[async-await] (simpler) fix for Return in try/finally in async functions

src/ast/scopes.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_SCOPES_H_
 #define V8_AST_SCOPES_H_
 
 #include "src/base/compiler-specific.h"
 #include "src/base/hashmap.h"
 #include "src/globals.h"
@@ skipping 662 matching lines @@
   // Declare the function variable for a function literal. This variable
   // is in an intermediate scope between this function scope and the the
   // outer scope. Only possible for function scopes; at most one variable.
   //
   // This function needs to be called after all other variables have been
   // declared in the scope. It will add a variable for {name} to {variables_};
   // either the function variable itself, or a non-local in case the function
   // calls sloppy eval.
   Variable* DeclareFunctionVar(const AstRawString* name);
 
+  // Declare some special internal variables which must be accessible to
+  // Ignition without ScopeInfo.
+  Variable* DeclareGeneratorObjectVar(const AstRawString* name);
+  Variable* DeclarePromiseVar(const AstRawString* name);
+
   // Declare a parameter in this scope.  When there are duplicated
   // parameters the rightmost one 'wins'.  However, the implementation
   // expects all parameters to be declared and from left to right.
   Variable* DeclareParameter(const AstRawString* name, VariableMode mode,
                              bool is_optional, bool is_rest, bool* is_duplicate,
                              AstValueFactory* ast_value_factory);
 
   // Declare an implicit global variable in this scope which must be a
   // script scope.  The variable was introduced (possibly from an inner
   // scope) by a reference to an unresolved variable with no intervening
@@ skipping 18 matching lines @@
   // The variable corresponding to the 'new.target' value.
   Variable* new_target_var() { return new_target_; }
 
   // The variable holding the function literal for named function
   // literals, or NULL.  Only valid for function scopes.
   Variable* function_var() const {
     DCHECK(is_function_scope());
     return function_;
   }
 
+  Variable* generator_object_var() const {
+    DCHECK(is_function_scope() || is_module_scope());
+    return generator_object_;
+  }
+
+  Variable* promise_var() const {
+    DCHECK(is_function_scope());
+    DCHECK(IsAsyncFunction(function_kind_));
+    return promise_;
+  }
+
   // Parameters. The left-most parameter has index 0.
   // Only valid for function and module scopes.
   Variable* parameter(int index) const {
     DCHECK(is_function_scope() || is_module_scope());
     return params_[index];
   }
 
   // Returns the number of formal parameters, excluding a possible rest
   // parameter.  Examples:
   //   function foo(a, b) {}         ==> 2
@@ skipping 136 matching lines @@
   // Convenience variable.
   Variable* receiver_;
   // Function variable, if any; function scopes only.
   Variable* function_;
   // new.target variable, function scopes only.
   Variable* new_target_;
   // Convenience variable; function scopes only.
   Variable* arguments_;
   // Convenience variable; Subclass constructor only
   Variable* this_function_;
+
+  // Generator object, if any; generator function scopes and module scopes only.
+  Variable* generator_object_;
+  // Promise, if any; async function scopes only.
+  Variable* promise_;

[Dan Ehrenberg, 2017/02/08 21:12:56]

Will there be more live DeclarationScopes than FunctionStates at a time? If so,
moving the variables this way this might cause a (probably minor) increase in
memory usage.

 };
 
 class ModuleScope final : public DeclarationScope {
  public:
   ModuleScope(DeclarationScope* script_scope,
               AstValueFactory* ast_value_factory);
 
   // Deserialization.
   // The generated ModuleDescriptor does not preserve all information.  In
   // particular, its module_requests map will be empty because we no longer need
@@ skipping 11 matching lines @@
   void AllocateModuleVariables();
 
  private:
   ModuleDescriptor* module_descriptor_;
 };
 
 }  // namespace internal
 }  // namespace v8
 
 #endif  // V8_AST_SCOPES_H_