Improve dead code elimination by transitively marking live code and removing all dead code. Replace…

src/hydrogen.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 259 matching lines @@
   void InitializeInferredTypes();
   void InsertTypeConversions();
   void MergeRemovableSimulates();
   void InsertRepresentationChanges();
   void MarkDeoptimizeOnUndefined();
   void ComputeMinusZeroChecks();
   void ComputeSafeUint32Operations();
   void GlobalValueNumbering();
   bool ProcessArgumentsObject();
   void EliminateRedundantPhis();
-  void EliminateUnreachablePhis();
   void Canonicalize();
   void OrderBlocks();
   void AssignDominators();
   void SetupInformativeDefinitions();
   void EliminateRedundantBoundsChecks();
   void DehoistSimpleArrayIndexComputations();
-  void DeadCodeElimination();
   void RestoreActualValues();
+  void DeadCodeElimination(const char *phase_name);
   void PropagateDeoptimizingMark();
-  void EliminateUnusedInstructions();
 
   // Returns false if there are phi-uses of the arguments-object
   // which are not supported by the optimizing compiler.
   bool CheckArgumentsPhiUses();
 
   // Returns false if there are phi-uses of an uninitialized const
   // which are not supported by the optimizing compiler.
   bool CheckConstPhiUses();
 
   void CollectPhis();
@@ skipping 94 matching lines @@
     }
     uint32_instructions_->Add(instr, zone());
   }
 
  private:
   HConstant* GetConstantInt32(SetOncePointer<HConstant>* pointer,
                               int32_t integer_value);
   HConstant* GetConstantSmi(SetOncePointer<HConstant>* pointer,
                             int32_t integer_value);
 
+  void MarkLive(HValue* ref, HValue* instr, ZoneList<HValue*>* worklist);
+  void MarkLiveInstructions();
+  void RemoveDeadInstructions();
   void MarkAsDeoptimizingRecursively(HBasicBlock* block);
   void NullifyUnreachableInstructions();
   void InsertTypeConversions(HInstruction* instr);
   void PropagateMinusZeroChecks(HValue* value, BitVector* visited);
   void RecursivelyMarkPhiDeoptimizeOnUndefined(HPhi* phi);
   void InsertRepresentationChangeForUse(HValue* value,
                                         HValue* use_value,
                                         int use_index,
                                         Representation to);
   void InsertRepresentationChangesForValue(HValue* value);
@@ skipping 1598 matching lines @@
   EmbeddedVector<char, 64> filename_;
   HeapStringAllocator string_allocator_;
   StringStream trace_;
   int indent_;
 };
 
 
 } }  // namespace v8::internal
 
 #endif  // V8_HYDROGEN_H_