Use off-heap data for type feedback in PolymorphicInstanceCallInstr

runtime/vm/flow_graph_type_propagator.cc

Index: runtime/vm/flow_graph_type_propagator.cc
diff --git a/runtime/vm/flow_graph_type_propagator.cc b/runtime/vm/flow_graph_type_propagator.cc
index 92a4d78ae6827d40867f056abe5b192822238939..99967c638e2e60439d106e29b592e4bc99196ef3 100644
--- a/runtime/vm/flow_graph_type_propagator.cc
+++ b/runtime/vm/flow_graph_type_propagator.cc
@@ -296,8 +296,8 @@ void FlowGraphTypePropagator::VisitInstanceCall(InstanceCallInstr* instr) {
 
 void FlowGraphTypePropagator::VisitPolymorphicInstanceCall(
     PolymorphicInstanceCallInstr* instr) {
-  if (instr->instance_call()->has_unique_selector()) {
-    SetCid(instr->ArgumentAt(0), instr->ic_data().GetReceiverClassIdAt(0));
+  if (instr->HasSingleRecognizedCid()) {

[Vyacheslav Egorov (Google), 2017/04/10 10:59:27]

These changes are highly suspect. They definitely break AOT optimizer because
HasSingleRecognizedCid() is weaker than unique selector requirements:

class A {
  final uniqueField = "world";
  uniqueMethod() => "hello";
}

class B {
  noSuchMethod(mirror) => 42;
}

foobar(obj) {
  try {
    final a = obj.uniqueMethod();
    final b = obj.uniqueField;
    return "${a} ${b}";
  } catch (e) {
    return "thrown";
  }
}

main() {
  print(foobar(new A()));
  print(foobar(new B()));
}

[erikcorry, 2017/04/19 15:06:40]

The change to HasSingleRecognizedCid was reverted.

+    SetCid(instr->ArgumentAt(0), instr->SingleCid());
     return;
   }
   CheckNonNullSelector(instr, instr->ArgumentAt(0),
@@ -1024,8 +1024,8 @@ CompileType AllocateUninitializedContextInstr::ComputeType() const {
 
 
 CompileType PolymorphicInstanceCallInstr::ComputeType() const {
-  if (!HasSingleRecognizedTarget()) return CompileType::Dynamic();
-  const Function& target = Function::Handle(ic_data().GetTargetAt(0));
+  if (!HasSingleRecognizedCid()) return CompileType::Dynamic();

[erikcorry, 2017/04/19 15:06:40]

The change in this 'if' also reverted

+  const Function& target = *targets_[0].target;
   return (target.recognized_kind() != MethodRecognizer::kUnknown)
              ? CompileType::FromCid(MethodRecognizer::ResultCid(target))
              : CompileType::Dynamic();