typedef struct{ long a[2]; long *p; } strA; typedef struct{ long u[2]; long q; } strB; strB process(strA s){ strB r; r.u[0] = s.a[1]; r.u[1] = s.a[0]; r.q = *s.p; return r; } long eval (long x, long y, long z){ strA s; s.a[0] = x; s.a[1] = y; s.p = &z; strB r = process(s); return r.u[0] + r.u[1] + r.q; 

And the assembly is:

process: movq %rdi, %rax movq 24(%rsp), %rdx movq (%rdx), %rdx movq 16(%rsp), %rcx movq %rcx, (%rdi) movq 8(%rsp), %rcx movq %rcx, 8(%rdi) movq %rdx, 16(%rdi) ret eval: (x = %rdi, y = %rsi, z = %rdx) subq $104, $rsp movq %rdx, 24(%rsp) leaq 24(%rsp), %rax movq %rdi, (%rsp) movq %rsi, 8(%rsp) movq %rax, 16(%rsp) leaq 64(%rsp), %rdi call process movq 72(%rsp), %rax addq 64(%rsp), %rax addq 80(%rsp), %rax addq $104, %rsp ret 

A. We can see on line 2 of function eval that it allocates 104 bytes on the stack. Diagram the stack frame for eval, showing the values that it stores on the stack prior to calling process.

B. What value does eval pass in its cal to process?

C. How does the code for process access the elements of structure arguments?

D. How does the code for process set the fields of result structure r?

E. Complete your diagram of the stack frame for eval, showing how eval accesses the elements of structure r following the return from process.

F. What general principles can you discern about how structure values are passed as function arguments and how they are returned as function results?