[layout] Allocate iters in the context

Can be further optimized, but I think I didn't break anything.

Saves another 3% off Roboto shaping.

src/hb-ot-layout-gpos-table.hh

@@ -684,8 +684,7 @@ struct PairPosFormat1
     unsigned int index = (this+coverage).get_coverage  (buffer->cur().codepoint);
     if (likely (index == NOT_COVERED)) return TRACE_RETURN (false);
 
-    hb_apply_context_t::skipping_iterator_t skippy_iter;
-    skippy_iter.init (c);
+    hb_apply_context_t::skipping_iterator_t &skippy_iter = c->iter_input;
     skippy_iter.reset (buffer->idx, 1);
     if (!skippy_iter.next ()) return TRACE_RETURN (false);
 
@@ -755,8 +754,7 @@ struct PairPosFormat2
     unsigned int index = (this+coverage).get_coverage  (buffer->cur().codepoint);
     if (likely (index == NOT_COVERED)) return TRACE_RETURN (false);
 
-    hb_apply_context_t::skipping_iterator_t skippy_iter;
-    skippy_iter.init (c);
+    hb_apply_context_t::skipping_iterator_t &skippy_iter = c->iter_input;
     skippy_iter.reset (buffer->idx, 1);
     if (!skippy_iter.next ()) return TRACE_RETURN (false);
 
@@ -906,8 +904,7 @@ struct CursivePosFormat1
     const EntryExitRecord &this_record = entryExitRecord[(this+coverage).get_coverage  (buffer->cur().codepoint)];
     if (!this_record.exitAnchor) return TRACE_RETURN (false);
 
-    hb_apply_context_t::skipping_iterator_t skippy_iter;
-    skippy_iter.init (c);
+    hb_apply_context_t::skipping_iterator_t &skippy_iter = c->iter_input;
     skippy_iter.reset (buffer->idx, 1);
     if (!skippy_iter.next ()) return TRACE_RETURN (false);
 
@@ -1051,8 +1048,7 @@ struct MarkBasePosFormat1
     if (likely (mark_index == NOT_COVERED)) return TRACE_RETURN (false);
 
     /* now we search backwards for a non-mark glyph */
-    hb_apply_context_t::skipping_iterator_t skippy_iter;
-    skippy_iter.init (c);
+    hb_apply_context_t::skipping_iterator_t &skippy_iter = c->iter_input;
     skippy_iter.reset (buffer->idx, 1);
     skippy_iter.set_lookup_props (LookupFlag::IgnoreMarks);
     do {
@@ -1157,8 +1153,7 @@ struct MarkLigPosFormat1
     if (likely (mark_index == NOT_COVERED)) return TRACE_RETURN (false);
 
     /* now we search backwards for a non-mark glyph */
-    hb_apply_context_t::skipping_iterator_t skippy_iter;
-    skippy_iter.init (c);
+    hb_apply_context_t::skipping_iterator_t &skippy_iter = c->iter_input;
     skippy_iter.reset (buffer->idx, 1);
     skippy_iter.set_lookup_props (LookupFlag::IgnoreMarks);
     if (!skippy_iter.prev ()) return TRACE_RETURN (false);
@@ -1275,8 +1270,7 @@ struct MarkMarkPosFormat1
     if (likely (mark1_index == NOT_COVERED)) return TRACE_RETURN (false);
 
     /* now we search backwards for a suitable mark glyph until a non-mark glyph */
-    hb_apply_context_t::skipping_iterator_t skippy_iter;
-    skippy_iter.init (c);
+    hb_apply_context_t::skipping_iterator_t &skippy_iter = c->iter_input;
     skippy_iter.reset (buffer->idx, 1);
     skippy_iter.set_lookup_props (c->lookup_props & ~LookupFlag::IgnoreFlags);
     if (!skippy_iter.prev ()) return TRACE_RETURN (false);

src/hb-ot-layout-gsubgpos-private.hh

@@ -469,6 +469,7 @@ struct hb_apply_context_t
   unsigned int lookup_props;
   const GDEF &gdef;
   bool has_glyph_classes;
+  skipping_iterator_t iter_input, iter_context;
   unsigned int debug_depth;
 
 
@@ -485,13 +486,20 @@ struct hb_apply_context_t
 			lookup_props (0),
 			gdef (*hb_ot_layout_from_face (face)->gdef),
 			has_glyph_classes (gdef.has_glyph_classes ()),
+			iter_input (),
+			iter_context (),
 			debug_depth (0) {}
 
   inline void set_lookup_mask (hb_mask_t mask) { lookup_mask = mask; }
   inline void set_auto_zwj (bool auto_zwj_) { auto_zwj = auto_zwj_; }
   inline void set_recurse_func (recurse_func_t func) { recurse_func = func; }
-  inline void set_lookup_props (unsigned int lookup_props_) { lookup_props = lookup_props_; }
-  inline void set_lookup (const Lookup &l) { lookup_props = l.get_props (); }
+  inline void set_lookup (const Lookup &l) { set_lookup_props (l.get_props ()); }
+  inline void set_lookup_props (unsigned int lookup_props_)
+  {
+    lookup_props = lookup_props_;
+    iter_input.init (this, false);
+    iter_context.init (this, true);
+  }
 
   inline bool
   match_properties_mark (hb_codepoint_t  glyph,
@@ -704,8 +712,7 @@ static inline bool match_input (hb_apply_context_t *c,
 
   hb_buffer_t *buffer = c->buffer;
 
-  hb_apply_context_t::skipping_iterator_t skippy_iter;
-  skippy_iter.init (c);
+  hb_apply_context_t::skipping_iterator_t &skippy_iter = c->iter_input;
   skippy_iter.reset (buffer->idx, count - 1);
   skippy_iter.set_match_func (match_func, match_data, input);
 
@@ -874,8 +881,7 @@ static inline bool match_backtrack (hb_apply_context_t *c,
 {
   TRACE_APPLY (NULL);
 
-  hb_apply_context_t::skipping_iterator_t skippy_iter;
-  skippy_iter.init (c, true);
+  hb_apply_context_t::skipping_iterator_t &skippy_iter = c->iter_context;
   skippy_iter.reset (c->buffer->backtrack_len (), count);
   skippy_iter.set_match_func (match_func, match_data, backtrack);
 
@@ -895,8 +901,7 @@ static inline bool match_lookahead (hb_apply_context_t *c,
 {
   TRACE_APPLY (NULL);
 
-  hb_apply_context_t::skipping_iterator_t skippy_iter;
-  skippy_iter.init (c, true);
+  hb_apply_context_t::skipping_iterator_t &skippy_iter = c->iter_context;
   skippy_iter.reset (c->buffer->idx + offset - 1, count);
   skippy_iter.set_match_func (match_func, match_data, lookahead);
 

src/hb-ot-shape-fallback.cc

@@ -441,7 +441,7 @@ _hb_ot_shape_fallback_kern (const hb_ot_shape_plan_t *plan,
   OT::hb_apply_context_t c (1, font, buffer);
   c.set_lookup_mask (plan->kern_mask);
   c.set_lookup_props (OT::LookupFlag::IgnoreMarks);
-  OT::hb_apply_context_t::skipping_iterator_t skippy_iter;
+  OT::hb_apply_context_t::skipping_iterator_t &skippy_iter = c.iter_input;
   skippy_iter.init (&c);
 
   unsigned int count = buffer->len;