1 files changed, 84 insertions, 0 deletions
diff --git a/deps/v8/src/lookup-cache.cc b/deps/v8/src/lookup-cache.cc
new file mode 100644
index 0000000000..18729d630d
--- /dev/null
+++ b/deps/v8/src/lookup-cache.cc
@@ -0,0 +1,84 @@
+// Copyright 2016 the V8 project authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#include "src/lookup-cache.h"
+
+#include "src/objects-inl.h"
+
+namespace v8 {
+namespace internal {
+
+void DescriptorLookupCache::Clear() {
+  for (int index = 0; index < kLength; index++) keys_[index].source = NULL;
+}
+
+int KeyedLookupCache::Hash(Handle<Map> map, Handle<Name> name) {
+  DisallowHeapAllocation no_gc;
+  // Uses only lower 32 bits if pointers are larger.
+  uintptr_t addr_hash =
+      static_cast<uint32_t>(reinterpret_cast<uintptr_t>(*map)) >> kMapHashShift;
+  return static_cast<uint32_t>((addr_hash ^ name->Hash()) & kCapacityMask);
+}
+
+int KeyedLookupCache::Lookup(Handle<Map> map, Handle<Name> name) {
+  DisallowHeapAllocation no_gc;
+  int index = (Hash(map, name) & kHashMask);
+  for (int i = 0; i < kEntriesPerBucket; i++) {
+    Key& key = keys_[index + i];
+    if ((key.map == *map) && key.name->Equals(*name)) {
+      return field_offsets_[index + i];
+    }
+  }
+  return kNotFound;
+}
+
+void KeyedLookupCache::Update(Handle<Map> map, Handle<Name> name,
+                              int field_offset) {
+  DisallowHeapAllocation no_gc;
+  if (!name->IsUniqueName()) {
+    if (!StringTable::InternalizeStringIfExists(name->GetIsolate(),
+                                                Handle<String>::cast(name))
+             .ToHandle(&name)) {
+      return;
+    }
+  }
+  // This cache is cleared only between mark compact passes, so we expect the
+  // cache to only contain old space names.
+  DCHECK(!map->GetIsolate()->heap()->InNewSpace(*name));
+
+  int index = (Hash(map, name) & kHashMask);
+  // After a GC there will be free slots, so we use them in order (this may
+  // help to get the most frequently used one in position 0).
+  for (int i = 0; i < kEntriesPerBucket; i++) {
+    Key& key = keys_[index];
+    Object* free_entry_indicator = NULL;
+    if (key.map == free_entry_indicator) {
+      key.map = *map;
+      key.name = *name;
+      field_offsets_[index + i] = field_offset;
+      return;
+    }
+  }
+  // No free entry found in this bucket, so we move them all down one and
+  // put the new entry at position zero.
+  for (int i = kEntriesPerBucket - 1; i > 0; i--) {
+    Key& key = keys_[index + i];
+    Key& key2 = keys_[index + i - 1];
+    key = key2;
+    field_offsets_[index + i] = field_offsets_[index + i - 1];
+  }
+
+  // Write the new first entry.
+  Key& key = keys_[index];
+  key.map = *map;
+  key.name = *name;
+  field_offsets_[index] = field_offset;
+}
+
+void KeyedLookupCache::Clear() {
+  for (int index = 0; index < kLength; index++) keys_[index].map = NULL;
+}
+
+}  // namespace internal
+}  // namespace v8