Skip the mapcheck on the global object since the global proxy and cell are already checked (or the …

src/ic/x64/handler-compiler-x64.cc

 // Copyright 2014 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"
 
 #if V8_TARGET_ARCH_X64
 
 #include "src/ic/call-optimization.h"
 #include "src/ic/handler-compiler.h"
@@ skipping 459 matching lines @@
       GenerateDictionaryNegativeLookup(masm(), miss, reg, name, scratch1,
                                        scratch2);
 
       __ movp(scratch1, FieldOperand(reg, HeapObject::kMapOffset));
       reg = holder_reg;  // From now on the object will be in holder_reg.
       __ movp(reg, FieldOperand(scratch1, Map::kPrototypeOffset));
     } else {
       Register map_reg = scratch1;
       __ movp(map_reg, FieldOperand(reg, HeapObject::kMapOffset));
 
-      if (depth != 1 || check == CHECK_ALL_MAPS) {
+      if (current_map->IsJSGlobalObjectMap()) {
+        GenerateCheckPropertyCell(masm(), Handle<JSGlobalObject>::cast(current),
+                                  name, scratch2, miss);
+      } else if (depth != 1 || check == CHECK_ALL_MAPS) {
         Handle<WeakCell> cell = Map::WeakCellForMap(current_map);
         __ CmpWeakValue(map_reg, cell, scratch2);
         __ j(not_equal, miss);
       }
 
-      if (current_map->IsJSGlobalObjectMap()) {
-        GenerateCheckPropertyCell(masm(), Handle<JSGlobalObject>::cast(current),
-                                  name, scratch2, miss);
-      }
       reg = holder_reg;  // From now on the object will be in holder_reg.
 
       __ movp(reg, FieldOperand(map_reg, Map::kPrototypeOffset));
     }
 
     // Go to the next object in the prototype chain.
     current = prototype;
     current_map = handle(current->map());
   }
 
+  DCHECK(!current_map->IsJSGlobalProxyMap());
+
   // Log the check depth.
   LOG(isolate(), IntEvent("check-maps-depth", depth + 1));
 
   if (depth != 0 || check == CHECK_ALL_MAPS) {
     __ movp(scratch1, FieldOperand(reg, HeapObject::kMapOffset));
     Handle<WeakCell> cell = Map::WeakCellForMap(current_map);
     __ CmpWeakValue(scratch1, cell, scratch2);
     __ j(not_equal, miss);
   }
 
@@ skipping 249 matching lines @@
   // Return the generated code.
   return GetCode(kind(), Code::NORMAL, name);
 }
 
 
 #undef __
 }
 }  // namespace v8::internal
 
 #endif  // V8_TARGET_ARCH_X64