RFR: Fix ExtendedDTraceProbes with Shenandoah

[Roman Kennke]

Am 21.09.2018 um 10:34 schrieb Aleksey Shipilev:
> On 09/21/2018 09:13 AM, Roman Kennke wrote:
>> The interesting question is: is this reproducible with upstream+G1
>> somehow? Can you make a testcase against G1, and fix it upstream?
>>
>> Also, might we have more 'hidden-ctrl-flow-bugs' lurking in our code?
> 
> And on top of that, is there a way to mechanically check there is no control flow within the C1 BB?
> This sounds like a serious trouble that needs to be asserted by the compiler itself.
> 
> -Aleksey
> 

Except that we have this stuff everywhere (look at e.g. SATB barriers).
I guess we have reasonable workarounds in those places.

Roman