The paper was specifically about hand doing your schedules, not the compiler doing them automagically, which is a huge pipe dream at any rate. For the programs in the class, you are looking at a few orders of magnitude in perf differences for different schedules, which is why the programmer needs control so they can be guaranteed the performance they are expecting. Compilers only reliably optimize at the few percentage point nice to have level.
You're right, I completely misunderstood the purpose of Halide. I read up on it and I see now that they simplify how developers can do the copious implementation by hand. The schedule must be specified by the developer, the compiler doesn't to that.
