Fix uncommon GC related reload crash

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/code_generator.h"
 #include "vm/compiler.h"
 #include "vm/dart_api_impl.h"
@@ skipping 172 matching lines @@
       num_saved_libs_(-1),
       script_uri_(String::null()),
       error_(Error::null()),
       old_classes_set_storage_(Array::null()),
       class_map_storage_(Array::null()),
       old_libraries_set_storage_(Array::null()),
       library_map_storage_(Array::null()),
       become_map_storage_(Array::null()),
       saved_root_library_(Library::null()),
       saved_libraries_(GrowableObjectArray::null()) {
-  // Preallocate storage for maps.
-  old_classes_set_storage_ =
-      HashTables::New<UnorderedHashSet<ClassMapTraits> >(4);
-  class_map_storage_ =
-      HashTables::New<UnorderedHashMap<ClassMapTraits> >(4);
-  old_libraries_set_storage_ =
-      HashTables::New<UnorderedHashSet<LibraryMapTraits> >(4);
-  library_map_storage_ =
-      HashTables::New<UnorderedHashMap<LibraryMapTraits> >(4);
-  become_map_storage_ =
-      HashTables::New<UnorderedHashMap<BecomeMapTraits> >(4);
+  // NOTE: DO NOT ALLOCATE ANY RAW OBJECTS HERE. The IsolateReloadContext is not
+  // associated with the isolate yet and if a GC is triggered here the raw
+  // objects will not be properly accounted for.
 }
 
 
 IsolateReloadContext::~IsolateReloadContext() {
 }
 
 
 void IsolateReloadContext::ReportError(const Error& error) {
   has_error_ = true;
   error_ = error.raw();
@@ skipping 13 matching lines @@
 
 void IsolateReloadContext::ReportSuccess() {
   ServiceEvent service_event(I, ServiceEvent::kIsolateReload);
   Service::HandleEvent(&service_event);
 }
 
 
 void IsolateReloadContext::StartReload() {
   TIMELINE_SCOPE(Reload);
   Thread* thread = Thread::Current();
+  ASSERT(isolate() == thread->isolate());
 
   // Grab root library before calling CheckpointBeforeReload.
   const Library& root_lib = Library::Handle(object_store()->root_library());
   ASSERT(!root_lib.IsNull());
   const String& root_lib_url = String::Handle(root_lib.url());
 
+  // Preallocate storage for maps.
+  old_classes_set_storage_ =
+      HashTables::New<UnorderedHashSet<ClassMapTraits> >(4);
+  class_map_storage_ =
+      HashTables::New<UnorderedHashMap<ClassMapTraits> >(4);
+  old_libraries_set_storage_ =
+      HashTables::New<UnorderedHashSet<LibraryMapTraits> >(4);
+  library_map_storage_ =
+      HashTables::New<UnorderedHashMap<LibraryMapTraits> >(4);
+  become_map_storage_ =
+      HashTables::New<UnorderedHashMap<BecomeMapTraits> >(4);
+
   // Disable the background compiler while we are performing the reload.
   BackgroundCompiler::Disable();
 
   if (FLAG_write_protect_code) {
     // Disable code page write protection while we are reloading.
     I->heap()->WriteProtectCode(false);
   }
 
   // Ensure all functions on the stack have unoptimized code.
   EnsuredUnoptimizedCodeForStack();
@@ skipping 817 matching lines @@
         ASSERT(!super_cls.IsNull());
         super_cls.AddDirectSubclass(cls);
       }
     }
   }
 }
 
 #endif  // !PRODUCT
 
 }  // namespace dart