RFR: Don't check store value in Shenandoah C2 verifier

[Roman Kennke]

>> Here comes the real fix: CreateEx nodes don't require a barrier (the
>> exception is either new, or one of the pre-generated exceptions that we
>> keep guaranteed in to-space), and the verifier needs to be extended for
>> this:
>>
>> http://cr.openjdk.java.net/~rkennke/fixoptoverifier/webrev.01/
> 
> Patch looks okay.
> 
> But let me ask this: the same must be true for our mainline non-LRB Shenandoah too? If so, why
> verification started to fail only with LRB?

I believe we don't guarantee to-spaciness on pre-generated exceptions
pre-LRB, and thus always generated (or did not elide) barriers.

Roman