[Interpreter] GetExpression(0) in InterpretedFrames gets first local.

src/frames.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_FRAMES_H_
 #define V8_FRAMES_H_
 
 #include "src/allocation.h"
 #include "src/handles.h"
 #include "src/safepoint-table.h"
@@ skipping 174 matching lines @@
   // FP-relative.
   static const int kNewTargetFromFp =
       -StandardFrameConstants::kFixedFrameSizeFromFp - 1 * kPointerSize;
   static const int kBytecodeArrayFromFp =
       -StandardFrameConstants::kFixedFrameSizeFromFp - 2 * kPointerSize;
   static const int kBytecodeOffsetFromFp =
       -StandardFrameConstants::kFixedFrameSizeFromFp - 3 * kPointerSize;
   static const int kRegisterFilePointerFromFp =
       -StandardFrameConstants::kFixedFrameSizeFromFp - 4 * kPointerSize;
 
+  static const int kExpressionsOffset = kRegisterFilePointerFromFp;
+
   // Expression index for {StandardFrame::GetExpressionAddress}.
-  static const int kBytecodeArrayExpressionIndex = 1;
-  static const int kBytecodeOffsetExpressionIndex = 2;
-  static const int kRegisterFileExpressionIndex = 3;
+  static const int kBytecodeArrayExpressionIndex = -2;
+  static const int kBytecodeOffsetExpressionIndex = -1;
+  static const int kRegisterFileExpressionIndex = 0;
 
   // Register file pointer relative.
   static const int kLastParamFromRegisterPointer =
       StandardFrameConstants::kFixedFrameSize + 4 * kPointerSize;
 
   static const int kBytecodeOffsetFromRegisterPointer = 1 * kPointerSize;
   static const int kBytecodeArrayFromRegisterPointer = 2 * kPointerSize;
   static const int kNewTargetFromRegisterPointer = 3 * kPointerSize;
   static const int kFunctionFromRegisterPointer = 4 * kPointerSize;
   static const int kContextFromRegisterPointer = 5 * kPointerSize;
@@ skipping 282 matching lines @@
   // Testers.
   bool is_standard() const override { return true; }
 
   // Accessors.
   inline Object* context() const;
 
   // Access the expressions in the stack frame including locals.
   inline Object* GetExpression(int index) const;
   inline void SetExpression(int index, Object* value);
   int ComputeExpressionsCount() const;
-  static Object* GetExpression(Address fp, int index);
 
   void SetCallerFp(Address caller_fp) override;
 
   static StandardFrame* cast(StackFrame* frame) {
     DCHECK(frame->is_standard());
     return static_cast<StandardFrame*>(frame);
   }
 
  protected:
   inline explicit StandardFrame(StackFrameIteratorBase* iterator);
@@ skipping 10 matching lines @@
 
   // Computes the address of the constant pool  field in the standard
   // frame given by the provided frame pointer.
   static inline Address ComputeConstantPoolAddress(Address fp);
 
   // Iterate over expression stack including stack handlers, locals,
   // and parts of the fixed part including context and code fields.
   void IterateExpressions(ObjectVisitor* v) const;
 
   // Returns the address of the n'th expression stack element.
-  Address GetExpressionAddress(int n) const;
-  static Address GetExpressionAddress(Address fp, int n);
+  virtual Address GetExpressionAddress(int n) const;
 
   // Determines if the standard frame for the given frame pointer is
   // an arguments adaptor frame.
   static inline bool IsArgumentsAdaptorFrame(Address fp);
 
   // Determines if the standard frame for the given frame pointer is a
   // construct frame.
   static inline bool IsConstructFrame(Address fp);
 
   // Used by OptimizedFrames and StubFrames.
@@ skipping 205 matching lines @@
 
   // Access to the interpreter register file for this frame.
   Object* GetInterpreterRegister(int register_index) const;
 
   // Build a list with summaries for this frame including all inlined frames.
   void Summarize(List<FrameSummary>* frames) override;
 
  protected:
   inline explicit InterpretedFrame(StackFrameIteratorBase* iterator);
 
+  Address GetExpressionAddress(int n) const override;
+
  private:
   friend class StackFrameIteratorBase;
 };
 
 
 // Arguments adaptor frames are automatically inserted below
 // JavaScript frames when the actual number of parameters does not
 // match the formal number of parameters.
 class ArgumentsAdaptorFrame: public JavaScriptFrame {
  public:
   Type type() const override { return ARGUMENTS_ADAPTOR; }
 
   // Determine the code for the frame.
   Code* unchecked_code() const override;
 
   static ArgumentsAdaptorFrame* cast(StackFrame* frame) {
     DCHECK(frame->is_arguments_adaptor());
     return static_cast<ArgumentsAdaptorFrame*>(frame);
   }
 
   // Printing support.
   void Print(StringStream* accumulator, PrintMode mode,
              int index) const override;
 
+  static int GetLength(Address fp);
+
  protected:
   inline explicit ArgumentsAdaptorFrame(StackFrameIteratorBase* iterator);
 
   int GetNumberOfIncomingArguments() const override;
 
   Address GetCallerStackPointer() const override;
 
  private:
   friend class StackFrameIteratorBase;
 };
@@ skipping 212 matching lines @@
 
 
 // Reads all frames on the current stack and copies them into the current
 // zone memory.
 Vector<StackFrame*> CreateStackMap(Isolate* isolate, Zone* zone);
 
 }  // namespace internal
 }  // namespace v8
 
 #endif  // V8_FRAMES_H_