Make keyed operations use the unchecked index but still depend on the checked one.

src/hydrogen.cc

 // 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 3466 matching lines @@
                        Key()->IndexBase(),
                        new_check->index()->representation(),
                        new_offset);
         lower_check_->SetOperandAt(0, added_lower_index_);
       }
     } else {
       ASSERT(false);
     }
 
     if (!keep_new_check) {
-      new_check->DeleteAndReplaceWith(NULL);
+      new_check->DeleteAndReplaceWith(new_check->index());
     }
   }
 
   void RemoveZeroOperations() {
     RemoveZeroAdd(&added_lower_index_, &added_lower_offset_);
     RemoveZeroAdd(&added_upper_index_, &added_upper_offset_);
   }
 
   BoundsCheckBbData(BoundsCheckKey* key,
                     int32_t lower_offset,
@@ skipping 86 matching lines @@
     Remove(key, key->Hash());
   }
 
   explicit BoundsCheckTable(Zone* zone)
       : ZoneHashMap(BoundsCheckKeyMatch, ZoneHashMap::kDefaultHashMapCapacity,
                     ZoneAllocationPolicy(zone)) { }
 };
 
 
 // Eliminates checks in bb and recursively in the dominated blocks.
-// Also replace the results of check instructions with the original value, if
-// the result is used. This is safe now, since we don't do code motion after
-// this point. It enables better register allocation since the value produced
-// by check instructions is really a copy of the original value.
 void HGraph::EliminateRedundantBoundsChecks(HBasicBlock* bb,
                                             BoundsCheckTable* table) {
   BoundsCheckBbData* bb_data_list = NULL;
 
   for (HInstruction* i = bb->first(); i != NULL; i = i->next()) {
     if (!i->IsBoundsCheck()) continue;
-
     HBoundsCheck* check = HBoundsCheck::cast(i);
-    check->ReplaceAllUsesWith(check->index());
-
-    if (!FLAG_array_bounds_checks_elimination) continue;
 
     int32_t offset;
     BoundsCheckKey* key =
         BoundsCheckKey::Create(zone(), check, &offset);
     if (key == NULL) continue;
     BoundsCheckBbData** data_p = table->LookupOrInsert(key, zone());
     BoundsCheckBbData* data = *data_p;
     if (data == NULL) {
       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)) {
-      check->DeleteAndReplaceWith(NULL);
+      check->DeleteAndReplaceWith(check->index());
     } else if (data->BasicBlock() == bb) {
       data->CoverCheck(check, offset);
     } else {
       int32_t new_lower_offset = offset < data->LowerOffset()
           ? offset
           : data->LowerOffset();
       int32_t new_upper_offset = offset > data->UpperOffset()
           ? offset
           : data->UpperOffset();
       bb_data_list = new(zone()) BoundsCheckBbData(key,
@@ skipping 19 matching lines @@
     if (data->FatherInDominatorTree()) {
       table->Insert(data->Key(), data->FatherInDominatorTree(), zone());
     } else {
       table->Delete(data->Key());
     }
   }
 }
 
 
 void HGraph::EliminateRedundantBoundsChecks() {
+  if (!FLAG_array_bounds_checks_elimination) return;

[Sven Panne, 2012/12/06 14:59:02]

For consistency with the other phases, move this to the call site.

[Massi, 2012/12/07 10:11:11]

Done.

+
   HPhase phase("H_Eliminate bounds checks", this);
   BoundsCheckTable checks_table(zone());
   EliminateRedundantBoundsChecks(entry_block(), &checks_table);
 }
 
 
 static void DehoistArrayIndex(ArrayInstructionInterface* array_operation) {
   HValue* index = array_operation->GetKey();
   if (!index->representation().IsInteger32()) return;
 
@@ skipping 6382 matching lines @@
     }
   }
 
 #ifdef DEBUG
   if (graph_ != NULL) graph_->Verify(false);  // No full verify.
   if (allocator_ != NULL) allocator_->Verify();
 #endif
 }
 
 } }  // namespace v8::internal