RAX is big enough to hold the entire structure. At 0x00000000004004c7 you're loading the entire structure (with mov), not its address (you'd use lea instead).
The x86-64 System V ABI's calling convention returns C structs up to 16 bytes in RDX:RAX or RAX. C++ on x86-64: when are structs/classes passed and returned in registers?
For larger structs, the there's a "hidden" output pointer arg passed by the caller.
