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

[Aleksey Shipilev]

On Fri, 10 Jan 2025 16:22:06 GMT, Coleen Phillimore <coleenp at openjdk.org> wrote:

>> Yes, now it is unconditional. x86_64 [requires](https://github.com/openjdk/jdk/blob/ec7393e9190c1b93ca08e1107f734c869f400b89/src/hotspot/cpu/x86/vm_version_x86.cpp#L896-L903) UseSSE >= 2. Only x86_32 cared about UseSSE < 2, so now we can eliminate these checks. I think I got the majority, if not all of the cases where these checks are now redundant: there are more in various assemblers and compiler code.
>
> Maybe this should change from range (2,4) then.
>   product(int, UseSSE, 4,                                                   \
>           "Highest supported SSE instructions set on x86/x64")              \
>           range(0, 4)                                                       \

Right. Now that I am thinking more deeply about it, maybe that would be a first step here: lift UseSSE >= 2 for x86_32 ahead of this JEP, eliminate all UseSSE < 2 parts. I can see how intrusive this gets.

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PR Review Comment: https://git.openjdk.org/jdk/pull/22567#discussion_r1910843574