RFR: 8340576: Some JVMCI flags are inconsistent

[Todd V. Jonker]

On Mon, 23 Sep 2024 07:37:01 GMT, Doug Simon <dnsimon at openjdk.org> wrote:

>> This will conflict with my change https://github.com/openjdk/jdk/pull/21069/commits/b75504633bc0f4fcecc1c08552e556b26d9ffbb9.
>
> No problem - I'll resolve it once your PR is merged.

Based just off the flag docs, I think its easy to think that `+EnableJVMCI` is a prerequisite to enabling the other JVMCI flags, along the line of `+UnlockExperimentalVMOptions`. (That was for sure my newbie reading.)

Perhaps its docs ([here](https://github.com/openjdk/jdk/blob/0b8c9f6d2397dcb480dc5ae109607d86f2b15619/src/hotspot/share/jvmci/jvmci_globals.hpp#L47-L48)) should be updated to say "Defaults to true if UseJVMCICompiler is true"?

TBH I can't wrap my head around what `+EnableJVMCI` _means_; these options have a few chains of "this enables that" making it hard to grok the interactions.

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PR Review Comment: https://git.openjdk.org/jdk/pull/21120#discussion_r1774158571