RFR: 8320995: RISC-V: C2 PopCountVI [v4]

[Fei Yang]

On Tue, 7 May 2024 16:00:07 GMT, Hamlin Li <mli at openjdk.org> wrote:

>> Hi,
>> Can you help to review this patch?
>> Both auto-vect and vector api depends on this intrinsic.
>> Thanks!
>> 
>> ## Performance
>> Not performance test was done, as this depends on vcpop.v instruction in zvbb extension and the code seqeunce is rather simple than non-intrinsic version.
>
> Hamlin Li has updated the pull request incrementally with one additional commit since the last revision:
> 
>   minor fix

One minor comment remains, otherwise looks good. Thanks.

test/hotspot/jtreg/compiler/vectorization/TestPopCountVectorLong.java line 30:

> 28: * @requires ((os.arch=="x86" | os.arch=="i386" | os.arch=="amd64" | os.arch=="x86_64") & vm.cpu.features ~= ".*avx512bw.*") |
> 29: *           os.simpleArch == "aarch64" |
> 30: *           (os.arch == "riscv64" & vm.cpu.features ~= ".*zvbb,.*")

Suggestion: `(os.arch == "riscv64" & vm.cpu.features ~= ".*zvbb.*")`
The comma should not be there. See: https://bugs.openjdk.org/browse/JDK-8327689

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Changes requested by fyang (Reviewer).

PR Review: https://git.openjdk.org/jdk/pull/19065#pullrequestreview-2044401508
PR Review Comment: https://git.openjdk.org/jdk/pull/19065#discussion_r1593228927