Fix bug in field type tracking and polymorphic inlining.

runtime/vm/flow_graph_builder.cc

Index: runtime/vm/flow_graph_builder.cc
===================================================================
--- runtime/vm/flow_graph_builder.cc	(revision 27611)
+++ runtime/vm/flow_graph_builder.cc	(working copy)
@@ -45,6 +45,7 @@
 FlowGraphBuilder::FlowGraphBuilder(ParsedFunction* parsed_function,
                                    const Array& ic_data_array,
                                    InlineExitCollector* exit_collector,
+                                   GrowableArray<const Field*>* guarded_fields,
                                    intptr_t osr_id)
   : parsed_function_(parsed_function),
     ic_data_array_(ic_data_array),
@@ -55,6 +56,7 @@
         : 0),
     num_stack_locals_(parsed_function->num_stack_locals()),
     exit_collector_(exit_collector),
+    guarded_fields_(guarded_fields),
     last_used_block_id_(0),  // 0 is used for the graph entry.
     context_level_(0),
     try_index_(CatchClauseNode::kInvalidTryIndex),
@@ -70,6 +72,20 @@
 }
 
 
+void FlowGraphBuilder::AddToGuardedFields(const Field& field) const {
+  if ((field.guarded_cid() == kDynamicCid) ||
+      (field.guarded_cid() == kIllegalCid)) {
+    return;
+  }
+  for (intptr_t j = 0; j < guarded_fields_->length(); j++) {
+    if ((*guarded_fields_)[j]->raw() == field.raw()) {
+      return;
+    }
+  }
+  guarded_fields_->Add(&field);
+}
+
+
 void InlineExitCollector::PrepareGraphs(FlowGraph* callee_graph) {
   ASSERT(callee_graph->graph_entry()->SuccessorCount() == 1);
   ASSERT(callee_graph->max_block_id() > caller_graph_->max_block_id());
@@ -3039,6 +3055,17 @@
       node->field().Offset(),
       AbstractType::ZoneHandle(node->field().type()));
   load->set_field(&node->field());
+  if (owner()->exit_collector() != NULL) {
+    // While inlining into an optimized function, the field has
+    // to be added to the list of guarded fields of the caller.
+    if (node->field().guarded_cid() != kIllegalCid) {
+      if (!node->field().is_nullable() ||
+          (node->field().guarded_cid() == kNullCid)) {
+        load->set_result_cid(node->field().guarded_cid());
+      }
+      owner()->AddToGuardedFields(node->field());
+    }
+  }
   ReturnDefinition(load);
 }