From 3a1d7ee7e8471c3a9e59ab74551d99eba93410a9 Mon Sep 17 00:00:00 2001
From: Behdad Esfahbod <behdad@behdad.org>
Date: Tue, 4 Feb 2025 17:33:42 +0000
Subject: [PATCH] [aat] Remove the buffer-digest threshold

This can help us skip entire subchains, eg. when they are for
different scripts.

Speeds up LucidaGrande with ASCII text by 20%.
---
 src/hb-aat-layout-common.hh     | 2 --
 src/hb-aat-layout-kerx-table.hh | 5 +----
 src/hb-aat-layout-morx-table.hh | 5 +----
 3 files changed, 2 insertions(+), 10 deletions(-)

diff --git a/src/hb-aat-layout-common.hh b/src/hb-aat-layout-common.hh
index 37d919a17..5db0d1212 100644
--- a/src/hb-aat-layout-common.hh
+++ b/src/hb-aat-layout-common.hh
@@ -40,8 +40,6 @@ namespace AAT {
 
 using namespace OT;
 
-#define HB_AAT_BUFFER_DIGEST_THRESHOLD 32
-
 struct ankr;
 
 using hb_aat_class_cache_t = hb_cache_t<15, 8, 7>;
diff --git a/src/hb-aat-layout-kerx-table.hh b/src/hb-aat-layout-kerx-table.hh
index 72d696212..d5f46c66e 100644
--- a/src/hb-aat-layout-kerx-table.hh
+++ b/src/hb-aat-layout-kerx-table.hh
@@ -967,10 +967,7 @@ struct KerxTable
   {
     c->buffer->unsafe_to_concat ();
 
-    if (c->buffer->len < HB_AAT_BUFFER_DIGEST_THRESHOLD)
-      c->buffer_digest = c->buffer->digest ();
-    else
-      c->buffer_digest = hb_set_digest_t::full ();
+    c->buffer_digest = c->buffer->digest ();
 
     typedef typename T::SubTable SubTable;
 
diff --git a/src/hb-aat-layout-morx-table.hh b/src/hb-aat-layout-morx-table.hh
index 1b836944e..65ad91303 100644
--- a/src/hb-aat-layout-morx-table.hh
+++ b/src/hb-aat-layout-morx-table.hh
@@ -1404,10 +1404,7 @@ struct mortmorx
 
     c->buffer->unsafe_to_concat ();
 
-    if (c->buffer->len < HB_AAT_BUFFER_DIGEST_THRESHOLD)
-      c->buffer_digest = c->buffer->digest ();
-    else
-      c->buffer_digest = hb_set_digest_t::full ();
+    c->buffer_digest = c->buffer->digest ();
 
     c->set_lookup_index (0);
     const Chain<Types> *chain = &firstChain;