Internal code reuse in apps and autoschedulers

[BachiLi]

Currently there is no easy way to reuse some internal code, which is causing code duplication for some autoschedulers. For example, the error/assertion macro (e.g. user_error) needs to be replicated by apps/autoscheduler.

[shoaibkamil]

Isn’t the fundamental problem here that these should not be apps, but should be something in the Halide namespace?

I don’t think we should use internal code like this in apps. That said, I don’t know if the situation for plugins is better.

[BachiLi]

Yeah this is mostly for autoscheduler plugins. So far it seems that the outstanding issue is the error macros. Not sure if there is other.

[steven-johnson]

See also #4349

[alexreinking]

Position: apps/ should not have access to any internal code, include paths, etc. They should be self-contained, and built as an end-user would build them. Thus, since autoschedulers are not apps, but plugins, they should be relocated and treated differently as discussed in #4349 #4053 .

Similarly, the code in tests/ straddles that boundary. Since they're fundamentally integration tests, not unit tests, and reference Halide.h, they should also be built separately and take the fully built libHalide as a dependency - again, in the same way a user would, just with somewhat more automation.

[steven-johnson]

Position: apps/ should not have access to any internal code, include paths, etc.

I regret I can give only a single +1

[abadams]

I also concur.

[alexreinking]

I will make violating this principle impossible in the CMake build, in that case.

[alexreinking]

Apps in #4644 are now built fully standalone.