Meh, the problem is the preprocessor. A lot of really silly things are produced by macro expansion, so the "obviously silly" optimizations really do end up mattering.
That sounds interesting, but I'm suspicious. Do you have any examples of such macros and maybe some statistics or ideas how often they are actually seen in the wild?
There are also libraries such as libCello[0] and Viola[1] (mine) to really simplify C through macros. libCello is some really cool stuff.