RFR: 8375443: AVX-512: Disabling through UseSHA doesn't affect UseSHA3Intrinsics [v3]

[Manuel Hässig]

On Sun, 18 Jan 2026 16:18:55 GMT, Ramkumar Sunderbabu <rsunderbabu at openjdk.org> wrote:

>> UseSHA flag is not respected while enabling/disabling UseSHA3Intrinsics flag in x86 builds.
>> Added UseSHA in the mix.
>> 
>> Testing: Only Basic testing done. I will run more compiler related testing.
>
> Ramkumar Sunderbabu has updated the pull request incrementally with one additional commit since the last revision:
> 
>   whitespace issue fixed

Thank you for addressing my comments and adding a test. I have another suggestion regarding the test.

test/hotspot/jtreg/compiler/arguments/TestUseSHA3IntrinsicsWithUseSHADisabled.java line 31:

> 29:  * @library /test/lib /
> 30:  * @requires vm.flagless
> 31:  * @requires os.arch == "amd64" | os.arch == "x86_64"

Suggestion:

 * @requires os.simpleArch == "x64"

IIRC, this is the more reliable way to detect x86_64.

test/hotspot/jtreg/compiler/arguments/TestUseSHA3IntrinsicsWithUseSHADisabled.java line 32:

> 30:  * @requires vm.flagless
> 31:  * @requires os.arch == "amd64" | os.arch == "x86_64"
> 32:  * @requires vm.cpu.features ~= ".*avx512f.*" & vm.cpu.features ~= ".*avx512bw.*"

It would be great to also test that the warning is emitted when `-XX:+UseSHA3Intrinsics` is passed, but is not supported by the CPU. You could remove this line and detect the features using `WHITE_BOX.getCPUFeatures()`.

-------------

Changes requested by mhaessig (Committer).

PR Review: https://git.openjdk.org/jdk/pull/29266#pullrequestreview-3683477539
PR Review Comment: https://git.openjdk.org/jdk/pull/29266#discussion_r2709416526
PR Review Comment: https://git.openjdk.org/jdk/pull/29266#discussion_r2709484685