It's not obvious how prefetching the next address would make things run that much faster - you don't know a given address until you execute the load. That said, there is definitely an extra cycle in your dependency chain to do the XOR, which you might well notice if your linked list is in cache (that extra cycle will show up).
We had a discussion on Twitter about some sort of superfast magic prefetcher that may well have been on the M1 which arguably could shave some cycles off list traversal, and there was a theory that an XOR-list would have been a good negative benchmark to prove/disprove this, but nothing came of it.
The limitation is worse than you say; you can't even navigate from an item just by knowing its address (not just remove/erase something). So any given iterator into this list has to have 2 pointers (say, the item and its predecessor).
It's a weird structure. There's probably almost certainly some peculiar use case for it somewhere, but I've never encountered such a case.
We had a discussion on Twitter about some sort of superfast magic prefetcher that may well have been on the M1 which arguably could shave some cycles off list traversal, and there was a theory that an XOR-list would have been a good negative benchmark to prove/disprove this, but nothing came of it.
The limitation is worse than you say; you can't even navigate from an item just by knowing its address (not just remove/erase something). So any given iterator into this list has to have 2 pointers (say, the item and its predecessor).
It's a weird structure. There's probably almost certainly some peculiar use case for it somewhere, but I've never encountered such a case.