Improve our simple elimination of hole checks.

src/hydrogen.cc

 // Copyright 2011 the V8 project authors. All rights reserved.
 // Redistribution and use in source and binary forms, with or without
 // modification, are permitted provided that the following conditions are
 // met:
 //
 //     * Redistributions of source code must retain the above copyright
 //       notice, this list of conditions and the following disclaimer.
 //     * Redistributions in binary form must reproduce the above
 //       copyright notice, this list of conditions and the following
 //       disclaimer in the documentation and/or other materials provided
@@ skipping 3150 matching lines @@
           LookupGlobalProperty(variable, &lookup, false);
 
       if (type == kUseCell &&
           info()->global_object()->IsAccessCheckNeeded()) {
         type = kUseGeneric;
       }
 
       if (type == kUseCell) {
         Handle<GlobalObject> global(info()->global_object());
         Handle<JSGlobalPropertyCell> cell(global->GetPropertyCell(&lookup));
-        bool check_hole = !lookup.IsDontDelete() || lookup.IsReadOnly();
-        HLoadGlobalCell* instr = new(zone()) HLoadGlobalCell(cell, check_hole);
+        bool deleteable_or_const =
+            !lookup.IsDontDelete() || lookup.IsReadOnly();
+        HLoadGlobalCell* instr =
+            new(zone()) HLoadGlobalCell(cell, deleteable_or_const);
         return ast_context()->ReturnInstruction(instr, expr->id());
       } else {
         HValue* context = environment()->LookupContext();
         HGlobalObject* global_object = new(zone()) HGlobalObject(context);
         AddInstruction(global_object);
         HLoadGlobalGeneric* instr =
             new(zone()) HLoadGlobalGeneric(context,
                                            global_object,
                                            variable->name(),
                                            ast_context()->is_for_typeof());
@@ skipping 440 matching lines @@
 // Because not every expression has a position and there is not common
 // superclass of Assignment and CountOperation, we cannot just pass the
 // owning expression instead of position and ast_id separately.
 void HGraphBuilder::HandleGlobalVariableAssignment(Variable* var,
                                                    HValue* value,
                                                    int position,
                                                    int ast_id) {
   LookupResult lookup;
   GlobalPropertyAccess type = LookupGlobalProperty(var, &lookup, true);
   if (type == kUseCell) {
-    bool check_hole = !lookup.IsDontDelete() || lookup.IsReadOnly();
+    bool deleteable_or_const = !lookup.IsDontDelete() || lookup.IsReadOnly();
     Handle<GlobalObject> global(info()->global_object());
     Handle<JSGlobalPropertyCell> cell(global->GetPropertyCell(&lookup));
-    HInstruction* instr = new(zone()) HStoreGlobalCell(value, cell, check_hole);
+    HInstruction* instr =
+        new(zone()) HStoreGlobalCell(value, cell, deleteable_or_const);
     instr->set_position(position);
     AddInstruction(instr);
     if (instr->HasSideEffects()) AddSimulate(ast_id);
   } else {
     HValue* context =  environment()->LookupContext();
     HGlobalObject* global_object = new(zone()) HGlobalObject(context);
     AddInstruction(global_object);
     HStoreGlobalGeneric* instr =
         new(zone()) HStoreGlobalGeneric(context,
                                         global_object,
@@ skipping 3252 matching lines @@
     }
   }
 
 #ifdef DEBUG
   if (graph_ != NULL) graph_->Verify(false);  // No full verify.
   if (allocator_ != NULL) allocator_->Verify();
 #endif
 }
 
 } }  // namespace v8::internal