Testing long RCE

[Maurizio Cimadamore]

Hi Rado,
to achieve performance parity in existing benchmarks there's another 
piece we need:

https://bugs.openjdk.java.net/browse/JDK-8276116

Without that patch, the VM only optimizes if it detects a loop on a long 
variable (but all our benchmarks use an int variable).

I suggest you use this branch (against jdk/jdk):

https://github.com/mcimadamore/jdk/tree/long_loop_workarounds_removal

Which contains full removal of existing workaround - I've been testing 
this with Roland over the last few months.

Cheers
Maurizio

On 04/12/2021 18:49, Rado Smogura wrote:
> Hi all,
>
> I tried to test long range checks 8259609 - as this is long awaiting 
> thing. I'm not sure if I do something wrong, but I can't get a good 
> results
>
>
> Approach 1.
> LoopOverNonConstant.segment_loop change int to long as counter
>
> AbstractMemorySegmentImpl.checkBounds I used followed code
>
> if (length < 0) {
>     throw outOfBoundException(offset, length);
> }
>
> Objects.checkIndex(offset, this.length - (length - 1));
>
> Results were like Iteration   8: 0.376 ms/op
>
>
> Approach 2
>
> AbstractMemorySegmentImpl.checkBounds use code like in 1, but without 
> segment_loop changes
>
> Iteration   8: 0.239 ms/op
>
> Approach 3 - original test
> Iteration   8: 0.230 ms/op
>
> Sorry for not posting whole results (just grabbed partial results). In 
> graph as well I can see number of range checks in main loop :(
>
> Kind regards,
> Rado
>