Array bounds check elimination.

src/hydrogen.h

Index: src/hydrogen.h
diff --git a/src/hydrogen.h b/src/hydrogen.h
index 98b05d147a290d67e10cbe57daae8bc2f73b02ea..ca159f63337ecc018a7c55d85c58fd09ce541c6f 100644
--- a/src/hydrogen.h
+++ b/src/hydrogen.h
@@ -91,6 +91,8 @@ class HBasicBlock: public ZoneObject {
   void set_last_instruction_index(int index) {
     last_instruction_index_ = index;
   }
+  bool is_osr_entry() { return is_osr_entry_; }
+  void set_osr_entry() { is_osr_entry_ = true; }
 
   void AttachLoopInformation();
   void DetachLoopInformation();
@@ -193,6 +195,7 @@ class HBasicBlock: public ZoneObject {
   bool is_inline_return_target_;
   bool is_deoptimizing_;
   bool dominates_loop_successors_;
+  bool is_osr_entry_;
 };
 
 
@@ -225,6 +228,9 @@ class HLoopInformation: public ZoneObject {
   const ZoneList<HBasicBlock*>* back_edges() const { return &back_edges_; }
   const ZoneList<HBasicBlock*>* blocks() const { return &blocks_; }
   HBasicBlock* loop_header() const { return loop_header_; }
+  HBasicBlock* loop_pre_header() const {
+    return loop_header_->predecessors()->at(0);
+  }
   HBasicBlock* GetLastBackEdge() const;
   void RegisterBackEdge(HBasicBlock* block);
 
@@ -243,6 +249,8 @@ class HLoopInformation: public ZoneObject {
 };
 
 class BoundsCheckTable;
+class BoundsCheckValueInfoTable;
+class BoundsCheckRemovalBlockContext;
 class HGraph: public ZoneObject {
  public:
   explicit HGraph(CompilationInfo* info);
@@ -271,6 +279,7 @@ class HGraph: public ZoneObject {
   void AssignDominators();
   void ReplaceCheckedValues();
   void EliminateRedundantBoundsChecks();
+  void EliminateOrDehoistBoundsChecks();
   void DehoistSimpleArrayIndexComputations();
   void DeadCodeElimination();
   void PropagateDeoptimizingMark();
@@ -290,6 +299,7 @@ class HGraph: public ZoneObject {
     undefined_constant_.set(constant);
   }
   HConstant* GetConstantUndefined() const { return undefined_constant_.get(); }
+  HConstant* GetConstant0();
   HConstant* GetConstant1();
   HConstant* GetConstantMinus1();
   HConstant* GetConstantTrue();
@@ -388,7 +398,11 @@ class HGraph: public ZoneObject {
   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);
+  void EliminateRedundantBoundsChecks(HBasicBlock* bb,
+                                      BoundsCheckTable* table);
+  void EliminateOrDehoistBoundsChecks(
+      HBasicBlock* bb,
+      BoundsCheckRemovalBlockContext* previous_context);
 
   Isolate* isolate_;
   int next_block_id_;
@@ -399,6 +413,7 @@ class HGraph: public ZoneObject {
   ZoneList<HPhi*>* phi_list_;
   ZoneList<HInstruction*>* uint32_instructions_;
   SetOncePointer<HConstant> undefined_constant_;
+  SetOncePointer<HConstant> constant_0_;
   SetOncePointer<HConstant> constant_1_;
   SetOncePointer<HConstant> constant_minus1_;
   SetOncePointer<HConstant> constant_true_;