RFR (sh/jdk11): Relax Shenandoah/C2 verifier against JDK11 shortcomings

[Aleksey Shipilev]

On 7/30/19 12:28 AM, Roman Kennke wrote:
> - A couple of intrinsics are a bit careless and don't check+cast their
> inputs to not-null. Our verifier doesn't like. Let's special-case them
> and silence the verifier. (We might want to fix the cases via jdk11u
> properly.)

I understand this is missing in 11u?
 https://bugs.openjdk.java.net/browse/JDK-8209684

> http://cr.openjdk.java.net/~rkennke/jdk11-c2-verifier-fixes/webrev.00/

Please put "TODO:" in the comments, and maybe reference the bug above?

-- 
Thanks,
-Aleksey