RFR: 8282722: Regard mapping array in enum switches as stable for constant folding

[Jatin Bhateja]

On Mon, 7 Mar 2022 11:58:42 GMT, Joshua Zhu <jzhu at openjdk.org> wrote:

> > Fix is checking an integer array field name starting with "$SwitchMap" to be marked as stable if it is decorated with ACC_STATIC | ACC_FINAL attributes. Wandering why is not being honored during constant folding currently.
> 
> "static final int[] $SwitchMap$xxx" does not mean elements in the array are immutable. Hence it is necessary to treat mapping array generated in enum switches as stable so that their elements can be constant-folded. Please do not miss JVM_ACC_SYNTHETIC flag in this change. "A field marked with the ACC_SYNTHETIC flag indicates that it was generated by a compiler and does not appear in source code."

Thanks @JoshuaZhuwj , Got it,  
FTR references from JLS17 section 4.12.4  (final) and Stable documentation give the necessary details on semantics. https://github.com/openjdk/jdk/blob/master/src/java.base/share/classes/jdk/internal/vm/annotation/Stable.java#L51

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PR: https://git.openjdk.java.net/jdk/pull/7721