From 482c6e5dc41402e60acf609fca0d9d8e8fbc4d9d Mon Sep 17 00:00:00 2001
From: Garret Rieger <grieger@google.com>
Date: Wed, 18 May 2022 19:58:55 +0000
Subject: [PATCH] [subset-perf] Speed up Coverage::serialize by caching
 iterator.

---
 src/hb-ot-layout-common.hh | 7 +++++--
 1 file changed, 5 insertions(+), 2 deletions(-)

diff --git a/src/hb-ot-layout-common.hh b/src/hb-ot-layout-common.hh
index 7c4d827c8..b0f2faaf5 100644
--- a/src/hb-ot-layout-common.hh
+++ b/src/hb-ot-layout-common.hh
@@ -1725,9 +1725,12 @@ struct Coverage
     | hb_filter (glyphset)
     | hb_map_retains_sorting (glyph_map)
     ;
+    // Cache the iterator result as it will be iterated multiple times
+    // by the serialize code below.
+    hb_sorted_vector_t<hb_codepoint_t> glyphs (it);
 
-    bool ret = bool (it);
-    Coverage_serialize (c->serializer, it);
+    bool ret = bool (glyphs);
+    Coverage_serialize (c->serializer, glyphs.iter ());
     return_trace (ret);
   }