Failures in large eBPF programs with complex control flow can be hard to analyze. Of particular concern is that an assertion failure can result in invariants being removed from the post-invariant set, which causes a cascade of subsequent assertion failures which strip invariants.

Locating the initial invariant violation that triggers this cascade of failures can be challenging assuming the failures are printed in label order (as labels don't necessarily match the control flow).

One possible solution is to provide an option to print errors in WTO (weak topographical order), which will tend to place initial failures earlier in the list of failures.

A recent case in point is a verification failure in a Cilium program, where a single correlated branch failure triggers around 500 subsequent failures. Because of significant inlining and branch folding by LLVM, the initial failure was present in the middle of the list of 500 failures making it difficult to locate.

When sorting the errors in WTO, the failure is close to the top of the list.