Yes, inlining is one exception. Function variants for constant propagation are another. But both of those have been around for a long time and if neither of them apply compilers won't even reorder arguments where that makes sense or deviate from the platform calling convention based on register pressure inside the functions or drop unused arguments or reorder arguments if that improves things. Feels like in general internal function boundaries in the code should be just a hint to and optimizing compiler but somehow there has been very little development in that area. Similar for struct/class layout, compilers won't touch that even if they can see all uses.