Interior pointers and fast GC

[Nick Treleaven via Digitalmars-d]

On Saturday, 14 January 2017 at 15:30:42 UTC, Rainer Schuetze 
wrote:
> In addition, you need to lookup the pool anyway to figure out 
> if the pointer points to non-managed memory (stack, global 
> data, malloc'd memory).

Makes me wonder about a GC'd language where each pointer is 
actually a member of a struct which also has a base allocation 
pointer. The base pointer could either only be set for managed 
allocations, or the low bit of the base address could be used to 
indicate such instead*. This would make for faster GC scans, but 
would also cause slowdowns when copying pointers. Pointer 
arithmetic would be just as efficient though.

(*) With this scheme, pointer arithmetic can be @safe in assert 
mode.