RFR: 8316657: Support whitebox testing in microbenchmarks

[Claes Redestad]

On Wed, 6 Dec 2023 15:32:14 GMT, Magnus Ihse Bursie <ihse at openjdk.org> wrote:

> The need to use whitebox-testing (wb.jar) from JMH microbenchmarks has recently arisen.

Adding wb.jar to the test image is great. Maybe that could be done separately?

I think we need a different solution here that does not pollute the bootclasspath for all microbenchmarks with wb.jar. Ideally `make test TEST=micro:foo` should be strictly an alias for `$JDK/bin/java -jar test/micro/benchmarks.jar foo` (none of our scripts and lab setups use the `make` support to run microbenchmarks but rather download the test image and run the jar directly); this PR steps away from that ideal.

Something self-contained where the wb.jar is appended explicitly to forked runs by those tests that explicitly need it would be strongly preferred. Perhaps we can do so in a robust fashion with annotations alone since the wb.jar should be relative to the benchmarks.jar, perhaps through the JMH java API.

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PR Comment: https://git.openjdk.org/jdk/pull/16996#issuecomment-1847306934