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[layout] Memoize collect_features 

Fixes https://github.com/harfbuzz/harfbuzz/pull/1317
Fixes https://oss-fuzz.com/v2/testcase-detail/6543700493598720
This commit is contained in:
Behdad Esfahbod 2018-10-25 21:42:19 -07:00
parent 84098b1639
commit eb44bfc864
1 changed files with 48 additions and 7 deletions
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55
src/hb-ot-layout.cc
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@ -664,8 +664,46 @@ struct hb_collect_features_context_t
: g (get_gsubgpos_table (face, table_tag)),
feature_indexes (feature_indexes_) {}
bool inline visited (const OT::Script &s)
{
/* We might have Null() object here. Don't want to involve
* that in the memoize. So, detect empty objects and return. */
if (unlikely (!s.has_default_lang_sys () &&
!s.get_lang_sys_count ()))
return true;
return visited (s, visited_script);
}
bool inline visited (const OT::LangSys &l)
{
/* We might have Null() object here. Don't want to involve
* that in the memoize. So, detect empty objects and return. */
if (unlikely (!l.has_required_feature () &&
!l.get_feature_count ()))
return true;
return visited (l, visited_langsys);
}
private:
template <typename T>
bool inline visited (const T &p, hb_set_t &visited_set)
{
hb_codepoint_t delta = (hb_codepoint_t) ((uintptr_t) &p - (uintptr_t) &g);
if (visited_set.has (delta))
return true;
visited_set.add (delta);
return false;
}
public:
const OT::GSUBGPOS &g;
hb_set_t *feature_indexes;
private:
hb_auto_t<hb_set_t> visited_script;
hb_auto_t<hb_set_t> visited_langsys;
};
static void
@ -673,12 +711,13 @@ langsys_collect_features (hb_collect_features_context_t *c,
const OT::LangSys &l,
const hb_tag_t *features)
{
if (c->visited (l)) return;
if (!features)
{
/* All features. */
unsigned int index = l.get_required_feature_index ();
if (index != HB_OT_LAYOUT_NO_FEATURE_INDEX)
c->feature_indexes->add (index);
if (l.has_required_feature ())
c->feature_indexes->add (l.get_required_feature_index ());
l.add_feature_indexes_to (c->feature_indexes);
}
@ -688,7 +727,6 @@ langsys_collect_features (hb_collect_features_context_t *c,
for (; *features; features++)
{
hb_tag_t feature_tag = *features;
unsigned int feature_index;
unsigned int num_features = l.get_feature_count ();
for (unsigned int i = 0; i < num_features; i++)
{
@ -710,12 +748,15 @@ script_collect_features (hb_collect_features_context_t *c,
const hb_tag_t *languages,
const hb_tag_t *features)
{
if (c->visited (s)) return;
if (!languages)
{
/* All languages. */
langsys_collect_features (c,
s.get_default_lang_sys (),
features);
if (s.has_default_lang_sys ())
langsys_collect_features (c,
s.get_default_lang_sys (),
features);
unsigned int count = s.get_lang_sys_count ();
for (unsigned int language_index = 0; language_index < count; language_index++)