From 3261e05bdbb067cb9411a38a585bb04be1fb2542 Mon Sep 17 00:00:00 2001
From: Behdad Esfahbod <behdad@behdad.org>
Date: Wed, 11 May 2022 13:16:31 -0600
Subject: [PATCH] [subset] Optimize ClassDef1::intersected_class_glyphs() for
 class0

---
 src/hb-ot-layout-common.hh | 11 +++++++----
 1 file changed, 7 insertions(+), 4 deletions(-)

diff --git a/src/hb-ot-layout-common.hh b/src/hb-ot-layout-common.hh
index f2a58028e..655bd39a4 100644
--- a/src/hb-ot-layout-common.hh
+++ b/src/hb-ot-layout-common.hh
@@ -2057,10 +2057,13 @@ struct ClassDefFormat1
     unsigned count = classValue.len;
     if (klass == 0)
     {
-      hb_codepoint_t endGlyph = startGlyph + count -1;
-      for (hb_codepoint_t g : glyphs->iter ())
-        if (g < startGlyph || g > endGlyph)
-          intersect_glyphs->add (g);
+      for (unsigned g = HB_SET_VALUE_INVALID;
+	   hb_set_next (glyphs, &g) && g < startGlyph;)
+	intersect_glyphs->add (g);
+
+      for (unsigned g = startGlyph + count - 1;
+	   hb_set_next (glyphs, &g);)
+	intersect_glyphs->add (g);
 
       return;
     }