RFR: 8351159: Remaining cleanups in cpu/x86 after 32-bit x86 removal [v2]

[Anton Seoane Ampudia]

On Tue, 28 Oct 2025 16:39:43 GMT, Vladimir Kozlov <kvn at openjdk.org> wrote:

>> Anton Seoane Ampudia has updated the pull request incrementally with one additional commit since the last revision:
>> 
>>   Apply review comments
>
> Main concern is merge of `.ad` files. One big file may be not optimal for JVM build as I remember. Please check JVM build time, especially `adlc` run time. If VM build times increased consider keeping files separate.
> 
> Note, `x86.ad` is mostly used for vector instructions definition. I suggest to rename it to `x64_vect.ad` and `x86_64.ad` to `x64.ad` if you keep files separate.

@vnkozlov I have tried building under different configurations and my measurements don't show any increase (± 4s, which can be attributted, and possibly is, just noise). I have been digging and all `.ad` source files end up being concatenated into a single file before being fed to `adlc`, so in the end it should be the same.

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PR Comment: https://git.openjdk.org/jdk/pull/27987#issuecomment-3460457460