The problem is backward compatibility with external linking because this expects another word on the call stack. It also relies on the programmer to be smart ab

The problem is backward compatibility with external linking because this expects another word on the call stack. It also relies on the programmer to be smart about bounds, which, they’re already intentionally ignoring, so, I don’t know. However, there are some attempts at a hardware solution to provide memory safety without modifying the stack: https://en.m.wikipedia.org/wiki/Intel_MPX https://en.m.wikipedia.org/wiki/Intel_MPX. At array creation time, the pointer bounds are loaded into a register and the address is translated between a safe address and a real address. I don’t actually know if this works in a transparent backward-compatible way, as in, ignoring unregistered pointers and translating without being told to. I should also mention that AddressSanitizer also does something similar in software, and is becoming ubiquitous. The performance/size penalties are significant, bu it seems to me that the hardware translation should be fast if it is separately integrated with the existing cache address translation and memory bus.