[parser] Directly keep track of the scope stack on the parser again.

By now lazy allocation of block scopes probably doesn't make that much sense anymore, since the memory overhead significantly reduced. Not indirecting scope() over ScopeState is faster, which is more important at this point.

BUG=v8:5209

Change-Id: I2968f01252769e7b1198a0a0876765a06ab0d3bd
Reviewed-on: https://chromium-review.googlesource.com/445025Reviewed-by: Toon Verwaest <verwaest@chromium.org>
Reviewed-by: Marja Hölttä <marja@chromium.org>
Commit-Queue: Toon Verwaest <verwaest@chromium.org>
Cr-Commit-Position: refs/heads/master@{#43313}

src/parsing/parser.cc

@@ -181,8 +181,7 @@ FunctionLiteral* Parser::DefaultConstructor(const AstRawString* name,
   ZoneList<Statement*>* body = NULL;
 
   {
-    FunctionState function_state(&function_state_, &scope_state_,
-                                 function_scope);
+    FunctionState function_state(&function_state_, &scope_, function_scope);
 
     body = new (zone()) ZoneList<Statement*>(call_super ? 2 : 1, zone());
     if (call_super) {
@@ -657,7 +656,7 @@ FunctionLiteral* Parser::DoParseProgram(ParseInfo* info) {
   // Note that this function can be called from the main thread or from a
   // background thread. We should not access anything Isolate / heap dependent
   // via ParseInfo, and also not pass it forward.
-  DCHECK_NULL(scope_state_);
+  DCHECK_NULL(scope_);
   DCHECK_NULL(target_stack_);
 
   ParsingModeScope mode(this, allow_lazy_ ? PARSE_LAZILY : PARSE_EAGERLY);
@@ -681,7 +680,7 @@ FunctionLiteral* Parser::DoParseProgram(ParseInfo* info) {
 
     scope->set_start_position(0);
 
-    FunctionState function_state(&function_state_, &scope_state_, scope);
+    FunctionState function_state(&function_state_, &scope_, scope);
 
     ZoneList<Statement*>* body = new(zone()) ZoneList<Statement*>(16, zone());
     bool ok = true;
@@ -823,7 +822,7 @@ FunctionLiteral* Parser::DoParseFunction(ParseInfo* info,
                                          const AstRawString* raw_name,
                                          Utf16CharacterStream* source) {
   scanner_.Initialize(source);
-  DCHECK_NULL(scope_state_);
+  DCHECK_NULL(scope_);
   DCHECK_NULL(target_stack_);
 
   DCHECK(ast_value_factory());
@@ -844,9 +843,8 @@ FunctionLiteral* Parser::DoParseFunction(ParseInfo* info,
     Scope* outer = original_scope_;
     DeclarationScope* outer_function = outer->GetClosureScope();
     DCHECK(outer);
-    FunctionState function_state(&function_state_, &scope_state_,
-                                 outer_function);
-    BlockState block_state(&scope_state_, outer);
+    FunctionState function_state(&function_state_, &scope_, outer_function);
+    BlockState block_state(&scope_, outer);
     DCHECK(is_sloppy(outer->language_mode()) ||
            is_strict(info->language_mode()));
     FunctionLiteral::FunctionType function_type = ComputeFunctionType(info);
@@ -886,7 +884,7 @@ FunctionLiteral* Parser::DoParseFunction(ParseInfo* info,
         // Parsing patterns as variable reference expression creates
         // NewUnresolved references in current scope. Entrer arrow function
         // scope for formal parameter parsing.
-        BlockState block_state(&scope_state_, scope);
+        BlockState block_state(&scope_, scope);
         if (Check(Token::LPAREN)) {
           // '(' StrictFormalParameters ')'
           ParseFormalParameterList(&formals, &ok);
@@ -2252,7 +2250,7 @@ Statement* Parser::DesugarLexicalBindingsInForStatement(
 
   Block* inner_block = factory()->NewBlock(NULL, 3, false, kNoSourcePosition);
   {
-    BlockState block_state(&scope_state_, inner_scope);
+    BlockState block_state(&scope_, inner_scope);
 
     Block* ignore_completion_block = factory()->NewBlock(
         nullptr, for_info.bound_names.length() + 3, true, kNoSourcePosition);
@@ -2962,14 +2960,14 @@ Block* Parser::BuildParameterInitializationBlock(
                                        param_scope);
     }
 
-    BlockState block_state(&scope_state_, param_scope);
+    BlockState block_state(&scope_, param_scope);
     DeclarationParsingResult::Declaration decl(
         parameter->pattern, parameter->initializer_end_position, initial_value);
     PatternRewriter::DeclareAndInitializeVariables(
         this, param_block, &descriptor, &decl, nullptr, CHECK_OK);
 
     if (param_block != init_block) {
-      param_scope = block_state.FinalizedBlockScope();
+      param_scope = param_scope->FinalizeBlockScope();
       if (param_scope != nullptr) {
         CheckConflictingVarDeclarations(param_scope, CHECK_OK);
       }
@@ -3122,7 +3120,7 @@ ZoneList<Statement*>* Parser::ParseFunction(
     bool* has_duplicate_parameters, int* expected_property_count, bool* ok) {
   ParsingModeScope mode(this, allow_lazy_ ? PARSE_LAZILY : PARSE_EAGERLY);
 
-  FunctionState function_state(&function_state_, &scope_state_, function_scope);
+  FunctionState function_state(&function_state_, &scope_, function_scope);
 
   DuplicateFinder duplicate_finder;
   ExpressionClassifier formals_classifier(this, &duplicate_finder);
@@ -3307,7 +3305,7 @@ void Parser::InsertShadowingVarBindingInitializers(Block* inner_block) {
   DCHECK(inner_scope->is_declaration_scope());
   Scope* function_scope = inner_scope->outer_scope();
   DCHECK(function_scope->is_function_scope());
-  BlockState block_state(&scope_state_, inner_scope);
+  BlockState block_state(&scope_, inner_scope);
   for (Declaration* decl : *inner_scope->declarations()) {
     if (decl->proxy()->var()->mode() != VAR || !decl->IsVariableDeclaration()) {
       continue;

src/parsing/preparser.cc

@@ -103,10 +103,11 @@ PreParser::PreParseResult PreParser::PreParseFunction(
   ResetFunctionLiteralId();
 
   // The caller passes the function_scope which is not yet inserted into the
-  // scope_state_. All scopes above the function_scope are ignored by the
+  // scope stack. All scopes above the function_scope are ignored by the
   // PreParser.
-  DCHECK_NULL(scope_state_);
-  FunctionState function_state(&function_state_, &scope_state_, function_scope);
+  DCHECK_NULL(function_state_);
+  DCHECK_NULL(scope_);
+  FunctionState function_state(&function_state_, &scope_, function_scope);
   // This indirection is needed so that we can use the CHECK_OK macros.
   bool ok_holder = true;
   bool* ok = &ok_holder;
@@ -143,7 +144,7 @@ PreParser::PreParseResult PreParser::PreParseFunction(
   }
 
   {
-    BlockState block_state(&scope_state_, inner_scope);
+    BlockState block_state(&scope_, inner_scope);
     result = ParseStatementListAndLogFunction(
         &formals, has_duplicate_parameters, may_abort, ok);
   }
@@ -234,7 +235,7 @@ PreParser::Expression PreParser::ParseFunctionLiteral(
 
   DeclarationScope* function_scope = NewFunctionScope(kind);
   function_scope->SetLanguageMode(language_mode);
-  FunctionState function_state(&function_state_, &scope_state_, function_scope);
+  FunctionState function_state(&function_state_, &scope_, function_scope);
   DuplicateFinder duplicate_finder;
   ExpressionClassifier formals_classifier(this, &duplicate_finder);
   GetNextFunctionLiteralId();

src/parsing/preparser.h

@@ -905,7 +905,7 @@ class PreParser : public ParserBase<PreParser> {
   // captured the syntax error), and false if a stack-overflow happened
   // during parsing.
   PreParseResult PreParseProgram(bool is_module = false) {
-    DCHECK_NULL(scope_state_);
+    DCHECK_NULL(scope_);
     DeclarationScope* scope = NewScriptScope();
 #ifdef DEBUG
     scope->set_is_being_lazily_parsed(true);
@@ -916,7 +916,7 @@ class PreParser : public ParserBase<PreParser> {
     // the global scope.
     if (is_module) scope = NewModuleScope(scope);
 
-    FunctionState top_scope(&function_state_, &scope_state_, scope);
+    FunctionState top_scope(&function_state_, &scope_, scope);
     bool ok = true;
     int start_position = scanner()->peek_location().beg_pos;
     parsing_module_ = is_module;