4-th round RFR (XS) 8068162: jvmtiRedefineClasses.cpp: guarantee(false) failed: OLD and/or OBSOLETE method(s) found

[serguei.spitsyn at oracle.com]

Please, review the fix for:
   https://bugs.openjdk.java.net/browse/JDK-8068162


Open webrevs:
http://cr.openjdk.java.net/~sspitsyn/webrevs/2015/hotspot/8068162-JVMTI-old.4/
http://cr.openjdk.java.net/~sspitsyn/webrevs/2015/jdk/8068162-Test-IsModifiableAgent/


Summary:

    The sun.misc.Unsafe:throwIllegalAccessError() method is used in 
place of a default
    interface method in the itable if a default method was not defined 
in the interface.
    In fact, it happens for two interfaces that purhaps are auto-generated:
      java/nio/CharBuffer
      java/nio/HeapCharBuffer

    This approach creates a problem when the class sun.misc.Unsafe is 
retransformed.
    The Method* pointer to the old (redefined) method in the itable 
triggers an assert
    (see the hs_err log in the bug report).
    Coleen told me that a similar approach is going to be implemented 
for some vtable entries.
    Coleen, thanks for suggesting a better fix for this issue!

    The fix is to replace the old Unsafe method in the itable/vtable 
with the latest method version.


Testing:
   In progress: nsk.jdi.testlist, JTREG java/lang/instrument tests


Thanks,
Serguei