RFR: 8377307: Refactor code for AOT cache pointer compression [v2]

[Ashutosh Mehra]

On Sat, 7 Feb 2026 04:07:27 GMT, Ioi Lam <iklam at openjdk.org> wrote:

>> AOT cache uses pointer compression to store 64-bit pointers in 32 bits. Currently the compression algorithm is simply (base + narrowPtr). However, in [JDK-8376125](https://bugs.openjdk.org/browse/JDK-8376125), we may change it to (base + narrowPtr << 3).
>> 
>> This RFE changed the encoded pointer from an u4 to (thanks to @jdksjolen for the idea):
>> 
>> 
>> enum class narrowPtr : u4;
>> 
>> 
>> This allows better tracking of where the encoded pointers are stored. Also, we can distinguish between byte offsets vs encoded pointers -- they currently have the same numerical values but after [JDK-8376125](https://bugs.openjdk.org/browse/JDK-8376125), they will be different.
>> 
>> Also minor clean up in ArchiveBuilder to change some `uintx` to `size_t`, which is used by `pointer_delta()`.
>
> Ioi Lam has updated the pull request incrementally with two additional commits since the last revision:
> 
>  - restored assert
>  - @jdksjolen review comments

looks good.

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Marked as reviewed by asmehra (Committer).

PR Review: https://git.openjdk.org/jdk/pull/29590#pullrequestreview-3766197738