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This commit replaces the previous livelock detection heuristic with the implementation of a new algorithm that uses user-inserted progress transitions along with single schedule exploration beyond the max-transitions-depth bound to detect livelock.
The new flag, --explore-round-robin|-r can be used to alter the default scheduling behaviour: round-robin instead of lowest-thread-id-first.
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This commit implements the progress transition as a bookkeeping mechanism to detect long per-thread executions that do not make progress, indicating a livelock-like situation.
A per-thread no-progress counter is incremented for every transition. Whenever the target executes MC_PROGRESS(), the counter for the corresponding thread is reset. If at the end of execution, the no-progress counter for any thread exceeds a configurable threshold, the trace is then checked for cycles. A potential livelock is reported only when both conditions hold: no-progress and repetition.