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

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

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

Modern compilers employ sophisticated algorithms to determine what values are

computed in a program and how they are used.