What about datetime, random, system, etc?
More generally, using system calls directly for things like getting the current time makes sense only if you don't care about portability.
C can support both portable and non-portable code. Both are important.
I get the impression that C is too high-level, and assembly language is too tedious, to fully support your requirements. I sympathize with your situation, but it's not one that most programmers share.
Definitely seems that way to me as well. Still, if I bend C enough it turns into something that's almost what I want. I just wish GCC had a couple more flags to control code generation in these surprising cases.