RFR: 8315841: RISC-V: Check for hardware TSO support [v8]

[Ludovic Henry]

On Mon, 11 Sep 2023 06:41:36 GMT, Fei Yang <fyang at openjdk.org> wrote:

>> Ludovic Henry has updated the pull request incrementally with one additional commit since the last revision:
>> 
>>   fixup! 8315841: RISC-V: Check for hardware TSO support
>
> LGTM. Any tests performed?

@RealFYang I've tested with jcstress on QEMU on x86 with the change and with an obvious breakage (not emitting barriers at all). It would fail when not emitting barriers at all (makes sense, x86 is not a sequential consistency memory model) and it would succeed with this patch (also makes sense given x86 is a TSO).

It's obviously lacking testing on an actual hardware that supports TSO and RVWMO, but I'm not aware of any on the market at the moment. We (Rivos) will make sure to test as soon as we have our hardware available, and we'll report back.

-------------

PR Comment: https://git.openjdk.org/jdk/pull/15613#issuecomment-1713364178