RFR: 8276227: ciReplay: SIGSEGV if classfile for replay compilation is not present after JDK-8275868

[Christian Hagedorn]

On Mon, 1 Nov 2021 13:25:03 GMT, Christian Hagedorn <chagedorn at openjdk.org> wrote:

> The fix for [JDK-8275868](https://bugs.openjdk.java.net/browse/JDK-8275868) does not handle the case when the classfile for the method to be replay compiled is not present. This will fail to load the klass. Afterwards, we are trying to access the protection domain of the failed to load klass (i.e. a null pointer) which results in a segmentation fault. The fix is straight forward to only set the new protection domain if the klass was loaded successfully. I additionally changed the code such that we are only trying to set the protection domain when reading the first `instanceKlass` entry. This avoids some potential problems with older replay files where we do not have this additional first entry set by JDK-8275868.
> 
> Thanks,
> Christian

Thanks Vladimir for your review! Unfortunately, none of our tests caught this. I observed this when I did some additional testing and had not specified the correct class paths. I've added a test which covers this.

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PR: https://git.openjdk.java.net/jdk/pull/6189