Computer Architect questions: C TO MIPS

Question

a)
Assume the following C code. Translate both functions to MIPS using the caller callee conventions as presented in class. Do not translate the print statement:
int main(){

int g=0; /*global variable */

int u= fib(5);

printf("%d",g); /*print the number of times you called fib */
}
int fib(int n){

g+=1 /*increase global variable every time you have a funtion call */

if (n==0) return 0;

else

if (n==1) return 1;

else

return fib(n-1) +fib(n-2);}


b)What is printed by the previous program? For arbitrary n what is the formula that gives g (i.e. How many times if fib(n) being called for arbitrary n)? Is fib effective? Explain

c)Rewrite a for Loop definition for fib and translate it to MIPS code.

d) Can you achieve the same effectiveness with a recursive definition? Give a fib implementation that behaves like a for loop given that your compiler optimizes tail call elimination(hint: the new function should have 3 arguments) .Give the MIPS code produced in such a compiler.

Answer 1

g(int*, int):

        daddiu  $sp,$sp,-64

        sd      $31,56($sp)

        sd      $fp,48($sp)

        sd      $28,40($sp)

        sd      $16,32($sp)

        move    $fp,$sp

Little bit code...Feel free to connect with me if you need more specific help