I posted above, but most of the 'really hard' bits come from the unreasonable complexity of actual computing vs the more manageable complexity of computing-with-idealized-software.

That is, an algorithm and compiler and tool safety smoke test and improvement thereby is good. But you also need to think hard about what happens when someone induces an RF pulse at specific timings targeted at a certain part of a circuit board, say, when you're trying to harden these algorithmic implementations. Lots of things that compiler architects typically say is "not my problem".