RFR: 8371955: Support AVX10 floating point comparison instructions [v8]

[Mohamed Issa]

On Tue, 27 Jan 2026 07:57:03 GMT, Emanuel Peter <epeter at openjdk.org> wrote:

>> Mohamed Issa has updated the pull request with a new target base due to a merge or a rebase. The pull request now contains 25 commits:
>> 
>>  - Merge branch 'master' into user/missa-prime/avx10_2
>>  - Merge branch 'master' into user/missa-prime/avx10_2
>>  - Change function names and extend IR encoding rules for CMove tests
>>  - Merge remote-tracking branch 'origin/master' into user/missa-prime/avx10_2
>>  - Remove unnecessary CMOV blocks and adjust predicates involving APX and AVX10.2
>>  - Remove extra jump instruction in signum floating point and unify three-way floating point comparison logic in x86.ad
>>  - Also update copyright year in IREncodingPrinter.java
>>  - Include apx_f in list of verified CPU features for IR encoding
>>  - Fix CMove IR tests to account for APX presence
>>  - Merge branch 'master' into user/missa-prime/avx10_2
>>  - ... and 15 more: https://git.openjdk.org/jdk/compare/44b74e16...09d1e44d
>
> test/hotspot/jtreg/compiler/c2/irTests/CMoveLConstants.java line 65:
> 
>> 63:         applyIfPlatform = {"x64", "true"},
>> 64:         applyIfCPUFeatureAnd = {"apx_f", "true", "avx10_2", "true"},
>> 65:         phase = CompilePhase.FINAL_CODE)
> 
> These are all `CMove` cases. I see you added branch/call cases in the benchmark. Would it make sense to have some similar cases here?
> 
> And: this here is a test for `float`. Where do we cover `double`, which you are also making VM changes for?

Unlike CMove, the branch/call cases don't have special definitions in the `x86.ad` file for constants. The jump instructions behave the same way for all value types because they only check the register flags. So, I think the branch tests in `TestFPComparison.java` are sufficient since they cover the comparison instructions as well.

As for double precision, I just added a test mirroring the single precision one. Thanks for noting that.

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PR Review Comment: https://git.openjdk.org/jdk/pull/28337#discussion_r2733456586