RFR: 8334474: RISC-V: verify perf of ExpandBits/CompressBits (rvv)

[Fei Yang]

On Thu, 14 Nov 2024 11:45:13 GMT, Hamlin Li <mli at openjdk.org> wrote:

> Hi, 
> Can you help to review the patch?
> It removes the previous added intrinsic for Long/Integer.expand/compress, as on several real hardware, I observe obvious performance regression.
> 
> Thanks
> 
> ## Performance
> Tests on bananapi, for other platform, please check jbs issue for test data.
> 
> ### Before
> data
> <google-sheets-html-origin style="caret-color: rgb(0, 0, 0); color: rgb(0, 0, 0); font-style: normal; font-variant-caps: normal; font-weight: 400; letter-spacing: normal; orphans: auto; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; widows: auto; word-spacing: 0px; -webkit-text-stroke-width: 0px; text-decoration: none;">
> Benchmark - keep intrinsic | (maxNumbits) | (size) | Mode | Cnt | Score | Error | Units
> -- | -- | -- | -- | -- | -- | -- | --
> o.o.b.j.lang.Integers.compress | N/A | 500 | avgt | 10 | 11710.439 | 17.936 | ns/op
> o.o.b.j.lang.Integers.expand | N/A | 500 | avgt | 10 | 14878.742 | 23.472 | ns/op
> o.o.b.j.lang.Longs.compress | N/A | 500 | avgt | 10 | 24555.06 | 2.632 | ns/op
> o.o.b.j.lang.Longs.expand | N/A | 500 | avgt | 10 | 35827.714 | 25.022 | ns/op
> 
> </google-sheets-html-origin>
> 
> 
> ### After
> data
> <google-sheets-html-origin style="caret-color: rgb(0, 0, 0); color: rgb(0, 0, 0); font-style: normal; font-variant-caps: normal; font-weight: 400; letter-spacing: normal; orphans: auto; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; widows: auto; word-spacing: 0px; -webkit-text-stroke-width: 0px; text-decoration: none;">
> Benchmark - remove intrinsic | (maxNumbits) | (size) | Mode | Cnt | Score | Error | Units
> -- | -- | -- | -- | -- | -- | -- | --
> o.o.b.j.lang.Integers.compress | N/A | 500 | avgt | 10 | 9294.835 | 1.459 | ns/op
> o.o.b.j.lang.Integers.expand | N/A | 500 | avgt | 10 | 5749.835 | 0.945 | ns/op
> o.o.b.j.lang.Longs.compress | N/A | 500 | avgt | 10 | 4735.15 | 1.082 | ns/op
> o.o.b.j.lang.Longs.expand | N/A | 500 | avgt | 10 | 5668.552 | 2.168 | ns/op
> 
> </google-sheets-html-origin>

Thanks for performing the test. Revert change looks good.

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Marked as reviewed by fyang (Reviewer).

PR Review: https://git.openjdk.org/jdk/pull/22102#pullrequestreview-2435923360