Non-Silent Exit if Wrong Subroutine is Given

[FabianSchuetze]

The change notify users that a wrong subroutine argument is given. Currently class such as halide_benchmarks sgemm 1024 return immediately without a message.

[alexreinking]

Happy to merge this, but I'm curious how you encountered it? Normally, we run these tests via CTest.

[FabianSchuetze]

Thanks, @alexreinking, for the encouragement.

I think Halide's apps are a gem, and I use them often.

After building the linalg app, I just typed halide_benchmarks sgemm 1024 and forgot to _notrans specifier. The app then outputs nothing, and I would have appreciated short feedback (especially as the main function of the app already provides feedback).

[mcourteaux]

Shouldn't we print to cerr to catch this in ctest, or at least exit with status code 1?

[FabianSchuetze]

Good point about the output stream. My first inclination was to use cerr, but I did otherwise to keep symmetry with the main function.

The return code would also be interesting. I didn't do it to avoid refactoring too many functions in the call stack.

Happy to implement any of your suggestions, Martijn, though.

[alexreinking]

Shouldn't we print to cerr to catch this in ctest, or at least exit with status code 1?

Yeah, I think printing to std::cerr and calling abort(); is the right behavior here. While we're looking at this, why don't we also validate the char type value in main? There should be a final else branch down there.