Reduce the memory footprint of expression classifiers

src/parsing/parser-base.h

 // Copyright 2012 the V8 project authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef V8_PARSING_PARSER_BASE_H
 #define V8_PARSING_PARSER_BASE_H
 
 #include "src/ast/scopes.h"
 #include "src/bailout-reason.h"
 #include "src/hashmap.h"
@@ skipping 367 matching lines @@
       DCHECK(is_resumable());
       generator_object_variable_ = variable;
     }
     typename Traits::Type::GeneratorVariable* generator_object_variable()
         const {
       return generator_object_variable_;
     }
 
     typename Traits::Type::Factory* factory() { return factory_; }
 
-    const List<DestructuringAssignment>& destructuring_assignments_to_rewrite()
-        const {
+    const ZoneList<DestructuringAssignment>&
+        destructuring_assignments_to_rewrite() const {
       return destructuring_assignments_to_rewrite_;
     }
 
     TailCallExpressionList& tail_call_expressions() {
       return tail_call_expressions_;
     }
     void AddImplicitTailCallExpression(ExpressionT expression) {
       if (return_expr_context() ==
           ReturnExprContext::kInsideValidReturnStatement) {
         tail_call_expressions_.AddImplicitTailCall(expression);
       }
     }
     void AddExplicitTailCallExpression(ExpressionT expression,
                                        const Scanner::Location& loc) {
       DCHECK(expression->IsCall());
       if (return_expr_context() ==
           ReturnExprContext::kInsideValidReturnStatement) {
         tail_call_expressions_.AddExplicitTailCall(expression, loc);
       }
     }
 
+    ZoneList<typename ExpressionClassifier::Error>* GetReportedErrorList() {
+      return &reported_errors_;
+    }
+
     ReturnExprContext return_expr_context() const {
       return return_expr_context_;
     }
     void set_return_expr_context(ReturnExprContext context) {
       return_expr_context_ = context;
     }
 
     ZoneList<ExpressionT>* non_patterns_to_rewrite() {
       return &non_patterns_to_rewrite_;
     }
 
     void next_function_is_parenthesized(bool parenthesized) {
       next_function_is_parenthesized_ = parenthesized;
     }
 
     bool this_function_is_parenthesized() const {
       return this_function_is_parenthesized_;
     }
 
    private:
     void AddDestructuringAssignment(DestructuringAssignment pair) {
-      destructuring_assignments_to_rewrite_.Add(pair);
+      destructuring_assignments_to_rewrite_.Add(pair, (*scope_stack_)->zone());
     }
 
     V8_INLINE Scope* scope() { return *scope_stack_; }
 
-    void AddNonPatternForRewriting(ExpressionT expr) {
+    void AddNonPatternForRewriting(ExpressionT expr, bool* ok) {
       non_patterns_to_rewrite_.Add(expr, (*scope_stack_)->zone());
+      if (non_patterns_to_rewrite_.length() >=
+          std::numeric_limits<uint16_t>::max())
+        *ok = false;
     }
 
     // Used to assign an index to each literal that needs materialization in
     // the function.  Includes regexp literals, and boilerplate for object and
     // array literals.
     int next_materialized_literal_index_;
 
     // Properties count estimation.
     int expected_property_count_;
 
@@ skipping 10 matching lines @@
     // For generators, this variable may hold the generator object. It variable
     // is used by yield expressions and return statements. It is not necessary
     // for generator functions to have this variable set.
     Variable* generator_object_variable_;
 
     FunctionState** function_state_stack_;
     FunctionState* outer_function_state_;
     Scope** scope_stack_;
     Scope* outer_scope_;
 
-    List<DestructuringAssignment> destructuring_assignments_to_rewrite_;
+    ZoneList<DestructuringAssignment> destructuring_assignments_to_rewrite_;
     TailCallExpressionList tail_call_expressions_;
     ReturnExprContext return_expr_context_;
     ZoneList<ExpressionT> non_patterns_to_rewrite_;
 
+    ZoneList<typename ExpressionClassifier::Error> reported_errors_;
+
     typename Traits::Type::Factory* factory_;
 
     // If true, the next (and immediately following) function literal is
     // preceded by a parenthesis.
     bool next_function_is_parenthesized_;
 
     // The value of the parents' next_function_is_parenthesized_, as it applies
     // to this function. Filled in by constructor.
     bool this_function_is_parenthesized_;
 
@@ skipping 702 matching lines @@
       expected_property_count_(0),
       this_location_(Scanner::Location::invalid()),
       return_location_(Scanner::Location::invalid()),
       super_location_(Scanner::Location::invalid()),
       kind_(kind),
       generator_object_variable_(NULL),
       function_state_stack_(function_state_stack),
       outer_function_state_(*function_state_stack),
       scope_stack_(scope_stack),
       outer_scope_(*scope_stack),
+      destructuring_assignments_to_rewrite_(16, scope->zone()),
       tail_call_expressions_(scope->zone()),
       return_expr_context_(ReturnExprContext::kInsideValidBlock),
       non_patterns_to_rewrite_(0, scope->zone()),
+      reported_errors_(16, scope->zone()),
       factory_(factory),
       next_function_is_parenthesized_(false),
       this_function_is_parenthesized_(false) {
   *scope_stack_ = scope;
   *function_state_stack = this;
   if (outer_function_state_) {
     this_function_is_parenthesized_ =
         outer_function_state_->next_function_is_parenthesized_;
     outer_function_state_->next_function_is_parenthesized_ = false;
   }
@@ skipping 336 matching lines @@
 
     case Token::LBRACE:
       return this->ParseObjectLiteral(classifier, ok);
 
     case Token::LPAREN: {
       // Arrow function formal parameters are either a single identifier or a
       // list of BindingPattern productions enclosed in parentheses.
       // Parentheses are not valid on the LHS of a BindingPattern, so we use the
       // is_valid_binding_pattern() check to detect multiple levels of
       // parenthesization.
-      if (!classifier->is_valid_binding_pattern()) {
-        ArrowFormalParametersUnexpectedToken(classifier);
-      }
+      bool pattern_error = !classifier->is_valid_binding_pattern();
       classifier->RecordPatternError(scanner()->peek_location(),
                                      MessageTemplate::kUnexpectedToken,
                                      Token::String(Token::LPAREN));
+      if (pattern_error) ArrowFormalParametersUnexpectedToken(classifier);
       Consume(Token::LPAREN);
       if (Check(Token::RPAREN)) {
         // ()=>x.  The continuation that looks for the => is in
         // ParseAssignmentExpression.
         classifier->RecordExpressionError(scanner()->location(),
                                           MessageTemplate::kUnexpectedToken,
                                           Token::String(Token::RPAREN));
         return factory()->NewEmptyParentheses(beg_pos);
       } else if (Check(Token::ELLIPSIS)) {
         // (...x)=>x.  The continuation that looks for the => is in
@@ skipping 112 matching lines @@
     if (peek() == Token::ELLIPSIS) {
       // 'x, y, ...z' in CoverParenthesizedExpressionAndArrowParameterList only
       // as the formal parameters of'(x, y, ...z) => foo', and is not itself a
       // valid expression or binding pattern.
       ExpressionUnexpectedToken(classifier);
       BindingPatternUnexpectedToken(classifier);
       Consume(Token::ELLIPSIS);
       seen_rest = is_rest = true;
     }
     int pos = position(), expr_pos = peek_position();
+    ExpressionClassifier binding_classifier(this);
     ExpressionT right = this->ParseAssignmentExpression(
         accept_IN, &binding_classifier, CHECK_OK);
     classifier->Accumulate(&binding_classifier,
                            ExpressionClassifier::AllProductions);
     if (is_rest) {
       if (!this->IsIdentifier(right) && !IsValidPattern(right)) {
         classifier->RecordArrowFormalParametersError(
             Scanner::Location(pos, scanner()->location().end_pos),
             MessageTemplate::kInvalidRestParameter);
       }
@@ skipping 67 matching lines @@
   }
   Expect(Token::RBRACK, CHECK_OK);
 
   // Update the scope information before the pre-parsing bailout.
   int literal_index = function_state_->NextMaterializedLiteralIndex();
 
   ExpressionT result = factory()->NewArrayLiteral(values, first_spread_index,
                                                   literal_index, pos);
   if (first_spread_index >= 0) {
     result = factory()->NewRewritableExpression(result);
-    Traits::QueueNonPatternForRewriting(result);
+    Traits::QueueNonPatternForRewriting(result, ok);
+    if (!*ok) {
+      // If the non-pattern rewriting mechanism is used in the future for
+      // rewriting other things than spreads, this error message will have
+      // to change.  Also, this error message will never appear while pre-
+      // parsing (this is OK, as it is an implementation limitation).
+      ReportMessage(MessageTemplate::kTooManySpreads);
+      return this->EmptyExpression();
+    }
   }
   return result;
 }
 
 template <class Traits>
 typename ParserBase<Traits>::ExpressionT ParserBase<Traits>::ParsePropertyName(
     IdentifierT* name, bool* is_get, bool* is_set, bool* is_await,
     bool* is_computed_name, ExpressionClassifier* classifier, bool* ok) {
   Token::Value token = peek();
   int pos = peek_position();
@@ skipping 426 matching lines @@
 
   if (is_async && peek_any_identifier() && PeekAhead() == Token::ARROW) {
     // async Identifier => AsyncConciseBody
     IdentifierT name =
         ParseAndClassifyIdentifier(&arrow_formals_classifier, CHECK_OK);
     expression = this->ExpressionFromIdentifier(
         name, position(), scanner()->location().end_pos, scope_, factory());
   }
 
   if (peek() == Token::ARROW) {
-    classifier->RecordPatternError(scanner()->peek_location(),
-                                   MessageTemplate::kUnexpectedToken,
-                                   Token::String(Token::ARROW));
+    Scanner::Location arrow_loc = scanner()->peek_location();
     ValidateArrowFormalParameters(&arrow_formals_classifier, expression,
                                   parenthesized_formals, is_async, CHECK_OK);
     // This reads strangely, but is correct: it checks whether any
     // sub-expression of the parameter list failed to be a valid formal
     // parameter initializer. Since YieldExpressions are banned anywhere
     // in an arrow parameter list, this is correct.
     // TODO(adamk): Rename "FormalParameterInitializerError" to refer to
     // "YieldExpression", which is its only use.
     ValidateFormalParameterInitializer(&arrow_formals_classifier, ok);
 
@@ skipping 16 matching lines @@
     scope->set_start_position(lhs_beg_pos);
     Scanner::Location duplicate_loc = Scanner::Location::invalid();
     this->ParseArrowFunctionFormalParameterList(&parameters, expression, loc,
                                                 &duplicate_loc, CHECK_OK);
     if (duplicate_loc.IsValid()) {
       arrow_formals_classifier.RecordDuplicateFormalParameterError(
           duplicate_loc);
     }
     expression = this->ParseArrowFunctionLiteral(
         accept_IN, parameters, is_async, arrow_formals_classifier, CHECK_OK);
+    arrow_formals_classifier.Discard();
+    classifier->RecordPatternError(arrow_loc,
+                                   MessageTemplate::kUnexpectedToken,
+                                   Token::String(Token::ARROW));
 
     if (fni_ != nullptr) fni_->Infer();
 
     return expression;
   }
 
   if (this->IsValidReferenceExpression(expression)) {
     arrow_formals_classifier.ForgiveAssignmentPatternError();
   }
 
@@ skipping 219 matching lines @@
   //   LogicalOrExpression
   //   LogicalOrExpression '?' AssignmentExpression ':' AssignmentExpression
 
   int pos = peek_position();
   // We start using the binary expression parser for prec >= 4 only!
   ExpressionT expression =
       this->ParseBinaryExpression(4, accept_IN, classifier, CHECK_OK);
   if (peek() != Token::CONDITIONAL) return expression;
   CheckNoTailCallExpressions(classifier, CHECK_OK);
   Traits::RewriteNonPattern(classifier, CHECK_OK);
+  BindingPatternUnexpectedToken(classifier);
   ArrowFormalParametersUnexpectedToken(classifier);
-  BindingPatternUnexpectedToken(classifier);
   Consume(Token::CONDITIONAL);
   // In parsing the first assignment expression in conditional
   // expressions we always accept the 'in' keyword; see ECMA-262,
   // section 11.12, page 58.
   ExpressionT left = ParseAssignmentExpression(true, classifier, CHECK_OK);
   Traits::RewriteNonPattern(classifier, CHECK_OK);
   Expect(Token::COLON, CHECK_OK);
   ExpressionT right =
       ParseAssignmentExpression(accept_IN, classifier, CHECK_OK);
   Traits::RewriteNonPattern(classifier, CHECK_OK);
@@ skipping 1076 matching lines @@
     has_seen_constructor_ = true;
     return;
   }
 }
 
 
 }  // namespace internal
 }  // namespace v8
 
 #endif  // V8_PARSING_PARSER_BASE_H