stub-cache.h.svn-base

Google浏览器V8内核代码

// Copyright 2006-2008 the V8 project authors. All rights reserved.
// Redistribution and use in source and binary forms, with or without
// modification, are permitted provided that the following conditions are
// met:
//
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//       notice, this list of conditions and the following disclaimer.
//     * Redistributions in binary form must reproduce the above
//       copyright notice, this list of conditions and the following
//       disclaimer in the documentation and/or other materials provided
//       with the distribution.
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//       contributors may be used to endorse or promote products derived
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#ifndef V8_STUB_CACHE_H_
#define V8_STUB_CACHE_H_

#include "macro-assembler.h"

namespace v8 { namespace internal {


// The stub cache is used for megamorphic calls and property accesses.
// It maps (map, name, type)->Code*

// The design of the table uses the inline cache stubs used for
// mono-morphic calls. The beauty of this, we do not have to
// invalidate the cache whenever a prototype map is changed.  The stub
// validates the map chain as in the mono-morphic case.

class SCTableReference;

class StubCache : public AllStatic {
 public:
  struct Entry {
    String* key;
    Code* value;
  };


  static void Initialize(bool create_heap_objects);

  // Computes the right stub matching. Inserts the result in the
  // cache before returning.  This might compile a stub if needed.
  static Object* ComputeLoadField(String* name,
                                  JSObject* receiver,
                                  JSObject* holder,
                                  int field_index);

  static Object* ComputeLoadCallback(String* name,
                                     JSObject* receiver,
                                     JSObject* holder,
                                     AccessorInfo* callback);

  static Object* ComputeLoadConstant(String* name,
                                     JSObject* receiver,
                                     JSObject* holder,
                                     Object* value);

  static Object* ComputeLoadInterceptor(String* name,
                                        JSObject* receiver,
                                        JSObject* holder);

  static Object* ComputeLoadNormal(String* name, JSObject* receiver);


  // ---

  static Object* ComputeKeyedLoadField(String* name,
                                       JSObject* receiver,
                                       JSObject* holder,
                                       int field_index);

  static Object* ComputeKeyedLoadCallback(String* name,
                                          JSObject* receiver,
                                          JSObject* holder,
                                          AccessorInfo* callback);

  static Object* ComputeKeyedLoadConstant(String* name, JSObject* receiver,
                                          JSObject* holder, Object* value);

  static Object* ComputeKeyedLoadInterceptor(String* name,
                                             JSObject* receiver,
                                             JSObject* holder);

  static Object* ComputeKeyedLoadArrayLength(String* name, JSArray* receiver);

  static Object* ComputeKeyedLoadShortStringLength(String* name,
                                                   String* receiver);

  static Object* ComputeKeyedLoadMediumStringLength(String* name,
                                                    String* receiver);

  static Object* ComputeKeyedLoadLongStringLength(String* name,
                                                  String* receiver);

  static Object* ComputeKeyedLoadFunctionPrototype(String* name,
                                                   JSFunction* receiver);

  // ---

  static Object* ComputeStoreField(String* name,
                                   JSObject* receiver,
                                   int field_index,
                                   Map* transition = NULL);

  static Object* ComputeStoreCallback(String* name,
                                      JSObject* receiver,
                                      AccessorInfo* callback);

  static Object* ComputeStoreInterceptor(String* name, JSObject* receiver);

  // ---

  static Object* ComputeKeyedStoreField(String* name,
                                        JSObject* receiver,
                                        int field_index,
                                        Map* transition = NULL);

  // ---

  static Object* ComputeCallField(int argc,
                                  String* name,
                                  Object* object,
                                  JSObject* holder,
                                  int index);

  static Object* ComputeCallConstant(int argc,
                                     String* name,
                                     Object* object,
                                     JSObject* holder,
                                     JSFunction* function);

  static Object* ComputeCallNormal(int argc, String* name, JSObject* receiver);

  static Object* ComputeCallInterceptor(int argc,
                                        String* name,
                                        Object* object,
                                        JSObject* holder);

  // ---

  static Object* ComputeCallInitialize(int argc);
  static Object* ComputeCallPreMonomorphic(int argc);
  static Object* ComputeCallNormal(int argc);
  static Object* ComputeCallMegamorphic(int argc);
  static Object* ComputeCallMiss(int argc);

  // Finds the Code object stored in the Heap::non_monomorphic_cache().
  static Code* FindCallInitialize(int argc);

  static Object* ComputeCallDebugBreak(int argc);
  static Object* ComputeCallDebugPrepareStepIn(int argc);

  static Object* ComputeLazyCompile(int argc);


  // Update cache for entry hash(name, map).
  static Code* Set(String* name, Map* map, Code* code);

  // Clear the lookup table (@ mark compact collection).
  static void Clear();

  // Functions for generating stubs at startup.
  static void GenerateMiss(MacroAssembler* masm);

  // Generate code for probing the stub cache table.
  static void GenerateProbe(MacroAssembler* masm,
                            Code::Flags flags,
                            Register receiver,
                            Register name,
                            Register scratch);

  enum Table {
    kPrimary,
    kSecondary
  };

 private:
  friend class SCTableReference;
  static const int kPrimaryTableSize = 2048;
  static const int kSecondaryTableSize = 512;
  static Entry primary_[];
  static Entry secondary_[];

  // Computes the hashed offsets for primary and secondary caches.
  static int PrimaryOffset(String* name, Code::Flags flags, Map* map) {
    // Compute the hash of the name (use entire length field).
    uint32_t name_hash = name->length_field();
    ASSERT(name_hash & String::kHashComputedMask);
    // Base the offset on a simple combination of name, flags, and map.
    uint32_t key = (reinterpret_cast<uint32_t>(map) + name_hash) ^ flags;
    return key & ((kPrimaryTableSize - 1) << kHeapObjectTagSize);
  }

  static int SecondaryOffset(String* name, Code::Flags flags, int seed) {
    // Use the seed from the primary cache in the secondary cache.
    uint32_t key = seed - reinterpret_cast<uint32_t>(name) + flags;
    return key & ((kSecondaryTableSize - 1) << kHeapObjectTagSize);
  }

  // Compute the entry for a given offset in exactly the same way as
  // we done in generated code. This makes it a lot easier to avoid
  // making mistakes in the hashed offset computations.
  static Entry* entry(Entry* table, int offset) {
    return reinterpret_cast<Entry*>(
        reinterpret_cast<Address>(table) + (offset << 1));
  }
};


class SCTableReference {
 public:
  static SCTableReference keyReference(StubCache::Table table) {
    return SCTableReference(
        reinterpret_cast<Address>(&first_entry(table)->key));
  }


  static SCTableReference valueReference(StubCache::Table table) {
    return SCTableReference(
        reinterpret_cast<Address>(&first_entry(table)->value));
  }