From 5287ccc935c86b6f5e6867592b64bc2461384f45 Mon Sep 17 00:00:00 2001
From: Behdad Esfahbod <behdad@behdad.org>
Date: Thu, 10 Aug 2017 14:25:53 -0700
Subject: [PATCH] [unsafe-to-break] Allocate public bits from 0

---
 src/hb-buffer.h  |  5 +++--
 src/hb-ot-map.cc | 15 +++++++++------
 2 files changed, 12 insertions(+), 8 deletions(-)

diff --git a/src/hb-buffer.h b/src/hb-buffer.h
index 995191a9d..0869fafea 100644
--- a/src/hb-buffer.h
+++ b/src/hb-buffer.h
@@ -72,8 +72,9 @@ typedef struct hb_glyph_info_t {
 } hb_glyph_info_t;
 
 typedef enum { /*< flags >*/
-  HB_GLYPH_FLAG_UNSAFE_TO_BREAK		= 0x00000002,
-  HB_GLYPH_FLAG_DEFINED			= 0x00000002 /* OR of all defined flags */
+  HB_GLYPH_FLAG_UNSAFE_TO_BREAK		= 0x00000001,
+
+  HB_GLYPH_FLAG_DEFINED			= 0x00000001 /* OR of all defined flags */
 } hb_glyph_flags_t;
 
 /**
diff --git a/src/hb-ot-map.cc b/src/hb-ot-map.cc
index 174fd529f..5764a1104 100644
--- a/src/hb-ot-map.cc
+++ b/src/hb-ot-map.cc
@@ -138,7 +138,11 @@ hb_ot_map_builder_t::compile (hb_ot_map_t  &m,
 			      const int    *coords,
 			      unsigned int  num_coords)
 {
-  m.global_mask = 1;
+  ASSERT_STATIC (!(HB_GLYPH_FLAG_DEFINED & (HB_GLYPH_FLAG_DEFINED + 1)));
+  unsigned int global_bit_mask = HB_GLYPH_FLAG_DEFINED + 1;
+  unsigned int global_bit_shift = _hb_popcount32 (HB_GLYPH_FLAG_DEFINED);
+
+  m.global_mask = global_bit_mask;
 
   unsigned int required_feature_index[2];
   hb_tag_t required_feature_tag[2];
@@ -190,8 +194,7 @@ hb_ot_map_builder_t::compile (hb_ot_map_t  &m,
 
 
   /* Allocate bits now */
-  unsigned int next_bit = 1;
-  next_bit++; /* Allocate for HB_GLYPH_FLAG_UNSAFE_TO_BREAK */
+  unsigned int next_bit = global_bit_shift + 1;
 
   for (unsigned int i = 0; i < feature_infos.len; i++)
   {
@@ -251,8 +254,8 @@ hb_ot_map_builder_t::compile (hb_ot_map_t  &m,
     map->auto_zwj = !(info->flags & F_MANUAL_ZWJ);
     if ((info->flags & F_GLOBAL) && info->max_value == 1) {
       /* Uses the global bit */
-      map->shift = 0;
-      map->mask = 1;
+      map->shift = global_bit_shift;
+      map->mask = global_bit_mask;
     } else {
       map->shift = next_bit;
       map->mask = (1u << (next_bit + bits_needed)) - (1u << next_bit);
@@ -289,7 +292,7 @@ hb_ot_map_builder_t::compile (hb_ot_map_t  &m,
 	add_lookups (m, face, table_index,
 		     required_feature_index[table_index],
 		     variations_index,
-		     1 /* mask */);
+		     global_bit_mask);
 
       for (unsigned i = 0; i < m.features.len; i++)
         if (m.features[i].stage[table_index] == stage)