Eliminate map checks of constant values.

src/hydrogen-instructions.h

 // Copyright 2012 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 2714 matching lines @@
   virtual bool DataEquals(HValue* other) { return true; }
 
  private:
   virtual bool IsDeletable() const { return true; }
 };
 
 
 class HCheckMaps: public HTemplateInstruction<2> {
  public:
   static HCheckMaps* New(HValue* value, Handle<Map> map, Zone* zone,
-                         HValue *typecheck = NULL) {
-    HCheckMaps* check_map = new(zone) HCheckMaps(value, zone, typecheck);
-    check_map->map_set_.Add(map, zone);
-    return check_map;
-  }
-
+                         CompilationInfo* info, HValue *typecheck = NULL);
   static HCheckMaps* New(HValue* value, SmallMapList* maps, Zone* zone,
                          HValue *typecheck = NULL) {
     HCheckMaps* check_map = new(zone) HCheckMaps(value, zone, typecheck);
     for (int i = 0; i < maps->length(); i++) {
       check_map->map_set_.Add(maps->at(i), zone);
     }
     check_map->map_set_.Sort();
     return check_map;
   }
 
@@ skipping 13 matching lines @@
       Map* transitioned_map =
           map->LookupElementsTransitionMap(kind);
       if (transitioned_map) {
         check_map->map_set_.Add(Handle<Map>(transitioned_map), zone);
       }
     };
     check_map->map_set_.Sort();
     return check_map;
   }
 
+  bool CanOmitMapChecks() { return omit_; }
+
   virtual bool HasEscapingOperandAt(int index) { return false; }
   virtual Representation RequiredInputRepresentation(int index) {
     return Representation::Tagged();
   }
   virtual void HandleSideEffectDominator(GVNFlag side_effect,
                                          HValue* dominator);
   virtual void PrintDataTo(StringStream* stream);
   virtual HType CalculateInferredType();
 
   HValue* value() { return OperandAt(0); }
@@ skipping 15 matching lines @@
       if (map_unique_ids_.at(i) != b->map_unique_ids_.at(i)) {
         return false;
       }
     }
     return true;
   }
 
  private:
   // Clients should use one of the static New* methods above.
   HCheckMaps(HValue* value, Zone *zone, HValue* typecheck)
-      : map_unique_ids_(0, zone) {
+      : omit_(false), map_unique_ids_(0, zone) {
     SetOperandAt(0, value);
     // Use the object value for the dependency if NULL is passed.
     // TODO(titzer): do GVN flags already express this dependency?
     SetOperandAt(1, typecheck != NULL ? typecheck : value);
     set_representation(Representation::Tagged());
     SetFlag(kUseGVN);
     SetFlag(kTrackSideEffectDominators);
     SetGVNFlag(kDependsOnMaps);
     SetGVNFlag(kDependsOnElementsKind);
   }
 
+  void omit(CompilationInfo* info) {
+    omit_ = true;
+    for (int i = 0; i < map_set_.length(); i++) {
+      Handle<Map> map = map_set_.at(i);
+      map->AddDependentCompilationInfo(DependentCode::kPrototypeCheckGroup,
+                                       info);
+    }
+  }
+
+  bool omit_;
   SmallMapList map_set_;
   ZoneList<UniqueValueId> map_unique_ids_;
 };
 
 
 class HCheckFunction: public HUnaryOperation {
  public:
   HCheckFunction(HValue* value, Handle<JSFunction> function)
       : HUnaryOperation(value), target_(function), target_unique_id_() {
     set_representation(Representation::Tagged());
@@ skipping 458 matching lines @@
       Factory* factory = Isolate::Current()->factory();
       // Default arguments to is_not_in_new_space depend on this heap number
       // to be tenured so that it's guaranteed not be be located in new space.
       handle_ = factory->NewNumber(double_value_, TENURED);
     }
     AllowDeferredHandleDereference smi_check;
     ASSERT(has_int32_value_ || !handle_->IsSmi());
     return handle_;
   }
 
+  bool InstanceOf(Handle<Map> map) {
+    return handle_->IsJSObject() &&
+        Handle<JSObject>::cast(handle_)->map() == *map;
+  }
+
   bool IsSpecialDouble() const {
     return has_double_value_ &&
         (BitCast<int64_t>(double_value_) == BitCast<int64_t>(-0.0) ||
          FixedDoubleArray::is_the_hole_nan(double_value_) ||
          std::isnan(double_value_));
   }
 
   bool NotInNewSpace() const {
     return is_not_in_new_space_;
   }
@@ skipping 3385 matching lines @@
   virtual bool IsDeletable() const { return true; }
 };
 
 
 #undef DECLARE_INSTRUCTION
 #undef DECLARE_CONCRETE_INSTRUCTION
 
 } }  // namespace v8::internal
 
 #endif  // V8_HYDROGEN_INSTRUCTIONS_H_