The following declaration defines a class of structures for use in constructing binary trees:

1 typedef struct ELE *tree_ptr; 2 3 struct ELE { 4 long val; 5 tree_ptr left; 6 tree_ptr right; 7 }; For a function with the following prototype: long trace(tree_ptr tp); gcc generates the following x86-64 code:

1 trace: tp in %rdi 2 movl $0, %eax 3 testq %rdi, %rdi 4 je .L3 5 .L5: 6 movq (%rdi), %rax 7 movq 16(%rdi), %rdi 8 testq %rdi, %rdi 9 jne .L5 10 .L3: 11 rep 12 ret A. Generate a C version of the function, using a while loop.