RFR: 8295282: Use Zicboz/cbo.zero to zero-out memory on RISC-V [v8]

[Vladimir Kempik]

On Fri, 21 Oct 2022 09:10:02 GMT, Ludovic Henry <luhenry at openjdk.org> wrote:

>> Similarly to AArch64 DC.ZVA, the RISC-V Zicboz [1] extension provides the cbo.zero [2] instruction that allows to zero out memory a cache-line at a time. This should be faster than storing zeroes 64bits at a time.
>> 
>> [1] https://github.com/riscv/riscv-CMOs
>> [2] https://github.com/riscv/riscv-CMOs/blob/master/cmobase/Zicboz.adoc#insns-cbo_zero
>
> Ludovic Henry has updated the pull request incrementally with one additional commit since the last revision:
> 
>   Remove unused movptr(Label)

I think in some near feature well need to group all of this "UseZicbom,UseZicbop,UzeZba, etc.." flags under one umbrella flag - .e.g UseAppProfile22, and cache line size would be a part of it too.

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PR: https://git.openjdk.org/jdk/pull/10718