This is one of the most high-impact tools Google has. Although it is difficult to use and the data it produces hard to analyze, it can tell you things that no other tool can. My favorite mode is dead code coverage mode. At startup all the trace hooks are enabled. At first function entry the hook is logged and then disabled (overwritten with a run of nop). A function that hasn&#x27;t logged by the time the program exits may be dead code.