I was an engineering manager for a commercial C/C++ toolchain used in embedded systems development. We, and our customers, examined the generated code continously. In our case, to figure out better optimizations (and fix bugs). For some of our customers, because their device had severe memory constraints or trying to do difficult performance optimizations.

Moving up to an MMU and running Linux was a different (more abstract) world. Although since it was embedded, low-level functions might still be in both assembly and C if not the apps on top.