Allow removal of obsolete map checks after transitions.

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 175 matching lines @@
   V(UseConst)                                  \
   V(ValueOf)                                   \
   V(ForInPrepareMap)                           \
   V(ForInCacheArray)                           \
   V(CheckMapValue)                             \
   V(LoadFieldByIndex)                          \
   V(DateField)                                 \
   V(WrapReceiver)
 
 #define GVN_TRACKED_FLAG_LIST(V)               \
+  V(Maps)                                      \
   V(NewSpacePromotion)
 
 #define GVN_UNTRACKED_FLAG_LIST(V)             \
   V(Calls)                                     \
   V(InobjectFields)                            \
   V(BackingStoreFields)                        \
   V(ElementsKind)                              \
   V(ElementsPointer)                           \
   V(ArrayElements)                             \
   V(DoubleArrayElements)                       \
   V(SpecializedArrayElements)                  \
   V(GlobalVars)                                \
-  V(Maps)                                      \
   V(ArrayLengths)                              \
   V(ContextSlots)                              \
   V(OsrEntries)
 
 #define DECLARE_ABSTRACT_INSTRUCTION(type)          \
   virtual bool Is##type() const { return true; }    \
   static H##type* cast(HValue* value) {             \
     ASSERT(value->Is##type());                      \
     return reinterpret_cast<H##type*>(value);       \
   }
@@ skipping 2022 matching lines @@
 class HCheckMaps: public HTemplateInstruction<2> {
  public:
   HCheckMaps(HValue* value, Handle<Map> map, Zone* zone,
              HValue* typecheck = NULL) {
     SetOperandAt(0, value);
     // If callers don't depend on a typecheck, they can pass in NULL. In that
     // case we use a copy of the |value| argument as a dummy value.
     SetOperandAt(1, typecheck != NULL ? typecheck : value);
     set_representation(Representation::Tagged());
     SetFlag(kUseGVN);
+    SetFlag(kTrackSideEffectDominators);
     SetGVNFlag(kDependsOnMaps);
     SetGVNFlag(kDependsOnElementsKind);
     map_set()->Add(map, zone);
   }
   HCheckMaps(HValue* value, SmallMapList* maps, Zone* zone) {
     SetOperandAt(0, value);
     SetOperandAt(1, value);
     set_representation(Representation::Tagged());
     SetFlag(kUseGVN);
+    SetFlag(kTrackSideEffectDominators);
     SetGVNFlag(kDependsOnMaps);
     SetGVNFlag(kDependsOnElementsKind);
     for (int i = 0; i < maps->length(); i++) {
       map_set()->Add(maps->at(i), zone);
     }
     map_set()->Sort();
   }
 
   static HCheckMaps* NewWithTransitions(HValue* object, Handle<Map> map,
                                         Zone* zone) {
@@ skipping 14 matching lines @@
         map_set->Add(Handle<Map>(transitioned_map), zone);
       }
     };
     map_set->Sort();
     return check_map;
   }
 
   virtual Representation RequiredInputRepresentation(int index) {
     return Representation::Tagged();
   }
-
+  virtual void SetSideEffectDominator(GVNFlag side_effect, HValue* dominator);
   virtual void PrintDataTo(StringStream* stream);
   virtual HType CalculateInferredType();
 
   HValue* value() { return OperandAt(0); }
   SmallMapList* map_set() { return &map_set_; }
 
   DECLARE_CONCRETE_INSTRUCTION(CheckMaps)
 
  protected:
   virtual bool DataEquals(HValue* other) {
@@ skipping 3198 matching lines @@
   virtual bool IsDeletable() const { return true; }
 };
 
 
 #undef DECLARE_INSTRUCTION
 #undef DECLARE_CONCRETE_INSTRUCTION
 
 } }  // namespace v8::internal
 
 #endif  // V8_HYDROGEN_INSTRUCTIONS_H_