Yeah, even with assembly, your timing guarantees are limited on modern architectures. But if you REALLY need something specific from the machine, that's where you go.
CPUs are actually much better at making those guarantees than compilers are.
https://lore.kernel.org/all/851920c5-31c9-ddd9-3e2d-57d379aa...
In other words, they have announced the possibility of breaking that guarantee years before touching it, which is something the clang developers would never do.
Even most managed languages provide a way to get down into Assembly dumps from their AOT and JIT compiler toolchains.
Maybe we need some TikTok videos showing how to do such workflows.
If you are doing really low level stuff, sometimes it’s worth rolling out your own little RTOS with just the bits and pieces you need.
Not that long ago, I realised most 8-bit (and MS-DOS) computer games had their own RTOS woven into the game code, with multi-tasking, hardware management, IO, and so on.