VM: Regex is not responsive to service requests

[rmacnak-google]

The irregexp interpreter doesn't check for interrupts at all, and compiled irregexp functions seem to only include one check.

[rmacnak-google]

@aam This is same issue as being slow to safepoint because the underlying check is the stack overflow check.

[aam]

We looked at slow-to-safepoint problem in context of JIT only so far. And there regex is responsive(albeit slow) to service requests(observatory seemingly works fine).

The irregexp interpreter(which doesn't check for requested safepoints at all) is used in AOT only, correct?

[mkustermann]

The irregexp interpreter(which doesn't check for requested safepoints at all) is used in AOT only, correct?

Yes.