On Tue, 24 May 2022 15:28:27 GMT, Maurizio Cimadamore <mcimadam...@openjdk.org> 

>> Constructing indexed var handles using the `MemoryLayout` API produces 
>> `VarHandle` which do not check the input indices for out-of-bounds 
>> conditions.
>> While this can never result in a VM crash (after all the memory segment will 
>> protect against "true" OOB access), it is still possible for an access 
>> expression to refer to parts of a segment that are logically unrelated.
>> This patch adds a "logical" bound check to all indexed var handles generated 
>> using the layout API.
>> Benchmarks are not affected by the check. Users are still able to create 
>> custom "unchecked" var handles, using the combinator API in `MethodHandles`.
> Maurizio Cimadamore has updated the pull request incrementally with one 
> additional commit since the last revision:
>   Tweak javadoc for ValueLayout::arrayElementVarHandle

src/java.base/share/classes/java/lang/foreign/MemoryLayout.java line 374:

> 372:      *
> 373:      * Additionally, the provided dynamic values must conform to some 
> bound which is derived from the layout path, that is,
> 374:      * {@code 0 <= x_i <= b_i}, where {@code 0 <= i <= n}, or {@link 
> IndexOutOfBoundsException} is thrown.


     * {@code 0 <= x_i < b_i}, where {@code 1 <= i <= n}, or {@link 
IndexOutOfBoundsException} is thrown.

We refer later to `B` being an exclusive upper bound (computed using `ceilDiv`).


PR: https://git.openjdk.java.net/jdk/pull/8868

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