The expression "((int)b[i] & 0xff))" at line 11 is the unsigned byte
idiom. The compiler should understand that it can simply do an unsigned
load instead of slower (at least on sparc) signed load, and eliminate
the "& 0xff".

- The server compiler (sparc) does this in the pre- and post-loop,
but not the main unrolled loop body. I think the server compiler does
the transformation at code generation time, but the loop unrolling code
moved the LOAD and the AND so far apart that the optimization does not
detected the pattern. 

01 public class CRC32 implements Checksum {
02   private static final int[] crc_table = {...}; /* 256 constants */
03
04   /*  Rolled, use "unsigned byte idiom" */
05   private static int updateBytes(int crc, byte[] b,
06                                  final int off, final int len) {
07     final int[] table = crc_table;
08     final int limit = off + len;
09     crc = crc ^ 0xffffffff;
10     for (int i = off; i < limit; i++) {
11       crc = table[(crc ^ ((int)b[i] & 0xff)) & 0xff]
12             ^ (crc >>> 8);
13     }
14     return crc ^ 0xffffffff;
15   }
16 }
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