It feels like a leaky abstraction, and similarly implies there should be some way to drop down a layer and work directly with what’s beneath. Something in between C and non-portable assembly.

Asserting retroactively that compilers produce the correct assemvbly feels like just plain giving up on everything in between. Surely the best we can do isn’t a bunch of flaky weirdly interacting optimizations, UB footguns everywhere, things changing when updating the toolchain, etc?