Cleanup ScopeInfo and SerializedScopeInfo.

src/scopeinfo.cc

 // Copyright 2011 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
@@ skipping 28 matching lines @@
 
 
 static int CompareLocal(Variable* const* v, Variable* const* w) {
   int x = (*v)->index();
   int y = (*w)->index();
   // Consider sorting them according to type as well?
   return x - y;
 }
 
 
-template<class Allocator>
-ScopeInfo<Allocator>::ScopeInfo(Scope* scope)
-    : function_name_(FACTORY->empty_symbol()),
-      calls_eval_(scope->calls_eval()),
-      is_strict_mode_(scope->is_strict_mode()),
-      type_(scope->type()),
-      parameters_(scope->num_parameters()),
-      stack_slots_(scope->num_stack_slots()),
-      context_slots_(scope->num_heap_slots()),
-      context_modes_(scope->num_heap_slots()) {
+Handle<ScopeInfo> ScopeInfo::Create(Scope* scope) {

[Kevin Millikin (Chromium), 2011/11/02 16:31:19]

Now that you've removed the template parameter, I think you can make some other
functions non-templated too (Scope::CollectUsedVariables is the one I'm thinking
of).

[Steven, 2011/11/02 18:52:59]

Done.

+  ZoneList<Variable*> variables(32);  // 32 is a wild guess

[Kevin Millikin (Chromium), 2011/11/02 16:31:19]

Again, not your code, but the "wild guess" here seems silly to me.  I'd bet that
most variables are used, so we'd get a both a tighter upper bound, that also
guaranteed no need to grow the list, if we just used the scope's number of
variables (parameters, locals, and temps).

[Steven, 2011/11/02 18:52:59]

Will do this in a new CL. Here we are only interested in stack and context
locals. The only other client is
is FunctionInfoListener::SerializeFunctionScope in liveedit.cc which is only
interested in the context locals. So we can do even better here.

On 2011/11/02 16:31:19, Kevin Millikin wrote:

+  ASSERT(variables.is_empty());
+  scope->CollectUsedVariables(&variables);
+
+  ZoneList<Variable*> stack_locals(scope->num_stack_slots());
+  ZoneList<Variable*> context_locals(scope->num_heap_slots());
+
+  // Collect stack and context locals.
+  for (int i = 0; i < variables.length(); i++) {
+    Variable* var = variables[i];
+    if (!var->is_used()) continue;

[Kevin Millikin (Chromium), 2011/11/02 16:31:19]

It's not clear how "CollectUsedVariables" can collect one that's unused.  Do you
have any idea?

[Steven, 2011/11/02 18:52:59]

A bit flip because of faulty hardware :P
Done.
On 2011/11/02 16:31:19, Kevin Millikin wrote:

+    switch (var->location()) {
+      case Variable::UNALLOCATED:
+      case Variable::PARAMETER:
+        break;
+
+      case Variable::LOCAL:
+        stack_locals.Add(var);
+        break;
+
+      case Variable::CONTEXT:
+        context_locals.Add(var);
+        break;
+
+      case Variable::LOOKUP:
+        // We don't expect lookup variables in the locals list.
+        UNREACHABLE();
+        break;
+    }
+  }
+
+  // Determine use and location of the function variable if it is present.
+  FunctionVariableInfo function_name_info;
+  VariableMode function_variable_mode;
+  if (scope->is_function_scope() && scope->function() != NULL) {
+    Variable* var = scope->function()->var();
+    if (!var->is_used()) {
+      function_name_info = UNUSED;
+    } else if (var->IsContextSlot()) {
+      function_name_info = CONTEXT;
+    } else {
+      ASSERT(var->IsStackLocal());
+      function_name_info = STACK;
+    }
+    function_variable_mode = var->mode();
+  } else {
+    function_name_info = NONE;
+    function_variable_mode = VAR;
+  }
+
+  const bool has_function_name = function_name_info != NONE;
+  const int num_parameters = scope->num_parameters();
+  const int num_stack_locals = stack_locals.length();
+  const int num_context_locals = context_locals.length();
+  const int length = VARIABLE_PART_INDEX
+      + num_parameters + num_stack_locals + 2 * num_context_locals
+      + (has_function_name ? 2 : 0);
+
+  Handle<ScopeInfo> scope_info = FACTORY->NewScopeInfo(length);
+
+  // Encode the flags.
+  int flags = TypeField::encode(scope->type()) |
+      CallsEvalField::encode(scope->calls_eval()) |
+      StrictModeField::encode(scope->is_strict_mode()) |
+      FunctionVariableField::encode(function_name_info) |
+      FunctionVariableMode::encode(function_variable_mode);
+  scope_info->set_flags(flags);
+  scope_info->set_num_parameters(num_parameters);
+  scope_info->set_num_stack_locals(num_stack_locals);
+  scope_info->set_num_context_locals(num_context_locals);
+
+  int index = VARIABLE_PART_INDEX;
   // Add parameters.
-  for (int i = 0; i < scope->num_parameters(); i++) {
-    ASSERT(parameters_.length() == i);
-    parameters_.Add(scope->parameter(i)->name());
-  }
-
-  // Add stack locals and collect heap locals.
-  // We are assuming that the locals' slots are allocated in
-  // increasing order, so we can simply add them to the
-  // ScopeInfo lists. However, due to usage analysis, this is
-  // not true for context-allocated locals: Some of them
-  // may be parameters which are allocated before the
-  // non-parameter locals. When the non-parameter locals are
-  // sorted according to usage, the allocated slot indices may
-  // not be in increasing order with the variable list anymore.
-  // Thus, we first collect the context-allocated locals, and then
-  // sort them by context slot index before adding them to the
-  // ScopeInfo list.
-  List<Variable*, Allocator> locals(32);  // 32 is a wild guess
-  ASSERT(locals.is_empty());
-  scope->CollectUsedVariables(&locals);
-  locals.Sort(&CompareLocal);
-
-  List<Variable*, Allocator> heap_locals(locals.length());
-  for (int i = 0; i < locals.length(); i++) {
-    Variable* var = locals[i];
-    if (var->is_used()) {
-      switch (var->location()) {
-        case Variable::UNALLOCATED:
-        case Variable::PARAMETER:
-          break;
-
-        case Variable::LOCAL:
-          ASSERT(stack_slots_.length() == var->index());
-          stack_slots_.Add(var->name());
-          break;
-
-        case Variable::CONTEXT:
-          heap_locals.Add(var);
-          break;
-
-        case Variable::LOOKUP:
-          // We don't expect lookup variables in the locals list.
-          UNREACHABLE();
-          break;
+  ASSERT(index == scope_info->ParameterEntriesIndex());
+  for (int i = 0; i < num_parameters; ++i) {
+    scope_info->set(index++, *scope->parameter(i)->name());
+  }
+
+  // Add stack locals' names. We are assuming that the stack locals'
+  // slots are allocated in increasing order, so we can simply add
+  // them to the ScopeInfo object.
+  ASSERT(index == scope_info->StackLocalEntriesIndex());
+  for (int i = 0; i < num_stack_locals; ++i) {
+    ASSERT(stack_locals[i]->index() == i);
+    scope_info->set(index++, *stack_locals[i]->name());
+  }
+
+  // Due to usage analysis, context-allocated locals are not necessarily in
+  // increasing order: Some of them may be parameters which are allocated before
+  // the non-parameter locals. When the non-parameter locals are sorted
+  // according to usage, the allocated slot indices may not be in increasing
+  // order with the variable list anymore. Thus, we first need to sort them by
+  // context slot index before adding them to the ScopeInfo object.
+  context_locals.Sort(&CompareLocal);
+
+  // Add context locals' names.
+  ASSERT(index == scope_info->ContextLocalNameEntriesIndex());
+  for (int i = 0; i < num_context_locals; ++i) {
+    scope_info->set(index++, *context_locals[i]->name());
+  }
+
+  // Add context locals' modes.
+  ASSERT(index == scope_info->ContextLocalModeEntriesIndex());
+  for (int i = 0; i < num_context_locals; ++i) {
+    scope_info->set(index++, Smi::FromInt(context_locals[i]->mode()));
+  }
+
+  // If present, add the function variable name and its index.
+  ASSERT(index == scope_info->FunctionNameEntryIndex());
+  if (has_function_name) {
+    int var_index = scope->function()->var()->index();
+    scope_info->set(index++, *scope->function()->name());
+    scope_info->set(index++, Smi::FromInt(var_index));
+    ASSERT(function_name_info != STACK ||
+           (var_index == scope_info->num_stack_locals() &&
+            var_index == scope_info->NumberOfStackSlots() - 1));
+    ASSERT(function_name_info != CONTEXT ||
+           var_index == scope_info->NumberOfContextSlots() - 1);
+  }
+
+  ASSERT(index == scope_info->length());
+  ASSERT(scope->num_parameters() == scope_info->num_parameters());
+  ASSERT(scope->num_stack_slots() == scope_info->NumberOfStackSlots());
+  ASSERT(scope->num_heap_slots() == scope_info->NumberOfContextSlots());
+  return scope_info;
+}
+
+
+ScopeInfo* ScopeInfo::Empty() {
+  return reinterpret_cast<ScopeInfo*>(HEAP->empty_fixed_array());
+}
+
+
+ScopeType ScopeInfo::Type() {
+  ASSERT(length() > 0);
+  return TypeField::decode(flags());
+}
+
+
+bool ScopeInfo::CallsEval() {

[Kevin Millikin (Chromium), 2011/11/02 16:31:19]

I like

return length() > 0 && CallsEvalField::decode(flags());

but maybe you don't.

[Steven, 2011/11/02 18:52:59]

Done.

+  if (length() > 0) {
+    return CallsEvalField::decode(flags());
+  } else {
+    return false;
+  }
+}
+
+
+bool ScopeInfo::IsStrictMode() {
+  if (length() > 0) {
+    return StrictModeField::decode(flags());
+  } else {
+    return false;
+  }
+}
+
+
+int ScopeInfo::NumberOfLocals() {
+  return num_stack_locals() + num_context_locals();
+}
+
+
+int ScopeInfo::NumberOfStackSlots() {
+  if (length() > 0) {
+    bool function_name_stack_slot = STACK ==

[Kevin Millikin (Chromium), 2011/11/02 16:31:19]

Hmmm, I could see this requiring two tries to read it correctly.  Break at the
lower precedence operator:

bool function_name_stack_slot =
  STACK == FunctionVariableField::decode(flags());

I sort of like STACK on the right.

[Steven, 2011/11/02 18:52:59]

Done.

+        FunctionVariableField::decode(flags());
+    return num_stack_locals() + (function_name_stack_slot ? 1 : 0);
+  }
+  return 0;
+}
+
+
+int ScopeInfo::NumberOfContextSlots() {
+  if (length() > 0) {
+    int context_locals = num_context_locals();
+    bool function_name_context_slot = CONTEXT ==

[Kevin Millikin (Chromium), 2011/11/02 16:31:19]

Same comment as just above.

[Steven, 2011/11/02 18:52:59]

Done.

+        FunctionVariableField::decode(flags());
+    bool has_context = context_locals > 0 ||
+        function_name_context_slot ||
+        Type() == WITH_SCOPE ||
+        (Type() == FUNCTION_SCOPE && CallsEval());
+    if (has_context) {
+      return Context::MIN_CONTEXT_SLOTS + context_locals +
+          (function_name_context_slot ? 1 : 0);
+    }
+  }
+  return 0;
+}
+
+
+bool ScopeInfo::HasFunctionName() {
+  if (length() > 0) {
+    return NONE != FunctionVariableField::decode(flags());
+  } else {
+    return false;
+  }
+}
+
+
+bool ScopeInfo::HasHeapAllocatedLocals() {
+  if (length() > 0) {
+    return num_context_locals() > 0;
+  } else {
+    return false;
+  }
+}
+
+
+bool ScopeInfo::HasContext() {
+  if (length() > 0) {
+    return NumberOfContextSlots() > 0;
+  } else {
+    return false;
+  }
+}
+
+
+Handle<String> ScopeInfo::function_name() {
+  if (HasFunctionName()) {
+    return Handle<String>(String::cast(get(FunctionNameEntryIndex())));
+  } else {
+    return Handle<String>();
+  }
+}
+
+
+Handle<String> ScopeInfo::parameter_name(int var) {
+  ASSERT(0 <= var && var < num_parameters());
+  int info_index = ParameterEntriesIndex() + var;
+  return Handle<String>(String::cast(get(info_index)));
+}
+
+
+Handle<String> ScopeInfo::local_name(int var) {
+  ASSERT(0 <= var && var < NumberOfLocals());
+  ASSERT(StackLocalEntriesIndex() + num_stack_locals() ==
+         ContextLocalNameEntriesIndex());
+  int info_index = StackLocalEntriesIndex() + var;
+  return Handle<String>(String::cast(get(info_index)));
+}
+
+
+Handle<String> ScopeInfo::stack_local_name(int var) {
+  ASSERT(0 <= var && var < num_stack_locals());
+  int info_index = StackLocalEntriesIndex() + var;
+  return Handle<String>(String::cast(get(info_index)));
+}
+
+
+Handle<String> ScopeInfo::context_local_name(int var) {
+  ASSERT(0 <= var && var < num_context_locals());
+  int info_index = ContextLocalNameEntriesIndex() + var;
+  return Handle<String>(String::cast(get(info_index)));
+}
+
+
+VariableMode ScopeInfo::context_local_mode(int var) {
+  ASSERT(0 <= var && var < num_context_locals());
+  int info_index = ContextLocalModeEntriesIndex() + var;
+  return static_cast<VariableMode>(Smi::cast(get(info_index))->value());
+}
+
+
+int ScopeInfo::StackSlotIndex(String* name) {
+  ASSERT(name->IsSymbol());
+  if (length() > 0) {
+    int start = StackLocalEntriesIndex();
+    int end = StackLocalEntriesIndex() + num_stack_locals();
+    for (int i = start; i < end; ++i) {
+      if (name == get(i)) {
+        return i - start;
       }
     }
   }
-
-  // Add heap locals.
-  if (scope->num_heap_slots() > 0) {
-    // Add user-defined slots.
-    for (int i = 0; i < heap_locals.length(); i++) {
-      ASSERT(heap_locals[i]->index() - Context::MIN_CONTEXT_SLOTS ==
-             context_slots_.length());
-      ASSERT(heap_locals[i]->index() - Context::MIN_CONTEXT_SLOTS ==
-             context_modes_.length());
-      context_slots_.Add(heap_locals[i]->name());
-      context_modes_.Add(heap_locals[i]->mode());
-    }
-
-  } else {
-    ASSERT(heap_locals.length() == 0);
-  }
-
-  // Add the function context slot, if present.
-  // For now, this must happen at the very end because of the
-  // ordering of the scope info slots and the respective slot indices.
-  if (scope->is_function_scope()) {
-    VariableProxy* proxy = scope->function();
-    if (proxy != NULL &&
-        proxy->var()->is_used() &&
-        proxy->var()->IsContextSlot()) {
-      function_name_ = proxy->name();
-      // Note that we must not find the function name in the context slot
-      // list - instead it must be handled separately in the
-      // Contexts::Lookup() function. Thus record an empty symbol here so we
-      // get the correct number of context slots.
-      ASSERT(proxy->var()->index() - Context::MIN_CONTEXT_SLOTS ==
-             context_slots_.length());
-      ASSERT(proxy->var()->index() - Context::MIN_CONTEXT_SLOTS ==
-             context_modes_.length());
-      context_slots_.Add(FACTORY->empty_symbol());
-      context_modes_.Add(proxy->var()->mode());
-    }
-  }
-}
-
-
-// Encoding format in a FixedArray object:
-//
-// - function name
-//
-// - calls eval boolean flag
-//
-// - is strict mode scope
-//
-// - scope type
-//
-// - number of variables in the context object (smi) (= function context
-//   slot index + 1)
-// - list of pairs (name, Var mode) of context-allocated variables (starting
-//   with context slot 0)
-//
-// - number of parameters (smi)
-// - list of parameter names (starting with parameter 0 first)
-//
-// - number of variables on the stack (smi)
-// - list of names of stack-allocated variables (starting with stack slot 0)
-
-// The ScopeInfo representation could be simplified and the ScopeInfo
-// re-implemented (with almost the same interface). Here is a
-// suggestion for the new format:
-//
-// - have a single list with all variable names (parameters, stack locals,
-//   context locals), followed by a list of non-Object* values containing
-//   the variables information (what kind, index, attributes)
-// - searching the linear list of names is fast and yields an index into the
-//   list if the variable name is found
-// - that list index is then used to find the variable information in the
-//   subsequent list
-// - the list entries don't have to be in any particular order, so all the
-//   current sorting business can go away
-// - the ScopeInfo lookup routines can be reduced to perhaps a single lookup
-//   which returns all information at once
-// - when gathering the information from a Scope, we only need to iterate
-//   through the local variables (parameters and context info is already
-//   present)
-
-
-template <class T>
-static inline Object** ReadInt(Object** p, T* x) {
-  *x = static_cast<T>((reinterpret_cast<Smi*>(*p++))->value());
-  return p;
-}
-
-
-static inline Object** ReadBool(Object** p, bool* x) {
-  *x = (reinterpret_cast<Smi*>(*p++))->value() != 0;
-  return p;
-}
-
-
-template <class T>
-static inline Object** ReadObject(Object** p, Handle<T>* s) {
-  *s = Handle<T>::cast(Handle<Object>(*p++));
-  return p;
-}
-
-
-template <class Allocator, class T>
-static Object** ReadList(Object** p, List<Handle<T>, Allocator >* list) {
-  ASSERT(list->is_empty());
-  int n;
-  p = ReadInt(p, &n);
-  while (n-- > 0) {
-    Handle<T> s;
-    p = ReadObject(p, &s);
-    list->Add(s);
-  }
-  return p;
-}
-
-
-template <class Allocator>
-static Object** ReadList(Object** p,
-                         List<Handle<String>, Allocator>* list,
-                         List<VariableMode, Allocator>* modes) {
-  ASSERT(list->is_empty());
-  int n;
-  p = ReadInt(p, &n);
-  while (n-- > 0) {
-    Handle<String> s;
-    int m;
-    p = ReadObject(p, &s);
-    p = ReadInt(p, &m);
-    list->Add(s);
-    modes->Add(static_cast<VariableMode>(m));
-  }
-  return p;
-}
-
-
-template<class Allocator>
-ScopeInfo<Allocator>::ScopeInfo(SerializedScopeInfo* data)
-  : function_name_(FACTORY->empty_symbol()),
-    parameters_(4),
-    stack_slots_(8),
-    context_slots_(8),
-    context_modes_(8) {
-  if (data->length() > 0) {
-    Object** p0 = data->data_start();
-    Object** p = p0;
-    p = ReadObject(p, &function_name_);
-    p = ReadBool(p, &calls_eval_);
-    p = ReadBool(p, &is_strict_mode_);
-    p = ReadInt(p, &type_);
-    p = ReadList<Allocator>(p, &context_slots_, &context_modes_);
-    p = ReadList<Allocator>(p, &parameters_);
-    p = ReadList<Allocator>(p, &stack_slots_);
-    ASSERT((p - p0) == FixedArray::cast(data)->length());
-  }
-}
-
-
-static inline Object** WriteInt(Object** p, int x) {
-  *p++ = Smi::FromInt(x);
-  return p;
-}
-
-
-static inline Object** WriteBool(Object** p, bool b) {
-  *p++ = Smi::FromInt(b ? 1 : 0);
-  return p;
-}
-
-
-template <class T>
-static inline Object** WriteObject(Object** p, Handle<T> s) {
-  *p++ = *s;
-  return p;
-}
-
-
-template <class Allocator, class T>
-static Object** WriteList(Object** p, List<Handle<T>, Allocator >* list) {
-  const int n = list->length();
-  p = WriteInt(p, n);
-  for (int i = 0; i < n; i++) {
-    p = WriteObject(p, list->at(i));
-  }
-  return p;
-}
-
-
-template <class Allocator>
-static Object** WriteList(Object** p,
-                          List<Handle<String>, Allocator>* list,
-                          List<VariableMode, Allocator>* modes) {
-  const int n = list->length();
-  p = WriteInt(p, n);
-  for (int i = 0; i < n; i++) {
-    p = WriteObject(p, list->at(i));
-    p = WriteInt(p, modes->at(i));
-  }
-  return p;
-}
-
-
-template<class Allocator>
-Handle<SerializedScopeInfo> ScopeInfo<Allocator>::Serialize() {
-  // function name, calls eval, is_strict_mode, scope type,
-  // length for 3 tables:
-  const int extra_slots = 1 + 1 + 1 + 1 + 3;
-  int length = extra_slots +
-               context_slots_.length() * 2 +
-               parameters_.length() +
-               stack_slots_.length();
-
-  Handle<SerializedScopeInfo> data(
-      SerializedScopeInfo::cast(*FACTORY->NewSerializedScopeInfo(length)));
-  AssertNoAllocation nogc;
-
-  Object** p0 = data->data_start();
-  Object** p = p0;
-  p = WriteObject(p, function_name_);
-  p = WriteBool(p, calls_eval_);
-  p = WriteBool(p, is_strict_mode_);
-  p = WriteInt(p, type_);
-  p = WriteList(p, &context_slots_, &context_modes_);
-  p = WriteList(p, &parameters_);
-  p = WriteList(p, &stack_slots_);
-  ASSERT((p - p0) == length);
-
-  return data;
-}
-
-
-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
-  // Context::MIN_CONTEXT_SLOTS 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;
-}
-
-
-Handle<SerializedScopeInfo> SerializedScopeInfo::Create(Scope* scope) {
-  ScopeInfo<ZoneListAllocationPolicy> sinfo(scope);
-  return sinfo.Serialize();
-}
-
-
-SerializedScopeInfo* SerializedScopeInfo::Empty() {
-  return reinterpret_cast<SerializedScopeInfo*>(HEAP->empty_fixed_array());
-}
-
-
-Object** SerializedScopeInfo::ContextEntriesAddr() {
-  ASSERT(length() > 0);
-  // +4 for function name, calls eval, strict mode, scope type.
-  return data_start() + 4;
-}
-
-
-Object** SerializedScopeInfo::ParameterEntriesAddr() {
-  ASSERT(length() > 0);
-  Object** p = ContextEntriesAddr();
-  int number_of_context_slots;
-  p = ReadInt(p, &number_of_context_slots);
-  return p + number_of_context_slots*2;  // *2 for pairs
-}
-
-
-Object** SerializedScopeInfo::StackSlotEntriesAddr() {
-  ASSERT(length() > 0);
-  Object** p = ParameterEntriesAddr();
-  int number_of_parameter_slots;
-  p = ReadInt(p, &number_of_parameter_slots);
-  return p + number_of_parameter_slots;
-}
-
-
-bool SerializedScopeInfo::CallsEval() {
-  if (length() > 0) {
-    Object** p = data_start() + 1;  // +1 for function name.
-    bool calls_eval;
-    p = ReadBool(p, &calls_eval);
-    return calls_eval;
-  }
-  return false;
-}
-
-
-bool SerializedScopeInfo::IsStrictMode() {
-  if (length() > 0) {
-    Object** p = data_start() + 2;  // +2 for function name, calls eval.
-    bool strict_mode;
-    p = ReadBool(p, &strict_mode);
-    return strict_mode;
-  }
-  return false;
-}
-
-
-ScopeType SerializedScopeInfo::Type() {
-  ASSERT(length() > 0);
-  // +3 for function name, calls eval, strict mode.
-  Object** p = data_start() + 3;
-  ScopeType type;
-  p = ReadInt(p, &type);
-  return type;
-}
-
-
-int SerializedScopeInfo::NumberOfStackSlots() {
-  if (length() > 0) {
-    Object** p = StackSlotEntriesAddr();
-    int number_of_stack_slots;
-    ReadInt(p, &number_of_stack_slots);
-    return number_of_stack_slots;
-  }
-  return 0;
-}
-
-
-int SerializedScopeInfo::NumberOfContextSlots() {
-  if (length() > 0) {
-    Object** p = ContextEntriesAddr();
-    int number_of_context_slots;
-    ReadInt(p, &number_of_context_slots);
-    return number_of_context_slots + Context::MIN_CONTEXT_SLOTS;
-  }
-  return 0;
-}
-
-
-bool SerializedScopeInfo::HasHeapAllocatedLocals() {
-  if (length() > 0) {
-    Object** p = ContextEntriesAddr();
-    int number_of_context_slots;
-    ReadInt(p, &number_of_context_slots);
-    return number_of_context_slots > 0;
-  }
-  return false;
-}
-
-
-bool SerializedScopeInfo::HasContext() {
-  return HasHeapAllocatedLocals() ||
-      Type() == WITH_SCOPE;
-}
-
-
-int SerializedScopeInfo::StackSlotIndex(String* name) {
+  return -1;
+}
+
+
+int ScopeInfo::ContextSlotIndex(String* name, VariableMode* mode) {
   ASSERT(name->IsSymbol());
   if (length() > 0) {
-    // Slots start after length entry.
-    Object** p0 = StackSlotEntriesAddr();
-    int number_of_stack_slots;
-    p0 = ReadInt(p0, &number_of_stack_slots);
-    Object** p = p0;
-    Object** end = p0 + number_of_stack_slots;
-    while (p != end) {
-      if (*p == name) return static_cast<int>(p - p0);
-      p++;
-    }
-  }
-  return -1;
-}
-
-int SerializedScopeInfo::ContextSlotIndex(String* name, VariableMode* mode) {
-  ASSERT(name->IsSymbol());
-  Isolate* isolate = GetIsolate();
-  int result = isolate->context_slot_cache()->Lookup(this, name, mode);
-  if (result != ContextSlotCache::kNotFound) return result;
-  if (length() > 0) {
-    // Slots start after length entry.
-    Object** p0 = ContextEntriesAddr();
-    int number_of_context_slots;
-    p0 = ReadInt(p0, &number_of_context_slots);
-    Object** p = p0;
-    Object** end = p0 + number_of_context_slots * 2;
-    while (p != end) {
-      if (*p == name) {
-        ASSERT(((p - p0) & 1) == 0);
-        int v;
-        ReadInt(p + 1, &v);
-        VariableMode mode_value = static_cast<VariableMode>(v);
+    ContextSlotCache* context_slot_cache = GetIsolate()->context_slot_cache();
+    int result = context_slot_cache->Lookup(this, name, mode);
+    if (result != ContextSlotCache::kNotFound) {
+      ASSERT(result < NumberOfContextSlots());
+      return result;
+    }
+
+    int start = ContextLocalNameEntriesIndex();
+    int end = ContextLocalNameEntriesIndex() + num_context_locals();
+    for (int i = start; i < end; ++i) {
+      if (name == get(i)) {
+        int var = i - start;
+        VariableMode mode_value = context_local_mode(var);
         if (mode != NULL) *mode = mode_value;
-        result = static_cast<int>((p - p0) >> 1) + Context::MIN_CONTEXT_SLOTS;
-        isolate->context_slot_cache()->Update(this, name, mode_value, result);
+        result = Context::MIN_CONTEXT_SLOTS + var;
+        context_slot_cache->Update(this, name, mode_value, result);
+        ASSERT(result < NumberOfContextSlots());
         return result;
       }
-      p += 2;
-    }
-  }
-  isolate->context_slot_cache()->Update(this, name, INTERNAL, -1);
+    }
+    context_slot_cache->Update(this, name, INTERNAL, -1);
+  }
   return -1;
 }
 
 
-int SerializedScopeInfo::ParameterIndex(String* name) {
+int ScopeInfo::ParameterIndex(String* name) {
   ASSERT(name->IsSymbol());
   if (length() > 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();
-    int number_of_parameter_slots;
-    Object** p0 = ReadInt(p, &number_of_parameter_slots);
-    p = p0 + number_of_parameter_slots;
-    while (p > p0) {
-      p--;
-      if (*p == name) return static_cast<int>(p - p0);
+    int start = ParameterEntriesIndex();
+    int end = ParameterEntriesIndex() + num_parameters();
+    for (int i = end - 1; i >= start; --i) {
+      if (name == get(i)) {
+        return i - start;
+      }
     }
   }
   return -1;
 }
 
 
-int SerializedScopeInfo::FunctionContextSlotIndex(String* name,
-                                                  VariableMode* mode) {
+int ScopeInfo::FunctionContextSlotIndex(String* name, VariableMode* mode) {
   ASSERT(name->IsSymbol());
   if (length() > 0) {
-    Object** p = data_start();
-    if (*p == name) {
-      p = ContextEntriesAddr();
-      int number_of_context_slots;
-      p = ReadInt(p, &number_of_context_slots);
-      ASSERT(number_of_context_slots != 0);
-      // The function context slot is the last entry.
-      if (mode != NULL) {
-        // Seek to context slot entry.
-        p += (number_of_context_slots - 1) * 2;
-        // Seek to mode.
-        ++p;
-        ReadInt(p, mode);
-      }
-      return number_of_context_slots + Context::MIN_CONTEXT_SLOTS - 1;
+    if (FunctionVariableField::decode(flags()) == CONTEXT &&
+        *function_name() == name) {
+       if (mode != NULL) *mode = FunctionVariableMode::decode(flags());
+      return Smi::cast(get(FunctionNameEntryIndex() + 1))->value();
     }
   }
   return -1;
 }
 
 
+int ScopeInfo::ParameterEntriesIndex() {
+  ASSERT(length() > 0);
+  return VARIABLE_PART_INDEX;
+}
+
+
+int ScopeInfo::StackLocalEntriesIndex() {
+  return ParameterEntriesIndex() + num_parameters();
+}
+
+
+int ScopeInfo::ContextLocalNameEntriesIndex() {
+  return StackLocalEntriesIndex() + num_stack_locals();
+}
+
+
+int ScopeInfo::ContextLocalModeEntriesIndex() {
+  return ContextLocalNameEntriesIndex() + num_context_locals();
+}
+
+
+int ScopeInfo::FunctionNameEntryIndex() {
+  return ContextLocalModeEntriesIndex() + num_context_locals();
+}
+
+
 int ContextSlotCache::Hash(Object* data, String* name) {
   // Uses only lower 32 bits if pointers are larger.
   uintptr_t addr_hash =
       static_cast<uint32_t>(reinterpret_cast<uintptr_t>(data)) >> 2;
   return static_cast<int>((addr_hash ^ name->Hash()) % kLength);
 }
 
 
 int ContextSlotCache::Lookup(Object* data,
                              String* name,
@@ skipping 46 matching lines @@
     Key& key = keys_[index];
     ASSERT(key.data == data);
     ASSERT(key.name->Equals(name));
     Value result(values_[index]);
     ASSERT(result.mode() == mode);
     ASSERT(result.index() + kNotFound == slot_index);
   }
 }
 
 
-template <class Allocator>
 static void PrintList(const char* list_name,
                       int nof_internal_slots,
-                      List<Handle<String>, Allocator>& list) {
-  if (list.length() > 0) {
+                      int start,
+                      int end,
+                      ScopeInfo* scope_info) {
+  if (start < end) {
     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();
+    for (int i = nof_internal_slots; start < end; ++i, ++start) {
+      PrintF("  %2d ", i);
+      String::cast(scope_info->get(start))->ShortPrint();
       PrintF("\n");
     }
   }
 }
 
 
-template<class Allocator>
-void ScopeInfo<Allocator>::Print() {
+void ScopeInfo::Print() {
   PrintF("ScopeInfo ");
-  if (function_name_->length() > 0)
-    function_name_->ShortPrint();
-  else
+  if (HasFunctionName()) {
+    function_name()->ShortPrint();
+  } else {
     PrintF("/* no function name */");
+  }
   PrintF("{");
 
-  PrintList<Allocator>("parameters", 0, parameters_);
-  PrintList<Allocator>("stack slots", 0, stack_slots_);
-  PrintList<Allocator>("context slots", Context::MIN_CONTEXT_SLOTS,
-                       context_slots_);
+  PrintList("parameters", 0,
+            ParameterEntriesIndex(),
+            ParameterEntriesIndex() + num_parameters(),
+            this);
+  PrintList("stack slots", 0,
+            StackLocalEntriesIndex(),
+            StackLocalEntriesIndex() + num_stack_locals(),
+            this);
+  PrintList("context slots",
+            Context::MIN_CONTEXT_SLOTS,
+            ContextLocalNameEntriesIndex(),
+            ContextLocalNameEntriesIndex() + num_context_locals(),
+            this);
 
   PrintF("}\n");
 }
 #endif  // DEBUG
 
-
-// Make sure the classes get instantiated by the template system.
-template class ScopeInfo<FreeStoreAllocationPolicy>;
-template class ScopeInfo<PreallocatedStorage>;
-template class ScopeInfo<ZoneListAllocationPolicy>;
-
 } }  // namespace v8::internal