// Reproduces a regression in Halide V15:
// Using .compute_at() causes huge slow-downs.
class halide15_bug_generator : public Halide::Generator<halide15_bug_generator>
{
public:
    Input<Buffer<uint8_t>> input{"input", 2};
    Output<Buffer<uint8_t>> output{"output", 2};

    // Typically used for image coordinates
    Var x, y, xo, yo, xi, yi;

    Func intermediate{"intermediate"};

    void generate()
    {
        const int radius = 16;

        Func input_repeat = BoundaryConditions::repeat_edge(input);

        RDom r(-radius, radius*2);

        intermediate(x, y) = sum(2.3456f * cast<float>(input_repeat(x + r, y)));

        output(x, y) = saturating_cast<uint8_t>( intermediate(x, y) * 255.f );
    }

    void schedule()
    {
        const int vsize = natural_vector_size(output.type());

        output.tile(x, y, xo, yo, xi, yi, 64, 64)
            .vectorize(xi, vsize);

        // Adding this line causes V15 to go 5x slower.
        intermediate.compute_at(output, yi);
    }
};