RFR: 8353192: C2: Clean up x86 backend after 32-bit x86 removal [v2]

[Emanuel Peter]

On Tue, 8 Apr 2025 17:20:12 GMT, Aleksey Shipilev <shade at openjdk.org> wrote:

>> src/hotspot/cpu/x86/x86.ad line 1659:
>> 
>>> 1657:         return false;
>>> 1658:       }
>>> 1659:       break;
>> 
>> So just `!VM_Version::supports_bmi2()` is not possible any more?
>
> It is possible. I just coalesced the cases for `Op_CompressBits` and `Op_ExpandBits`, see a few lines below.

Aaaah right 😅 🙈

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PR Review Comment: https://git.openjdk.org/jdk/pull/24300#discussion_r2033705441