[jdk16u] RFR: 8258946: Fix optimization-unstable code involving signed integer overflow

[Tobias Hartmann]

On Mon, 1 Feb 2021 15:58:13 GMT, Vladimir Kozlov <kvn at openjdk.org> wrote:

>> Backport of [JDK-8258946](https://bugs.openjdk.java.net/browse/JDK-8258946). Applies cleanly.
>
> Good.

Thanks for the review, Vladimir!

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PR: https://git.openjdk.java.net/jdk16u/pull/9