The main sting here seems to be that MemorySegment when allocated from Java code requires bounds checks on all accesses, which the JVM cannot optimise away on r

The main sting here seems to be that MemorySegment when allocated from Java code requires bounds checks on all accesses, which the JVM cannot optimise away on random accesses. However, MemorySegment itself already supports unbounded access when wrapping a native pointer. It’s necessary for even basic interactions with native code (e.g. reading a c-str). It should be easy to “wash” an off-heap MemorySegment through native code to obtain an unbounded MemorySegment from it. Something like: void *vanish_bounds(void *ptr) { return ptr; } I think it would be nice if the FFI provided a way to get an unbounded MemorySegment without resorting to native code hacks though. It can obviously be made restricted like unbounded MemorySegment’s already are. That should take most of the sting out of this proposal (although it still sounds like a painful transition for a very modest gain).