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/*
* 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;
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",
table_size (),
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 (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[i];
if (link.objidx != child_index)
continue;
if ((obj.head + link.position) != offset)
continue;
obj.real_links.remove (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++)
{
// 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 ();
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];
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_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;
for (const auto& link : node.real_links)
{
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)
{
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);
}
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.
*/
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;
}
/*
* 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;
}
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 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);
}
}
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_;
hb_vector_t<char*> buffers;
};
}
#endif // GRAPH_GRAPH_HH
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