Question

Translate function f into RISC-V assembly language. Assume the function declaration for g is int g(int a, int b). e code for function f is as follows: int f(int a, int b, int c, int d){ return g(g(a,b), c d); }

Answer 1

To translate the function f into RISC-V assembly language, we need to convert each line of the C code into RISC-V instructions using the stack to pass arguments and the return value. The RISC-V assembly language code will include instructions to copy values, call the function g, and store the return value. Finally, we use the return value of the second g call as the result of the function f.

Step-by-step explanation:

To translate the function f into RISC-V assembly language, we need to convert each line of the C code into RISC-V instructions.

1. First, we need to translate the inner call to the function g. Since the return value of g(a, b) is used as the first argument to g, we can use the stack to pass arguments and the return value. Here's an example:
2. 
   
3. 
   
4. addi t0, a0, 0 // Copy a to t0
5. 
   
6. addi t1, a1, 0 // Copy b to t1
7. 
   
8. call g // Call g(a, b)
9. 
   
10. addi a0, v0, 0 // Copy the return value to a0
11. 
    
12. call g // Call g(return value, c, d)
13. 
    
14. 
    
15. For the second call to g with arguments (return value, c, d), we use a0 (which now holds the return value of the first g call) as the first argument, and c and d as the second and third arguments respectively. Here's an example:
16. 
    
17. 
    
18. addi t2, a2, 0 // Copy c to t2
19. 
    
20. addi t3, a3, 0 // Copy d to t3
21. 
    
22. addi a0, v0, 0 // Copy return value of previous g call to a0
23. 
    
24. call g // Call g(return value, c, d)
25. 
    
26. 
    
27. Finally, we can use the return value of the second g call as the result of the function f. Here's an example:
28. 
    
29. 
    
30. addi a0, v0, 0 // Copy return value of previous g call to a0
31. 
    
32. jal ra // Jump and link to return from the function f

Answer 2

int f(int a, int b, int c) {

return func(func(a, b), c);

}

f: addiu $sp, $sp, -8 # allocate frame = 8 bytes

sw $ra, 0($sp) # save return address

sw $a2, 4($sp) # save c

jal func # call func(a,b)

move $a0, $v0 # $a0 = result of func(a,b)

lw $a1, 4($sp) # $a1 = c

jal func # call func(func(a,b),c)

lw $ra, 0($sp) # restore return address

addiu $sp, $sp, 8 # free stack frame

jr $ra # return to caller