Background compiler should validate CHA decisions before committing the code.

runtime/vm/compiler.cc

 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 #include "vm/compiler.h"
 
 #include "vm/assembler.h"
 
 #include "vm/ast_printer.h"
 #include "vm/block_scheduler.h"
@@ skipping 595 matching lines @@
          }
         }
       }
       if (loading_invalidation_gen_at_start() !=
           isolate()->loading_invalidation_gen()) {
         code_is_valid = false;
         if (trace_compiler) {
           THR_Print("--> FAIL: Loading invalidation.");
         }
       }
+      if (!thread()->cha()->IsConsistentWithCurrentHierarchy()) {
+        code_is_valid = false;
+        if (trace_compiler) {
+          THR_Print("--> FAIL: Class hierarchy has new subclasses.");
+        }
+      }
+
       // Setting breakpoints at runtime could make a function non-optimizable.
       if (code_is_valid && Compiler::CanOptimizeFunction(thread(), function)) {
         const bool is_osr = osr_id() != Compiler::kNoOSRDeoptId;
         ASSERT(!is_osr);  // OSR is not compiled in background.
         function.InstallOptimizedCode(code, is_osr);
         code_was_installed = true;
       }
       if (function.usage_counter() < 0) {
         // Reset to 0 so that it can be recompiled if needed.
         if (code_is_valid) {
           function.set_usage_counter(0);
         } else {
           // Trigger another optimization pass soon.
           function.set_usage_counter(FLAG_optimization_counter_threshold - 100);
         }
       }
     }
 
     if (code_was_installed) {
-      // Register code with the classes it depends on because of CHA and
-      // fields it depends on because of store guards, unless we cannot
-      // deopt.
-      for (intptr_t i = 0;
-           i < thread()->cha()->leaf_classes().length();
-           ++i) {
-        thread()->cha()->leaf_classes()[i]->RegisterCHACode(code);
-      }
+      // The generated code was compiled under certain assumptions about
+      // class hierarchy and field types. Register these dependencies
+      // to ensure that the code will be deoptimized if they are violated.
+      thread()->cha()->RegisterDependencies(code);
+
       const ZoneGrowableArray<const Field*>& guarded_fields =
           *flow_graph->parsed_function().guarded_fields();
       for (intptr_t i = 0; i < guarded_fields.length(); i++) {
         const Field* field = guarded_fields[i];
         field->RegisterDependentCode(code);
       }
     }
   } else {  // not optimized.
     if (function.ic_data_array() == Array::null()) {
       function.SaveICDataMap(
@@ skipping 1528 matching lines @@
 
 
 bool BackgroundCompiler::IsDisabled() {
   UNREACHABLE();
   return true;
 }
 
 #endif  // DART_PRECOMPILED_RUNTIME
 
 }  // namespace dart