[generators] Implement %GeneratorGetSourcePosition.

src/objects.h

 // Copyright 2015 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_OBJECTS_H_
 #define V8_OBJECTS_H_
 
 #include <iosfwd>
 
 #include "src/assert-scope.h"
@@ skipping 7345 matching lines @@
  public:
   // [function]: The function corresponding to this generator object.
   DECL_ACCESSORS(function, JSFunction)
 
   // [context]: The context of the suspended computation.
   DECL_ACCESSORS(context, Context)
 
   // [receiver]: The receiver of the suspended computation.
   DECL_ACCESSORS(receiver, Object)
 
-  // [input]: The most recent input value.
-  DECL_ACCESSORS(input, Object)
+  // [input_or_debug_pos]
+  // For executing generators: the most recent input value.
+  // For suspended new-style generators: debug information (bytecode offset).
+  // For suspended old-style generators: unused.
+  // There is currently no need to remember the most recent input value for a
+  // suspended generator.
+  DECL_ACCESSORS(input_or_debug_pos, Object)
 
   // [resume_mode]: The most recent resume mode.
   enum ResumeMode { kNext, kReturn, kThrow };
   DECL_INT_ACCESSORS(resume_mode)
 
-  // [continuation]: Offset into code of continuation.
+  // [continuation]
   //
-  // A positive offset indicates a suspended generator.  The special
+  // A positive value indicates a suspended generator.  The special
   // kGeneratorExecuting and kGeneratorClosed values indicate that a generator
   // cannot be resumed.
   inline int continuation() const;
   inline void set_continuation(int continuation);
-  inline bool is_closed();
-  inline bool is_executing();
-  inline bool is_suspended();
+  inline bool is_closed() const;
+  inline bool is_executing() const;
+  inline bool is_suspended() const;
+
+  // For suspended generators: the source position at which the generator
+  // is suspended.
+  int source_position() const;
 
   // [operand_stack]: Saved operand stack.
   DECL_ACCESSORS(operand_stack, FixedArray)
 
   DECLARE_CAST(JSGeneratorObject)
 
   // Dispatched behavior.
   DECLARE_VERIFIER(JSGeneratorObject)
 
   // Magic sentinel values for the continuation.
   static const int kGeneratorExecuting = -2;
   static const int kGeneratorClosed = -1;
 
   // Layout description.
   static const int kFunctionOffset = JSObject::kHeaderSize;
   static const int kContextOffset = kFunctionOffset + kPointerSize;
   static const int kReceiverOffset = kContextOffset + kPointerSize;
-  static const int kInputOffset = kReceiverOffset + kPointerSize;
-  static const int kResumeModeOffset = kInputOffset + kPointerSize;
+  static const int kInputOrDebugPosOffset = kReceiverOffset + kPointerSize;
+  static const int kResumeModeOffset = kInputOrDebugPosOffset + kPointerSize;
   static const int kContinuationOffset = kResumeModeOffset + kPointerSize;
   static const int kOperandStackOffset = kContinuationOffset + kPointerSize;
   static const int kSize = kOperandStackOffset + kPointerSize;
 
  private:
   DISALLOW_IMPLICIT_CONSTRUCTORS(JSGeneratorObject);
 };
 
 
 // Representation for module instance objects.
@@ skipping 3394 matching lines @@
     }
     return value;
   }
 };
 
 
 }  // NOLINT, false-positive due to second-order macros.
 }  // NOLINT, false-positive due to second-order macros.
 
 #endif  // V8_OBJECTS_H_