From 882d328839da03c1dff455592eb42776682d2e90 Mon Sep 17 00:00:00 2001
From: Behdad Esfahbod <behdad@behdad.org>
Date: Tue, 25 Feb 2025 16:34:55 -0700
Subject: [PATCH] [glyf] Port to decycler for composite glyphs

5% speed up drawing Roboto-Regular.ttf.
---
 src/OT/glyf/Glyph.hh | 26 ++++++++++----------------
 1 file changed, 10 insertions(+), 16 deletions(-)

diff --git a/src/OT/glyf/Glyph.hh b/src/OT/glyf/Glyph.hh
index 825c7a5b0..b3aa3b7c0 100644
--- a/src/OT/glyf/Glyph.hh
+++ b/src/OT/glyf/Glyph.hh
@@ -3,6 +3,7 @@
 
 
 #include "../../hb-open-type.hh"
+#include "../../hb-decycler.hh"
 
 #include "GlyphHeader.hh"
 #include "SimpleGlyph.hh"
@@ -314,7 +315,7 @@ struct Glyph
 		   bool use_my_metrics = true,
 		   bool phantom_only = false,
 		   hb_array_t<const int> coords = hb_array_t<const int> (),
-		   hb_map_t *current_glyphs = nullptr,
+		   hb_decycler_t *decycler = nullptr,
 		   unsigned int depth = 0,
 		   unsigned *edge_count = nullptr) const
   {
@@ -324,10 +325,6 @@ struct Glyph
     if (unlikely (*edge_count > HB_MAX_GRAPH_EDGE_COUNT)) return false;
     (*edge_count)++;
 
-    hb_map_t current_glyphs_stack;
-    if (current_glyphs == nullptr)
-      current_glyphs = &current_glyphs_stack;
-
     if (head_maxp_info)
     {
       head_maxp_info->maxComponentDepth = hb_max (head_maxp_info->maxComponentDepth, depth);
@@ -412,16 +409,20 @@ struct Glyph
       break;
     case COMPOSITE:
     {
+      hb_decycler_t decycler_stack; // TODO Move out of here
+      if (!decycler)
+	decycler = &decycler_stack;
+
+      hb_decycler_node_t decycler_node (*decycler);
+
       unsigned int comp_index = 0;
       for (auto &item : get_composite_iterator ())
       {
 	hb_codepoint_t item_gid = item.get_gid ();
 
-        if (unlikely (current_glyphs->has (item_gid)))
+        if (unlikely (!decycler_node.visit (item_gid)))
 	  continue;
 
-	current_glyphs->add (item_gid);
-
 	unsigned old_count = all_points.length;
 
 	if (unlikely ((!phantom_only || (use_my_metrics && item.is_use_my_metrics ())) &&
@@ -437,13 +438,10 @@ struct Glyph
 						    use_my_metrics,
 						    phantom_only,
 						    coords,
-						    current_glyphs,
+						    decycler,
 						    depth + 1,
 						    edge_count)))
-	{
-	  current_glyphs->del (item_gid);
 	  return false;
-	}
 
 	auto comp_points = all_points.as_array ().sub_array (old_count);
 
@@ -479,13 +477,9 @@ struct Glyph
 	all_points.resize (all_points.length - PHANTOM_COUNT);
 
 	if (all_points.length > HB_GLYF_MAX_POINTS)
-	{
-	  current_glyphs->del (item_gid);
 	  return false;
-	}
 
 	comp_index++;
-        current_glyphs->del (item_gid);
       }
 
       if (head_maxp_info && depth == 0)