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

src/hydrogen-bce.cc

 // Copyright 2013 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 171 matching lines @@
                                      new_offset);
         if (!result) return false;
         lower_check_->ReplaceAllUsesWith(lower_check_->index());
         lower_check_->SetOperandAt(0, added_lower_index_);
       }
     } else {
       ASSERT(false);
     }
 
     if (!keep_new_check) {
+      new_check->block()->graph()->isolate()->counters()->
+          bounds_checks_eliminated()->Increment();
       new_check->DeleteAndReplaceWith(new_check->ActualValue());
     }
 
     return true;
   }
 
   void RemoveZeroOperations() {
     RemoveZeroAdd(&added_lower_index_, &added_lower_offset_);
     RemoveZeroAdd(&added_upper_index_, &added_upper_offset_);
   }
@@ skipping 138 matching lines @@
       bb_data_list = new(zone()) BoundsCheckBbData(key,
                                                    offset,
                                                    offset,
                                                    bb,
                                                    check,
                                                    check,
                                                    bb_data_list,
                                                    NULL);
       *data_p = bb_data_list;
     } else if (data->OffsetIsCovered(offset)) {
+      bb->graph()->isolate()->counters()->
+          bounds_checks_eliminated()->Increment();
       check->DeleteAndReplaceWith(check->ActualValue());
     } else if (data->BasicBlock() != bb ||
                !data->CoverCheck(check, offset)) {
       // If the check is in the current BB we try to modify it by calling
       // "CoverCheck", but if also that fails we record the current offsets
       // in a new data instance because from now on they are covered.
       int32_t new_lower_offset = offset < data->LowerOffset()
           ? offset
           : data->LowerOffset();
       int32_t new_upper_offset = offset > data->UpperOffset()
@@ skipping 21 matching lines @@
     data->RemoveZeroOperations();
     if (data->FatherInDominatorTree()) {
       table_.Insert(data->Key(), data->FatherInDominatorTree(), zone());
     } else {
       table_.Delete(data->Key());
     }
   }
 }
 
 } }  // namespace v8::internal