> That did happen in practice as programmers used the highest bits to stuff metadata and relied on the automatic masking The old Mac OS did this: https://en.wi

> That did happen in practice as programmers used the highest bits to stuff metadata and relied on the automatic masking The old Mac OS did this: https://en.wikipedia.org/wiki/Mac_OS_memory_management#32-bit_clean https://en.wikipedia.org/wiki/Mac_OS_memory_management#32-bi...