RFR: 8240529: CheckUnhandledOops breaks NULL check in Modules::define_module

[Stefan Karlsson]

Thanks, Coleen.

StefanK

On 2020-03-04 15:59, coleen.phillimore at oracle.com wrote:
> +1
> Coleen
>
> On 3/4/20 9:36 AM, Harold Seigel wrote:
>> Looks good and trivial.  Thanks for finding and fixing this.
>>
>> Harold
>>
>> On 3/4/2020 9:25 AM, Stefan Karlsson wrote:
>>> Hi all,
>>>
>>> Please review this small fix to CheckUnhandledOops.
>>>
>>> https://cr.openjdk.java.net/~stefank/8240529/webrev.01
>>> https://bugs.openjdk.java.net/browse/JDK-8240529
>>>
>>> 'loader' is an unhandled oop that is alive across a safepoint check 
>>> and then is used for a NULL check. When the safepoint check executes 
>>> the value of the oop is changed to 0xff...ff1. If the oop was NULL 
>>> then the check now starts to fail. When this happens 
>>> ClassLoader::_exploded_entries isn't populated as expected, causing 
>>> class loading failures with exploded builds.
>>>
>>> Thanks,
>>> StefanK
>