Implement a 'trial parse' step, that will abort pre-parsing excessively

src/ast.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_AST_H_
 #define V8_AST_H_
 
 #include "src/v8.h"
 
 #include "src/assembler.h"
@@ skipping 2412 matching lines @@
     kHasDuplicateParameters = 1
   };
 
   enum IsFunctionFlag {
     kGlobalOrEval,
     kIsFunction
   };
 
   enum EagerCompileHint { kShouldEagerCompile, kShouldLazyCompile };
 
+  enum ShouldBeUsedOnceHint { kShouldBeUsedOnce, kDontKnowIfShouldBeUsedOnce };
+
   enum ArityRestriction {
     NORMAL_ARITY,
     GETTER_ARITY,
     SETTER_ARITY
   };
 
   DECLARE_NODE_TYPE(FunctionLiteral)
 
   Handle<String> name() const { return raw_name_->string(); }
   const AstRawString* raw_name() const { return raw_name_; }
@@ skipping 75 matching lines @@
   // function will be called immediately:
   // - (function() { ... })();
   // - var x = function() { ... }();
   bool should_eager_compile() const {
     return EagerCompileHintBit::decode(bitfield_) == kShouldEagerCompile;
   }
   void set_should_eager_compile() {
     bitfield_ = EagerCompileHintBit::update(bitfield_, kShouldEagerCompile);
   }
 
+  // A hint that we expect this function to be called (exactly) once,
+  // i.e. we suspect it's an initialization function.
+  bool should_be_used_once_hint() const {
+    return ShouldBeUsedOnceHintBit::decode(bitfield_) == kShouldBeUsedOnce;
+  }
+  void set_should_be_used_once_hint() {
+    bitfield_ = ShouldBeUsedOnceHintBit::update(bitfield_, kShouldBeUsedOnce);
+  }
+
   FunctionKind kind() { return FunctionKindBits::decode(bitfield_); }
 
   int ast_node_count() { return ast_properties_.node_count(); }
   AstProperties::Flags* flags() { return ast_properties_.flags(); }
   void set_ast_properties(AstProperties* ast_properties) {
     ast_properties_ = *ast_properties;
   }
   const ZoneFeedbackVectorSpec* feedback_vector_spec() const {
     return ast_properties_.get_spec();
   }
@@ skipping 24 matching lines @@
         expected_property_count_(expected_property_count),
         handler_count_(handler_count),
         parameter_count_(parameter_count),
         function_token_position_(RelocInfo::kNoPosition) {
     bitfield_ = IsExpression::encode(function_type != DECLARATION) |
                 IsAnonymous::encode(function_type == ANONYMOUS_EXPRESSION) |
                 Pretenure::encode(false) |
                 HasDuplicateParameters::encode(has_duplicate_parameters) |
                 IsFunction::encode(is_function) |
                 EagerCompileHintBit::encode(eager_compile_hint) |
-                FunctionKindBits::encode(kind);
+                FunctionKindBits::encode(kind) |
+                ShouldBeUsedOnceHintBit::encode(kDontKnowIfShouldBeUsedOnce);
     DCHECK(IsValidFunctionKind(kind));
   }
 
  private:
   const AstRawString* raw_name_;
   Handle<String> name_;
   Handle<SharedFunctionInfo> shared_info_;
   Scope* scope_;
   ZoneList<Statement*>* body_;
   const AstString* raw_inferred_name_;
   Handle<String> inferred_name_;
   AstProperties ast_properties_;
   BailoutReason dont_optimize_reason_;
 
   int materialized_literal_count_;
   int expected_property_count_;
   int handler_count_;
   int parameter_count_;
   int function_token_position_;
 
   unsigned bitfield_;
   class IsExpression : public BitField<bool, 0, 1> {};
   class IsAnonymous : public BitField<bool, 1, 1> {};
   class Pretenure : public BitField<bool, 2, 1> {};
   class HasDuplicateParameters : public BitField<ParameterFlag, 3, 1> {};
   class IsFunction : public BitField<IsFunctionFlag, 4, 1> {};
   class EagerCompileHintBit : public BitField<EagerCompileHint, 5, 1> {};
   class FunctionKindBits : public BitField<FunctionKind, 6, 8> {};
+  class ShouldBeUsedOnceHintBit : public BitField<ShouldBeUsedOnceHint, 15, 1> {
+  };
 };
 
 
 class ClassLiteral final : public Expression {
  public:
   typedef ObjectLiteralProperty Property;
 
   DECLARE_NODE_TYPE(ClassLiteral)
 
   Handle<String> name() const { return raw_name_->string(); }
@@ skipping 881 matching lines @@
 
  private:
   Zone* zone_;
   AstValueFactory* ast_value_factory_;
 };
 
 
 } }  // namespace v8::internal
 
 #endif  // V8_AST_H_