Name: mf23781 Date: 05/27/98


The following code, if evecuted in JDK 1.1.6 using the JIT, will
hang in the JIT compiler and not print anything to the screen:
 
class t5
{ public static void main (String [] args)
     {
             byte[] data = new byte[16];
             foo ();
     }

     public static int FF (int a, int b, int c, int d, int x, int s, int ac)
     {
             return (((a += ((b & c) | (~b & d)) + x + ac) << s) | (a >>> (32-s)))+ b;
     }
     static void foo ()
     {
             System.out.println ("Starting foo ...");
             int[] W = new int[16];
 
             int a = 0x67452301;
             int b = 0xefcdab89;
             int c = 0x98badcfe;
             int d = 0x10325476;
 
             for (int i = 0; i < 16; i++)
             {
                   a = FF (a, b, c, d, W[0], 7, 0xd76aa478);
                   d = FF (d, a, b, c, W[1], 12, 0xe8c7b756);
                   c = FF (c, d, a, b, W[2], 17, 0x242070db);
                   b = FF (b, c, d, a, W[3], 22, 0xc1bdceee);
                   a = FF (a, b, c, d, W[4], 7, 0xf57c0faf);
                   d = FF (d, a, b, c, W[5], 12, 0x4787c62a);
                   c = FF (c, d, a, b, W[6], 17, 0xa8304613);
                   b = FF (b, c, d, a, W[7], 22, 0xfd469501);
              }
                    System.out.println ("foo ended.");
       }
}
 
If we modify (simplify) the code much beyond what is here, the code executes
in the JIT compiler. However, all of the above code (and more, we have greatly
simplified the test case) is needed since this is part of an important algorithm.

Actually, if you comment out the last call to FF() near the bottom of the
code, a different symptom will appear. The JIT compiler will accumulate memory
quickly and eventually crash when it runs out. However, if you leave the last FF()
call in, the JIT compiler spins hard in a loop and never (the
best we can tell) exits.

If you run the exact same code and specify the -nojit option, it runs
normally.

This is an important problem as an IBM product which ships within a month is depending on it
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