[debugger] fix stepping over await calls for ignition generators.

src/interpreter/interpreter.cc

Index: src/interpreter/interpreter.cc
diff --git a/src/interpreter/interpreter.cc b/src/interpreter/interpreter.cc
index 5a5ce40d8144ee7fac3bb39574345eaad7722a4f..bc4bbd5ad02732aeedebb8eaa70278252ec032fa 100644
--- a/src/interpreter/interpreter.cc
+++ b/src/interpreter/interpreter.cc
@@ -1791,10 +1791,20 @@ void Interpreter::DoNop(InterpreterAssembler* assembler) { __ Dispatch(); }
 void Interpreter::DoSuspendGenerator(InterpreterAssembler* assembler) {
   Node* generator_reg = __ BytecodeOperandReg(0);
   Node* generator = __ LoadRegister(generator_reg);
+  Node* context = __ GetContext();
+
+  Node* debug_is_active = __ DebuggerIsActive();
+  Label if_debugging(assembler), debugger_done(assembler);

[rmcilroy, 2016/06/14 06:23:11]

Please make if_debugging deferred. (It's the only call in this handler, so if
it's deferred the handler won't build a frame unless it enters this branch).

[Yang, 2016/06/14 09:17:02]

Done. However, I think we always build a frame for this bytecode handler.

[rmcilroy, 2016/06/14 10:00:22]

We do on ia32 due to lack of registers, but not on x64 currently. We shouldn't
need to on Arm either, but seem to for some reason, I'll look into that at some
point. Thanks.

+  __ BranchIf(debug_is_active, &if_debugging, &debugger_done);
+  __ Bind(&if_debugging);
+  {
+    __ CallRuntime(Runtime::kDebugRecordAsyncFunction, context, generator);

[caitp (gmail), 2016/06/13 13:38:13]

Is it possible to know at this point in the interpreter whether or not the
generator being suspended is an async function or not? Or does it just not
matter since it only applies to debugging anyways?

[Yang, 2016/06/13 13:42:26]

We could expand a bit more and load the function of the generator, and load the
shared function info, and then load the bitfield...

But that's pretty cumbersome, and probably doesn't matter. We only do this when
debugger is active.

+    __ Goto(&debugger_done);
+  }
+  __ Bind(&debugger_done);
 
   Node* array =
       __ LoadObjectField(generator, JSGeneratorObject::kOperandStackOffset);
-  Node* context = __ GetContext();
   Node* state = __ GetAccumulator();
 
   __ ExportRegisterFile(array);