RFR (S) 8181171: Deleting method for RedefineClasses breaks ResolvedMethodName

[coleen.phillimore at oracle.com]

On 2/25/19 7:58 AM, David Holmes wrote:
> On 25/02/2019 11:04 pm, coleen.phillimore at oracle.com wrote:
>>
>> David, Thank you for the code review.
>>
>> On 2/24/19 8:04 PM, David Holmes wrote:
>>> Hi Coleen,
>>>
>>> On 23/02/2019 9:36 am, coleen.phillimore at oracle.com wrote:
>>>> 8210457: JVM crash in ResolvedMethodTable::add_method(Handle)
>>>> Summary: Add a function to call NSME in ResolvedMethodTable to 
>>>> replace deleted methods.
>>>
>>> Given the existing code just seems to say "I don't know what to do 
>>> here", this change seems quite reasonable.
>>>
>>> A few minor style nits in 
>>> test/jdk/java/lang/instrument/NamedBuffer.java:
>>>
>>> +         final byte FirstByte = className.getBytes()[0];
>>>
>>> No need for final
>> Fixed and the name changed to firstByte.
>>>
>>> s/First/first/
>>>
>>> +             if(checkMatch
>>>
>>> Space after if
>>
>> Fixed.
>>>
>>> Also could you add a comment on bytesForHostClass explaining exactly 
>>> what it does please. I have to keep re-reading it to figure out what 
>>> is the name of the actual classfile on disk and how it then gets 
>>> transformed. IIUC given className it replaces the first letter with 
>>> "replace" and reads that classfile from disk, and then iterates 
>>> through the bytes looking for the modified name and updating it to 
>>> be "className" (which just requires changing the first byte).
>>
>> How about:
>>
>>      // This function reads a class file from disk and replaces the 
>> first character of
>>      // the name with the one passed as "replace".  Then goes through 
>> the bytecodes to
>>      // replace all instances of the name of the class with the new 
>> name.  The
>>      // redefinition tests use this to redefine Host$ classes with 
>> precompiled class files
>>      // Xost.java, Yost.java and Zost.java.
>
> Yep that's good - thanks.

Great thanks.  I forgot to give credit to Serguei who wrote the 
NamedBuffer function.

thanks,
Coleen
>
> David
>
>> Thanks,
>> Coleen
>>
>>>
>>> Thanks,
>>> David
>>> -----
>>>
>>>> This Unsafe.throwX trick is also used for vtable initialization for 
>>>> throwing IllegalAccessError. Tested with redefinition tests in the 
>>>> repository and tier1-3, and added tests.
>>>>
>>>> open webrev at 
>>>> http://cr.openjdk.java.net/~coleenp/2019/8181171.01/webrev
>>>> bug link https://bugs.openjdk.java.net/browse/JDK-8181171
>>>>
>>>> Thanks,
>>>> Coleen
>>