RFR: 8340241: RISC-V: Returns mispredicted [v12]

[Robbin Ehn]

On Tue, 15 Oct 2024 17:19:15 GMT, Robbin Ehn <rehn at openjdk.org> wrote:

>> As we are throwing an exception we get away with it in this case. (as in no test failures)
>> I was expecting that maybe some test would see it, as it maybe observable in some cases, but no test fails due to it. And then forgot about it :) 
>> 
>> As C1 only have a subset of registers available to the allocator we could use maybe use on of those to not override a local value which may be in the oopmap?
>
> Also note that this should be slow case, so here we can actually use **ra** as we are probably about to unwind the stack, which means all predictions will be wrong.

I'm thinking about x18.

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PR Review Comment: https://git.openjdk.org/jdk/pull/21406#discussion_r1801700582