[interpreter, debugger] support debug breaks via bytecode array copy

src/debug/debug-frames.cc

Index: src/debug/debug-frames.cc
diff --git a/src/debug/debug-frames.cc b/src/debug/debug-frames.cc
index f01354500b0e5ce1670a45e8e7afe6087158f99f..1d4c6eb03b5dfb28668b2624c0c73ef88a19558f 100644
--- a/src/debug/debug-frames.cc
+++ b/src/debug/debug-frames.cc
@@ -15,6 +15,7 @@ FrameInspector::FrameInspector(JavaScriptFrame* frame,
   has_adapted_arguments_ = frame_->has_adapted_arguments();
   is_bottommost_ = inlined_jsframe_index == 0;
   is_optimized_ = frame_->is_optimized();
+  is_interpreted_ = frame_->is_interpreted();
   // Calculate the deoptimized frame.
   if (frame->is_optimized()) {
     // TODO(turbofan): Revisit once we support deoptimization.
@@ -69,6 +70,12 @@ Handle<Object> FrameInspector::GetExpression(int index) {
 int FrameInspector::GetSourcePosition() {
   if (is_optimized_) {
     return deoptimized_frame_->GetSourcePosition();
+  } else if (is_interpreted_) {
+    InterpretedFrame* frame = reinterpret_cast<InterpretedFrame*>(frame_);
+    // TODO(yangguo): Get the bytecode array from the frame.

[Michael Starzinger, 2016/02/22 09:37:49]

Not sure about this TODO, why do we need to get the bytecode array from the
frame? The source position information should be the same for all versions that
could be active in the frame. That's one reason why I am so keen on preserving
the structure (i.e. same jump offsets, same bytecode offsets) of the bytecode
when we create the patched copy. I think everything we need to reason about the
bytecode should not depend on which version is active in the frame. WDYT? Am I
missing somehting here?

[Yang, 2016/02/22 12:48:43]

Absolutely correct. This is a stale TODO I forgot to remove.

+    BytecodeArray* bytecode_array =
+        frame->function()->shared()->bytecode_array();
+    return bytecode_array->SourcePosition(frame->GetBytecodeOffset());
   } else {
     Code* code = frame_->LookupCode();
     int offset = static_cast<int>(frame_->pc() - code->instruction_start());
@@ -95,6 +102,7 @@ void FrameInspector::SetArgumentsFrame(JavaScriptFrame* frame) {
   DCHECK(has_adapted_arguments_);
   frame_ = frame;
   is_optimized_ = frame_->is_optimized();
+  is_interpreted_ = frame_->is_interpreted();
   DCHECK(!is_optimized_);
 }