RFR(S): 8235673: [C1, C2] Split inlining control flags

[Tobias Hartmann]

Hi Martin,

On 07.05.20 15:42, Doerr, Martin wrote:
> Hi Tobias,
> 
> thanks for looking at my change.
> It is only expected to influence startup, not peak performance.
> 
> Nevertheless, I've run benchmarks to check peak performance as well: SPEC jvm 2008, SPEC jbb 2015
> No regressions observable, as expected.

Okay, great.

> For startup performance, I've ran SPEC jbb 2005 with throughput measurements every 1.5 seconds like I had shown in my fosdem talk (https://fosdem.org/2020/schedule/event/jit2020/).
> I couldn't observe any regression, either.
> 
> It would be very helpful if other people (e.g. from Oracle) could run additional benchmarks. I don't know what you use to check startup performance.

Okay, I'll run it through our startup benchmark suite. Will report back once it finished.

>> Did you verify that tests using these flags are still working as expected (i.e.,
>> intend to only adjust C2's behavior)?
> Using the existing flags still works for C2. So there's no issue with C2 tests.
> I'm not aware of any test which requires one of these flags to modify C1 behavior.
> 
> I've run a substantial amount of tests and couldn't find any related issues:
> jtreg, jck (normal, with -Xcomp, with -Xcomp -XX:-TieredCompilation), SAP's proprietary tests

I meant that the authors of these tests might have intended to tweak C1 behavior when adding the
flag whereas with your change, only C2 behavior is affected. That doesn't necessarily mean that the
test will fail now but it could mean that the regression the test was written for is not triggered
anymore. You might just want to add the C1 flag as well (in another @run), Vladimir K. also
mentioned this in his review.

Best regards,
Tobias