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[subset-perf] remove sort_kahn from repacker. 

Without an optimized FIFO queue implementation it's nearly as slow as the now optimized sort_shortest_distance.
This commit is contained in:
Garret Rieger 2022-05-19 20:45:39 +00:00 committed by Behdad Esfahbod
parent 4266cf3be2
commit b32ca2a292
2 changed files with 0 additions and 137 deletions
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53
src/hb-repacker.hh
View File

@ -248,58 +248,6 @@ struct graph_t
return c.copy_blob ();
}
/*
* Generates a new topological sorting of graph using Kahn's
* algorithm: https://en.wikipedia.org/wiki/Topological_sorting#Algorithms
*/
void sort_kahn ()
{
positions_invalid = true;
if (vertices_.length <= 1) {
// Graph of 1 or less doesn't need sorting.
return;
}
hb_vector_t<unsigned> 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.push (root_idx ());
int new_id = vertices_.length - 1;
while (!queue.in_error () && queue.length)
{
unsigned next_id = queue[0];
queue.remove (0);
vertex_t& next = vertices_[next_id];
sorted_graph[new_id] = next;
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]))
queue.push (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);
}
/*
* Generates a new topological sorting of graph ordered by the shortest
* distance to each node.
@ -1218,7 +1166,6 @@ hb_resolve_overflows (const T& packed,
// Kahn sort is ~twice as fast as shortest distance sort and works for many fonts
// so try it first to save time.
graph_t sorted_graph (packed);
sorted_graph.sort_kahn ();
if (!sorted_graph.will_overflow ())
{
return sorted_graph.serialize ();

84
src/test-repacker.cc
View File

@ -728,26 +728,6 @@ populate_serializer_with_split_spaces_expected_2 (hb_serialize_context_t* c)
c->end_serialize();
}
static void
populate_serializer_complex_1 (hb_serialize_context_t* c)
{
c->start_serialize<char> ();
unsigned obj_4 = add_object ("jkl", 3, c);
unsigned obj_3 = add_object ("ghi", 3, c);
start_object ("def", 3, c);
add_offset (obj_3, c);
unsigned obj_2 = c->pop_pack (false);
start_object ("abc", 3, c);
add_offset (obj_2, c);
add_offset (obj_4, c);
c->pop_pack (false);
c->end_serialize();
}
static void
populate_serializer_complex_2 (hb_serialize_context_t* c)
{
@ -831,68 +811,6 @@ populate_serializer_virtual_link (hb_serialize_context_t* c)
c->end_serialize();
}
static void test_sort_kahn_1 ()
{
size_t buffer_size = 100;
void* buffer = malloc (buffer_size);
hb_serialize_context_t c (buffer, buffer_size);
populate_serializer_complex_1 (&c);
graph_t graph (c.object_graph ());
graph.sort_kahn ();
assert(strncmp (graph.object (3).head, "abc", 3) == 0);
assert(graph.object (3).real_links.length == 2);
assert(graph.object (3).real_links[0].objidx == 2);
assert(graph.object (3).real_links[1].objidx == 1);
assert(strncmp (graph.object (2).head, "def", 3) == 0);
assert(graph.object (2).real_links.length == 1);
assert(graph.object (2).real_links[0].objidx == 0);
assert(strncmp (graph.object (1).head, "jkl", 3) == 0);
assert(graph.object (1).real_links.length == 0);
assert(strncmp (graph.object (0).head, "ghi", 3) == 0);
assert(graph.object (0).real_links.length == 0);
free (buffer);
}
static void test_sort_kahn_2 ()
{
size_t buffer_size = 100;
void* buffer = malloc (buffer_size);
hb_serialize_context_t c (buffer, buffer_size);
populate_serializer_complex_2 (&c);
graph_t graph (c.object_graph ());
graph.sort_kahn ();
assert(strncmp (graph.object (4).head, "abc", 3) == 0);
assert(graph.object (4).real_links.length == 3);
assert(graph.object (4).real_links[0].objidx == 3);
assert(graph.object (4).real_links[1].objidx == 0);
assert(graph.object (4).real_links[2].objidx == 2);
assert(strncmp (graph.object (3).head, "def", 3) == 0);
assert(graph.object (3).real_links.length == 1);
assert(graph.object (3).real_links[0].objidx == 1);
assert(strncmp (graph.object (2).head, "mn", 2) == 0);
assert(graph.object (2).real_links.length == 0);
assert(strncmp (graph.object (1).head, "ghi", 3) == 0);
assert(graph.object (1).real_links.length == 1);
assert(graph.object (1).real_links[0].objidx == 0);
assert(strncmp (graph.object (0).head, "jkl", 3) == 0);
assert(graph.object (0).real_links.length == 0);
free (buffer);
}
static void test_sort_shortest ()
{
size_t buffer_size = 100;
@ -1336,8 +1254,6 @@ int
main (int argc, char **argv)
{
test_serialize ();
test_sort_kahn_1 ();
test_sort_kahn_2 ();
test_sort_shortest ();
test_will_overflow_1 ();
test_will_overflow_2 ();