RFR(M): 8223051: support loops with long (64b) trip counts

[Tobias Hartmann]

Hi Roland,

On 03.06.20 11:16, Roland Westrelin wrote:
>>>> Tobias might wish to run some regression tests on the final changes.
>>
>> I've submitted some testing. Will report back once it finished.
> 
> Thanks.

I'm seeing some failures with -XX:StressLongCountedLoop=429496729. Will follow-up offline.

>> loopnode.cpp:
>> - line 504: "check_stride_overflow" is already in 8244504
> 
> Right but the one in this webrev is for longs so doesn't have the same
> signature.

Right and as John already mentioned it's probably not worth using templates here.

>> loopnode.hpp:
>> - line 1462: Shouldn't _loop_invokes/_loop_work also be volatile and be incremented atomically?
> 
> I think so too. That they are not incremented atomically implies nobody
> uses them AFAICT. If we want all of them to be handled correctly then
> someone needs to go over Compile::print_statistics() and all methods it
> calls.

Right that's out of scope of this change.

Best regards,
Tobias