[master] RFR: 8319185: [Lilliput] Enable and fix vectorization tests

[Roman Kennke]

On Tue, 21 Nov 2023 10:54:01 GMT, Roman Kennke <rkennke at openjdk.org> wrote:

> The change does two (related) things:
> - It white-lists the UseCompactObjectHeaders flag in the IR testing framework. Without this, the flag would not be passed through to any IR framework test.
> - That first change makes 3 tests fail. Those are all vectorization tests, and they are failing because 'small' array types (4-byte-elements and smaller) no longer have their elements aligned at 8-byte-boundaries. This throws off vectorization because this only kicks in on aligned accesses. The fix is to allocate those arrays a little larger and align-up the test data to the next 8-byte-boundary. (And no, Lilliput does not break vectorization in general, but it can change the characteristics in particular cases.)
> 
> Testing:
>  - [x] compiler/c2/irTests/TestVectorizationMismatchedAccess.java +UCOH
>  - [x] compiler/c2/irTests/TestVectorizationNotRun.java +UCOH
>  - [x] compiler/loopopts/superword/TestIndependentPacksWithCyclicDependency.java +UCOH
>  - [x] compiler/c2/irTests/TestVectorizationMismatchedAccess.java -UCOH
>  - [x] compiler/c2/irTests/TestVectorizationNotRun.java -UCOH
>  - [x] compiler/loopopts/superword/TestIndependentPacksWithCyclicDependency.java -UCOH
>  - [x] tier1 +UCOH
>  - [x] tier1 -UCOH

Closing in favour of #125.

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PR Comment: https://git.openjdk.org/lilliput/pull/118#issuecomment-1906370067