This header file make_boxed_from_unboxed_functor.h defines a template that can be used to create a boxed version of an unboxed functor. It is part of the executorch extension in the torch namespace.

Requirements

This header requires C++17 or later.

Usage

The template takes an unboxed function pointer and wraps it into a functor that takes KernelRuntimeContext and EValues as inputs and returns void. The wrapped functor will unbox all inputs and forward them to the unboxed kernel. Here is an example of how to use the template:

Tensor& my_op(KernelRuntimeContext& ctx, const Tensor& self, const Tensor& other, Tensor& out) {
  // ...
  return out;
}
Kernel my_kernel = Kernel::make_boxed_kernel("my_ns::my_op", EXECUTORCH_FN(my_op));
static auto res = register_kernels({my_kernel});

Alternatively, you can use the EXECUTORCH_LIBRARY macro to simplify the process:

EXECUTORCH_LIBRARY(my_ns, "my_op", my_op);

Details

The template uses a lot of C++17 features to convert each EValue to the inferred argument type. It checks if the first argument is KernelRuntimeContext, and if so, it removes it. The call method of the WrapUnboxedIntoFunctor struct calls the unboxed function with the corresponding arguments. The EXECUTORCH_LIBRARY macro registers the kernel for the operation and stores the result in a static variable.

Note

The KernelRuntimeContext is a context object that lets kernels handle errors and allocate temp memory. It can be used to add support for other actions in the future.