[repacker] for ext promotion choose lookups from highest subtables per byte to lowest.

Attempts to roughly maximize the number of subtables that are non-ext.
This commit is contained in:
Garret Rieger 2022-07-25 21:55:03 +00:00
parent e4fd5ff727
commit f2b9065246
3 changed files with 35 additions and 17 deletions

View File

@ -348,6 +348,8 @@ HB_SUBSET_sources = \
hb-subset.hh \ hb-subset.hh \
hb-repacker.hh \ hb-repacker.hh \
graph/graph.hh \ graph/graph.hh \
graph/gsubgpos-graph.hh \
graph/gsubgpos-graph.cc \
graph/serialize.hh \ graph/serialize.hh \
$(NULL) $(NULL)

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@ -41,14 +41,29 @@ using graph::graph_t;
* docs/repacker.md * docs/repacker.md
*/ */
struct lookup_size_t
{
unsigned lookup_index;
size_t size;
unsigned num_subtables;
};
inline int compare_sizes (const void* a, const void* b) inline int compare_sizes (const void* a, const void* b)
{ {
hb_pair_t<unsigned, size_t>* size_a = (hb_pair_t<unsigned, size_t>*) a; lookup_size_t* size_a = (lookup_size_t*) a;
hb_pair_t<unsigned, size_t>* size_b = (hb_pair_t<unsigned, size_t>*) b; lookup_size_t* size_b = (lookup_size_t*) b;
if (size_a->second == size_b->second) {
return size_b->first - size_a->first; double subtables_per_byte_a = (double) size_a->num_subtables / (double) size_a->size;
double subtables_per_byte_b = (double) size_b->num_subtables / (double) size_b->size;
if (subtables_per_byte_a == subtables_per_byte_b) {
return size_b->lookup_index - size_b->lookup_index;
} }
return size_a->second - size_b->second; double cmp = subtables_per_byte_b - subtables_per_byte_a;
if (cmp < 0) return -1;
if (cmp > 0) return 1;
return 0;
} }
/* /*
@ -80,15 +95,17 @@ bool _promote_extensions_if_needed (graph::make_extension_context_t& ext_context
// solution. // solution.
if (!ext_context.lookups) return true; if (!ext_context.lookups) return true;
hb_vector_t<hb_pair_t<unsigned, size_t>> lookup_sizes; hb_vector_t<lookup_size_t> lookup_sizes;
lookup_sizes.alloc (ext_context.lookups.get_population ()); lookup_sizes.alloc (ext_context.lookups.get_population ());
for (unsigned lookup_index : ext_context.lookups.keys ()) for (unsigned lookup_index : ext_context.lookups.keys ())
{ {
const graph::Lookup* lookup = ext_context.lookups.get(lookup_index);
hb_set_t visited; hb_set_t visited;
lookup_sizes.push (hb_pair_t<unsigned, size_t> { lookup_sizes.push (lookup_size_t {
lookup_index, lookup_index,
ext_context.graph.find_subgraph_size (lookup_index, visited) ext_context.graph.find_subgraph_size (lookup_index, visited),
lookup->number_of_subtables (),
}); });
} }
@ -103,8 +120,7 @@ bool _promote_extensions_if_needed (graph::make_extension_context_t& ext_context
// if it's decided to not make a lookup extension. // if it's decided to not make a lookup extension.
for (auto p : lookup_sizes) for (auto p : lookup_sizes)
{ {
unsigned lookup_index = p.first; unsigned subtables_size = p.num_subtables * 8;
unsigned subtables_size = ext_context.lookups.get(lookup_index)->number_of_subtables () * 8;
l3_l4_size += subtables_size; l3_l4_size += subtables_size;
l4_plus_size += subtables_size; l4_plus_size += subtables_size;
} }
@ -112,22 +128,21 @@ bool _promote_extensions_if_needed (graph::make_extension_context_t& ext_context
bool layers_full = false; bool layers_full = false;
for (auto p : lookup_sizes) for (auto p : lookup_sizes)
{ {
unsigned lookup_index = p.first; const graph::Lookup* lookup = ext_context.lookups.get(p.lookup_index);
const graph::Lookup* lookup = ext_context.lookups.get(lookup_index);
if (lookup->is_extension (ext_context.table_tag)) if (lookup->is_extension (ext_context.table_tag))
// already an extension so size is counted by the loop above. // already an extension so size is counted by the loop above.
continue; continue;
if (!layers_full) if (!layers_full)
{ {
size_t lookup_size = ext_context.graph.vertices_[lookup_index].table_size (); size_t lookup_size = ext_context.graph.vertices_[p.lookup_index].table_size ();
hb_set_t visited; hb_set_t visited;
size_t subtables_size = ext_context.graph.find_subgraph_size (lookup_index, visited, 1) - lookup_size; size_t subtables_size = ext_context.graph.find_subgraph_size (p.lookup_index, visited, 1) - lookup_size;
size_t remaining_size = p.second - subtables_size - lookup_size; size_t remaining_size = p.size - subtables_size - lookup_size;
l2_l3_size += lookup_size; l2_l3_size += lookup_size;
l3_l4_size += lookup_size + subtables_size; l3_l4_size += lookup_size + subtables_size;
l3_l4_size -= lookup->number_of_subtables () * 8; l3_l4_size -= p.num_subtables * 8;
l4_plus_size += subtables_size + remaining_size; l4_plus_size += subtables_size + remaining_size;
if (l2_l3_size < (1 << 16) if (l2_l3_size < (1 << 16)
@ -137,7 +152,7 @@ bool _promote_extensions_if_needed (graph::make_extension_context_t& ext_context
layers_full = true; layers_full = true;
} }
if (!ext_context.lookups.get(lookup_index)->make_extension (ext_context, lookup_index)) if (!ext_context.lookups.get(p.lookup_index)->make_extension (ext_context, p.lookup_index))
return false; return false;
} }

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@ -1485,4 +1485,5 @@ main (int argc, char **argv)
test_resolve_with_extension_promotion (); test_resolve_with_extension_promotion ();
// TODO(grieger): test with extensions already mixed in as well. // TODO(grieger): test with extensions already mixed in as well.
// TODO(grieger): test two layer ext promotion setup. // TODO(grieger): test two layer ext promotion setup.
// TODO(grieger): test sorting by subtables per byte in ext. promotion.
} }