RFR: 8254913: Increase InlineSmallCode default from 2000 to 2500 for x64

[Andriy Plokhotnyuk]

On Wed, 21 Oct 2020 20:49:06 GMT, Vladimir Kozlov <kvn at openjdk.org> wrote:

>> We have seen some specific benefits to increasing InlineSmallCode to 2500 from 2000, and across the whole promo build perf test collection the change is neutral to slightly positive, where the tests are run on modern OCI systems.
>> 
>> Passed tier1 testing, some ad-hoc perf testing and more compiler related parts of the weekly promo performance set.
>> 
>> JBS: https://bugs.openjdk.java.net/browse/JDK-8254913
>> Thanks,
>> Eric
>
> Good.

I'm got ~10% regression after adding `-XX:InlineSmallCode=2500` in some JSON parsing benchmarks where huge methods were generated for some data structures with big number of fields.

Steps to reproduce:
1. Clone the jsoniter-scala repo:
git clone --depth 1 git at github.com:plokhotnyuk/jsoniter-scala.git
2. Run benchmarks with default options:
sbt -java-home /usr/lib/jvm/openjdk-16 'jsoniter-scala-benchmarkJVM/jmh:run -wi 10 -i 10 TwitterAPIReading.jsoniterScala'
3. Run benchmarks with an additional `-XX:InlineSmallCode=2500` option:
sbt -java-home /usr/lib/jvm/openjdk-16 'jsoniter-scala-benchmarkJVM/jmh:run -wi 10 -i 10 -jvmArgsAppend "-XX:InlineSmallCode=2500" TwitterAPIReading.jsoniterScala'

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PR: https://git.openjdk.java.net/jdk/pull/705