RFR: 8351159: Remaining cleanups in cpu/x86 after 32-bit x86 removal [v3]

[Stefan Karlsson]

On Wed, 29 Oct 2025 13:42:41 GMT, Anton Seoane Ampudia <aseoane at openjdk.org> wrote:

>> This PR carries out cleanup on the `cpu` and `os_cpu` directories after the removal of the 32-bit x86 architecture from HotSpot.
>> 
>> Mainly, code guarded by `IA32` or `X32`, or `!AMD64` or `!LP64` in a x86 context, has been removed. These guards are now redundant (e.g. checking for 64bit on a x86 context) or the code blocks never executed (e.g. code under `#ifdef X32`). Additionally, x86 AD files have been merged.
>> 
>> Please note that this changeset limits itself to changes under `cpu/x86` and `os_cpu/x86`. Other cleanups are filed under a different RFE, and consequently addressed in a different PR: [JDK-8351149](https://github.com/openjdk/jdk/pull/27990).
>> 
>> **Testing:** passes tiers 1-5
>
> Anton Seoane Ampudia has updated the pull request with a new target base due to a merge or a rebase. The pull request now contains 15 commits:
> 
>  - Merge changes from JDK-8369346
>  - Apply review comments
>  - Update copyright years
>  - Reintroduce changes from JDK-8369569
>  - Merge upstream changes
>  - Merge x86 AD files
>  - Roll back changes that are targeted in JDK-8354853
>  - Cleanup _M_AMD64 from cpu/ and os_cpu/
>  - Cleanup LP64_ONLY and NOT_LP64 from cpu/ and os_cpu/
>  - Cleanup LP64 from os_cpu/
>  - ... and 5 more: https://git.openjdk.org/jdk/compare/2c07214d...4e58e509

Marked as reviewed by stefank (Reviewer).

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PR Review: https://git.openjdk.org/jdk/pull/27987#pullrequestreview-3398288713