Integrated: 8293654: Improve SharedRuntime handling of continuation helper out-arguments

[Aleksey Shipilev]

On Mon, 12 Sep 2022 16:59:45 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`

This pull request has now been integrated.

Changeset: 2baf2516
Author:    Aleksey Shipilev <shade at openjdk.org>
URL:       https://git.openjdk.org/jdk/commit/2baf2516e1d172268ec7c4c066a1b53bb0bf0779
Stats:     49 lines in 2 files changed: 32 ins; 12 del; 5 mod

8293654: Improve SharedRuntime handling of continuation helper out-arguments

Reviewed-by: dlong, kvn

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