When working on startup improvements, I noticed that the method handle returned by `MemoryLayout::offsetHandle` can overflow if the client calls the handle with a base offset that is too big.
In other similar situations, the layout API always fails with `ArithmeticException` (see `MemoryLayout::scale`), so we should do the same here. The fix is to use a `Math::addExact(long, long)` for the outermost add operation in the computation of the offset method handle. That outermost computation in fact is the only one that can overflow: it is an addition between a user-provided base offset `B` and a layout offset `L`. `L` is guaranteed not to overflow, by construction (as `L` is derived from a layout path). But `B` + `L` might overflow, so the new logic checks for that. ------------- Commit messages: - Initial push Changes: https://git.openjdk.org/jdk/pull/20662/files Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=20662&range=00 Issue: https://bugs.openjdk.org/browse/JDK-8338731 Stats: 23 lines in 3 files changed: 14 ins; 1 del; 8 mod Patch: https://git.openjdk.org/jdk/pull/20662.diff Fetch: git fetch https://git.openjdk.org/jdk.git pull/20662/head:pull/20662 PR: https://git.openjdk.org/jdk/pull/20662
