RFR: 8351949: RISC-V: Cleanup and enable store-load peephole for membars [v4]

[Robbin Ehn]

On Tue, 18 Mar 2025 07:10:35 GMT, Fei Yang <fyang at openjdk.org> wrote:

>> Robbin Ehn has updated the pull request incrementally with one additional commit since the last revision:
>> 
>>   Review comments
>
> src/hotspot/cpu/riscv/riscv.ad line 7979:
> 
>> 7977:   ins_cost(VOLATILE_REF_COST);
>> 7978: 
>> 7979:   format %{ "membar_volatile_rvtso\n\t"
> 
> It's a bit confusing to me to see this `membar_volatile_rvtso` followed by a `fence w, r`.
> Seems better if we put a `#@` prefix making it a code comment for this `fence w, r` in the opto assembly.
> I mean: `#@membar_volatile_rvtso`

No other platform uses '@' in their ad files?
E.g.

  format %{ "membar_acquire\n\t"
                     "dmb ishld" %}


It just looked weird that riscv have it's special way to format things.

I can agree with '#', but why add a @ ?

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PR Review Comment: https://git.openjdk.org/jdk/pull/24035#discussion_r2000474785