A CIL Tutorial - Department of Computer Science - ETH Zürich

CHAPTER 10. ADDING A NEW KIND OF STATEMENT 89
10.3 Exercises
1. Given the example code in this chapter. It is straightforward to add statements that report
on other performance counters, both hardware and software. Look in linux/perf event.h,
and add another statement that proles a dierent performance counter.
2. We might also prole values that are specic to a particular application. Notice that, since
we know how to translate attribute parameters into C expressions, we could just as well have
allowed arguments to be passed to the proling statement we added, e.g. cache report(e) {}.
Extend this statement to accept the address of an integer value, whose value is proled instead
of a performance counter.
3. In ciltut-lib/src/ciltut libc.c, reading the performance counters is implemented only
for Linux. Implement perf get cache miss and perf get cache refs for another OS.
10.4 Further Reading
This technique for adding a new statement is exactly the same as the one used by the Shelters [1]
extension to C, which adds an atomic {} statement. The statement is replaced by calls into the the
Shelters language runtime, which enforces mutual exclusion in multithreaded programs for selected
objects touched inside of the statement.