From 64dbeaf0f4ca5ab0d0c76158d7febbf2cd770c9f Mon Sep 17 00:00:00 2001
From: Behdad Esfahbod <behdad@behdad.org>
Date: Fri, 28 Feb 2025 00:54:39 -0700
Subject: [PATCH] [glyf] Mover decycler to the scratch pad

---
 src/OT/glyf/Glyph.hh        |  9 +--------
 src/hb-decycler.hh          | 13 ++++++++-----
 src/hb-ot-var-gvar-table.hh |  2 ++
 3 files changed, 11 insertions(+), 13 deletions(-)

diff --git a/src/OT/glyf/Glyph.hh b/src/OT/glyf/Glyph.hh
index ccd460ba0..2c289d511 100644
--- a/src/OT/glyf/Glyph.hh
+++ b/src/OT/glyf/Glyph.hh
@@ -3,7 +3,6 @@
 
 
 #include "../../hb-open-type.hh"
-#include "../../hb-decycler.hh"
 
 #include "GlyphHeader.hh"
 #include "SimpleGlyph.hh"
@@ -315,7 +314,6 @@ struct Glyph
 		   bool use_my_metrics = true,
 		   bool phantom_only = false,
 		   hb_array_t<const int> coords = hb_array_t<const int> (),
-		   hb_decycler_t *decycler = nullptr,
 		   unsigned int depth = 0,
 		   unsigned *edge_count = nullptr) const
   {
@@ -421,11 +419,7 @@ 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);
+      hb_decycler_node_t decycler_node (scratch.decycler);
 
       unsigned int comp_index = 0;
       for (auto &item : get_composite_iterator ())
@@ -453,7 +447,6 @@ struct Glyph
 						    use_my_metrics,
 						    phantom_only,
 						    coords,
-						    decycler,
 						    depth + 1,
 						    edge_count)))
 	{
diff --git a/src/hb-decycler.hh b/src/hb-decycler.hh
index 49dbe5be0..95b961027 100644
--- a/src/hb-decycler.hh
+++ b/src/hb-decycler.hh
@@ -89,7 +89,7 @@ struct hb_decycler_t
   friend struct hb_decycler_node_t;
 
   private:
-  bool tortoise_asleep = true;
+  bool tortoise_awake = false;
   hb_decycler_node_t *tortoise = nullptr;
   hb_decycler_node_t *hare = nullptr;
 };
@@ -100,15 +100,18 @@ struct hb_decycler_node_t
   {
     u.decycler = &decycler;
 
-    decycler.tortoise_asleep = !decycler.tortoise_asleep;
+    decycler.tortoise_awake = !decycler.tortoise_awake;
 
     if (!decycler.tortoise)
     {
       // First node.
+      assert (decycler.tortoise_awake);
+      assert (!decycler.hare);
       decycler.tortoise = decycler.hare = this;
       return;
     }
-    if (!decycler.tortoise_asleep)
+
+    if (decycler.tortoise_awake)
       decycler.tortoise = decycler.tortoise->u.next; // Time to move.
 
     this->prev = decycler.hare;
@@ -128,10 +131,10 @@ struct hb_decycler_node_t
       prev->u.decycler = &decycler;
 
     assert (decycler.tortoise);
-    if (!decycler.tortoise_asleep)
+    if (decycler.tortoise_awake)
       decycler.tortoise = decycler.tortoise->prev;
 
-    decycler.tortoise_asleep = !decycler.tortoise_asleep;
+    decycler.tortoise_awake = !decycler.tortoise_awake;
   }
 
   bool visit (uintptr_t value_)
diff --git a/src/hb-ot-var-gvar-table.hh b/src/hb-ot-var-gvar-table.hh
index 9cd22f6d6..7ea8ee129 100644
--- a/src/hb-ot-var-gvar-table.hh
+++ b/src/hb-ot-var-gvar-table.hh
@@ -28,6 +28,7 @@
 #ifndef HB_OT_VAR_GVAR_TABLE_HH
 #define HB_OT_VAR_GVAR_TABLE_HH
 
+#include "hb-decycler.hh"
 #include "hb-open-type.hh"
 #include "hb-ot-var-common.hh"
 
@@ -43,6 +44,7 @@ struct hb_glyf_scratch_t
   // glyf
   contour_point_vector_t all_points;
   contour_point_vector_t comp_points;
+  hb_decycler_t decycler;
 
   // gvar
   contour_point_vector_t orig_points;