A. before calling process.
|stack|
| ... |
| z |
| &z |
| y |
| x | <- %rsp
B. The first address of s, %rsp + 64.
C. %rsp + offset
D. u[0] in %rdi, u[1] in %rdi + 8, y in %rdi + 16, and return %rdi.
E. return from process.
|stack|
| ... |
| z |
| x |
| y | <- %rdi
| ... |
| z |
| &z |
| y |
| x | `eval`'s %rsp
| | `process`'s %rsp
F. The stack address.