[master] RFR: 8347710: [Lilliput] Implement 4 byte headers

[Thomas Stuefe]

On Tue, 21 Jan 2025 13:11:53 GMT, Roman Kennke <rkennke at openjdk.org> wrote:

> Packs/reduces header bits to just 4 bytes.
> 
> This reduces the number of Klass* bits to 19 bits, which allows for ~500,000 classes.
> 
> Testing:
> 
> - tier1 (-UCOH)
> - tier2 (-UCOH)
> - tier1 (+UCOH)
> - tier2 (+UCOH)

Marked as reviewed by stuefe (Reviewer).

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PR Review: https://git.openjdk.org/lilliput/pull/193#pullrequestreview-2564845254