Notice I'm being careful to mention semantics not performance(although those semantics largely help with the latter). The ASM<->C bridge is much smaller since y

Notice I'm being careful to mention semantics not performance(although those semantics largely help with the latter). The ASM<->C bridge is much smaller since you're talking about registers and possibly custom instructions that are usually exposed via intrinsics. For me the dividing line is if your language abstracts away memory management. If I don't get control over where memory lives and how I access it not low level. PC is this nice homogeneous memory structure but there's many systems that have specific semantics around different address spaces and you may need to be able to access and manipulate them in specific ways.