[jdk21u] RFR: 8316396: Endless loop in C2 compilation triggered by AddNode::IdealIL

[Tobias Hartmann]

On Mon, 16 Oct 2023 19:32:21 GMT, Aleksey Shipilev <shade at openjdk.org> wrote:

> Clean backport to fix potential C2 problem. "Potential", because neither of fuzzer tests from the issue, nor the new regression test actually triggers the issue. I suppose that is because some other C2 optimization/bugfix is missing. However, it seems profitable to protect from this issue in 21u as well. @TobiHartmann, do you agree?
> 
> Additional testing:
>  - [x] macos-aarch64-server-fastdebug, new regression test passes before and after the patch
>  - [x] linux-aarch64-server-fastdebug, `tier1 tier2 tier3`

Yes, looks good to me.

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

Marked as reviewed by thartmann (Reviewer).

PR Review: https://git.openjdk.org/jdk21u/pull/259#pullrequestreview-1682044917