In a project I'm working on[0], there's an array object type used throughout, which can sometimes point to arbitrary data elsewhere. In a funky edge-case[1], such an array can be built with an unaligned data pointer.

Thus, if gcc/clang started seriously utilizing aligned pointer accesses everywhere, nearly every single load & store in the entire project would have to be replaced with something significantly more verbose. Maybe in a more fancy language you could have ptr<int> vs unaligned_ptr<int> or similar, but in C you kinda just have compiler flags, and maybe __attribute__-s if you can spare some verbosity.

C UB is often genuinely useful, but imo having an opt-out option for certain things is, regardless, a very reasonable request.

[0]: https://github.com/dzaima/CBQN

[1]: Any regularly allocated array has appropriate alignment. But there are some functions that take a slice of the array "virtually" (i.e. pointing to it instead of copying), and another one that bitwise-reinterprets an array to one with a different element type (again, operating virtually). This leads to a problem when e.g. taking i8 elements [3;7) and reinterpreting as an i32 array. A workaround would be to make the reinterpret copy memory if necessary (and this would have to be done if targeting something without unaligned load/store), but that'd ruin it being a nice O(1).