[liveedit] reimplement frame restarting.

src/interpreter/interpreter-assembler.cc

Index: src/interpreter/interpreter-assembler.cc
diff --git a/src/interpreter/interpreter-assembler.cc b/src/interpreter/interpreter-assembler.cc
index 1ccd342f0662470b54d283ea416cc361244ba2ef..c50bcba24b9f2a80bacc4bec649ee069ff8b2c58 100644
--- a/src/interpreter/interpreter-assembler.cc
+++ b/src/interpreter/interpreter-assembler.cc
@@ -1183,6 +1183,25 @@ void InterpreterAssembler::AbortIfWordNotEqual(Node* lhs, Node* rhs,
   Bind(&ok);
 }
 
+void InterpreterAssembler::MaybeDropFrames(Node* context) {
+  Node* new_fp_address =
+      ExternalConstant(ExternalReference::debug_new_fp_address(isolate()));
+  Node* new_fp = Load(MachineType::TaggedPointer(), new_fp_address);

[jgruber, 2017/01/17 13:29:58]

Is new_fp really a TaggedPointer? Looking at the FrameDropperTrampoline, it
seems like a raw pointer (MachineType::PointerRepresentation()) to me.

[Michael Starzinger, 2017/01/17 14:45:27]

+1, nice catch, I totally missed that!

[Yang, 2017/01/18 07:49:08]

Done.

+  Node* null = IntPtrConstant(static_cast<intptr_t>(0));

[jgruber, 2017/01/17 13:29:58]

Nit: we don't need the static_cast.

[Yang, 2017/01/18 07:49:08]

Done.

+
+  Label ok(this), drop_frames(this);
+  Branch(IntPtrEqual(new_fp, null), &ok, &drop_frames);
+
+  Bind(&drop_frames);
+  // We don't expect this call to return since the frame dropper tears down
+  // the stack and jumps into the function on the target frame to restart it.
+  CallStub(CodeFactory::FrameDropperTrampoline(isolate()), context, new_fp);
+  Abort(kUnexpectedReturnFromFrameDropper);
+  Goto(&ok);
+
+  Bind(&ok);
+}
+
 void InterpreterAssembler::TraceBytecode(Runtime::FunctionId function_id) {
   CallRuntime(function_id, GetContext(), BytecodeArrayTaggedPointer(),
               SmiTag(BytecodeOffset()), GetAccumulatorUnchecked());