New array bounds check elimination pass (focused on induction variables and bitwise operations).

src/hydrogen.h

Index: src/hydrogen.h
diff --git a/src/hydrogen.h b/src/hydrogen.h
index f1962fe1c4fb06d4bfb2bcef13cdb72dbb90e201..44166befe3d5cf3f7073e046eaffdd5aa53704ab 100644
--- a/src/hydrogen.h
+++ b/src/hydrogen.h
@@ -69,6 +69,11 @@ class HBasicBlock: public ZoneObject {
   void set_last(HInstruction* instr) { last_ = instr; }
   HControlInstruction* end() const { return end_; }
   HLoopInformation* loop_information() const { return loop_information_; }
+  HLoopInformation* current_loop() const {
+    return IsLoopHeader() ? loop_information()
+                          : (parent_loop_header() != NULL
+                            ? parent_loop_header()->loop_information() : NULL);
+  }
   const ZoneList<HBasicBlock*>* predecessors() const { return &predecessors_; }
   bool HasPredecessor() const { return predecessors_.length() > 0; }
   const ZoneList<HBasicBlock*>* dominated_blocks() const {
@@ -271,6 +276,20 @@ class HLoopInformation: public ZoneObject {
     stack_check_ = stack_check;
   }
 
+  bool IsNestedInThisLoop(HLoopInformation* other) {
+    while (other != NULL) {
+      if (other == this) {
+        return true;
+      }
+      other = other->parent_loop();
+    }
+    return false;
+  }
+  HLoopInformation* parent_loop() {
+    HBasicBlock* parent_header = loop_header()->parent_loop_header();
+    return parent_header != NULL ? parent_header->loop_information() : NULL;
+  }
+
  private:
   void AddBlock(HBasicBlock* block);
 
@@ -282,6 +301,7 @@ class HLoopInformation: public ZoneObject {
 
 
 class BoundsCheckTable;
+class InductionVariableBlocksTable;
 class HGraph: public ZoneObject {
  public:
   explicit HGraph(CompilationInfo* info);
@@ -448,6 +468,7 @@ class HGraph: public ZoneObject {
   void CheckForBackEdge(HBasicBlock* block, HBasicBlock* successor);
   void SetupInformativeDefinitionsInBlock(HBasicBlock* block);
   void SetupInformativeDefinitionsRecursively(HBasicBlock* block);
+  void EliminateRedundantBoundsChecksUsingInductionVariables();
 
   Isolate* isolate_;
   int next_block_id_;