Runtime autoschedule

[chkone]

I would like to run the auto-schedule at runtime for a Func not known at the compilation time.

For that I design a function:

class AutoScheduledDynamic : public Generator<AutoScheduledDynamic>
{
public:
	static GeneratorInput<Buffer<f32>>	oInput;
	static GeneratorOutput<Buffer<f32>>	oOutput;

	void generate()
	{
		oStart();
		Func oPassthrough{ "Passthrough" };
		oPassthrough( x, y, c ) = oInput( x, y, c );
		Func oOperation = oFunc( oPassthrough );
		oOutput( x, y, c ) = oOperation( x, y, c );
		oEnd();
	}

	void schedule()
	{
		if (auto_schedule)
		{
			oInput.set_estimates(oRegInput);
			oOutput.set_estimates(oRegOutput);
		}
	}

	static Region oRegInput;
	static Region oRegOutput;

	static std::function<Func(Func)> oFunc;
	static std::function<void()> oStart;
	static std::function<void()> oEnd;

	static Var x, y, c;
};

Where oFunc is defined on the code. We can imagine an stack of operations for image processing stacked by a user behind a UI.
Like:
Blur > Resize > ... > Sharpen
And we want to perform an autoschedule to have an overall optimization.

At the runtime level we do:

AutoScheduledDynamic::oRegInput = { {0, iWidth}, {0, iHeight}, {0, iChannel} };
AutoScheduledDynamic::oRegOutput = { {0, iWidth}, {0, iHeight}, {0, iChannel} };

auto ctx = Halide::GeneratorContext{ target, true, Halide::MachineParams{ GetCore(), 16777216, GetMemoryScale() } };


AutoScheduledDynamic::oStart = [iChannel]() {
	AutoScheduledDynamic::oInput.dim(0)
		.set_stride(iChannel)
		.dim(2)
		.set_stride(1)
		.set_extent(iChannel);
};
AutoScheduledDynamic::oFunc = &HERE_THE_OPERATIONS_STACKED;
AutoScheduledDynamic::oEnd = [iChannel]() {
	AutoScheduledDynamic::oOperation.reorder(
						AutoScheduledDynamic::c,
						AutoScheduledDynamic::x,
						AutoScheduledDynamic::y);
	AutoScheduledDynamic::oOperation.output_buffer()
		.dim(0)
		.set_stride(iChannel)
		.dim(2)
		.set_stride(1)
		.set_extent(iChannel);
};

To replace the macro:

auto factory = [](const Halide::GeneratorContext& context) -> std::unique_ptr<Halide::Internal::GeneratorBase> {
	return AutoScheduledDynamic::create(context, "gen_name", "gen_name");
};
Halide::Internal::RegisterGenerator reg_gen_name = Halide::Internal::RegisterGenerator("gen_name", factory);

As a toy-test I used:
Halide::Internal::generate_filter_main(18, const_cast<char**>(&values[0]), std::cout);

Nevertheless I have:
Unhandled exception: Error: Must use Output<> with generate() method.

I tried to add a dummy non-static GeneratorOutput<> which fix that.
I tried to check the code, wasn't able to find a solution.
Do we have a comment with my approch? Or a solution?