[foreign-memaccess+abi] RFR: 8274157: java.foreign: Add method MemorySegment::isOverlapping

[Radoslaw Smogura]

On Tue, 28 Sep 2021 12:59:19 GMT, Julia Boes <jboes at openjdk.org> wrote:

> This change adds a method to the MemorySegment API that detects if two segments are overlapping.

src/jdk.incubator.foreign/share/classes/jdk/internal/foreign/AbstractMemorySegmentImpl.java line 272:

> 270:             final long thisEnd = thisStart + this.byteSize() - 1L;
> 271:             final long thatEnd = thatStart + that.byteSize() - 1L;
> 272:             if (thisStart < thatStart && thisEnd >= thatStart) {

Not sure if this is relevant, would it make sense to replace this checks by
`thisStart <= thatEnd && thisEnd >= thatStart`
I think it can be more performant.

Maybe we will be able to drop subtract of 1 and use strong equality

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PR: https://git.openjdk.java.net/panama-foreign/pull/585