[interpreter] Switch context during stack unwinding.

src/frames.cc

 // 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.
 
 #include "src/frames.h"
 
 #include <sstream>
 
 #include "src/ast/ast.h"
 #include "src/ast/scopeinfo.h"
@@ skipping 1145 matching lines @@
 
 
 void InterpretedFrame::PatchBytecodeOffset(int new_offset) {
   const int index = InterpreterFrameConstants::kBytecodeOffsetExpressionIndex;
   DCHECK_EQ(InterpreterFrameConstants::kBytecodeOffsetFromFp,
             StandardFrameConstants::kExpressionsOffset - index * kPointerSize);
   int raw_offset = new_offset + BytecodeArray::kHeaderSize - kHeapObjectTag;
   SetExpression(index, Smi::FromInt(raw_offset));
 }
 
+Object* InterpretedFrame::GetInterpreterRegister(int register_index) const {
+  const int index = InterpreterFrameConstants::kRegisterFileExpressionIndex;
+  DCHECK_EQ(InterpreterFrameConstants::kRegisterFilePointerFromFp,
+            StandardFrameConstants::kExpressionsOffset - index * kPointerSize);
+  return GetExpression(index + register_index);
+}
+
 void InterpretedFrame::Summarize(List<FrameSummary>* functions) {
   DCHECK(functions->length() == 0);
   AbstractCode* abstract_code =
       AbstractCode::cast(function()->shared()->bytecode_array());
   FrameSummary summary(receiver(), function(), abstract_code,
                        GetBytecodeOffset(), IsConstructor());
   functions->Add(summary);
 }
 
 int ArgumentsAdaptorFrame::GetNumberOfIncomingArguments() const {
@@ skipping 458 matching lines @@
   for (StackFrameIterator it(isolate); !it.done(); it.Advance()) {
     StackFrame* frame = AllocateFrameCopy(it.frame(), zone);
     list.Add(frame, zone);
   }
   return list.ToVector();
 }
 
 
 }  // namespace internal
 }  // namespace v8