RFR: 8357689: Refactor JVMCI to enable replay compilation in Graal

[Andrej Pečimúth]

On Tue, 27 May 2025 12:10:29 GMT, Doug Simon <dnsimon at openjdk.org> wrote:

>> This PR introduces a few minor JVMCI refactorings to make replay compilation possible in the Graal compiler.
>
> src/jdk.internal.vm.ci/share/classes/jdk/vm/ci/code/BytecodeFrame.java line 397:
> 
>> 395:      * @return a copy of the slot kinds array
>> 396:      */
>> 397:     public JavaKind[] getSlotKinds() {
> 
> Keep in mind that `slotKinds` is being [converted](https://github.com/openjdk/jdk/pull/25442/files#diff-43834727ed7dcd5128c10238ba56963c7d8feb66578b036c75dcf734bfa2ec92R80) to a List. In that context, can we return the list without making a copy? Or is the caller expected to be able to mutate the return value?

Applied the changes provided by @mur47x111.

> src/jdk.internal.vm.ci/share/classes/jdk/vm/ci/code/VirtualObject.java line 325:
> 
>> 323:      *         values have not been initialized.
>> 324:      */
>> 325:     public JavaKind[] getSlotKinds() {
> 
> Same comments as for BytecodeFrame.getSlotKinds. This applies to all other non-primitive array return values added by this PR.

I left `Object[]` as the return value of `EncodedSpeculationReason#getReason` since the array could contain null elements, preventing the use of an immutable list like everywhere else.

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PR Review Comment: https://git.openjdk.org/jdk/pull/25433#discussion_r2189993024
PR Review Comment: https://git.openjdk.org/jdk/pull/25433#discussion_r2190003945