scopeinfo.cc.svn-base

Google浏览器V8内核代码

static Object** WriteList(Object** p, List<Handle<String>, Allocator >* list) {
  const int n = list->length();
  p = WriteInt(p, n);
  for (int i = 0; i < n; i++) {
    p = WriteSymbol(p, list->at(i));
  }
  return WriteSentinel(p);
}


template <class Allocator>
static Object** WriteList(Object** p,
                          List<Handle<String>, Allocator>* list,
                          List<Variable::Mode, Allocator>* modes) {
  const int n = list->length();
  p = WriteInt(p, n);
  for (int i = 0; i < n; i++) {
    p = WriteSymbol(p, list->at(i));
    p = WriteInt(p, modes->at(i));
  }
  return WriteSentinel(p);
}


template<class Allocator>
int ScopeInfo<Allocator>::Serialize(Code* code) {
  // function name, supports eval, length & sentinel for 3 tables:
  const int extra_slots = 1 + 1 + 2 * 3;
  int size = (extra_slots +
              context_slots_.length() * 2 +
              parameters_.length() +
              stack_slots_.length()) * kPointerSize;

  if (code != NULL) {
    CHECK(code->sinfo_size() == size);
    Object** p0 = &Memory::Object_at(code->sinfo_start());
    Object** p = p0;
    p = WriteSymbol(p, function_name_);
    p = WriteInt(p, supports_eval_);
    p = WriteList(p, &context_slots_, &context_modes_);
    p = WriteList(p, &parameters_);
    p = WriteList(p, &stack_slots_);
    ASSERT((p - p0) * kPointerSize == size);
  }

  return size;
}


template<class Allocator>
void ScopeInfo<Allocator>::IterateScopeInfo(Code* code, ObjectVisitor* v) {
  Object** start = &Memory::Object_at(code->sinfo_start());
  Object** end = &Memory::Object_at(code->sinfo_start() + code->sinfo_size());
  v->VisitPointers(start, end);
}


static Object** ContextEntriesAddr(Code* code) {
  ASSERT(code->sinfo_size() > 0);
  // +2 for function name, supports eval:
  return &Memory::Object_at(code->sinfo_start()) + 2;
}


static Object** ParameterEntriesAddr(Code* code) {
  ASSERT(code->sinfo_size() > 0);
  Object** p = ContextEntriesAddr(code);
  int n;  // number of context slots;
  p = ReadInt(p, &n);
  return p + n*2 + 1;  // *2 for pairs, +1 for sentinel
}


static Object** StackSlotEntriesAddr(Code* code) {
  ASSERT(code->sinfo_size() > 0);
  Object** p = ParameterEntriesAddr(code);
  int n;  // number of parameter slots;
  p = ReadInt(p, &n);
  return p + n + 1;  // +1 for sentinel
}


template<class Allocator>
bool ScopeInfo<Allocator>::SupportsEval(Code* code) {
  bool result = false;
  if (code->sinfo_size() > 0) {
    ReadBool(&Memory::Object_at(code->sinfo_start()) + 1, &result);
  }
#ifdef DEBUG
  { ScopeInfo info(code);
    ASSERT(result == info.supports_eval_);
  }
#endif
  return result;
}


template<class Allocator>
int ScopeInfo<Allocator>::NumberOfStackSlots(Code* code) {
  if (code->sinfo_size() > 0) {
    Object** p = StackSlotEntriesAddr(code);
    int n;  // number of stack slots;
    ReadInt(p, &n);
    return n;
  }
  return 0;
}


template<class Allocator>
int ScopeInfo<Allocator>::NumberOfContextSlots(Code* code) {
  if (code->sinfo_size() > 0) {
    Object** p = ContextEntriesAddr(code);
    int n;  // number of context slots;
    ReadInt(p, &n);
    return n + Context::MIN_CONTEXT_SLOTS;
  }
  return 0;
}


template<class Allocator>
int ScopeInfo<Allocator>::StackSlotIndex(Code* code, String* name) {
  ASSERT(name->IsSymbol());
  if (code->sinfo_size() > 0) {
    // Loop below depends on the NULL sentinel after the stack slot names.
    ASSERT(NumberOfStackSlots(code) > 0 ||
           *(StackSlotEntriesAddr(code) + 1) == NULL);
    // slots start after length entry
    Object** p0 = StackSlotEntriesAddr(code) + 1;
    Object** p = p0;
    while (*p != NULL) {
      if (*p == name) return p - p0;
      p++;
    }
  }
  return -1;
}


template<class Allocator>
int ScopeInfo<Allocator>::ContextSlotIndex(Code* code,
                                           String* name,
                                           Variable::Mode* mode) {
  ASSERT(name->IsSymbol());
  if (code->sinfo_size() > 0) {
    // Loop below depends on the NULL sentinel after the context slot names.
    ASSERT(NumberOfContextSlots(code) >= Context::MIN_CONTEXT_SLOTS ||
           *(ContextEntriesAddr(code) + 1) == NULL);
    // slots start after length entry
    Object** p0 = ContextEntriesAddr(code) + 1;
    Object** p = p0;
    // contexts may have no variable slots (in the presence of eval()).
    while (*p != NULL) {
      if (*p == name) {
        ASSERT(((p - p0) & 1) == 0);
        if (mode != NULL) {
          ReadInt(p + 1, reinterpret_cast<int*>(mode));
        }
        return ((p - p0) >> 1) + Context::MIN_CONTEXT_SLOTS;
      }
      p += 2;
    }
  }
  return -1;
}


template<class Allocator>
int ScopeInfo<Allocator>::ParameterIndex(Code* code, String* name) {
  ASSERT(name->IsSymbol());
  if (code->sinfo_size() > 0) {
    // We must read parameters from the end since for
    // multiply declared parameters the value of the
    // last declaration of that parameter is used
    // inside a function (and thus we need to look
    // at the last index). Was bug# 1110337.
    //
    // Eventually, we should only register such parameters
    // once, with corresponding index. This requires a new
    // implementation of the ScopeInfo code. See also other
    // comments in this file regarding this.
    Object** p = ParameterEntriesAddr(code);
    int n;  // number of parameters
    Object** p0 = ReadInt(p, &n);
    p = p0 + n;
    while (p > p0) {
      p--;
      if (*p == name) return p - p0;
    }
  }
  return -1;
}


template<class Allocator>
int ScopeInfo<Allocator>::FunctionContextSlotIndex(Code* code, String* name) {
  ASSERT(name->IsSymbol());
  if (code->sinfo_size() > 0) {
    Object** p = &Memory::Object_at(code->sinfo_start());
    if (*p == name) {
      p = ContextEntriesAddr(code);
      int n;  // number of context slots
      ReadInt(p, &n);
      ASSERT(n != 0);
      // The function context slot is the last entry.
      return n + Context::MIN_CONTEXT_SLOTS - 1;
    }
  }
  return -1;
}


template<class Allocator>
Handle<String> ScopeInfo<Allocator>::LocalName(int i) const {
  // A local variable can be allocated either on the stack or in the context.
  // For variables allocated in the context they are always preceded by the
  // number Context::MIN_CONTEXT_SLOTS number of fixed allocated slots in the
  // context.
  if (i < number_of_stack_slots()) {
    return stack_slot_name(i);
  } else {
    return context_slot_name(i - number_of_stack_slots() +
                             Context::MIN_CONTEXT_SLOTS);
  }
}


template<class Allocator>
int ScopeInfo<Allocator>::NumberOfLocals() const {
  int number_of_locals = number_of_stack_slots();
  if (number_of_context_slots() > 0) {
    ASSERT(number_of_context_slots() >= Context::MIN_CONTEXT_SLOTS);
    number_of_locals += number_of_context_slots() - Context::MIN_CONTEXT_SLOTS;
  }
  return number_of_locals;
}


#ifdef DEBUG
template <class Allocator>
static void PrintList(const char* list_name,
                      int nof_internal_slots,
                      List<Handle<String>, Allocator>& list) {
  if (list.length() > 0) {
    PrintF("\n  // %s\n", list_name);
    if (nof_internal_slots > 0) {
      PrintF("  %2d - %2d [internal slots]\n", 0 , nof_internal_slots - 1);
    }
    for (int i = 0; i < list.length(); i++) {
      PrintF("  %2d ", i + nof_internal_slots);
      list[i]->ShortPrint();
      PrintF("\n");
    }
  }
}


template<class Allocator>
void ScopeInfo<Allocator>::Print() {
  PrintF("ScopeInfo ");
  if (function_name_->length() > 0)
    function_name_->ShortPrint();
  else
    PrintF("/* no function name */");
  PrintF("{");

  if (supports_eval_)
    PrintF("\n  // supports eval\n");

  PrintList<Allocator>("parameters", 0, parameters_);
  PrintList<Allocator>("stack slots", 0, stack_slots_);
  PrintList<Allocator>("context slots", Context::MIN_CONTEXT_SLOTS,
                       context_slots_);

  PrintF("}\n");
}
#endif  // DEBUG


// Make sure the classes get instantiated by the template system.
template class ScopeInfo<FreeStoreAllocationPolicy>;
template class ScopeInfo<PreallocatedStorage>;

} }  // namespace v8::internal