How would you modify the standard and/or optimization passes for the first example in the article?
As soon as your first pass decides to rely on the presence of the dereference as a reason for removing the null check, the dereference needs to be flagged as critical, such that it cannot be removed by a subsequent pass.
Better still, if the compiler does try to remove something that was relied on by an earlier optimization step, alert the user that something is probably wrong with the code.
Also, this would prevent one of the main benefits of function inlining. Once you have inlined a function, the values of some of the parameters may be known at compile time, resulting in lots of those if(0) parameters. But that is something that was relied on in previous passes, even though it is known to be a static value in the current pass.