8384834: Remove CompilationMode flag

[aprilivy]

As noted in https://bugs.openjdk.org/browse/JDK-8384834, remove the -XX:CompilationMode product flag now that JVMCI has been removed. Compiler policy paths previously branching on CompilationModeFlag have been replaced with existing CompilerConfig checks, and tests updated accordingly.

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Issue

• JDK-8384834: Remove CompilationMode flag (Enhancement - P4)

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[aprilivy]

@anton-seoane @mhaessig could you take a look? Thanks!

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• 00: Full (70c5d0df)

[mhaessig]

Thank you for this excellent work, @aprilivy!

Unfortunately, I filed this with too little information as this is my first time removing a product flag. CompilerMode is a product flag and by the Hotspot flags lifecycle we must deprecate it first.

Hence, we cannot go ahead with this yet. However, this change is more or less what is needed for obsoleting the flag, so we can use it then. This be in a one or two releases time.

Apologies for my negligent filing of this issue. But this will come in useful.

[aprilivy]

Thank you for this excellent work, @aprilivy!

Unfortunately, I filed this with too little information as this is my first time removing a product flag. CompilerMode is a product flag and by the Hotspot flags lifecycle we must deprecate it first.

Hence, we cannot go ahead with this yet. However, this change is more or less what is needed for obsoleting the flag, so we can use it then. This be in a one or two releases time.

Apologies for my negligent filing of this issue. But this will come in useful.

Thanks @mhaessig, and no need to apologise. Makes sense, and glad it'll be useful for the obsolete step down the line. I'll leave this up so the branch is ready to reuse when that step comes around, and I'll convert it to a draft in the meantime so it isn't sitting in the review queue. Thanks for walking me through the flag lifecycle.