I'm particularly excited for top byte ignore, as it can be used for some pretty creative things. In Vale, we're planning on storing a small "offset-to-generati

I'm particularly excited for top byte ignore, as it can be used for some pretty creative things. In Vale, we're planning on storing a small "offset-to-generation" integer in the top bits. This will let us easily find the top of the allocation that contains the object we're pointing to. When the user doesn't want to use the opt-in region borrow checker, this mechanism helps provide an easy fallback. The technique could theoretically also be used for RC'd languages to allow taking references to the interior of objects, which (I believe) would help those languages close the gap between them and high-performance languages like Rust, Zig, Vale, etc. I hope it catches on with more CPUs. Another reason I'm excited for memory tagging is that it can somewhat reliably help identify memory unsafety in development/testing. Perhaps a low-level language (Zig? Odin?) could even make it work correctly in the presence of tagless unions, to enable a more efficient alternative to tagged unions (like in Rust) for certain situations.