From 97a5c52af467df2dc9c4d2f22b4f1ad4adc2d018 Mon Sep 17 00:00:00 2001
From: Behdad Esfahbod <behdad@behdad.org>
Date: Mon, 24 Feb 2025 20:53:19 -0700
Subject: [PATCH] [VARC/MultiVarStore] Reduce malloc pressure more

---
 src/OT/Var/VARC/VARC.cc    |  5 +++--
 src/hb-ot-layout-common.hh | 19 +++++++++++++++----
 2 files changed, 18 insertions(+), 6 deletions(-)

diff --git a/src/OT/Var/VARC/VARC.cc b/src/OT/Var/VARC/VARC.cc
index a474054fd..af30fc5d1 100644
--- a/src/OT/Var/VARC/VARC.cc
+++ b/src/OT/Var/VARC/VARC.cc
@@ -381,7 +381,8 @@ VARC::get_path_at (hb_font_t *font,
 
   hb_ubytes_t record = (this+glyphRecords)[idx];
 
-  VarRegionList::cache_t *cache = coords ? (this+varStore).create_cache () : nullptr;
+  float static_cache[128];
+  VarRegionList::cache_t *cache = (this+varStore).create_cache (hb_array (static_cache));
 
   transform.scale (font->x_multf, font->y_multf);
 
@@ -392,7 +393,7 @@ VARC::get_path_at (hb_font_t *font,
 				  scratch,
 				  cache);
 
-  (this+varStore).destroy_cache (cache);
+  (this+varStore).destroy_cache (cache, hb_array (static_cache));
 
   return true;
 }
diff --git a/src/hb-ot-layout-common.hh b/src/hb-ot-layout-common.hh
index 1dfda05e3..f9a5c1b9c 100644
--- a/src/hb-ot-layout-common.hh
+++ b/src/hb-ot-layout-common.hh
@@ -3440,7 +3440,7 @@ struct MultiItemVariationStore
 {
   using cache_t = SparseVarRegionList::cache_t;
 
-  cache_t *create_cache () const
+  cache_t *create_cache (hb_array_t<float> static_cache = hb_array_t<float> ()) const
   {
 #ifdef HB_NO_VAR
     return nullptr;
@@ -3448,8 +3448,14 @@ struct MultiItemVariationStore
     auto &r = this+regions;
     unsigned count = r.regions.len;
 
-    float *cache = (float *) hb_malloc (sizeof (float) * count);
-    if (unlikely (!cache)) return nullptr;
+    float *cache;
+    if (count <= static_cache.length)
+      cache = static_cache.arrayZ;
+    else
+    {
+      cache = (float *) hb_malloc (sizeof (float) * count);
+      if (unlikely (!cache)) return nullptr;
+    }
 
     for (unsigned i = 0; i < count; i++)
       cache[i] = REGION_CACHE_ITEM_CACHE_INVALID;
@@ -3457,7 +3463,12 @@ struct MultiItemVariationStore
     return cache;
   }
 
-  static void destroy_cache (cache_t *cache) { hb_free (cache); }
+  static void destroy_cache (cache_t *cache,
+			     hb_array_t<float> static_cache = hb_array_t<float> ())
+  {
+    if (cache != static_cache.arrayZ)
+      hb_free (cache);
+  }
 
   private:
   void get_delta (unsigned int outer, unsigned int inner,