RFR: 8275086: compiler/c2/irTests/TestPostParseCallDevirtualization.java fails when compiler1 is disabled [v3]

[Igor Veresov]

On Tue, 2 Nov 2021 12:25:38 GMT, Christian Hagedorn <chagedorn at openjdk.org> wrote:

>> SUN Guoyun has updated the pull request incrementally with one additional commit since the last revision:
>> 
>>   8275086: compiler/c2/irTests/TestPostParseCallDevirtualization.java fails when compiler1 is disabled
>
> I think for now, going with ` @Warmup(5000)` seems reasonable. Some thoughts about the IR framework:
> - Default warmup: I agree that with `-XX:-TieredCompilation`, the warmup seems to be too short. I think it would make sense to use another default warmup value for C2-only configs if IR matching would be performed. Setting `@Warmup`, however, should always override it. I'm not sure what a good default value should be. Any thoughts @veresov?
> - On top of that, our CI currently only runs `-XX:-TieredCompilation` in combination with `CompileThreshold` which is not whitelisted. This means that IR matching is not performed in that case. That's the reason why we have not detected this bug here in our testing. I think the IR framework should be improved to just ignore any `CompileThreshold` flag settings and allow IR matching to be performed with `-XX:-TieredCompilation` in our CI.
> 
> If others agree, I will file RFEs for both of these.

@chhagedorn, ok, let's go with the current solution for now then.
As for the default warmup, I would probably expose `CompilationPolicy::min_invocations()` through the WB API and do the warmup based on that. There are a lot of ways different flags may affect the thresholds, I think we just need an authoritative API point to tell us the minimum number of invocations. I would also disable various feedback mechanisms in the policy to make it more deterministic. So, `Tier4LoadFeedback=1000000, Tier3LoadFeedback=1000000, Tier3DelayOn=1000000, Tier0Delay=1000000, TieredCompileTaskTimeout=1000000`; or we should add a single option to disable all adaptive features.

-------------

PR: https://git.openjdk.java.net/jdk/pull/5903