Capabilities and Limitations of Optimizing Compilers

Computer Systems A Programmer's Perspective Second Edition

#include <stdio.h>

main(){
    int wr;
    wr = func1();
//    wr=func2();
    printf("%d",wr);
}

int counter = 0;
int w(){
    return counter++;
}

int func1(){
    return w()+w()+w()+w();
}

int func2(){
    return 4*w();
}

 

Modern compilers employ sophisticated algorithms to determine what values are

computed in a program and how they are used.