A CIL Tutorial - Department of Computer Science - ETH Zürich

CHAPTER 4. INSTRUMENTATION 40
4.2 tut4.c
In this C le, we dene the two functions added by src/tut4.ml. tut begin loop currently does
nothing, but a more sophisticated analysis may wish to do some bookkeeping before each loop, so
we include it as a placeholder. tut end loop simply outputs the number of iterations that a loop
completed. We use c-1 because the counter is incremented at the top of the loop before the exit
test.
../ciltut-lib/src/tut4.c
# include
void tut_begin_loop(const char *f, int l) {}
void tut_end_loop(const char *f, int l, int c)
{
printf("loop: %s:%d - %d times\n", f, l, c - 1);
fflush(stdout);
return;
}
4.3 test/tut4.c
We can test the instrumentation on the small example below. At the end of each loop the instrumented
code will print a message stating how many iterations there were. Thus, we should get 10
messages for the inner loop stating that there were 5 iterations, and one message for the outer loop
stating that there were 10 iterations.
# include
int main()
{
int i, j;
int c = 1;
for (i = 0; i < 10; i++) {
for (j = 0; j < 5; j++) {
c *= i;
}
}
../test/tut4.c
}
return 0;
Now, we can build the test program by doing the following: