Add map-based read barrier to WeakCell

src/hydrogen.cc

 // Copyright 2013 the V8 project authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "src/hydrogen.h"
 
 #include <sstream>
 
 #include "src/v8.h"
 
@@ skipping 3050 matching lines @@
     if (type->NumClasses() == 1) {
       BuildCheckHeapObject(value);
       // For ICs, the map checked below is a sentinel map that gets replaced by
       // the monomorphic map when the code is used as a template to generate a
       // new IC. For optimized functions, there is no sentinel map, the map
       // emitted below is the actual monomorphic map.
       if (map_embedding == kEmbedMapsViaWeakCells) {
         HValue* cell =
             Add<HConstant>(Map::WeakCellForMap(type->Classes().Current()));
         HValue* expected_map = Add<HLoadNamedField>(
-            cell, nullptr, HObjectAccess::ForWeakCellValue());
+            cell, nullptr, HObjectAccess::ForWeakCellValueComparison());
         HValue* map =
             Add<HLoadNamedField>(value, nullptr, HObjectAccess::ForMap());
         IfBuilder map_check(this);
         map_check.IfNot<HCompareObjectEqAndBranch>(expected_map, map);
         map_check.ThenDeopt(Deoptimizer::kUnknownMap);
         map_check.End();
       } else {
         DCHECK(map_embedding == kEmbedMapsDirectly);
         Add<HCheckMaps>(value, type->Classes().Current());
       }
@@ skipping 10406 matching lines @@
   if (ShouldProduceTraceOutput()) {
     isolate()->GetHTracer()->TraceHydrogen(name(), graph_);
   }
 
 #ifdef DEBUG
   graph_->Verify(false);  // No full verify.
 #endif
 }
 
 } }  // namespace v8::internal