[aat] Limit number of DontAdvance transitions
Remove the faulty loop-detection logic. Use max-ops for breaking
out of infinite loops or heavy work.
https://twitter.com/behdadesfahbod/status/958065026262183936
diff --git a/src/hb-aat-layout-common-private.hh b/src/hb-aat-layout-common-private.hh
index d62bafc..b5395bb 100644
--- a/src/hb-aat-layout-common-private.hh
+++ b/src/hb-aat-layout-common-private.hh
@@ -615,13 +615,7 @@
machine (machine_),
buffer (buffer_),
num_glyphs (face_->get_num_glyphs ()),
- last_zero (0),
- dont_advance_set (nullptr) {}
-
- inline ~StateTableDriver (void)
- {
- hb_set_destroy (dont_advance_set);
- }
+ last_zero (0) {}
template <typename context_t>
inline void drive (context_t *c)
@@ -648,27 +642,7 @@
if (unlikely (!c->transition (this, entry)))
break;
- if (entry->flags & context_t::DontAdvance)
- {
- if (!last_was_dont_advance)
- {
- if (dont_advance_set)
- dont_advance_set->clear ();
- else
- dont_advance_set = hb_set_create ();
- }
-
- unsigned int key = info[buffer->idx].codepoint ^ (state << 16);
- if (likely (!dont_advance_set->has (key)))
- {
- dont_advance_set->add (key);
- last_was_dont_advance = true;
- }
- else
- last_was_dont_advance = false;
- }
- else
- last_was_dont_advance = false;
+ last_was_dont_advance = (entry->flags & context_t::DontAdvance) && buffer->max_ops--;
state = entry->newState;
@@ -692,9 +666,6 @@
hb_buffer_t *buffer;
unsigned int num_glyphs;
unsigned int last_zero;
-
- private:
- hb_set_t *dont_advance_set; /* Infinite-loop detection */
};
