Uh, no. Assuming 32-bit pointers, you'd add or subtract them using normal unsigned arithmetic which is modulo 2^32. Essentially the same trick definitely works

Uh, no. Assuming 32-bit pointers, you'd add or subtract them using normal unsigned arithmetic which is modulo 2^32. Essentially the same trick definitely works because all these operations (adding/subtracting/xoring a number) are invertible. The neat thing about xoring with a number is simply that that operation is its own inverse.