RFR: 8312570: [TESTBUG] Jtreg compiler/loopopts/superword/TestDependencyOffsets.java fails on 512-bit SVE

[Emanuel Peter]

On Mon, 28 Aug 2023 08:58:13 GMT, Pengfei Li <pli at openjdk.org> wrote:

>> @pfustc you will have to merge the changes from [JDK-8310308](https://bugs.openjdk.org/browse/JDK-8310308).
>
> Thanks @eme64 @vnkozlov for review. Patch is currently merged with master. The python generator file is also updated and attached to the JBS page.
> 
>> Ah. Just one more idea: Since you now have even longer vector widths with 2048 bits: Should we not add some cases with even larger dependency offsets? We should go further than -196, 196. We could consider adding 255, 256, 511, 512, 1024, 1536 (positive and negative). Of course the question is if that increases the runtime too much, what do you think?
> 
> This is a good suggestion but I don't think it's necessary now and in the near future. Although Arm architecture document says SVE vector length can be at most 2048 bits, so far, the largest SVE vector length of real AArch64 CPUs in the world is 512 bits. AFAIK, there will not be real CPUs with 1024-bit SVE in the short term. So I prefer keeping current offset values for now.

@pfustc ok, fair enough. If there is no real hardware, and not coming anytime soon, then we can leave the offsets as is. Thanks again for the fix!

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PR Comment: https://git.openjdk.org/jdk/pull/15010#issuecomment-1695495355