Most C compilers (including the GCC compilers) allow a user to ex- amine the machine instructions generated for a given source program. Run the following program through such a C compiler and examine the instructions generated for the for loop. Next, recompile the program, enabling optimization, and reexamine the instructions generated for the for loop. What improvements have been made? Assuming that the program spends all of its time in the for loop, estimate the speedup obtained. Write a suitable main C function that allocates and initializes a million-element array to pass to proc. Execute and time the unopti- mized and optimized versions of the program and evaluate the accuracy of your estimate.

int proc(int a[]) {

int sum = 0, i; for (i=0; i < 1000000; i++)

sum += a[i];

return sum;

}