RFR: 8345169: Implement JEP 503: Remove the 32-bit x86 Port

[Aleksey Shipilev]

On Thu, 6 Mar 2025 16:18:50 GMT, Magnus Ihse Bursie <ihse at openjdk.org> wrote:

>> This PR implements JEP 503: Remove the 32-bit x86 Port.
>> 
>> The JEP is proposed to target 25, we would not integrate until JEP is ready. Reviews are appreciated meanwhile.
>> 
>> This is only the removal of obvious 32-bit x86 parts, mostly files with `x86_32` in their name.  Those are only built when build system knows we are compiling for x86_32. There is therefore no impact on x86_64. The approach for removing x86_32 files only also makes this PR borderline trivial, and requires no additional testing beyond normal pre-integration checks.
>> 
>> The rest of the code is quite heavily intertwined with x86_64 and/or Zero, and would require accurate untangling. It would be much easier to review and test once we purge the free-standing parts of 32-bit x86 port, which is also a bulk of the port. The tangling with 32-bit x86 Zero is also why I did not touch most of the build system paths that handle x86. There is [JDK-8351148](https://bugs.openjdk.org/browse/JDK-8351148) umbrella that tracks further cleanup work. One can peek the final state that can be reached with all the cleanups in my earlier exploratory https://github.com/openjdk/jdk/pull/22567.
>> 
>> Additional testing:
>>  - [x] Linux x86_32 Server fastdebug, `make bootcycle-images` (now fails configure)
>>  - [x] Linux x86_64 Server fastdebug, `make bootcycle-images` (still works)
>>  - [x] Linux x86_32 Zero fastdebug, `make bootcycle-images` (still works)
>>  - [x] Linux x86_64 Zero fastdebug, `make bootcycle-images` (still works)
>
> make/autoconf/platform.m4 line 669:
> 
>> 667:   AC_ARG_ENABLE(deprecated-ports, [AS_HELP_STRING([--enable-deprecated-ports@<:@=yes/no@:>@],
>> 668:       [Suppress the error when configuring for a deprecated port @<:@no@:>@])])
>> 669:   # There are no deprecated ports. This option is left to be consistent with future deprecations.
> 
> Please remove. Old code is always present in git history if you want to reuse it.

I don't mind removing it, my concern would be to _remember_ this option was there! I guess it is okay to re-re-invent it later, possibly under a different name, when the next port gets deprecated.

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PR Review Comment: https://git.openjdk.org/jdk/pull/23906#discussion_r1983704213