This is a bug in the C2 compiler related to overflowing an array and loop optimizations. This is seen in JDK 6uXX and the latest JDK 7 HS 20 nightly builds.

Test machine(s):
OS: Solaris
CPU Sparc
JDK: 6u19, and JDK7 b120 - Java HotSpot(TM) Server VM (build 20.0-b03, mixed mode)

Os: SUSE Enterprise Server 11
CPU: AMD Opteron (tm) Processor 848
Kernel: Linux 2.6.27.19-5-default #1 SMP 2009-02-28 04:40:21 +0100 x86_64 x86_64 x86_64 GNU/Linux
JDK: 1.6.0_06, and JDK 7 b99

Test case: (also attached)
  public class OverflowTest{
      static int test(byte a[]){
          int result=0;
          for( int i=0; i<a.length; i+=((0x7fffffff>>1)+1) ){
              result += a[i];
          }
          return result;
      }
  
      public static void main(String [] args){
          byte a[]=new byte[(0x7fffffff>>1)+2];
          System.out.println(""+test(a));
      }
  }
 
 
Correct Results:

java -Xms2048m -Xint OverflowTest
 > Exception in thread "main" java.lang.ArrayIndexOutOfBoundsException: -2147483648
 > at OverflowTest.test(OverflowTest.java:5)
 > at OverflowTest.main(OverflowTest.java:12)
 
Incorrect Results:
java -Xms2048m -Xcomp -XX:CompileOnly=OverflowTest.test OverflowTest
 > 0
 
If you disable loop optimization, the result is correct.
java -Xms2048m -Xcomp -XX:CompileOnly=OverflowTest.test -XX:LoopOptsCount=0 OverflowTest
 > Exception in thread "main" java.lang.ArrayIndexOutOfBoundsException: -2147483648
 > at OverflowTest.test(OverflowTest.java:5)
 > at OverflowTest.main(OverflowTest.java:12)