bug 6869274 Re: Running ant with jdk7

[Tim Bell]

Xueming Shen wrote:
> It appears the failure has nothing to do with the zip code, attached 
> sample Foo started to fail
> ( the masking operation & BYTE_3_MASK seems failed) from b65 on 
> solaris-i586 (but works
> fine on sol-sparc, it failed on linux-amd64 as well, have not tried on 
> other platforms yet). Any
> idea where I should send this one to?

Interesting!  This could be a word tearing or optimization bug in
the server (C2) compiler.

Your test case will run for many minutes on my Solaris-x64 desktop
if I use "-Xint" or "-client"

If I run with "-server" I get a failure pretty quickly.  Here is
a slightly modified version of your test case that tracks the
iteration count:

% cat Foo.java
public class Foo {

    private static final long BYTE_3_MASK = 0xFF000000L;
    private static final int BYTE_3_SHIFT = 24;

    public static void main(String[] args) {
        java.util.Random r = new java.util.Random();
        byte[] bb = new byte[1];
        long nLoops = 0;

        while(true) {
            nLoops++;
            r.nextBytes(bb);

            long l = (bb[0] << BYTE_3_SHIFT) & BYTE_3_MASK;

            if (bb[0] < 0)
                System.out.printf("  [toLong]: %x -> %x%n",
                                  bb[0] & 0xff, l);

            if ((l & 0xf00000000L) != 0) {
                System.out.printf(nLoops + " Masking failed!%n");
                break;
            }
        }
    }
}

If I run with my local copy of JDK7 b67, I get a failure at about 14000
iterations, right after Foo:main is compiled:

% /opt/java/jdk1.7.0-b67/fastdebug/bin/java -server \
   -showversion -ea -esa -Xbatch -XX:+PrintCompilation Foo

    [... output trimmed...]

  [toLong]: d4 -> d4000000
  [toLong]: df -> df000000
  [toLong]: be -> be000000
  1%  b   Foo::main @ 14 (124 bytes)
  [toLong]: a7 -> ffffffffa7000000
  1%  made not entrant  (2)  Foo::main @ 14 (124 bytes)
14564 Masking failed!



If I add one more flag:  -XX:CompileOnly=Foo::main

/opt/java/jdk1.7.0-b67/fastdebug/bin/java -server \
   -showversion -ea -esa -Xbatch -XX:+PrintCompilation \
   -XX:CompileOnly=Foo::main Foo

I still get a failure:

  [toLong]: e8 -> e8000000
  [toLong]: f6 -> f6000000
  [toLong]: cc -> cc000000
  [toLong]: 9c -> 9c000000
  1%  b   Foo::main @ 14 (124 bytes)
  [toLong]: e4 -> ffffffffe4000000
  1%  made not entrant  (2)  Foo::main @ 14 (124 bytes)
14564 Masking failed!


I will update Bug-ID 6869274 and assign it to HVM/compiler2

Tim