Revert of Always deserialize scope infos for parsing

src/ast/context-slot-cache.h

+// 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.
+
+#ifndef V8_AST_CONTEXT_SLOT_CACHE_H_
+#define V8_AST_CONTEXT_SLOT_CACHE_H_
+
+#include "src/allocation.h"
+#include "src/ast/modules.h"
+#include "src/ast/variables.h"
+
+namespace v8 {
+namespace internal {
+
+// Cache for mapping (data, property name) into context slot index.
+// The cache contains both positive and negative results.
+// Slot index equals -1 means the property is absent.
+// Cleared at startup and prior to mark sweep collection.
+class ContextSlotCache {
+ public:
+  // Lookup context slot index for (data, name).
+  // If absent, kNotFound is returned.
+  int Lookup(Object* data, String* name, VariableMode* mode,
+             InitializationFlag* init_flag,
+             MaybeAssignedFlag* maybe_assigned_flag);
+
+  // Update an element in the cache.
+  void Update(Handle<Object> data, Handle<String> name, VariableMode mode,
+              InitializationFlag init_flag,
+              MaybeAssignedFlag maybe_assigned_flag, int slot_index);
+
+  // Clear the cache.
+  void Clear();
+
+  static const int kNotFound = -2;
+
+ private:
+  ContextSlotCache() {
+    for (int i = 0; i < kLength; ++i) {
+      keys_[i].data = NULL;
+      keys_[i].name = NULL;
+      values_[i] = kNotFound;
+    }
+  }
+
+  inline static int Hash(Object* data, String* name);
+
+#ifdef DEBUG
+  void ValidateEntry(Handle<Object> data, Handle<String> name,
+                     VariableMode mode, InitializationFlag init_flag,
+                     MaybeAssignedFlag maybe_assigned_flag, int slot_index);
+#endif
+
+  static const int kLength = 256;
+  struct Key {
+    Object* data;
+    String* name;
+  };
+
+  struct Value {
+    Value(VariableMode mode, InitializationFlag init_flag,
+          MaybeAssignedFlag maybe_assigned_flag, int index) {
+      DCHECK(ModeField::is_valid(mode));
+      DCHECK(InitField::is_valid(init_flag));
+      DCHECK(MaybeAssignedField::is_valid(maybe_assigned_flag));
+      DCHECK(IndexField::is_valid(index));
+      value_ = ModeField::encode(mode) | IndexField::encode(index) |
+               InitField::encode(init_flag) |
+               MaybeAssignedField::encode(maybe_assigned_flag);
+      DCHECK(mode == this->mode());
+      DCHECK(init_flag == this->initialization_flag());
+      DCHECK(maybe_assigned_flag == this->maybe_assigned_flag());
+      DCHECK(index == this->index());
+    }
+
+    explicit inline Value(uint32_t value) : value_(value) {}
+
+    uint32_t raw() { return value_; }
+
+    VariableMode mode() { return ModeField::decode(value_); }
+
+    InitializationFlag initialization_flag() {
+      return InitField::decode(value_);
+    }
+
+    MaybeAssignedFlag maybe_assigned_flag() {
+      return MaybeAssignedField::decode(value_);
+    }
+
+    int index() { return IndexField::decode(value_); }
+
+    // Bit fields in value_ (type, shift, size). Must be public so the
+    // constants can be embedded in generated code.
+    class ModeField : public BitField<VariableMode, 0, 4> {};
+    class InitField : public BitField<InitializationFlag, 4, 1> {};
+    class MaybeAssignedField : public BitField<MaybeAssignedFlag, 5, 1> {};
+    class IndexField : public BitField<int, 6, 32 - 6> {};
+
+   private:
+    uint32_t value_;
+  };
+
+  Key keys_[kLength];
+  uint32_t values_[kLength];
+
+  friend class Isolate;
+  DISALLOW_COPY_AND_ASSIGN(ContextSlotCache);
+};
+
+}  // namespace internal
+}  // namespace v8
+
+#endif  // V8_AST_CONTEXT_SLOT_CACHE_H_