Collect type feedback for fields.

runtime/vm/flow_graph_optimizer.cc

Index: runtime/vm/flow_graph_optimizer.cc
diff --git a/runtime/vm/flow_graph_optimizer.cc b/runtime/vm/flow_graph_optimizer.cc
index f89f0d287a5f10291ce2f0e0fb4b0d74ee58ae33..b5d00f9e22af0630731b8f86d455b9564dd16101 100644
--- a/runtime/vm/flow_graph_optimizer.cc
+++ b/runtime/vm/flow_graph_optimizer.cc
@@ -1233,6 +1233,12 @@ void FlowGraphOptimizer::InlineImplicitInstanceGetter(InstanceCallInstr* call) {
       field.Offset(),
       AbstractType::ZoneHandle(field.type()),
       field.is_final());
+  if (field.guarded_cid() != kIllegalCid) {
+    load->set_result_cid(field.GuardedCid());
+    load->set_field(&Field::ZoneHandle(field.raw()));
+  }
+  load->set_field_name(String::Handle(field.name()).ToCString());
+
   // Discard the environment from the original instruction because the load
   // can't deoptimize.
   call->RemoveEnvironment();
@@ -2016,6 +2022,17 @@ bool FlowGraphOptimizer::TryInlineInstanceSetter(InstanceCallInstr* instr,
                  Definition::kEffect);
     needs_store_barrier = kNoStoreBarrier;
   }
+
+  if (field.guarded_cid() != kDynamicCid) {
+    InsertBefore(instr,
+                 new GuardFieldInstr(new Value(instr->ArgumentAt(1)),
+                                     field,
+                                     instr->deopt_id()),
+                 instr->env(),
+                 Definition::kEffect);
+  }
+
+  // Field guard was detached.
   StoreInstanceFieldInstr* store = new StoreInstanceFieldInstr(
       field,
       new Value(instr->ArgumentAt(0)),
@@ -3777,6 +3794,7 @@ void ConstantPropagator::VisitCheckStackOverflow(
 
 void ConstantPropagator::VisitCheckClass(CheckClassInstr* instr) { }
 
+void ConstantPropagator::VisitGuardField(GuardFieldInstr* instr) { }
 
 void ConstantPropagator::VisitCheckSmi(CheckSmiInstr* instr) { }