RFR: 8340576: Some JVMCI flags are inconsistent [v2]

[Doug Simon]

On Tue, 24 Sep 2024 22:17:46 GMT, Todd V. Jonker <duke at openjdk.org> wrote:

>> 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.

I've pushed https://github.com/openjdk/jdk/pull/21120/commits/e26e68d9a70ee27b4e71da86ecb42dca11e9a24f to try clarify this a bit.

I know it's a little confusing and apologize. When JVMCI is no longer experimental, this should become much clearer.

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

PR Review Comment: https://git.openjdk.org/jdk/pull/21120#discussion_r1774982914