RFR: 8320725: C2: Add "requires_strict_order" flag for floating-point add-reduction [v10]

[Bhavana Kilambi]

On Fri, 24 May 2024 08:42:51 GMT, Emanuel Peter <epeter at openjdk.org> wrote:

>> Bhavana Kilambi has updated the pull request incrementally with one additional commit since the last revision:
>> 
>>   Modify JTREG IR rules and some style/format changes
>
> test/hotspot/jtreg/compiler/c2/irTests/TestVectorFPReduction.java line 67:
> 
>> 65:     @IR(applyIfCPUFeatureAnd = {"asimd", "true", "sve", "false"}, failOn = {IRNode.ADD_REDUCTION_VD})
>> 66:     @IR(applyIfCPUFeature = {"sve", "true"}, counts = {"requires_strict_order", ">=1", IRNode.ADD_REDUCTION_VD, ">=1"},
>> 67:         failOn = {"no_strict_order"}, phase = CompilePhase.PRINT_IDEAL)
> 
> Also: I realize that you only check for `asimd / sve` features. Can you also apply it for avx features?

I am not sure which specific avx/sse features/versions support these operations. Is it ok to add - 
`applyIfCPUFeatureOr = {"sve", "true", "avx", "true"}` ? 
or maybe anyone with x86 knowledge who would work on adding strict ordering conditions in their backend (after this patch is merged) can also modify these two testcases accordingly? Also in the vectorapi case, I have included only specific shapes of Vectors where the Reduction nodes would be generated on aarch64. It may or may not be the case for x86 and they might have to add more tests accordingly.

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PR Review Comment: https://git.openjdk.org/jdk/pull/18034#discussion_r1620576664