doubly-linked free-lists for thread caches and page heaps

third_party/tcmalloc/chromium/src/common.h

Index: third_party/tcmalloc/chromium/src/common.h
diff --git a/third_party/tcmalloc/chromium/src/common.h b/third_party/tcmalloc/chromium/src/common.h
index a3df8de02fd0056b750e096d0d74eb5477cde6bb..7494c9bcafab1b17224cb182d7649a195516e40f 100644
--- a/third_party/tcmalloc/chromium/src/common.h
+++ b/third_party/tcmalloc/chromium/src/common.h
@@ -1,4 +1,4 @@
-// Copyright (c) 2008, Google Inc.
+// Copyright (c) 2011, Google Inc.
 // All rights reserved.
 // 
 // Redistribution and use in source and binary forms, with or without
@@ -31,7 +31,6 @@
 // Author: Sanjay Ghemawat <opensource@google.com>
 //
 // Common definitions for tcmalloc code.
-
 #ifndef TCMALLOC_COMMON_H_
 #define TCMALLOC_COMMON_H_
 
@@ -40,6 +39,7 @@
 #ifdef HAVE_STDINT_H
 #include <stdint.h>                     // for uintptr_t, uint64_t
 #endif
+#include "free_list.h"  // for SIZE_CLASS macros
 #include "internal_logging.h"  // for ASSERT, etc
 
 // Type that can hold a page number
@@ -175,7 +175,11 @@ class SizeMap {
     const bool big = (s > kMaxSmallSize);
     const int add_amount = big ? (127 + (120<<7)) : 7;
     const int shift_amount = big ? 7 : 3;
-    return (s + add_amount) >> shift_amount;
+    const int size_class = (s + add_amount) >> shift_amount;
+    if ((s == 0) || (!IS_64_BIT_POINTERS) ||
+        (size_class > FIRST_USABLE_SIZE_CLASS))
+      return size_class;
+    return FIRST_USABLE_SIZE_CLASS;
   }
 
   int NumMoveSize(size_t size);