C AND ASSEMBLY (2)

The following questions consider this sequence of assembly instructions that contains two functions f and g using the standard x86-64 calling conventions:

f: cmpq $-12, %rsi jne .L2 movq %rsi, %rax movq %rdi, %rsi movq %rax, %rdi call f ret .L2: addq $1, %rdi movq %rsi, %rax imulq %rdi, %rax ret g: leaq -8(%rdi), %rsi leaq (%rdi,%rdi,2), %rdi call f ret 

Fill in the blanks in the C code skeleton below using the most simplified expressions (and no spaces):

long f(long x, long y) { if (y == ) return f(, ); return ; } 

cond:

farg1

farg2

ret

Suppose f is called with -2 in %rdi and 3 in %rsi. Give the values of the following registers just before f returns. It is recommended that you start from the beginning of f and trace the values of these registers as each instruction gets executed.

%rdi:

%rsi:

%rax:

Suppose f is called with 4 in %rdi and -12 in %rsi. Give the values of the following registers just before the original call to f returns. Again, it is recommended that you trace the register values through each instruction execution.

rdi:

rsi

rax