Reland "Recognize and optimize a.runtimeType == b.runtimeType pattern."

runtime/vm/isolate.h

 // Copyright (c) 2013, 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.
 
 #ifndef RUNTIME_VM_ISOLATE_H_
 #define RUNTIME_VM_ISOLATE_H_
 
 #include "include/dart_api.h"
 #include "platform/assert.h"
 #include "vm/atomic.h"
@@ skipping 206 matching lines @@
   }
   uint64_t terminate_capability() const { return terminate_capability_; }
 
   void SendInternalLibMessage(LibMsgId msg_id, uint64_t capability);
 
   Heap* heap() const { return heap_; }
   void set_heap(Heap* value) { heap_ = value; }
 
   ObjectStore* object_store() const { return object_store_; }
   void set_object_store(ObjectStore* value) { object_store_ = value; }
+  static intptr_t object_store_offset() {
+    return OFFSET_OF(Isolate, object_store_);
+  }
 
   ApiState* api_state() const { return api_state_; }
   void set_api_state(ApiState* value) { api_state_ = value; }
 
   void set_init_callback_data(void* value) {
     init_callback_data_ = value;
   }
   void* init_callback_data() const {
     return init_callback_data_;
   }
@@ skipping 489 matching lines @@
     return mutator_thread()->zone();
   }
 
   // Accessed from generated code:
   StoreBuffer* store_buffer_;
   Heap* heap_;
   uword user_tag_;
   RawUserTag* current_tag_;
   RawUserTag* default_tag_;
   RawCode* ic_miss_code_;
+  ObjectStore* object_store_;
+
+  // Note: ClassTable has different size between PRODUCT and non-product builds.

[rmacnak, 2016/10/31 20:23:30]

We don't care if product/release/debug have different field offsets. For this
and other reasons, snapshots generated in one of these modes can only run on a
VM of the same mode. The snapshot reader checks they match and issues a specific
error message.

We do care that SIMARM and XARM agree on the field offsets, which I suspect is
what you encountered. Probably from all the bool fields that were above
object_store, which ARM prefers to word align and Intel prefers to pack.

Please add Isolate::object_store_offset() to CheckOffsets in dart.cc

+  // This means precompiled code cannot reference anything below ClassTable
+  // from the precompiled code because offsets will be different.
   ClassTable class_table_;
   bool single_step_;
   bool skip_step_;  // skip the next single step.
 
   ThreadRegistry* thread_registry_;
   SafepointHandler* safepoint_handler_;
   Dart_MessageNotifyCallback message_notify_callback_;
   char* name_;
   char* debugger_name_;
   int64_t start_time_;
   Dart_Port main_port_;
   Dart_Port origin_id_;  // Isolates created by spawnFunc have some origin id.
   uint64_t pause_capability_;
   uint64_t terminate_capability_;
   bool errors_fatal_;
-  ObjectStore* object_store_;
   uword top_exit_frame_info_;
   void* init_callback_data_;
   Dart_EnvironmentCallback environment_callback_;
   Dart_LibraryTagHandler library_tag_handler_;
   ApiState* api_state_;
   Debugger* debugger_;
   bool resume_request_;
   int64_t last_resume_timestamp_;
   bool has_compiled_code_;  // Can check that no compilation occured.
   Random random_;
@@ skipping 261 matching lines @@
   intptr_t* spawn_count_;
 
   Dart_IsolateFlags isolate_flags_;
   bool paused_;
   bool errors_are_fatal_;
 };
 
 }  // namespace dart
 
 #endif  // RUNTIME_VM_ISOLATE_H_