RFR (XS): 8214523: Fix nmethod asserts for concurrent nmethod unloading

[coleen.phillimore at oracle.com]

This looks good to me.
Coleen

On 11/30/18 10:46 AM, Erik Österlund wrote:
> By popular demand, I decided to CC hotspot-dev. And Coleen.
>
> /Erik
>
> On 2018-11-30 11:29, Erik Österlund wrote:
>> Hi,
>>
>> There are some asserts in nmethod.cpp that do not play well with 
>> concurrent nmethod unloading. This patch adjusts said asserts and 
>> makes nmethod::maybe_invalidate_installed_code() return early if the 
>> nmethod is not JVMCI compiled, to dodge JVMCI requirements on 
>> locking, that is far from supported right now anyway for concurrent 
>> unloading.
>>
>> Bug:
>> https://bugs.openjdk.java.net/browse/JDK-8214523
>>
>> Webrev:
>> http://cr.openjdk.java.net/~eosterlund/8214523/webrev.00/
>>
>> Thanks,
>> /Erik