The object is evacuated (copied) to its destination generation. The destination is given by bd->dest pointer in the bdescr of the
block in which it lives; typically an object is promoted to the next highest generation, but the basic policy is affected by aging and eager promotion.
The header word of the original object is replaced by a forwarding pointer. The forwarding pointer is just the pointer to the new copy, with the least significant bit set to 1 so that forwarding pointers can be distinguished from info table pointers.
We scan objects that have been evacuated, and scavenge each one. Scavenging involves evacuating each of the pointers
in the object, replacing each pointer with a pointer to the evacuated copy.
When there are no more objects to be scavenged, the algorithm is complete. The memory containing the evacuated objects is retained, all the memory containing the old objects and forwarding pointers is discarded.