RFR: 8293654: Improve SharedRuntime handling of continuation helper out-arguments [v3]

[Vladimir Kozlov]

On Tue, 13 Sep 2022 07:56:49 GMT, Aleksey Shipilev <shade at openjdk.org> wrote:

>> (Found this while adapting current mainline to x86_32 port)
>> 
>> After [JDK-8292584](https://bugs.openjdk.org/browse/JDK-8292584), we have `gen_continuation_yield()` that generates compiled entry, and implicitly uses the defaults for other ones (interpreter, exception). We should be more explicit about these, and verify the generators properly initialized all out-parameters.
>> 
>> I think we are only using interpreter/exception entry in `enterContinuation`, but not in `yield`. Notably, `exception_offset` should be `-1` for `nmethod::new_native_nmethod` to treat it as "no exception handlers". 
>> 
>> There a many ways to strengthen this, this PR is the one I like. I can do the symmetric change in aarch64, once we are agree on x86_64 version.
>> 
>> Additional testing:
>>  - [x] Linux x86_64 fastdebug, `hotspot_loom jdk_loom`
>>  - [x] Linux x86_64 fastdebug, `tier1`
>
> Aleksey Shipilev has updated the pull request incrementally with one additional commit since the last revision:
> 
>   Also handle AArch64 parts

Good.

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Marked as reviewed by kvn (Reviewer).

PR: https://git.openjdk.org/jdk/pull/10241