RFR: 8310656: RISC-V: __builtin___clear_cache can fail silently. [v2]

[Robbin Ehn]

On Sat, 1 Jul 2023 10:34:48 GMT, Robbin Ehn <rehn at openjdk.org> wrote:

>> src/hotspot/os_cpu/linux_riscv/riscv_flush_icache.cpp line 62:
>> 
>>> 60: bool RiscvFlushIcache::test() {
>>> 61:   long ret;
>>> 62:   intptr_t end = ((intptr_t)&ret) + 64;
>> 
>> It looks a little bit odd to me here as `ret` is only 8 bytes. Maybe define a local array of 64 bytes and operate on that?
>
> We are not flushing ret, but the one/two cachelines around ret, since we know they are valid. (we just created the current frame(s) on to it)
> Ret is only used to get an stack address in current frame, i.e.. it could have been char just as well.
> 
> But I can change since this was obviously not clear.

Fixed, thanks!

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PR Review Comment: https://git.openjdk.org/jdk/pull/14670#discussion_r1248772332