RFR 8226690: SIGSEGV in MetadataOnStackClosure::do_metadata

[dean.long at oracle.com]

Saving and restoring redefinition_count for compiler replay doesn't make 
sense to me.  It won't affect the generated code, and we probably 
shouldn't even be installing/registering replay nmethods. I would remove 
the ciEnv::dump_replay_data_unsafe() and process_JvmtiExport() changes.

dl

On 9/25/19 7:33 AM, coleen.phillimore at oracle.com wrote:
> Summary: Dont create nmethod if classes have been redefined since 
> compilation start.
>
> The bug was caused by a new nmethod created with an old Method in the 
> metadata section.  Added verification (which hit on windows) and NSV 
> in the other place where the method can be replaced in the nmethod 
> metadata section.
>
> There are some jvmci changes (to vmStructs_jvmci.cpp) that might be 
> needed also in the graal compiler.
>
> Tested with tier1-6 and failing test 100 times.
>
> open webrev at http://cr.openjdk.java.net/~coleenp/2019/8226690.01/webrev
> bug link https://bugs.openjdk.java.net/browse/JDK-8226690
>
> Thanks,
> Coleen