RFR: 8308746: C2 IR test failures for TestFpMinMaxReductions.java with SSE2

[Christian Hagedorn]

On Thu, 25 May 2023 07:04:54 GMT, Roberto Castañeda Lozano <rcastanedalo at openjdk.org> wrote:

> `TestFpMinMaxReductions.java` requires `UseAVX > 0` to enforce that floating-point min/max computations are matched by specialized implementations in x64 (see [x86.ad](https://github.com/openjdk/jdk/blob/2a18e537d60c88c015bea738764eef2ca610abf1/src/hotspot/cpu/x86/x86.ad#L1539)). This changeset guards the test file with an `avx.*` CPU feature instead, which is more robust because it reflects the final AVX configuration after all flags are processed (including flags such as `UseSSE` that might affect the final AVX configuration).
> 
> #### Testing
> 
> - `TestFpMinMaxReductions.java` in tier1-5 (windows-x64, linux-x64, and macosx-x64).
> - `TestFpMinMaxReductions.java` with all possible combinations of `UseAVX` and `UseSSE`.

Looks good and trivial!

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Marked as reviewed by chagedorn (Reviewer).

PR Review: https://git.openjdk.org/jdk/pull/14141#pullrequestreview-1443510725