RFR: Backport: 8216549: Mismatched unsafe access to non escaping object fails

[Roman Kennke]

Ping! This is still awaiting review.

Thanks,
Roman


> This backports:
> https://bugs.openjdk.java.net/browse/JDK-8216549
> 
> Original change:
> hg.openjdk.java.net/jdk/jdk12/rev/f0490430ef7a
> 
> JDK11u backport:
> http://hg.openjdk.java.net/jdk-updates/jdk11u-dev/rev/d5fb6ad4203b
> 
> In order to make it work on 8u, I needed the extra change in
> library_call.cpp. Thanks Roland who helped with this.
> 
> Webrev:
> http://cr.openjdk.java.net/~rkennke/JDK-8216549-8u/webrev.00/
> 
> Testing:
> The new testcase fails without the fix, and passes with the fix. tier1 &
> tier2 show no regressions.
> 
> Can I please get a review?
> 
> Thanks,
> Roman
>