RFR: Guard interpreter keep alive barrier with ShenandoahKeepAliveBarrier

[Aleksey Shipilev]

On 01/16/2018 06:49 PM, Roman Kennke wrote:
> Am 16.01.2018 um 18:47 schrieb Aleksey Shipilev:
>> So the better fix would probably revisit all uses of keep_alive_barrier, and protect their relevant
>> blocks, then putting the assert(ShenandoahKeepAliveBarrier) in MacroAssembler::keep_alive_barrier?
>>
>> -Aleksey
>>
> 
> Yes, that is what I mean with 'this should need more refactoring' ;-) Only the code that I touched
> uses it, so we should infact move all that code under keep_alive_barrier() instead. Want me to do
> that now? Or wait until codegen for interpreter arrives and do it really properly?

I think it does not matter at this point. We usually use Shenandoah*Barrier as the performance
investigation tool, which means we do care about what compilers do. We are not really interested in
what interpreters do perf-wise. So, a better move resource-wise would be to make it right once,
after codegen interfaces arrive.

Or, does it affect Traversal GC perf?

Thanks,
-Aleksey