serialize.cc.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:
//
//     * Redistributions of source code must retain the above copyright
//       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.
//     * Neither the name of Google Inc. nor the names of its
//       contributors may be used to endorse or promote products derived
//       from this software without specific prior written permission.
//
// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.

#include "v8.h"

#include "accessors.h"
#include "api.h"
#include "execution.h"
#include "global-handles.h"
#include "ic-inl.h"
#include "natives.h"
#include "platform.h"
#include "runtime.h"
#include "serialize.h"
#include "stub-cache.h"
#include "v8threads.h"

namespace v8 { namespace internal {

// Encoding: a RelativeAddress must be able to fit in a pointer:
// it is encoded as an Address with (from MS to LS bits):
// 27 bits identifying a word in the space, in one of three formats:
// - MAP and OLD spaces: 16 bits of page number, 11 bits of word offset in page
// - NEW space:          27 bits of word offset
// - LO space:           27 bits of page number
// 3 bits to encode the AllocationSpace (special values for code in LO space)
// 2 bits identifying this as a HeapObject

const int kSpaceShift = kHeapObjectTagSize;
const int kSpaceBits = kSpaceTagSize;
const int kSpaceMask = kSpaceTagMask;

// These value are used instead of space numbers when serializing/
// deserializing.  They indicate an object that is in large object space, but
// should be treated specially.
// Make the pages executable on platforms that support it:
const int kLOSpaceExecutable = LAST_SPACE + 1;
// Reserve space for write barrier bits (for objects that can contain
// references to new space):
const int kLOSpacePointer = LAST_SPACE + 2;


const int kOffsetShift = kSpaceShift + kSpaceBits;
const int kOffsetBits = 11;
const int kOffsetMask = (1 << kOffsetBits) - 1;

const int kPageBits = 32 - (kOffsetBits + kSpaceBits + kHeapObjectTagSize);
const int kPageShift = kOffsetShift + kOffsetBits;
const int kPageMask = (1 << kPageBits) - 1;

const int kPageAndOffsetShift = kOffsetShift;
const int kPageAndOffsetBits = kPageBits + kOffsetBits;
const int kPageAndOffsetMask = (1 << kPageAndOffsetBits) - 1;


static inline AllocationSpace GetSpace(Address addr) {
  const int encoded = reinterpret_cast<int>(addr);
  int space_number = ((encoded >> kSpaceShift) & kSpaceMask);
  if (space_number == kLOSpaceExecutable) space_number = LO_SPACE;
  else if (space_number == kLOSpacePointer) space_number = LO_SPACE;
  return static_cast<AllocationSpace>(space_number);
}


static inline bool IsLargeExecutableObject(Address addr) {
  const int encoded = reinterpret_cast<int>(addr);
  const int space_number = ((encoded >> kSpaceShift) & kSpaceMask);
  if (space_number == kLOSpaceExecutable) return true;
  return false;
}


static inline bool IsLargeFixedArray(Address addr) {
  const int encoded = reinterpret_cast<int>(addr);
  const int space_number = ((encoded >> kSpaceShift) & kSpaceMask);
  if (space_number == kLOSpacePointer) return true;
  return false;
}


static inline int PageIndex(Address addr) {
  const int encoded = reinterpret_cast<int>(addr);
  return (encoded >> kPageShift) & kPageMask;
}


static inline int PageOffset(Address addr) {
  const int encoded = reinterpret_cast<int>(addr);
  return ((encoded >> kOffsetShift) & kOffsetMask) << kObjectAlignmentBits;
}


static inline int NewSpaceOffset(Address addr) {
  const int encoded = reinterpret_cast<int>(addr);
  return ((encoded >> kPageAndOffsetShift) & kPageAndOffsetMask) <<
      kObjectAlignmentBits;
}


static inline int LargeObjectIndex(Address addr) {
  const int encoded = reinterpret_cast<int>(addr);
  return (encoded >> kPageAndOffsetShift) & kPageAndOffsetMask;
}


// A RelativeAddress encodes a heap address that is independent of
// the actual memory addresses in real heap. The general case (for the
// OLD, CODE and MAP spaces) is as a (space id, page number, page offset)
// triple. The NEW space has page number == 0, because there are no
// pages. The LARGE_OBJECT space has page offset = 0, since there is
// exactly one object per page.  RelativeAddresses are encodable as
// Addresses, so that they can replace the map() pointers of
// HeapObjects. The encoded Addresses are also encoded as HeapObjects
// and allow for marking (is_marked() see mark(), clear_mark()...) as
// used by the Mark-Compact collector.

class RelativeAddress {
 public:
  RelativeAddress(AllocationSpace space,
                  int page_index,
                  int page_offset)
  : space_(space), page_index_(page_index), page_offset_(page_offset)  {
    ASSERT(space <= LAST_SPACE && space >= 0);
  }

  // Return the encoding of 'this' as an Address. Decode with constructor.
  Address Encode() const;

  AllocationSpace space() const {
    if (space_ == kLOSpaceExecutable) return LO_SPACE;
    if (space_ == kLOSpacePointer) return LO_SPACE;
    return static_cast<AllocationSpace>(space_);
  }
  int page_index() const { return page_index_; }
  int page_offset() const { return page_offset_; }

  bool in_paged_space() const {
    return space_ == CODE_SPACE ||
           space_ == OLD_POINTER_SPACE ||
           space_ == OLD_DATA_SPACE ||
           space_ == MAP_SPACE;
  }

  void next_address(int offset) { page_offset_ += offset; }
  void next_page(int init_offset = 0) {
    page_index_++;
    page_offset_ = init_offset;
  }

#ifdef DEBUG
  void Verify();
#endif

  void set_to_large_code_object() {
    ASSERT(space_ == LO_SPACE);
    space_ = kLOSpaceExecutable;
  }
  void set_to_large_fixed_array() {
    ASSERT(space_ == LO_SPACE);
    space_ = kLOSpacePointer;
  }


 private:
  int space_;
  int page_index_;
  int page_offset_;
};


Address RelativeAddress::Encode() const {
  ASSERT(page_index_ >= 0);
  int word_offset = 0;
  int result = 0;
  switch (space_) {
    case MAP_SPACE:
    case OLD_POINTER_SPACE:
    case OLD_DATA_SPACE:
    case CODE_SPACE:
      ASSERT_EQ(0, page_index_ & ~kPageMask);
      word_offset = page_offset_ >> kObjectAlignmentBits;
      ASSERT_EQ(0, word_offset & ~kOffsetMask);
      result = (page_index_ << kPageShift) | (word_offset << kOffsetShift);
      break;
    case NEW_SPACE:
      ASSERT_EQ(0, page_index_);
      word_offset = page_offset_ >> kObjectAlignmentBits;
      ASSERT_EQ(0, word_offset & ~kPageAndOffsetMask);
      result = word_offset << kPageAndOffsetShift;
      break;
    case LO_SPACE:
    case kLOSpaceExecutable:
    case kLOSpacePointer:
      ASSERT_EQ(0, page_offset_);
      ASSERT_EQ(0, page_index_ & ~kPageAndOffsetMask);
      result = page_index_ << kPageAndOffsetShift;
      break;
  }
  // OR in AllocationSpace and kHeapObjectTag
  ASSERT_EQ(0, space_ & ~kSpaceMask);
  result |= (space_ << kSpaceShift) | kHeapObjectTag;
  return reinterpret_cast<Address>(result);
}


#ifdef DEBUG
void RelativeAddress::Verify() {
  ASSERT(page_offset_ >= 0 && page_index_ >= 0);
  switch (space_) {
    case MAP_SPACE:
    case OLD_POINTER_SPACE:
    case OLD_DATA_SPACE:
    case CODE_SPACE:
      ASSERT(Page::kObjectStartOffset <= page_offset_ &&
             page_offset_ <= Page::kPageSize);
      break;
    case NEW_SPACE:
      ASSERT(page_index_ == 0);
      break;
    case LO_SPACE:
    case kLOSpaceExecutable:
    case kLOSpacePointer:
      ASSERT(page_offset_ == 0);
      break;
  }
}
#endif

enum GCTreatment {
  DataObject,     // Object that cannot contain a reference to new space.
  PointerObject,  // Object that can contain a reference to new space.
  CodeObject      // Object that contains executable code.
};

// A SimulatedHeapSpace simulates the allocation of objects in a page in
// the heap. It uses linear allocation - that is, it doesn't simulate the
// use of a free list. This simulated
// allocation must exactly match that done by Heap.

class SimulatedHeapSpace {
 public:
  // The default constructor initializes to an invalid state.
  SimulatedHeapSpace(): current_(LAST_SPACE, -1, -1) {}

  // Sets 'this' to the first address in 'space' that would be
  // returned by allocation in an empty heap.
  void InitEmptyHeap(AllocationSpace space);

  // Sets 'this' to the next address in 'space' that would be returned
  // by allocation in the current heap. Intended only for testing
  // serialization and deserialization in the current address space.
  void InitCurrentHeap(AllocationSpace space);

  // Returns the RelativeAddress where the next
  // object of 'size' bytes will be allocated, and updates 'this' to
  // point to the next free address beyond that object.
  RelativeAddress Allocate(int size, GCTreatment special_gc_treatment);

 private:
  RelativeAddress current_;
};


void SimulatedHeapSpace::InitEmptyHeap(AllocationSpace space) {
  switch (space) {
    case MAP_SPACE:
    case OLD_POINTER_SPACE:
    case OLD_DATA_SPACE:
    case CODE_SPACE:
      current_ = RelativeAddress(space, 0, Page::kObjectStartOffset);
      break;
    case NEW_SPACE:
    case LO_SPACE:
      current_ = RelativeAddress(space, 0, 0);
      break;
  }
}


void SimulatedHeapSpace::InitCurrentHeap(AllocationSpace space) {
  switch (space) {
    case MAP_SPACE:
    case OLD_POINTER_SPACE:
    case OLD_DATA_SPACE:
    case CODE_SPACE: {
      PagedSpace* ps;
      if (space == MAP_SPACE) {
        ps = Heap::map_space();
      } else if (space == OLD_POINTER_SPACE) {
        ps = Heap::old_pointer_space();
      } else if (space == OLD_DATA_SPACE) {
        ps = Heap::old_data_space();
      } else {
        ASSERT(space == CODE_SPACE);
        ps = Heap::code_space();
      }
      Address top = ps->top();
      Page* top_page = Page::FromAllocationTop(top);
      int page_index = 0;
      PageIterator it(ps, PageIterator::PAGES_IN_USE);
      while (it.has_next()) {
        if (it.next() == top_page) break;
        page_index++;
      }
      current_ = RelativeAddress(space,
                                 page_index,
                                 top_page->Offset(top));
      break;
    }
    case NEW_SPACE:
      current_ = RelativeAddress(space,
                                 0,
                                 Heap::NewSpaceTop() - Heap::NewSpaceStart());
      break;
    case LO_SPACE:
      int page_index = 0;
      for (LargeObjectIterator it(Heap::lo_space()); it.has_next(); it.next()) {
        page_index++;
      }
      current_ = RelativeAddress(space, page_index, 0);
      break;
  }
}


RelativeAddress SimulatedHeapSpace::Allocate(int size,
                                             GCTreatment special_gc_treatment) {
#ifdef DEBUG
  current_.Verify();
#endif
  int alloc_size = OBJECT_SIZE_ALIGN(size);
  if (current_.in_paged_space() &&
      current_.page_offset() + alloc_size > Page::kPageSize) {
    ASSERT(alloc_size <= Page::kMaxHeapObjectSize);
    current_.next_page(Page::kObjectStartOffset);
  }
  RelativeAddress result = current_;
  if (current_.space() == LO_SPACE) {
    current_.next_page();
    if (special_gc_treatment == CodeObject) {
      result.set_to_large_code_object();
    } else if (special_gc_treatment == PointerObject) {
      result.set_to_large_fixed_array();
    }
  } else {
    current_.next_address(alloc_size);
  }
#ifdef DEBUG
  current_.Verify();
  result.Verify();
#endif
  return result;
}

// -----------------------------------------------------------------------------
// Coding of external references.

// The encoding of an external reference. The type is in the high word.
// The id is in the low word.
static uint32_t EncodeExternal(TypeCode type, uint16_t id) {
  return static_cast<uint32_t>(type) << 16 | id;
}


static int* GetInternalPointer(StatsCounter* counter) {
  // All counters refer to dummy_counter, if deserializing happens without
  // setting up counters.
  static int dummy_counter = 0;
  return counter->Enabled() ? counter->GetInternalPointer() : &dummy_counter;
}


// ExternalReferenceTable is a helper class that defines the relationship
// between external references and their encodings. It is used to build
// hashmaps in ExternalReferenceEncoder and ExternalReferenceDecoder.
class ExternalReferenceTable {
 public:
  static ExternalReferenceTable* instance() {
    if (!instance_) instance_ = new ExternalReferenceTable();
    return instance_;
  }

  int size() const { return refs_.length(); }

  Address address(int i) { return refs_[i].address; }

  uint32_t code(int i) { return refs_[i].code; }

  const char* name(int i) { return refs_[i].name; }

  int max_id(int code) { return max_id_[code]; }

 private:
  static ExternalReferenceTable* instance_;

  ExternalReferenceTable();

  struct ExternalReferenceEntry {
    Address address;
    uint32_t code;
    const char* name;
  };

  void Add(Address address, TypeCode type, uint16_t id, const char* name) {
    CHECK_NE(NULL, address);
    ExternalReferenceEntry entry;
    entry.address = address;
    entry.code = EncodeExternal(type, id);
    entry.name = name;
    CHECK_NE(0, entry.code);
    refs_.Add(entry);
    if (id > max_id_[type]) max_id_[type] = id;
  }

  List<ExternalReferenceEntry> refs_;
  int max_id_[kTypeCodeCount];
};


ExternalReferenceTable* ExternalReferenceTable::instance_ = NULL;


ExternalReferenceTable::ExternalReferenceTable() : refs_(64) {
  for (int type_code = 0; type_code < kTypeCodeCount; type_code++) {
    max_id_[type_code] = 0;
  }

  // Define all entries in the table.

  // Builtins
#define DEF_ENTRY_C(name) \
  Add(Builtins::c_function_address(Builtins::c_##name), \
      C_BUILTIN, \
      Builtins::c_##name, \
      "Builtins::" #name);

  BUILTIN_LIST_C(DEF_ENTRY_C)
#undef DEF_ENTRY_C

#define DEF_ENTRY_C(name) \
  Add(Builtins::builtin_address(Builtins::name), \
      BUILTIN, \
      Builtins::name, \
      "Builtins::" #name);
#define DEF_ENTRY_A(name, kind, state) DEF_ENTRY_C(name)

  BUILTIN_LIST_C(DEF_ENTRY_C)
  BUILTIN_LIST_A(DEF_ENTRY_A)
#undef DEF_ENTRY_C
#undef DEF_ENTRY_A

  // Runtime functions
#define RUNTIME_ENTRY(name, nargs) \
  Add(Runtime::FunctionForId(Runtime::k##name)->entry, \
      RUNTIME_FUNCTION, \
      Runtime::k##name, \
      "Runtime::" #name);

  RUNTIME_FUNCTION_LIST(RUNTIME_ENTRY)
#undef RUNTIME_ENTRY

  // IC utilities
#define IC_ENTRY(name) \
  Add(IC::AddressFromUtilityId(IC::k##name), \
      IC_UTILITY, \
      IC::k##name, \
      "IC::" #name);

  IC_UTIL_LIST(IC_ENTRY)
#undef IC_ENTRY

  // Debug addresses
  Add(Debug_Address(Debug::k_after_break_target_address).address(),
      DEBUG_ADDRESS,
      Debug::k_after_break_target_address << kDebugIdShift,
      "Debug::after_break_target_address()");
  Add(Debug_Address(Debug::k_debug_break_return_address).address(),
      DEBUG_ADDRESS,
      Debug::k_debug_break_return_address << kDebugIdShift,
      "Debug::debug_break_return_address()");
  const char* debug_register_format = "Debug::register_address(%i)";
  size_t dr_format_length = strlen(debug_register_format);
  for (int i = 0; i < kNumJSCallerSaved; ++i) {
    Vector<char> name = Vector<char>::New(dr_format_length + 1);
    OS::SNPrintF(name, debug_register_format, i);
    Add(Debug_Address(Debug::k_register_address, i).address(),
        DEBUG_ADDRESS,
        Debug::k_register_address << kDebugIdShift | i,
        name.start());
  }