[pjmlp]

The thing with (x * 2) / 2 is that for all practical purposes you might even have written something else, so the expression cannot be replaced by x directly.

What happens is that after a few common expression eliminations, peephole optmisations, code inlining, and possibly other optimisation passes, the remaining AST will be (x * 2) / 2, and then the magic happens.

[matheusmoreira]

That makes sense... I agree, and I don't really have an elegant answer to that at the moment.

I simply accepted the fact that the magic might stop happening at (x * 2) / 2. This acceptance bought me certainty about overflow behavior. I think it was a good tradeoff.