Document raw pointer <-> usize casts.
@@ -360,6 +360,10 @@ Here `*T` means either `*const T` or `*mut T`.
* `char` casts to the value of the code point, then uses a numeric cast if needed.
* `u8` to `char` cast
* Casts to the `char` with the corresponding code point.
+* Pointer to address cast
+ * Casting from a valid raw pointer to `usize` will produce a numeric address representing the pointer.
+* Address to pointer cast
+ * Casting from `usize` to a raw pointer will produce a pointer with the same value as the original pointer if the `usize` was obtained through a pointer to address cast of a valid pointer of the same type.
\* if integer-to-float casts with this rounding mode and overflow behavior are
not supported natively by the hardware, these casts will likely be slower than
