vector_t<hb_serialize_context_t::object_t::link_t>& other_links, + const graph_t& graph, + const graph_t& other_graph, + unsigned depth) const + { + auto a = this_links.iter (); + auto b = other_links.iter (); + + while (a && b) + { + const auto& link_a = *a; + const auto& link_b = *b; + + if (link_a.width != link_b.width || + link_a.is_signed != link_b.is_signed || + link_a.whence != link_b.whence || + link_a.position != link_b.position || + link_a.bias != link_b.bias) + return false; + + if (!graph.vertices_[link_a.objidx].equals ( + other_graph.vertices_[link_b.objidx], graph, other_graph, depth + 1)) + return false; + + a++; + b++; + } + + if (bool (a) != bool (b)) + return false; + + return true; + } + }; + + template <typename T> + struct vertex_and_table_t + { + vertex_and_table_t () : index (0), vertex (nullptr), table (nullptr) + {} + + unsigned index; + vertex_t* vertex; + T* table; + + operator bool () { + return table && vertex; + } + }; + + /* + * 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), + buffers () + { + 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++) + { + // 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]; + + check_success (v->link_positions_valid (objects.length, removed_nil)); + + 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 (); + for (char* b : buffers) + hb_free (b); + } + + bool operator== (const graph_t& other) const + { + return root ().equals (other.root (), *this, other, 0); + } + + // Sorts links of all objects in a consistent manner and zeroes all offsets. + void normalize () + { + for (auto& v : vertices_.writer ()) + v.normalize (); + } + + 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; + } + + void add_buffer (char* buffer) + { + buffers.push (buffer); + } + + /* + * Adds a 16 bit link from parent_id to child_id + */ + template<typename T> + void add_link (T* offset, + unsigned parent_id, + unsigned child_id) + { + auto& v = vertices_[parent_id]; + auto* link = v.obj.real_links.push (); + link->width = 2; + link->objidx = child_id; + link->position = (char*) offset - (char*) v.obj.head; + vertices_[child_id].parents.push (parent_id); + } + + /* + * Generates a new topological sorting of graph ordered by the shortest + * distance to each node if positions are marked as invalid. + */ + void sort_shortest_distance_if_needed () + { + if (!positions_invalid) return; + sort_shortest_distance (); + } + + + /* + * 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]; + + if (unlikely (!check_success(new_id >= 0))) { + // We are out of ids. Which means we've visited a node more than once. + // This graph contains a cycle which is not allowed. + DEBUG_MSG (SUBSET_REPACK, nullptr, "Invalid graph. Contains cycle."); + return; + } + + 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 ()); + + remap_all_obj_indices (id_map, &sorted_graph); + hb_swap (vertices_, sorted_graph); + + if (!check_success (new_id == -1)) + print_orphaned_nodes (); + } + + /* + * Finds the set of nodes (placed into roots) that should be assigned unique spaces. + * More specifically this looks for the top most 24 bit or 32 bit links in the graph. + * Some special casing is done that is specific to the layout of GSUB/GPOS tables. + */ + void find_space_roots (hb_set_t& visited, hb_set_t& roots) + { + int root_index = (int) root_idx (); + for (int i = root_index; i >= 0; i--) + { + if (visited.has (i)) continue; + + // Only real links can form 32 bit spaces + for (auto& l : vertices_[i].obj.real_links) + { + if (l.is_signed || l.width < 3) + continue; + + if (i == root_index && l.width == 3) + // Ignore 24bit links from the root node, this skips past the single 24bit + // pointer to the lookup list. + continue; + + if (l.width == 3) + { + // A 24bit offset forms a root, unless there is 32bit offsets somewhere + // in it's subgraph, then those become the roots instead. This is to make sure + // that extension subtables beneath a 24bit lookup become the spaces instead + // of the offset to the lookup. + hb_set_t sub_roots; + find_32bit_roots (l.objidx, sub_roots); + if (sub_roots) { + for (unsigned sub_root_idx : sub_roots) { + roots.add (sub_root_idx); + find_subgraph (sub_root_idx, visited); + } + continue; + } + } + + roots.add (l.objidx); + find_subgraph (l.objidx, visited); + } + } + } + + template <typename T, typename ...Ts> + vertex_and_table_t<T> as_table (unsigned parent, const void* offset, Ts... ds) + { + return as_table_from_index<T> (index_for_offset (parent, offset), std::forward<Ts>(ds)...); + } + + template <typename T, typename ...Ts> + vertex_and_table_t<T> as_mutable_table (unsigned parent, const void* offset, Ts... ds) + { + return as_table_from_index<T> (mutable_index_for_offset (parent, offset), std::forward<Ts>(ds)...); + } + + template <typename T, typename ...Ts> + vertex_and_table_t<T> as_table_from_index (unsigned index, Ts... ds) + { + if (index >= vertices_.length) + return vertex_and_table_t<T> (); + + vertex_and_table_t<T> r; + r.vertex = &vertices_[index]; + r.table = (T*) r.vertex->obj.head; + r.index = index; + if (!r.table) + return vertex_and_table_t<T> (); + + if (!r.table->sanitize (*(r.vertex), std::forward<Ts>(ds)...)) + return vertex_and_table_t<T> (); + + return r; + } + + // Finds the object id of the object pointed to by the offset at 'offset' + // within object[node_idx]. + unsigned index_for_offset (unsigned node_idx, const void* offset) const + { + const auto& node = object (node_idx); + if (offset < node.head || offset >= node.tail) return -1; + + unsigned length = node.real_links.length; + for (unsigned i = 0; i < length; i++) + { + // Use direct access for increased performance, this is a hot method. + const auto& link = node.real_links.arrayZ[i]; + if (offset != node.head + link.position) + continue; + return link.objidx; + } + + return -1; + } + + // Finds the object id of the object pointed to by the offset at 'offset' + // within object[node_idx]. Ensures that the returned object is safe to mutate. + // That is, if the original child object is shared by parents other than node_idx + // it will be duplicated and the duplicate will be returned instead. + unsigned mutable_index_for_offset (unsigned node_idx, const void* offset) + { + unsigned child_idx = index_for_offset (node_idx, offset); + auto& child = vertices_[child_idx]; + for (unsigned p : child.parents) + { + if (p != node_idx) { + return duplicate (node_idx, child_idx); + } + } + + return child_idx; + } + + + /* + * Assign unique space numbers to each connected subgraph of 24 bit and/or 32 bit offset(s). + * Currently, this is implemented specifically tailored to the structure of a GPOS/GSUB + * (including with 24bit offsets) table. + */ + bool assign_spaces () + { + update_parents (); + + hb_set_t visited; + hb_set_t roots; + find_space_roots (visited, roots); + + // Mark everything not in the subgraphs of the roots as visited. This prevents + // subgraphs from being connected via nodes not in those subgraphs. + visited.invert (); + + if (!roots) return false; + + while (roots) + { + uint32_t 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([&] (uint32_t node_idx) { + const uint32_t *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. + uint32_t next = HB_SET_VALUE_INVALID; + while (roots.next (&next)) + { + const uint32_t *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 uint32_t *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); + } + + size_t find_subgraph_size (unsigned node_idx, hb_set_t& subgraph, unsigned max_depth = -1) + { + if (subgraph.has (node_idx)) return 0; + subgraph.add (node_idx); + + const auto& o = vertices_[node_idx].obj; + size_t size = o.tail - o.head; + if (max_depth == 0) + return size; + + for (const auto& link : o.all_links ()) + size += find_subgraph_size (link.objidx, subgraph, max_depth - 1); + return size; + } + + /* + * Finds the topmost children of 32bit offsets in the subgraph starting + * at node_idx. Found indices are placed into 'found'. + */ + void find_32bit_roots (unsigned node_idx, hb_set_t& found) + { + for (const auto& link : vertices_[node_idx].obj.all_links ()) + { + if (!link.is_signed && link.width == 4) { + found.add (link.objidx); + continue; + } + find_32bit_roots (link.objidx, found); + } + } + + /* + * Moves the child of old_parent_idx pointed to by old_offset to a new + * vertex at the new_offset. + */ + template<typename O> + void move_child (unsigned old_parent_idx, + const O* old_offset, + unsigned new_parent_idx, + const O* new_offset) + { + distance_invalid = true; + positions_invalid = true; + + auto& old_v = vertices_[old_parent_idx]; + auto& new_v = vertices_[new_parent_idx]; + + unsigned child_id = index_for_offset (old_parent_idx, + old_offset); + + auto* new_link = new_v.obj.real_links.push (); + new_link->width = O::static_size; + new_link->objidx = child_id; + new_link->position = (const char*) new_offset - (const char*) new_v.obj.head; + + auto& child = vertices_[child_id]; + child.parents.push (new_parent_idx); + + old_v.remove_real_link (child_id, old_offset); + child.remove_parent (old_parent_idx); + } + + /* + * 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. + */ + unsigned duplicate_if_shared (unsigned parent_idx, unsigned child_idx) + { + unsigned new_idx = duplicate (parent_idx, child_idx); + if (new_idx == (unsigned) -1) return child_idx; + return new_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. + */ + unsigned 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 -1; + } + + 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 clone_idx; + } + + + /* + * Adds a new node to the graph, not connected to anything. + */ + unsigned new_node (char* head, char* tail) + { + positions_invalid = true; + distance_invalid = true; + + auto* clone = vertices_.push (); + if (vertices_.in_error ()) { + return -1; + } + + clone->obj.head = head; + clone->obj.tail = tail; + clone->distance = 0; + clone->space = 0; + + unsigned clone_idx = vertices_.length - 2; + + // 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; + } + + /* + * 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; + } + + bool is_fully_connected () + { + update_parents(); + + if (root().parents) + // Root cannot have parents. + return false; + + for (unsigned i = 0; i < root_idx (); i++) + { + if (!vertices_[i].parents) + return false; + } + return true; + } + +#if 0 + /* + * Saves the current graph to a packed binary format which the repacker fuzzer takes + * as a seed. + */ + void save_fuzzer_seed (hb_tag_t tag) const + { + FILE* f = fopen ("./repacker_fuzzer_seed", "w"); + fwrite ((void*) &tag, sizeof (tag), 1, f); + + uint16_t num_objects = vertices_.length; + fwrite ((void*) &num_objects, sizeof (num_objects), 1, f); + + for (const auto& v : vertices_) + { + uint16_t blob_size = v.table_size (); + fwrite ((void*) &blob_size, sizeof (blob_size), 1, f); + fwrite ((const void*) v.obj.head, blob_size, 1, f); + } + + uint16_t link_count = 0; + for (const auto& v : vertices_) + link_count += v.obj.real_links.length; + + fwrite ((void*) &link_count, sizeof (link_count), 1, f); + + typedef struct + { + uint16_t parent; + uint16_t child; + uint16_t position; + uint8_t width; + } link_t; + + for (unsigned i = 0; i < vertices_.length; i++) + { + for (const auto& l : vertices_[i].obj.real_links) + { + link_t link { + (uint16_t) i, (uint16_t) l.objidx, + (uint16_t) l.position, (uint8_t) l.width + }; + fwrite ((void*) &link, sizeof (link), 1, f); + } + } + + fclose (f); + } +#endif + + 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(); + + if (root().parents) { + DEBUG_MSG (SUBSET_REPACK, nullptr, "Root node has incoming edges."); + } + + 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 24 or 32 bits 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 == 3 || 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); + } + } + + for (unsigned i = 0; i < vertices_.length; i++) + // parents arrays must be accurate or downstream operations like cycle detection + // and sorting won't work correctly. + check_success (!vertices_[i].parents.in_error ()); + + 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 uint32_t *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_; + hb_vector_t<char*> buffers; +}; + +} + +#endif // GRAPH_GRAPH_HH |