In background compilation make a copy of Field in order to freeze its state

runtime/vm/assembler_mips.cc

 // 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.
 
 #include "vm/globals.h"  // NOLINT
 #if defined(TARGET_ARCH_MIPS)
 
 #include "vm/assembler.h"
 #include "vm/longjump.h"
 #include "vm/runtime_entry.h"
@@ skipping 530 matching lines @@
       object_pool_wrapper_.FindObject(target, equivalence));
   LoadWordFromPoolOffset(CODE_REG, offset - kHeapObjectTag);
   lw(T9, FieldAddress(CODE_REG, Code::entry_point_offset()));
   jalr(T9);
   delay_slot_available_ = false;  // CodePatcher expects a nop.
 }
 
 
 bool Assembler::CanLoadFromObjectPool(const Object& object) const {
   ASSERT(!object.IsICData() || ICData::Cast(object).IsOriginal());
+  ASSERT(!object.IsField() || Field::Cast(object).IsOriginal());
   ASSERT(!Thread::CanLoadFromThread(object));
   if (!constant_pool_allowed()) {
     return false;
   }
 
   ASSERT(object.IsNotTemporaryScopedHandle());
   ASSERT(object.IsOld());
   return true;
 }
 
 
 void Assembler::LoadObjectHelper(Register rd,
                                  const Object& object,
                                  bool is_unique) {
   ASSERT(!object.IsICData() || ICData::Cast(object).IsOriginal());
+  ASSERT(!object.IsField() || Field::Cast(object).IsOriginal());
   ASSERT(!in_delay_slot_);
   if (Thread::CanLoadFromThread(object)) {
     // Load common VM constants from the thread. This works also in places where
     // no constant pool is set up (e.g. intrinsic code).
     lw(rd, Address(THR, Thread::OffsetFromThread(object)));
   } else if (object.IsSmi()) {
     // Relocation doesn't apply to Smis.
     LoadImmediate(rd, reinterpret_cast<int32_t>(object.raw()));
   } else if (CanLoadFromObjectPool(object)) {
     // Make sure that class CallPattern is able to decode this load from the
@@ skipping 38 matching lines @@
                                 const ExternalLabel* label,
                                 Patchability patchable) {
   const int32_t offset = ObjectPool::element_offset(
       object_pool_wrapper_.FindNativeEntry(label, patchable));
   LoadWordFromPoolOffset(rd, offset - kHeapObjectTag);
 }
 
 
 void Assembler::PushObject(const Object& object) {
   ASSERT(!object.IsICData() || ICData::Cast(object).IsOriginal());
+  ASSERT(!object.IsField() || Field::Cast(object).IsOriginal());
   ASSERT(!in_delay_slot_);
   LoadObject(TMP, object);
   Push(TMP);
 }
 
 
 // Preserves object and value registers.
 void Assembler::StoreIntoObjectFilterNoSmi(Register object,
                                            Register value,
                                            Label* no_update) {
@@ skipping 107 matching lines @@
     AddImmediate(TMP, object, offset - kHeapObjectTag);
     StoreIntoObjectNoBarrier(object, Address(TMP), value);
   }
 }
 
 
 void Assembler::StoreIntoObjectNoBarrier(Register object,
                                          const Address& dest,
                                          const Object& value) {
   ASSERT(!value.IsICData() || ICData::Cast(value).IsOriginal());
+  ASSERT(!value.IsField() || Field::Cast(value).IsOriginal());
   ASSERT(!in_delay_slot_);
   ASSERT(value.IsSmi() || value.InVMHeap() ||
          (value.IsOld() && value.IsNotTemporaryScopedHandle()));
   // No store buffer update.
   LoadObject(TMP, value);
   sw(TMP, dest);
 }
 
 
 void Assembler::StoreIntoObjectNoBarrierOffset(Register object,
@@ skipping 590 matching lines @@
   Label stop;
   b(&stop);
   Emit(reinterpret_cast<int32_t>(message));
   Bind(&stop);
   break_(Instr::kStopMessageCode);
 }
 
 }  // namespace dart
 
 #endif  // defined TARGET_ARCH_MIPS