Line data    Source code

       1             : // Copyright 2018 the V8 project authors. All rights reserved.
       2             : // Use of this source code is governed by a BSD-style license that can be
       3             : // found in the LICENSE file.
       4             : 
       5             : #ifndef V8_BUILTINS_CONSTANTS_TABLE_BUILDER_H_
       6             : #define V8_BUILTINS_CONSTANTS_TABLE_BUILDER_H_
       7             : 
       8             : #include "src/allocation.h"
       9             : #include "src/base/macros.h"
      10             : #include "src/handles.h"
      11             : #include "src/identity-map.h"
      12             : 
      13             : namespace v8 {
      14             : namespace internal {
      15             : 
      16             : class Isolate;
      17             : class Object;
      18             : 
      19             : // Utility class to build the builtins constants table and store it on the root
      20             : // list. The constants table contains constants used by builtins, and is there
      21             : // to avoid directly embedding them into code objects, which would not be
      22             : // possible for off-heap (and thus immutable) code objects.
      23          56 : class BuiltinsConstantsTableBuilder final {
      24             :  public:
      25             :   explicit BuiltinsConstantsTableBuilder(Isolate* isolate);
      26             : 
      27             :   // Returns the index within the builtins constants table for the given
      28             :   // object, possibly adding the object to the table. Objects are deduplicated.
      29             :   uint32_t AddObject(Handle<Object> object);
      30             : 
      31             :   // Self-references during code generation start out by referencing a handle
      32             :   // with a temporary dummy object. Once the final Code object exists, such
      33             :   // entries in the constants map must be patched up.
      34             :   void PatchSelfReference(Handle<Object> self_reference,
      35             :                           Handle<Code> code_object);
      36             : 
      37             :   // Should be called after all affected code (e.g. builtins and bytecode
      38             :   // handlers) has been generated.
      39             :   void Finalize();
      40             : 
      41             :  private:
      42             :   Isolate* isolate_;
      43             : 
      44             :   // Maps objects to corresponding indices within the constants list.
      45             :   typedef IdentityMap<uint32_t, FreeStoreAllocationPolicy> ConstantsMap;
      46             :   ConstantsMap map_;
      47             : 
      48             :   DISALLOW_COPY_AND_ASSIGN(BuiltinsConstantsTableBuilder);
      49             : };
      50             : 
      51             : }  // namespace internal
      52             : }  // namespace v8
      53             : 
      54             : #endif  // V8_BUILTINS_CONSTANTS_TABLE_BUILDER_H_