> However, in Chata's case, it needs to access a RISC-V assembler from within its C++ code. The alternative is to use some ugly C function like system() to run external software as if it were a human or script running a command in a terminal.
Have you tried LLVM's C++ API [0]?
To be fair, I do think there's merit in writing your own assembler with your own API. But you don't necessarily have to.
I'm not likely to go back to assembly unless my employer needs that extra level of optimization. But if/when I do, and the target platform is RISC-V, then I'll definitely consider Ultraseembler.
> It's not clear when exactly exceptions are slow. I had to do some research here.
There are plenty of cppcon presentations [1] about exceptions, performance, caveats, blah blah. There's also other C++ conferences that have similar presentations (or even, almost identical presentations because the presenters go to multiple conferences), though I don't have a link handy because I pretty much only attend cppcon.
[0]: https://stackoverflow.com/questions/10675661/what-exactly-is...
[1]: https://www.youtube.com/results?search_query=cppcon+exceptio...