Fix ARM: explicitly reduce shift count modulo word size.

runtime/vm/bit_set.h

 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 #ifndef VM_BIT_SET_H_
 #define VM_BIT_SET_H_
 
 #include "platform/utils.h"
 #include "vm/globals.h"
 
@@ skipping 23 matching lines @@
     ASSERT(i >= 0);
     ASSERT(i < N);
     uword mask = (static_cast<uword>(1) << (i & (kBitsPerWord - 1)));
     return (data_[i >> kBitsPerWordLog2] & mask) != 0;
   }
 
   intptr_t Next(intptr_t i) const {
     ASSERT(i >= 0);
     ASSERT(i < N);
     intptr_t w = i >> kBitsPerWordLog2;
-    uword mask = ~static_cast<uword>(0) << i;
+    uword mask = ~static_cast<uword>(0) << (i & (kBitsPerWord - 1));
     if ((data_[w] & mask) != 0) {
       uword tz = Utils::CountTrailingZeros(data_[w] & mask);
       return (w << kBitsPerWordLog2) + tz;
     }
     while (++w < kLengthInWords) {
       if (data_[w] != 0) {
         return (w << kBitsPerWordLog2) + Utils::CountTrailingZeros(data_[w]);
       }
     }
     return -1;
@@ skipping 39 matching lines @@
   }
 
  private:
   static const int kLengthInWords = 1 + ((N - 1) / kBitsPerWord);
   uword data_[kLengthInWords];
 };
 
 }  // namespace dart
 
 #endif  // VM_BIT_SET_H_