RFR: 8342958: Use jvmArgs consistently in microbenchmarks

[Claes Redestad]

On Mon, 28 Oct 2024 20:51:22 GMT, Andrey Turbanov <aturbanov at openjdk.org> wrote:

>> Many OpenJDK micros use `@Fork(jvmArgs/-Append/-Prepend)` to add JVM reasonable or necessary flags, but when deploying and running micros we often want to add or replace flags to tune to the machine, test different GCs, etc. The inconsistent use of the different `jvmArgs` options make it error prone, and we've had a few recent cases where we've not been testing with the expected set of flags. 
>> 
>> This PR suggests using `jvmArgs` consistently. I think this aligns with the intuition that when you use `jvmArgsAppend/-Prepend` intent is to add to a set of existing flags, while if you supply `jvmArgs` intent is "run with these and nothing else". Perhaps there are other opinions/preferences, and I don't feel strongly about which to consolidate to as long as we do so consistently. One argument could be made to consolidate on `jvmArgsAppend` since that one is (likely accidentally) the current most popular (143 compared to 59 `jvmArgsPrepend` and 18 `jvmArgs`).
>
> test/micro/org/openjdk/bench/vm/compiler/overhead/SimpleRepeatCompilation.java line 138:
> 
>> 136: 
>> 137:     @Benchmark
>> 138:     @Fork(jvmArgs={"-Xbatch",LARGE_METHOD})
> 
> Suggestion:
> 
>     @Fork(jvmArgs={"-Xbatch", LARGE_METHOD})

I don't think this PR is the place to address pre-existing and non-consequential style issues.

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PR Review Comment: https://git.openjdk.org/jdk/pull/21683#discussion_r1819860308