RFR: 8296975: RISC-V: Enable UseRVA20U64 profile by default

[Fei Yang]

On Tue, 15 Nov 2022 04:05:35 GMT, Xiaolin Zheng <xlinzheng at openjdk.org> wrote:

> The main purpose is to turn the option `UseRVC` on by default before JDK20 RDP 1. As per discussions [1], we can enable `UseRVA20U64`[2] by default to fulfill this.
> 
> 
>> build/linux-riscv64-server-fastdebug/images/jdk/bin/java -XX:+PrintFlagsFinal -version | grep -E "UseRVC|UseRVA20U64"
>      bool UseRVA20U64                              = true                                 {ARCH product} {default}
>      bool UseRVC                                   = true                                 {ARCH product} {default}
> openjdk version "20-internal" 2023-03-21
> OpenJDK Runtime Environment (fastdebug build 20-internal-adhoc..jdk)
> OpenJDK 64-Bit Server VM (fastdebug build 20-internal-adhoc..jdk, mixed mode)
> 
> 
> [1] https://mail.openjdk.org/pipermail/riscv-port-dev/2022-November/000668.html
> [2] https://github.com/openjdk/jdk/blob/873eccde01895de06e2216f6838d52d07188addd/src/hotspot/cpu/riscv/vm_version_riscv.cpp#L39-L44
> 
> Thanks,
> Xiaolin

You might want to disable UseRVA20U64 when the C extension is not available at the same time.

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PR: https://git.openjdk.org/jdk/pull/11155