RFR 8226690: SIGSEGV in MetadataOnStackClosure::do_metadata

[Gilles Duboscq]

It looks to me like `_jvmti_redefinition_count` only needs to be checked for consistency during code installation (which you do in jvmciEnv & ciEnv).
The compiler doesn't need to look at the value during the compilation process so I don't think we need it in `vmStructs_jvmci.cpp`.

  Gilles

On 25/09/2019 16:33, 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