RFR: 8341781: Improve Min/Max node identities [v2]

[Emanuel Peter]

On Thu, 31 Oct 2024 03:41:18 GMT, Jasmine Karthikeyan <jkarthikeyan at openjdk.org> wrote:

>> test/hotspot/jtreg/compiler/c2/irTests/TestMinMaxIdentities.java line 35:
>> 
>>> 33:  * @summary Test identities of MinNodes and MaxNodes.
>>> 34:  * @key randomness
>>> 35:  * @requires (os.simpleArch == "x64" & vm.cpu.features ~= ".*avx.*") | os.arch == "aarch64" | os.arch == "riscv64"
>> 
>> Is there a chance we can add these `requires` to the `@IR` rules instead? That way we can still do the result verification on all other platforms, which could be valuable on its own.
>
> From my understanding this isn't possible as-is since CPU features seem to be checked regardless of whether the architecture supports it or not, so we can't simply check for AVX because that would fail on aarch64 and riscv64. I think we could work around this with `applyIfCPUFeatureOr = {"avx", "true", "asimd", "true", "rvv", "true"}` to force a check for all 3 platforms but it'd be filtering more platforms than strictly necessary.

Which platforms would be filtered "more platforms than strictly necessary"?

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PR Review Comment: https://git.openjdk.org/jdk/pull/21439#discussion_r1824102379