[modules] Minor refactorings in scopes and scopeinfos.

R=adamk@chromium.org
BUG=v8:1569

Review-Url: https://codereview.chromium.org/2275943005
Cr-Commit-Position: refs/heads/master@{#38931}

src/ast/scopeinfo.cc

@@ -14,13 +14,11 @@ namespace internal {
 
 Handle<ScopeInfo> ScopeInfo::Create(Isolate* isolate, Zone* zone,
                                     Scope* scope) {
-  // Collect stack and context locals.
+  // Collect variables.
   ZoneList<Variable*> stack_locals(scope->StackLocalCount(), zone);
   ZoneList<Variable*> context_locals(scope->ContextLocalCount(), zone);
   ZoneList<Variable*> context_globals(scope->ContextGlobalCount(), zone);
-
-  scope->CollectStackAndContextLocals(&stack_locals, &context_locals,
-                                      &context_globals);
+  scope->CollectVariables(&stack_locals, &context_locals, &context_globals);
   const int stack_local_count = stack_locals.length();
   const int context_local_count = context_locals.length();
   const int context_global_count = context_globals.length();
@@ -148,10 +146,9 @@ Handle<ScopeInfo> ScopeInfo::Create(Isolate* isolate, Zone* zone,
   for (int i = 0; i < context_local_count; ++i) {
     Variable* var = context_locals[i];
     int context_index = var->index() - Context::MIN_CONTEXT_SLOTS;
-    uint32_t info =
-        ContextLocalMode::encode(var->mode()) |
-        ContextLocalInitFlag::encode(var->initialization_flag()) |
-        ContextLocalMaybeAssignedFlag::encode(var->maybe_assigned());
+    uint32_t info = VariableModeField::encode(var->mode()) |
+                    InitFlagField::encode(var->initialization_flag()) |
+                    MaybeAssignedFlagField::encode(var->maybe_assigned());
     scope_info->set(index + context_index, *var->name());
     scope_info->set(info_index + context_index, Smi::FromInt(info));
   }
@@ -166,10 +163,9 @@ Handle<ScopeInfo> ScopeInfo::Create(Isolate* isolate, Zone* zone,
     Variable* var = context_globals[i];
     scope_info->set(index + i, *var->name());
     // TODO(ishell): do we need this kind of info for globals here?
-    uint32_t info =
-        ContextLocalMode::encode(var->mode()) |
-        ContextLocalInitFlag::encode(var->initialization_flag()) |
-        ContextLocalMaybeAssignedFlag::encode(var->maybe_assigned());
+    uint32_t info = VariableModeField::encode(var->mode()) |
+                    InitFlagField::encode(var->initialization_flag()) |
+                    MaybeAssignedFlagField::encode(var->maybe_assigned());
     scope_info->set(info_index + i, Smi::FromInt(info));
   }
 
@@ -252,9 +248,9 @@ Handle<ScopeInfo> ScopeInfo::CreateGlobalThisBinding(Isolate* isolate) {
   DCHECK(index == scope_info->ContextLocalNameEntriesIndex());
   scope_info->set(index++, *isolate->factory()->this_string());
   DCHECK(index == scope_info->ContextLocalInfoEntriesIndex());
-  const uint32_t value = ContextLocalMode::encode(CONST) |
-                         ContextLocalInitFlag::encode(kCreatedInitialized) |
-                         ContextLocalMaybeAssignedFlag::encode(kNotAssigned);
+  const uint32_t value = VariableModeField::encode(CONST) |
+                         InitFlagField::encode(kCreatedInitialized) |
+                         MaybeAssignedFlagField::encode(kNotAssigned);
   scope_info->set(index++, Smi::FromInt(value));
 
   // And here we record that this scopeinfo binds a receiver.
@@ -428,7 +424,7 @@ VariableMode ScopeInfo::ContextLocalMode(int var) {
   DCHECK(0 <= var && var < ContextLocalCount() + ContextGlobalCount());
   int info_index = ContextLocalInfoEntriesIndex() + var;
   int value = Smi::cast(get(info_index))->value();
-  return ContextLocalMode::decode(value);
+  return VariableModeField::decode(value);
 }
 
 
@@ -436,7 +432,7 @@ InitializationFlag ScopeInfo::ContextLocalInitFlag(int var) {
   DCHECK(0 <= var && var < ContextLocalCount() + ContextGlobalCount());
   int info_index = ContextLocalInfoEntriesIndex() + var;
   int value = Smi::cast(get(info_index))->value();
-  return ContextLocalInitFlag::decode(value);
+  return InitFlagField::decode(value);
 }
 
 
@@ -444,7 +440,7 @@ MaybeAssignedFlag ScopeInfo::ContextLocalMaybeAssignedFlag(int var) {
   DCHECK(0 <= var && var < ContextLocalCount() + ContextGlobalCount());
   int info_index = ContextLocalInfoEntriesIndex() + var;
   int value = Smi::cast(get(info_index))->value();
-  return ContextLocalMaybeAssignedFlag::decode(value);
+  return MaybeAssignedFlagField::decode(value);
 }
 
 bool ScopeInfo::VariableIsSynthetic(String* name) {
@@ -462,7 +458,7 @@ int ScopeInfo::StackSlotIndex(String* name) {
   if (length() > 0) {
     int first_slot_index = Smi::cast(get(StackLocalFirstSlotIndex()))->value();
     int start = StackLocalEntriesIndex();
-    int end = StackLocalEntriesIndex() + StackLocalCount();
+    int end = start + StackLocalCount();
     for (int i = start; i < end; ++i) {
       if (name == get(i)) {
         return i - start + first_slot_index;
@@ -478,8 +474,10 @@ int ScopeInfo::ContextSlotIndex(Handle<ScopeInfo> scope_info,
                                 InitializationFlag* init_flag,
                                 MaybeAssignedFlag* maybe_assigned_flag) {
   DCHECK(name->IsInternalizedString());
-  DCHECK(mode != NULL);
-  DCHECK(init_flag != NULL);
+  DCHECK_NOT_NULL(mode);
+  DCHECK_NOT_NULL(init_flag);
+  DCHECK_NOT_NULL(maybe_assigned_flag);
+
   if (scope_info->length() > 0) {
     ContextSlotCache* context_slot_cache =
         scope_info->GetIsolate()->context_slot_cache();
@@ -491,8 +489,7 @@ int ScopeInfo::ContextSlotIndex(Handle<ScopeInfo> scope_info,
     }
 
     int start = scope_info->ContextLocalNameEntriesIndex();
-    int end = scope_info->ContextLocalNameEntriesIndex() +
-              scope_info->ContextLocalCount();
+    int end = start + scope_info->ContextLocalCount();
     for (int i = start; i < end; ++i) {
       if (*name == scope_info->get(i)) {
         int var = i - start;
@@ -511,17 +508,18 @@ int ScopeInfo::ContextSlotIndex(Handle<ScopeInfo> scope_info,
     context_slot_cache->Update(scope_info, name, TEMPORARY,
                                kNeedsInitialization, kNotAssigned, -1);
   }
+
   return -1;
 }
 
-
 int ScopeInfo::ContextGlobalSlotIndex(Handle<ScopeInfo> scope_info,
                                       Handle<String> name, VariableMode* mode,
                                       InitializationFlag* init_flag,
                                       MaybeAssignedFlag* maybe_assigned_flag) {
   DCHECK(name->IsInternalizedString());
-  DCHECK(mode != NULL);
-  DCHECK(init_flag != NULL);
+  DCHECK_NOT_NULL(mode);
+  DCHECK_NOT_NULL(init_flag);
+  DCHECK_NOT_NULL(maybe_assigned_flag);
   if (scope_info->length() > 0) {
     // This is to ensure that ContextLocalMode() and co. queries would work.
     DCHECK_EQ(scope_info->ContextGlobalNameEntriesIndex(),
@@ -529,8 +527,7 @@ int ScopeInfo::ContextGlobalSlotIndex(Handle<ScopeInfo> scope_info,
                   scope_info->ContextLocalCount());
     int base = scope_info->ContextLocalNameEntriesIndex();
     int start = scope_info->ContextGlobalNameEntriesIndex();
-    int end = scope_info->ContextGlobalNameEntriesIndex() +
-              scope_info->ContextGlobalCount();
+    int end = start + scope_info->ContextGlobalCount();
     for (int i = start; i < end; ++i) {
       if (*name == scope_info->get(i)) {
         int var = i - base;
@@ -564,7 +561,7 @@ int ScopeInfo::ParameterIndex(String* name) {
     // inside a function (and thus we need to look
     // at the last index). Was bug# 1110337.
     int start = ParameterEntriesIndex();
-    int end = ParameterEntriesIndex() + ParameterCount();
+    int end = start + ParameterCount();
     for (int i = end - 1; i >= start; --i) {
       if (name == get(i)) {
         return i - start;

src/ast/scopes.cc

@@ -148,9 +148,10 @@ DeclarationScope::DeclarationScope(Zone* zone, Scope* outer_scope,
   asm_function_ = outer_scope_->IsAsmModule();
 }
 
-ModuleScope::ModuleScope(Zone* zone, DeclarationScope* script_scope,
+ModuleScope::ModuleScope(DeclarationScope* script_scope,
                          AstValueFactory* ast_value_factory)
-    : DeclarationScope(zone, script_scope, MODULE_SCOPE) {
+    : DeclarationScope(ast_value_factory->zone(), script_scope, MODULE_SCOPE) {
+  Zone* zone = ast_value_factory->zone();
   module_descriptor_ = new (zone) ModuleDescriptor(zone);
   set_language_mode(STRICT);
   DeclareThis(ast_value_factory);
@@ -617,35 +618,36 @@ Variable* Scope::LookupInScopeInfo(const AstRawString* name) {
   // There should be no local slot with the given name.
   DCHECK(scope_info_->StackSlotIndex(*name_handle) < 0);
 
-  // Check context slot lookup.
   VariableMode mode;
-  VariableLocation location = VariableLocation::CONTEXT;
   InitializationFlag init_flag;
   MaybeAssignedFlag maybe_assigned_flag;
+
+  VariableLocation location = VariableLocation::CONTEXT;
   int index = ScopeInfo::ContextSlotIndex(scope_info_, name_handle, &mode,
                                           &init_flag, &maybe_assigned_flag);
   if (index < 0) {
     location = VariableLocation::GLOBAL;
     index = ScopeInfo::ContextGlobalSlotIndex(scope_info_, name_handle, &mode,
                                               &init_flag, &maybe_assigned_flag);
+    DCHECK(index < 0 || (is_script_scope() && mode == VAR));
   }
   if (index < 0) {
-    // Check parameters.
-    index = scope_info_->ParameterIndex(*name_handle);
-    if (index < 0) return NULL;
-
-    mode = DYNAMIC;
     location = VariableLocation::LOOKUP;
-    init_flag = kCreatedInitialized;
-    // Be conservative and flag parameters as maybe assigned. Better information
-    // would require ScopeInfo to serialize the maybe_assigned bit also for
-    // parameters.
-    maybe_assigned_flag = kMaybeAssigned;
-  } else {
-    DCHECK(location != VariableLocation::GLOBAL ||
-           (is_script_scope() && IsDeclaredVariableMode(mode) &&
-            !IsLexicalVariableMode(mode)));
+    index = scope_info_->ParameterIndex(*name_handle);
+    if (index >= 0) {
+      mode = DYNAMIC;
+      init_flag = kCreatedInitialized;
+      // Be conservative and flag parameters as maybe assigned. Better
+      // information would require ScopeInfo to serialize the maybe_assigned bit
+      // also for parameters.
+      maybe_assigned_flag = kMaybeAssigned;
+    }
+  }
+  if (index < 0 && scope_type() == MODULE_SCOPE) {
+    location = VariableLocation::MODULE;
+    index = -1;  // TODO(neis): Find module variables in scope info.
   }
+  if (index < 0) return nullptr;  // Nowhere found.
 
   Variable::Kind kind = Variable::NORMAL;
   if (location == VariableLocation::CONTEXT &&
@@ -822,9 +824,9 @@ Declaration* Scope::CheckLexDeclarationsConflictingWith(
   return nullptr;
 }
 
-void Scope::CollectStackAndContextLocals(ZoneList<Variable*>* stack_locals,
-                                         ZoneList<Variable*>* context_locals,
-                                         ZoneList<Variable*>* context_globals) {
+void Scope::CollectVariables(ZoneList<Variable*>* stack_locals,
+                             ZoneList<Variable*>* context_locals,
+                             ZoneList<Variable*>* context_globals) {
   // TODO(verwaest): Just pass out locals_ directly and walk it?
   DCHECK_NOT_NULL(stack_locals);
   DCHECK_NOT_NULL(context_locals);

src/ast/scopes.h

@@ -340,12 +340,11 @@ class Scope: public ZoneObject {
   // ---------------------------------------------------------------------------
   // Variable allocation.
 
-  // Collect stack and context allocated local variables in this scope. Note
-  // that the function variable - if present - is not collected and should be
-  // handled separately.
-  void CollectStackAndContextLocals(ZoneList<Variable*>* stack_locals,
-                                    ZoneList<Variable*>* context_locals,
-                                    ZoneList<Variable*>* context_globals);
+  // Collect variables in this scope. Note that the function variable - if
+  // present - is not collected and should be handled separately.
+  void CollectVariables(ZoneList<Variable*>* stack_locals,
+                        ZoneList<Variable*>* context_locals,
+                        ZoneList<Variable*>* context_globals);
 
   // Result of variable allocation.
   int num_stack_slots() const { return num_stack_slots_; }
@@ -836,7 +835,7 @@ class DeclarationScope : public Scope {
 
 class ModuleScope final : public DeclarationScope {
  public:
-  ModuleScope(Zone* zone, DeclarationScope* script_scope,
+  ModuleScope(DeclarationScope* script_scope,
               AstValueFactory* ast_value_factory);
 
   ModuleDescriptor* module() const {

src/crankshaft/typing.cc

@@ -87,8 +87,7 @@ void AstTyper::ObserveTypesAtOsrEntry(IterationStatement* stmt) {
     ZoneList<Variable*> local_vars(locals, zone());
     ZoneList<Variable*> context_vars(scope_->ContextLocalCount(), zone());
     ZoneList<Variable*> global_vars(scope_->ContextGlobalCount(), zone());
-    scope_->CollectStackAndContextLocals(&local_vars, &context_vars,
-                                         &global_vars);
+    scope_->CollectVariables(&local_vars, &context_vars, &global_vars);
     for (int i = 0; i < locals; i++) {
       PrintObserved(local_vars.at(i),
                     frame->GetExpression(i),

src/debug/liveedit.cc

@@ -1904,8 +1904,7 @@ Handle<Object> LiveEditFunctionTracker::SerializeFunctionScope(Scope* scope) {
     ZoneList<Variable*> context_list(current_scope->ContextLocalCount(), zone_);
     ZoneList<Variable*> globals_list(current_scope->ContextGlobalCount(),
                                      zone_);
-    current_scope->CollectStackAndContextLocals(&stack_list, &context_list,
-                                                &globals_list);
+    current_scope->CollectVariables(&stack_list, &context_list, &globals_list);
     for (int i = 0; i < context_list.length(); i++) {
       int context_index = context_list[i]->index() - Context::MIN_CONTEXT_SLOTS;
       int location = scope_info_length + context_index * 2;

src/objects.h

@@ -4507,12 +4507,10 @@ class ScopeInfo : public FixedArray {
   class FunctionKindField
       : public BitField<FunctionKind, HasSimpleParametersField::kNext, 9> {};
 
-  // BitFields representing the encoded information for context locals in the
-  // ContextLocalInfoEntries part.
-  class ContextLocalMode:      public BitField<VariableMode,         0, 3> {};
-  class ContextLocalInitFlag:  public BitField<InitializationFlag,   3, 1> {};
-  class ContextLocalMaybeAssignedFlag
-      : public BitField<MaybeAssignedFlag, 4, 1> {};
+  // Properties of variables.
+  class VariableModeField : public BitField<VariableMode, 0, 3> {};
+  class InitFlagField : public BitField<InitializationFlag, 3, 1> {};
+  class MaybeAssignedFlagField : public BitField<MaybeAssignedFlag, 4, 1> {};
 
   friend class ScopeIterator;
 };

src/parsing/parser-base.h

@@ -641,7 +641,7 @@ class ParserBase {
   }
 
   ModuleScope* NewModuleScope(DeclarationScope* parent) const {
-    return new (zone()) ModuleScope(zone(), parent, ast_value_factory());
+    return new (zone()) ModuleScope(parent, ast_value_factory());
   }
 
   DeclarationScope* NewEvalScope(Scope* parent) const {