[esnext] implement frontend changes for async/await proposal

src/ast/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_AST_H_
 #define V8_AST_AST_H_
 
 #include "src/assembler.h"
 #include "src/ast/ast-value-factory.h"
 #include "src/ast/modules.h"
@@ skipping 2581 matching lines @@
   Handle<String> name() const { return raw_name_->string(); }
   const AstString* raw_name() const { return raw_name_; }
   void set_raw_name(const AstString* name) { raw_name_ = name; }
   Scope* scope() const { return scope_; }
   ZoneList<Statement*>* body() const { return body_; }
   void set_function_token_position(int pos) { function_token_position_ = pos; }
   int function_token_position() const { return function_token_position_; }
   int start_position() const;
   int end_position() const;
   int SourceSize() const { return end_position() - start_position(); }
-  bool is_declaration() const { return IsDeclaration::decode(bitfield_); }
+  bool is_declaration() const { return function_type() == kDeclaration; }
   bool is_named_expression() const {
-    return IsNamedExpression::decode(bitfield_);
+    return function_type() == kNamedExpression;
   }
   bool is_anonymous_expression() const {
-    return IsAnonymousExpression::decode(bitfield_);
+    return function_type() == kAnonymousExpression;
   }
   LanguageMode language_mode() const;
 
   static bool NeedsHomeObject(Expression* expr);
 
   int materialized_literal_count() { return materialized_literal_count_; }
   int expected_property_count() { return expected_property_count_; }
   int parameter_count() { return parameter_count_; }
 
   bool AllowsLazyCompilation();
@@ skipping 56 matching lines @@
 
   // 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 ShouldBeUsedOnceHint::decode(bitfield_);
   }
   void set_should_be_used_once_hint() {
     bitfield_ = ShouldBeUsedOnceHint::update(bitfield_, true);
   }
 
+  FunctionType function_type() const {
+    return FunctionTypeBits::decode(bitfield_);
+  }
   FunctionKind kind() const { return FunctionKindBits::decode(bitfield_); }
 
   int ast_node_count() { return ast_properties_.node_count(); }
   AstProperties::Flags flags() const { return ast_properties_.flags(); }
   void set_ast_properties(AstProperties* ast_properties) {
     ast_properties_ = *ast_properties;
   }
   const FeedbackVectorSpec* feedback_vector_spec() const {
     return ast_properties_.get_spec();
   }
@@ skipping 25 matching lines @@
         body_(body),
         raw_inferred_name_(ast_value_factory->empty_string()),
         ast_properties_(zone),
         dont_optimize_reason_(kNoReason),
         materialized_literal_count_(materialized_literal_count),
         expected_property_count_(expected_property_count),
         parameter_count_(parameter_count),
         function_token_position_(RelocInfo::kNoPosition),
         yield_count_(0) {
     bitfield_ =
-        IsDeclaration::encode(function_type == kDeclaration) |
-        IsNamedExpression::encode(function_type == kNamedExpression) |
-        IsAnonymousExpression::encode(function_type == kAnonymousExpression) |
-        Pretenure::encode(false) |
+        FunctionTypeBits::encode(function_type) | Pretenure::encode(false) |
         HasDuplicateParameters::encode(has_duplicate_parameters ==
                                        kHasDuplicateParameters) |
         IsFunction::encode(is_function) |
         ShouldEagerCompile::encode(eager_compile_hint == kShouldEagerCompile) |
         FunctionKindBits::encode(kind) | ShouldBeUsedOnceHint::encode(false);
     DCHECK(IsValidFunctionKind(kind));
   }
 
  private:
-  class IsDeclaration : public BitField16<bool, 0, 1> {};
-  class IsNamedExpression : public BitField16<bool, 1, 1> {};
-  class IsAnonymousExpression : public BitField16<bool, 2, 1> {};
-  class Pretenure : public BitField16<bool, 3, 1> {};
-  class HasDuplicateParameters : public BitField16<bool, 4, 1> {};
-  class IsFunction : public BitField16<bool, 5, 1> {};
-  class ShouldEagerCompile : public BitField16<bool, 6, 1> {};
-  class ShouldBeUsedOnceHint : public BitField16<bool, 7, 1> {};
-  class FunctionKindBits : public BitField16<FunctionKind, 8, 8> {};
+  class FunctionTypeBits : public BitField16<FunctionType, 0, 2> {};

[Dan Ehrenberg, 2016/05/12 19:24:32]

I like this new way that you found the extra bit!

+  class Pretenure : public BitField16<bool, 2, 1> {};
+  class HasDuplicateParameters : public BitField16<bool, 3, 1> {};
+  class IsFunction : public BitField16<bool, 4, 1> {};
+  class ShouldEagerCompile : public BitField16<bool, 5, 1> {};
+  class ShouldBeUsedOnceHint : public BitField16<bool, 6, 1> {};
+  class FunctionKindBits : public BitField16<FunctionKind, 7, 9> {};
 
   // Start with 16-bit field, which should get packed together
   // with Expression's trailing 16-bit field.
   uint16_t bitfield_;
 
   const AstString* raw_name_;
   Scope* scope_;
   ZoneList<Statement*>* body_;
   const AstString* raw_inferred_name_;
   Handle<String> inferred_name_;
@@ skipping 797 matching lines @@
                                     : NULL;                                   \
   }
 AST_NODE_LIST(DECLARE_NODE_FUNCTIONS)
 #undef DECLARE_NODE_FUNCTIONS
 
 
 }  // namespace internal
 }  // namespace v8
 
 #endif  // V8_AST_AST_H_