[SOLVED] Ramp of lanes <= 1 exception when cross-compile Halide for RISC-V

Ramp of lanes <= 1 exception when cross-compile Halide for RISC-V

Tried this tutorial https://halide-lang.org/tutorials/tutorial_lesson_11_cross_compilation.html on x86 host machine (Ubuntu 20.04) but for RISC-V target architecture. Unfortunately, there is an exception from IR.cpp. The exception appears only when .vectorize(x, 16) is applied, so problem is somewhere in RISC-V Vectorization support. Any ideas how to debug this?

Internal Error at /home/dkurt/Halide/src/IR.cpp:272 triggered by user code at : Condition failed: lanes > 1: Ramp of lanes <= 1

Everything is OK locally for x86 target.

Halide @ https://github.com/halide/Halide/commit/16243da75944ce9ea8d4e8eb90d6f104f06284ec
LLVM 15.0.2

#include "Halide.h"

using namespace Halide;

int main(int argc, char** argv) {
    Func brighter;
    Var x, y;

    Param<uint8_t> offset;
    ImageParam input(type_of<uint8_t>(), 2);
    std::vector<Argument> args(2);
    args[0] = input;
    args[1] = offset;

    brighter(x, y) = input(x, y) + offset;

    brighter.bound(x, 0, 64).bound(y, 0, 64);

    brighter.vectorize(x, 16).parallel(y);

    Target target;
    target.os = Target::Linux;
    target.arch = Target::RISCV;
    target.bits = 64;

    std::vector<Target::Feature> features;
    features.push_back(Target::RVV);
    target.set_features(features);

    try {
        brighter.compile_to_static_library("compiled", args, "brighter", target);
    } catch(Halide::InternalError& ex) {
        std::cout << ex.what() << std::endl;
    }
}

Solution