Fetch global object from jsproxy prototype instead of embedding it in StoreGlobal.

src/code-stubs-hydrogen.cc

 // Copyright 2012 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/v8.h"
 
 #include "src/bailout-reason.h"
 #include "src/code-stubs.h"
 #include "src/field-index.h"
 #include "src/hydrogen.h"
@@ skipping 1295 matching lines @@
   return DoGenerateCode(this);
 }
 
 
 template <>
 HValue* CodeStubGraphBuilder<StoreGlobalStub>::BuildCodeInitializedStub() {
   StoreGlobalStub* stub = casted_stub();
   Handle<Object> placeholer_value(Smi::FromInt(0), isolate());
   Handle<PropertyCell> placeholder_cell =
       isolate()->factory()->NewPropertyCell(placeholer_value);
-
   HParameter* value = GetParameter(StoreDescriptor::kValueIndex);
-
   if (stub->check_global()) {
     // Check that the map of the global has not changed: use a placeholder map
     // that will be replaced later with the global object's map.
+    HParameter* proxy = GetParameter(StoreDescriptor::kReceiverIndex);
+    HValue* proxy_map =
+        Add<HLoadNamedField>(proxy, nullptr, HObjectAccess::ForMap());
+    HValue* global =
+        Add<HLoadNamedField>(proxy_map, nullptr, HObjectAccess::ForPrototype());
     Handle<Map> placeholder_map = isolate()->factory()->meta_map();
-    HValue* global = Add<HConstant>(
-        StoreGlobalStub::global_placeholder(isolate()));
-    Add<HCheckMaps>(global, placeholder_map);
+    HValue* cell = Add<HConstant>(Map::WeakCellForMap(placeholder_map));
+    HValue* expected_map =
+        Add<HLoadNamedField>(cell, nullptr, HObjectAccess::ForWeakCellValue());
+    HValue* map =
+        Add<HLoadNamedField>(global, nullptr, HObjectAccess::ForMap());
+    IfBuilder map_check(this);
+    map_check.IfNot<HCompareObjectEqAndBranch>(expected_map, map);
+    map_check.ThenDeopt("Unknown map");
+    map_check.End();
   }
 
   HValue* cell = Add<HConstant>(placeholder_cell);
   HObjectAccess access(HObjectAccess::ForCellPayload(isolate()));
   HValue* cell_contents = Add<HLoadNamedField>(cell, nullptr, access);
 
   if (stub->is_constant()) {
     IfBuilder builder(this);
     builder.If<HCompareObjectEqAndBranch>(cell_contents, value);
     builder.Then();
@@ skipping 880 matching lines @@
   // megamorphic case is handled as part of the default stub.
   DCHECK(!FLAG_vector_ics);
 
   // Probe the stub cache.
   Add<HTailCallThroughMegamorphicCache>(receiver, name);
 
   // We never continue.
   return graph()->GetConstant0();
 }
 } }  // namespace v8::internal