Fix Array index dehoisting.

src/hydrogen-dehoist.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 20 matching lines @@
 namespace internal {
 
 static void DehoistArrayIndex(ArrayInstructionInterface* array_operation) {
   HValue* index = array_operation->GetKey()->ActualValue();
   if (!index->representation().IsSmiOrInteger32()) return;
   if (!index->IsAdd() && !index->IsSub()) return;
 
   HConstant* constant;
   HValue* subexpression;
   HBinaryOperation* binary_operation = HBinaryOperation::cast(index);
-  if (binary_operation->left()->IsConstant()) {
+  if (binary_operation->left()->IsConstant() && index->IsAdd()) {
     subexpression = binary_operation->right();
     constant = HConstant::cast(binary_operation->left());
   } else if (binary_operation->right()->IsConstant()) {
     subexpression = binary_operation->left();
     constant = HConstant::cast(binary_operation->right());
   } else {
     return;
   }
 
   if (!constant->HasInteger32Value()) return;
@@ skipping 19 matching lines @@
       if (instr->IsLoadKeyed()) {
         DehoistArrayIndex(HLoadKeyed::cast(instr));
       } else if (instr->IsStoreKeyed()) {
         DehoistArrayIndex(HStoreKeyed::cast(instr));
       }
     }
   }
 }
 
 } }  // namespace v8::internal