VM: Correctly intrinsify implicit getters/setters when using field guards

runtime/vm/flow_graph_compiler.cc

Index: runtime/vm/flow_graph_compiler.cc
diff --git a/runtime/vm/flow_graph_compiler.cc b/runtime/vm/flow_graph_compiler.cc
index 34a6eec06d2cb94f5c953db25157e55609ee4048..2453fbe08eb8111894c1571b1f8c9bd43bb91b9b 100644
--- a/runtime/vm/flow_graph_compiler.cc
+++ b/runtime/vm/flow_graph_compiler.cc
@@ -1082,7 +1082,12 @@ void FlowGraphCompiler::FinalizeStaticCallTargetsTable(const Code& code) {
 bool FlowGraphCompiler::TryIntrinsify() {
   // Intrinsification skips arguments checks, therefore disable if in checked
   // mode.
-  if (FLAG_intrinsify && !isolate()->flags().type_checks()) {
+  // Only intrinsify getters/setters in precompiled code. Otherwise, unoptimized
+  // code cannot depend on guarded_cid since it may be regenerated lazily after
+  // code collection.
+  if (FLAG_precompilation &&

[Vyacheslav Egorov (Google), 2016/02/12 14:20:42]

FLAG_precompilation -> !FLAG_use_field_guards?

+      FLAG_intrinsify &&
+      !isolate()->flags().type_checks()) {
     if (parsed_function().function().kind() == RawFunction::kImplicitGetter) {
       // An implicit getter must have a specific AST structure.
       const SequenceNode& sequence_node = *parsed_function().node_sequence();