[jdk21u-dev] RFR: 8287325: AArch64: fix virtual threads with -XX:UseBranchProtection=pac-ret

[Andrew Haley]

On Thu, 6 Jun 2024 08:20:25 GMT, Aleksey Shipilev <shade at openjdk.org> wrote:

> Clean backport to improve PAC-RET support with Virtual Threads. Also unblocks more Loom backports.
> 
> Additional testing on AL2023 (has modern GCC) and Graviton 3 (has PAC extensions), `server fastdebug`:
>  - [x] Seen `VMContinuations` disabled without the fix, kept enabled with the fix
>  - [ ] `all` tests pass
>  - [ ] `all` tests pass with configured `--enable-branch-protection`
>  - [x] `all` tests pass with configured `--enable-branch-protection` and `-XX:UseBranchProtection=pac-ret`

Do we have to?

-------------

PR Comment: https://git.openjdk.org/jdk21u-dev/pull/671#issuecomment-2151740195