graal/com.oracle.graal.replacements/src/com/oracle/graal/replacements/nodes/BitScanForwardNode.java

*** 52,67 ****
          IntegerStamp valueStamp = (IntegerStamp) getValue().stamp();
          int min;
          int max;
          long mask = CodeUtil.mask(valueStamp.getBits());
          int firstAlwaysSetBit = scan(valueStamp.downMask() & mask);
          if (firstAlwaysSetBit == -1) {
              int lastMaybeSetBit = BitScanReverseNode.scan(valueStamp.upMask() & mask);
!             min = -1;
              max = lastMaybeSetBit;
          } else {
-             int firstMaybeSetBit = scan(valueStamp.upMask() & mask);
              min = firstMaybeSetBit;
              max = firstAlwaysSetBit;
          }
          return updateStamp(StampFactory.forInteger(Kind.Int, min, max));
      }
--- 52,67 ----
          IntegerStamp valueStamp = (IntegerStamp) getValue().stamp();
          int min;
          int max;
          long mask = CodeUtil.mask(valueStamp.getBits());
          int firstAlwaysSetBit = scan(valueStamp.downMask() & mask);
+         int firstMaybeSetBit = scan(valueStamp.upMask() & mask);
          if (firstAlwaysSetBit == -1) {
              int lastMaybeSetBit = BitScanReverseNode.scan(valueStamp.upMask() & mask);
!             min = firstMaybeSetBit;
              max = lastMaybeSetBit;
          } else {
              min = firstMaybeSetBit;
              max = firstAlwaysSetBit;
          }
          return updateStamp(StampFactory.forInteger(Kind.Int, min, max));
      }