Parser: store parameters in a ThreadedList instead of ZoneList.

ThreadedList is more memory-efficient than ZoneList. This also enables
us to use ThreadedList when making Preparser track parameters (upcoming
work).

BUG=v8:5501

Review-Url: https://codereview.chromium.org/2531593002
Cr-Commit-Position: refs/heads/master@{#41307}

src/parsing/parser-base.h

@@ -3520,10 +3520,7 @@ void ParserBase<Impl>::ParseFormalParameterList(FormalParametersT* parameters,
     }
   }
 
-  for (int i = 0; i < parameters->arity; ++i) {
-    auto parameter = parameters->at(i);
-    impl()->DeclareFormalParameter(parameters->scope, parameter);
-  }
+  impl()->DeclareFormalParameters(parameters->scope, parameters->params);
 }
 
 template <typename Impl>

src/parsing/parser.cc

@@ -964,7 +964,7 @@ FunctionLiteral* Parser::DoParseFunction(ParseInfo* info,
         } else {
           // BindingIdentifier
           ParseFormalParameter(&formals, &ok);
-          if (ok) DeclareFormalParameter(formals.scope, formals.at(0));
+          if (ok) DeclareFormalParameters(formals.scope, formals.params);
         }
       }
 
@@ -2476,15 +2476,11 @@ void Parser::DeclareArrowFunctionFormalParameters(
   if (!parameters->is_simple) {
     this->classifier()->RecordNonSimpleParameter();
   }
-  for (int i = 0; i < parameters->arity; ++i) {
-    auto parameter = parameters->at(i);
-    DeclareFormalParameter(parameters->scope, parameter);
-    if (!this->classifier()
-             ->is_valid_formal_parameter_list_without_duplicates() &&
-        !duplicate_loc->IsValid()) {
-      *duplicate_loc =
-          this->classifier()->duplicate_formal_parameter_error().location;
-    }
+  DeclareFormalParameters(parameters->scope, parameters->params);
+  if (!this->classifier()
+           ->is_valid_formal_parameter_list_without_duplicates()) {
+    *duplicate_loc =
+        this->classifier()->duplicate_formal_parameter_error().location;
   }
   DCHECK_EQ(parameters->is_simple, parameters->scope->has_simple_parameters());
 }
@@ -2493,9 +2489,9 @@ void Parser::ReindexLiterals(const ParserFormalParameters& parameters) {
   if (function_state_->materialized_literal_count() > 0) {
     AstLiteralReindexer reindexer;
 
-    for (const auto p : parameters.params) {
-      if (p.pattern != nullptr) reindexer.Reindex(p.pattern);
-      if (p.initializer != nullptr) reindexer.Reindex(p.initializer);
+    for (auto p : parameters.params) {
+      if (p->pattern != nullptr) reindexer.Reindex(p->pattern);
+      if (p->initializer != nullptr) reindexer.Reindex(p->initializer);
     }
 
     DCHECK(reindexer.count() <= function_state_->materialized_literal_count());
@@ -2926,44 +2922,44 @@ Block* Parser::BuildParameterInitializationBlock(
   DCHECK(!parameters.is_simple);
   DCHECK(scope()->is_function_scope());
   Block* init_block = factory()->NewBlock(NULL, 1, true, kNoSourcePosition);
-  for (int i = 0; i < parameters.params.length(); ++i) {
-    auto parameter = parameters.params[i];
-    if (parameter.is_rest && parameter.pattern->IsVariableProxy()) break;
+  int index = 0;
+  for (auto parameter : parameters.params) {
+    if (parameter->is_rest && parameter->pattern->IsVariableProxy()) break;
     DeclarationDescriptor descriptor;
     descriptor.declaration_kind = DeclarationDescriptor::PARAMETER;
     descriptor.scope = scope();
     descriptor.hoist_scope = nullptr;
     descriptor.mode = LET;
-    descriptor.declaration_pos = parameter.pattern->position();
+    descriptor.declaration_pos = parameter->pattern->position();
     // The position that will be used by the AssignmentExpression
     // which copies from the temp parameter to the pattern.
     //
     // TODO(adamk): Should this be kNoSourcePosition, since
     // it's just copying from a temp var to the real param var?
-    descriptor.initialization_pos = parameter.pattern->position();
+    descriptor.initialization_pos = parameter->pattern->position();
     Expression* initial_value =
-        factory()->NewVariableProxy(parameters.scope->parameter(i));
-    if (parameter.initializer != nullptr) {
+        factory()->NewVariableProxy(parameters.scope->parameter(index));
+    if (parameter->initializer != nullptr) {
       // IS_UNDEFINED($param) ? initializer : $param
 
       // Ensure initializer is rewritten
-      RewriteParameterInitializer(parameter.initializer, scope());
+      RewriteParameterInitializer(parameter->initializer, scope());
 
       auto condition = factory()->NewCompareOperation(
           Token::EQ_STRICT,
-          factory()->NewVariableProxy(parameters.scope->parameter(i)),
+          factory()->NewVariableProxy(parameters.scope->parameter(index)),
           factory()->NewUndefinedLiteral(kNoSourcePosition), kNoSourcePosition);
       initial_value = factory()->NewConditional(
-          condition, parameter.initializer, initial_value, kNoSourcePosition);
-      descriptor.initialization_pos = parameter.initializer->position();
+          condition, parameter->initializer, initial_value, kNoSourcePosition);
+      descriptor.initialization_pos = parameter->initializer->position();
     }
 
     Scope* param_scope = scope();
     Block* param_block = init_block;
-    if (!parameter.is_simple() && scope()->calls_sloppy_eval()) {
+    if (!parameter->is_simple() && scope()->calls_sloppy_eval()) {
       param_scope = NewVarblockScope();
       param_scope->set_start_position(descriptor.initialization_pos);
-      param_scope->set_end_position(parameter.initializer_end_position);
+      param_scope->set_end_position(parameter->initializer_end_position);
       param_scope->RecordEvalCall();
       param_block = factory()->NewBlock(NULL, 8, true, kNoSourcePosition);
       param_block->set_scope(param_scope);
@@ -2978,7 +2974,7 @@ Block* Parser::BuildParameterInitializationBlock(
 
     BlockState block_state(&scope_state_, param_scope);
     DeclarationParsingResult::Declaration decl(
-        parameter.pattern, parameter.initializer_end_position, initial_value);
+        parameter->pattern, parameter->initializer_end_position, initial_value);
     PatternRewriter::DeclareAndInitializeVariables(
         this, param_block, &descriptor, &decl, nullptr, CHECK_OK);
 
@@ -2989,6 +2985,7 @@ Block* Parser::BuildParameterInitializationBlock(
       }
       init_block->statements()->Add(param_block, zone());
     }
+    ++index;
   }
   return init_block;
 }

src/parsing/parser.h

@@ -14,6 +14,7 @@
 #include "src/parsing/preparse-data.h"
 #include "src/parsing/preparser.h"
 #include "src/pending-compilation-error-handler.h"
+#include "src/utils.h"
 
 namespace v8 {
 
@@ -135,7 +136,7 @@ class Parser;
 
 
 struct ParserFormalParameters : FormalParametersBase {
-  struct Parameter {
+  struct Parameter : public ZoneObject {
     Parameter(const AstRawString* name, Expression* pattern,
               Expression* initializer, int initializer_end_position,
               bool is_rest)
@@ -149,16 +150,17 @@ struct ParserFormalParameters : FormalParametersBase {
     Expression* initializer;
     int initializer_end_position;
     bool is_rest;
+    Parameter* next_parameter = nullptr;
     bool is_simple() const {
       return pattern->IsVariableProxy() && initializer == nullptr && !is_rest;
     }
+    Parameter** next() { return &next_parameter; }
+    Parameter* const* next() const { return &next_parameter; }
   };
 
   explicit ParserFormalParameters(DeclarationScope* scope)
-      : FormalParametersBase(scope), params(4, scope->zone()) {}
-  ZoneList<Parameter> params;
-
-  const Parameter& at(int i) const { return params[i]; }
+      : FormalParametersBase(scope) {}
+  ThreadedList<Parameter> params;
 };
 
 template <>
@@ -1045,34 +1047,39 @@ class V8_EXPORT_PRIVATE Parser : public NON_EXPORTED_BASE(ParserBase<Parser>) {
     const AstRawString* name = is_simple
                                    ? pattern->AsVariableProxy()->raw_name()
                                    : ast_value_factory()->empty_string();
-    parameters->params.Add(
-        ParserFormalParameters::Parameter(name, pattern, initializer,
-                                          initializer_end_position, is_rest),
-        parameters->scope->zone());
+    auto parameter =
+        new (parameters->scope->zone()) ParserFormalParameters::Parameter(
+            name, pattern, initializer, initializer_end_position, is_rest);
+
+    parameters->params.Add(parameter);
   }
 
-  V8_INLINE void DeclareFormalParameter(
+  V8_INLINE void DeclareFormalParameters(
       DeclarationScope* scope,
-      const ParserFormalParameters::Parameter& parameter) {
-    bool is_duplicate = false;
-    bool is_simple = classifier()->is_simple_parameter_list();
-    auto name = is_simple || parameter.is_rest
-                    ? parameter.name
-                    : ast_value_factory()->empty_string();
-    auto mode = is_simple || parameter.is_rest ? VAR : TEMPORARY;
-    if (!is_simple) scope->SetHasNonSimpleParameters();
-    bool is_optional = parameter.initializer != nullptr;
-    Variable* var =
-        scope->DeclareParameter(name, mode, is_optional, parameter.is_rest,
-                                &is_duplicate, ast_value_factory());
-    if (is_duplicate) {
-      classifier()->RecordDuplicateFormalParameterError(scanner()->location());
-    }
-    if (is_sloppy(scope->language_mode())) {
-      // TODO(sigurds) Mark every parameter as maybe assigned. This is a
-      // conservative approximation necessary to account for parameters
-      // that are assigned via the arguments array.
-      var->set_maybe_assigned();
+      const ThreadedList<ParserFormalParameters::Parameter>& parameters) {
+    for (auto parameter : parameters) {
+      bool is_duplicate = false;
+      bool is_simple = classifier()->is_simple_parameter_list();
+      auto name = is_simple || parameter->is_rest
+                      ? parameter->name
+                      : ast_value_factory()->empty_string();
+      auto mode = is_simple || parameter->is_rest ? VAR : TEMPORARY;
+      if (!is_simple) scope->SetHasNonSimpleParameters();
+      bool is_optional = parameter->initializer != nullptr;
+      Variable* var =
+          scope->DeclareParameter(name, mode, is_optional, parameter->is_rest,
+                                  &is_duplicate, ast_value_factory());
+      if (is_duplicate &&
+          classifier()->is_valid_formal_parameter_list_without_duplicates()) {
+        classifier()->RecordDuplicateFormalParameterError(
+            scanner()->location());
+      }
+      if (is_sloppy(scope->language_mode())) {
+        // TODO(sigurds) Mark every parameter as maybe assigned. This is a
+        // conservative approximation necessary to account for parameters
+        // that are assigned via the arguments array.
+        var->set_maybe_assigned();
+      }
     }
   }
 

src/parsing/preparser.h

@@ -752,7 +752,8 @@ class PreParserFactory {
 struct PreParserFormalParameters : FormalParametersBase {
   explicit PreParserFormalParameters(DeclarationScope* scope)
       : FormalParametersBase(scope) {}
-  PreParserIdentifier at(int i) { return PreParserIdentifier(); }  // Dummy
+
+  void* params = nullptr;  // Dummy
 };
 
 
@@ -1440,8 +1441,8 @@ class PreParser : public ParserBase<PreParser> {
     parameters->UpdateArityAndFunctionLength(!initializer.IsEmpty(), is_rest);
   }
 
-  V8_INLINE void DeclareFormalParameter(DeclarationScope* scope,
-                                        PreParserIdentifier parameter) {
+  V8_INLINE void DeclareFormalParameters(DeclarationScope* scope,
+                                         void* parameters) {
     if (!classifier()->is_simple_parameter_list()) {
       scope->SetHasNonSimpleParameters();
     }

src/utils.h

@@ -1627,9 +1627,31 @@ class ThreadedList final {
     friend class ThreadedList;
   };
 
+  class ConstIterator final {
+   public:
+    ConstIterator& operator++() {
+      entry_ = (*entry_)->next();
+      return *this;
+    }
+    bool operator!=(const ConstIterator& other) {
+      return entry_ != other.entry_;
+    }
+    const T* operator*() const { return *entry_; }
+
+   private:
+    explicit ConstIterator(T* const* entry) : entry_(entry) {}
+
+    T* const* entry_;
+
+    friend class ThreadedList;
+  };
+
   Iterator begin() { return Iterator(&head_); }
   Iterator end() { return Iterator(tail_); }
 
+  ConstIterator begin() const { return ConstIterator(&head_); }
+  ConstIterator end() const { return ConstIterator(tail_); }
+
   void Rewind(Iterator reset_point) {
     tail_ = reset_point.entry_;
     *tail_ = nullptr;