3 ms·

Are pointers in this environment bigger than usual? Or do they point at a descriptor that then points at (or contains) the real object? How does type punning

• stensal 8y ago
  No, the pointer always has the native pointer size. I think the type in my use of "dynamic type system" confused you. The type has a very narrow meaning, it has only two values. It is either POINTER or NON_POINTER. A POINTER type is like a tuple of size and liveness. It does not track the static types like integer, float, or struct, etc. Hope this clarify it. Perhaps, I should call it 'dynamic pointer tracking system'. Does it sound more clear?
  • cryptonector 8y ago
    That helps. In my mind I was picturing a double-wide pointer that (assuming 48-bit address spaces) carries 20 bits of type information, a pointer to an allocation descriptor, a pointer to / into the object, and 16-bit CRC of the allocation descriptor. The allocation descriptor itself would have a base address and size, a generation number, and maybe some bits for something else (what? perhaps another CRC?). However, this would change the ABI... And yes, I thought you were encoding the C type of the object pointed to in the pointer, which is why I was thinking wide pointers. Thanks for the clarification!
    • stensal 8y ago
      I changed it to "dynamic pointer typing". Thanks for your questions.