Eliminate redundant array bound checks (checks already performed earlier in the DT).

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 222 matching lines @@
 
  private:
   void AddBlock(HBasicBlock* block);
 
   ZoneList<HBasicBlock*> back_edges_;
   HBasicBlock* loop_header_;
   ZoneList<HBasicBlock*> blocks_;
   HStackCheck* stack_check_;
 };
 
-
+class BoundsCheckTable;
 class HGraph: public ZoneObject {
  public:
   explicit HGraph(CompilationInfo* info);
 
   Isolate* isolate() { return isolate_; }
   Zone* zone() { return isolate_->zone(); }
 
   const ZoneList<HBasicBlock*>* blocks() const { return &blocks_; }
   const ZoneList<HPhi*>* phi_list() const { return phi_list_; }
   HBasicBlock* entry_block() const { return entry_block_; }
   HEnvironment* start_environment() const { return start_environment_; }
 
   void InitializeInferredTypes();
   void InsertTypeConversions();
   void InsertRepresentationChanges();
   void MarkDeoptimizeOnUndefined();
   void ComputeMinusZeroChecks();
   bool ProcessArgumentsObject();
   void EliminateRedundantPhis();
   void EliminateUnreachablePhis();
   void Canonicalize();
   void OrderBlocks();
   void AssignDominators();
   void ReplaceCheckedValues();
+  void EliminateRedundantBoundsChecks();
   void PropagateDeoptimizingMark();
 
   // 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();
 
@@ skipping 72 matching lines @@
   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);
   void InferTypes(ZoneList<HValue*>* worklist);
   void InitializeInferredTypes(int from_inclusive, int to_inclusive);
   void CheckForBackEdge(HBasicBlock* block, HBasicBlock* successor);
+  void EliminateRedundantBoundsChecks(HBasicBlock* bb, BoundsCheckTable* table);
 
   Isolate* isolate_;
   int next_block_id_;
   HBasicBlock* entry_block_;
   HEnvironment* start_environment_;
   ZoneList<HBasicBlock*> blocks_;
   ZoneList<HValue*> values_;
   ZoneList<HPhi*>* phi_list_;
   SetOncePointer<HConstant> undefined_constant_;
   SetOncePointer<HConstant> constant_1_;
@@ skipping 1004 matching lines @@
   const char* filename_;
   HeapStringAllocator string_allocator_;
   StringStream trace_;
   int indent_;
 };
 
 
 } }  // namespace v8::internal
 
 #endif  // V8_HYDROGEN_H_