The following test case produces wrong results (var_bad) when
running jvm with 32bit server compiler on solaris-x86.

> JDK7b43/bin/java -server -Xcomp -XX:CompileOnly=TesterSmall_Class_0 TesterSmall
var_bad = -602947331
var_ok  = 0

============ TesterSmall.java ==============
class TesterSmall_Class_0 {
    static long var_bad = -1L;

    public TesterSmall_Class_0()
    {
      var_bad >>= 65;
      var_bad /= 65;
    }
}

public class TesterSmall {
    public static void main(String[] args)
    {
        TesterSmall_Class_0 t =  new TesterSmall_Class_0();

        long var_ok = -1L;
        var_ok >>= 65;
        var_ok /= 65;

        System.out.println("var_bad = " + TesterSmall_Class_0.var_bad);
        System.out.println("var_ok  = " + var_ok);
    }
}

=======================================

The test works fine on other platforms with bot 32bit and 64bit jvms.
Posted Date : 2009-01-19 16:07:00.0

N/A

The bug was introduced with 6603011 and 6732154 already fixed a problem in the new code.  I suspect this bug is similar to 6732154.
Posted Date : 2009-01-29 14:01:32.0

6732154 has been fixed in hs14-b04, but the test still fails with latest hs14-b10
as well as hs14-b04:

/java/re/jdk/7/promoted/all/b44/binaries/solaris-i586/bin/java -server -Xcomp -XX:CompileOnly=TesterSmall_Class_0 -showversion TesterSmall
java version "1.7.0-ea"
Java(TM) SE Runtime Environment (build 1.7.0-ea-b44)
Java HotSpot(TM) Server VM (build 14.0-b10, compiled mode)

var_bad = -602947331
var_ok  = 0

/java/re/jdk/7/promoted/all/b35/binaries/solaris-i586/bin/java -server -Xcomp -XX:CompileOnly=TesterSmall_Class_0 -showversion TesterSmall
java version "1.7.0-ea"
Java(TM) SE Runtime Environment (build 1.7.0-ea-b35)
Java HotSpot(TM) Server VM (build 14.0-b04, compiled mode)

var_bad = -602947331
var_ok  = 0
Posted Date : 2009-01-29 15:01:46.0

Obviously, because 6732154 fixes a similar but different problem.  Still investigating.
Posted Date : 2009-01-29 15:13:54.0

When the:

  // Masking off sign bits?  Dont make them!
  if( rop == Op_RShiftL ) {

special case in AndLNode::Ideal is commented, the generated code is correct.
Posted Date : 2009-01-29 16:26:23.0

As Tom suspected the bug is in the Op_URShiftL special case in AndLNode::Identity.  The constant shift value gets not masked before calculations are done.  Adding the line:

        shift &= (BitsPerJavaInteger * 2) - 1;  // semantics of Java shifts

fixes the bug.

It seems the same bug is in AndINode::Identity, but I couldn't create a testcase yet.  If I find one I will open a new CR.
Posted Date : 2009-01-30 10:12:27.0

http://hg.openjdk.java.net/jdk7/hotspot-comp/hotspot/rev/7628781568e1
Posted Date : 2009-02-03 12:22:02.0

The fix has been verified as part of hs15-b02 pit.
Posted Date : 2009-02-24 22:39:05.0