Add --hot-reload-rollback test mode

runtime/vm/isolate_reload.cc

 // Copyright (c) 2016, 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/isolate_reload.h"
 
 #include "vm/become.h"
 #include "vm/bit_vector.h"
 #include "vm/code_generator.h"
 #include "vm/compiler.h"
@@ skipping 14 matching lines @@
 namespace dart {
 
 DEFINE_FLAG(bool, trace_reload, false, "Trace isolate reloading");
 DEFINE_FLAG(bool, trace_reload_verbose, false,
             "trace isolate reloading verbose");
 DEFINE_FLAG(bool, identity_reload, false, "Enable checks for identity reload.");
 DEFINE_FLAG(int, reload_every, 0, "Reload every N stack overflow checks.");
 DEFINE_FLAG(bool, reload_every_optimized, true, "Only from optimized code.");
 DEFINE_FLAG(bool, reload_every_back_off, false,
             "Double the --reload-every value after each reload.");
+DEFINE_FLAG(bool, reload_force_rollback, false,
+            "Force all reloads to fail and rollback.");
 DEFINE_FLAG(bool, check_reloaded, false,
             "Assert that an isolate has reloaded at least once.")
 #ifndef PRODUCT
 
 #define I (isolate())
 #define Z (thread->zone())
 
 #define TIMELINE_SCOPE(name)                                                   \
     TimelineDurationScope tds##name(Thread::Current(),                         \
                                    Timeline::GetIsolateStream(),               \
@@ skipping 1053 matching lines @@
 }
 
 
 void IsolateReloadContext::AddInstanceMorpher(InstanceMorpher* morpher) {
   instance_morphers_.Add(morpher);
   cid_mapper_.Insert(morpher);
 }
 
 
 void IsolateReloadContext::ReportReasonsForCancelling() {
-  ASSERT(HasReasonsForCancelling());
+  ASSERT(FLAG_reload_force_rollback || HasReasonsForCancelling());
   for (int i = 0; i < reasons_to_cancel_reload_.length(); i++) {
     reasons_to_cancel_reload_.At(i)->Report(this);
   }
 }
 
 
 // The ObjectLocator is used for collecting instances that
 // needs to be morphed.
 class ObjectLocator : public ObjectVisitor {
  public:
@@ skipping 106 matching lines @@
       const intptr_t entry = it.Current();
       new_cls = Class::RawCast(map.GetKey(entry));
       cls = Class::RawCast(map.GetPayload(entry, 0));
       if (new_cls.raw() != cls.raw()) {
         cls.CheckReload(new_cls, this);
       }
     }
     map.Release();
   }
 
-  return !HasReasonsForCancelling();
+  return !FLAG_reload_force_rollback && !HasReasonsForCancelling();
 }
 
 
 RawClass* IsolateReloadContext::FindOriginalClass(const Class& cls) {
   return MappedClass(cls);
 }
 
 
 RawClass* IsolateReloadContext::GetClassForHeapWalkAt(intptr_t cid) {
   if (saved_class_table_ != NULL) {
@@ skipping 327 matching lines @@
         ASSERT(!super_cls.IsNull());
         super_cls.AddDirectSubclass(cls);
       }
     }
   }
 }
 
 #endif  // !PRODUCT
 
 }  // namespace dart