[master] RFR: 8319135: [Lilliput] Fix objArrayOop gtest

[Aleksey Shipilev]

On Mon, 30 Oct 2023 18:42:18 GMT, Roman Kennke <rkennke at openjdk.org> wrote:

> The objArrayOop gtest is broken with Lilliput. The test checks the size of obj-arrays under various settings (coops, ccp) and different alignments, but it does not consider UseCompactObjectHeaders, yet.
> 
> The change adds handling of UseCompactObjectHeaders.
> 
> Testing:
>  - [x] gtest:objArrayOop (+UCOH)
>  - [x] gtest:objArrayOop (-UCOH)

Were you able to run this test with combination of `ObjectAlignmentBytes` / `UseCompressedClassPointers` and `UseCompressedOops`? I think the test only selects one case out of the runtime configuration.

test/hotspot/gtest/oops/test_objArrayOop.cpp line 54:

> 52:     { 16,         false,  true,     true,   2 },  // 20 byte header, 4 byte oops, 16-byte align
> 53:     { 16,         true,   false,    true,   4 },  // 16 byte header, 8 byte oops, 16-byte align
> 54:     { 16,         true,   true,     true,   2 },  // 16 byte header, 4 byte oops, 16-byte align

Are these really "20 byte" and "16 byte headers" here? Thought they would be smaller.

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PR Review: https://git.openjdk.org/lilliput/pull/114#pullrequestreview-1708873881
PR Review Comment: https://git.openjdk.org/lilliput/pull/114#discussion_r1379210764