RFR: 8344393: RISC-V: Remove option UseRVVForBigIntegerShiftIntrinsics

[Hamlin Li]

On Mon, 18 Nov 2024 11:25:15 GMT, Fei Yang <fyang at openjdk.org> wrote:

> Seem that it's more reasonable to control BigInteger shift intrinsics with`UseRVV` option.
> I witnessed performance benefit on BPI-F3 with the RISC-V vector extension. And it's still
> possible to disable these two intrinsics with `-XX:DisableIntrinsic` option if we want.
> 
> JMH on BPI-F3 (has vector 1.0) for reference:
> 
> Without instrinsic:
> BigIntegers.testLeftShift                        N/A  avgt   15      4083.865 ±   224.139  ns/op
> BigIntegers.testRightShift                       N/A  avgt   15      1745.833 ±    44.855  ns/op
> 
> With instrinsic:
> BigIntegers.testLeftShift                        N/A  avgt   15      2243.095 ±    24.821  ns/op
> BigIntegers.testRightShift                       N/A  avgt   15      1558.770 ±    36.191  ns/op

Make sense to me. Thanks!

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Marked as reviewed by mli (Reviewer).

PR Review: https://git.openjdk.org/jdk/pull/22202#pullrequestreview-2442401523