Files
mfem/examples/dfem_minimal_example.cpp
T
2024-07-11 08:04:14 -07:00

116 lines
3.5 KiB
C++

#include <tuple>
#include <type_traits>
#include <iostream>
#include <enzyme/enzyme>
template <typename T>
constexpr auto get_type_name() -> std::string_view
{
#if defined(__clang__)
constexpr auto prefix = std::string_view {"[T = "};
constexpr auto suffix = "]";
constexpr auto function = std::string_view{__PRETTY_FUNCTION__};
#elif defined(__GNUC__)
constexpr auto prefix = std::string_view {"with T = "};
constexpr auto suffix = "; ";
constexpr auto function = std::string_view{__PRETTY_FUNCTION__};
#elif defined(_MSC_VER)
constexpr auto prefix = std::string_view {"get_type_name<"};
constexpr auto suffix = ">(void)";
constexpr auto function = std::string_view{__FUNCSIG__};
#else
#error Unsupported compiler
#endif
const auto start = function.find(prefix) + prefix.size();
const auto end = function.find(suffix);
const auto size = end - start;
return function.substr(start, size);
}
template <typename ... Ts>
constexpr auto decay_types(std::tuple<Ts...> const &)
-> std::tuple<std::remove_cv_t<std::remove_reference_t<Ts>>...>;
template <typename T>
using decay_tuple = decltype(decay_types(std::declval<T>()));
template <class F> struct FunctionSignature;
template <typename output_t, typename... input_ts>
struct FunctionSignature<output_t(input_ts...)>
{
using return_t = output_t;
using parameter_ts = std::tuple<input_ts...>;
};
template <class T> struct create_function_signature;
template <typename output_t, typename T, typename... input_ts>
struct create_function_signature<output_t (T::*)(input_ts...) const>
{
using type = FunctionSignature<output_t(input_ts...)>;
};
template <typename arg_ts, std::size_t... Is>
auto create_enzyme_args(arg_ts &args,
arg_ts &shadow_args,
std::index_sequence<Is...>)
{
((std::cout << std::get<Is>(shadow_args) << "\n"), ...);
return std::tuple<enzyme::Duplicated<decltype(std::get<Is>(args))>...>
{
{ std::get<Is>(args), std::get<Is>(shadow_args) }...
};
}
template <typename kernel_t, typename arg_ts>
auto fwddiff_apply_enzyme(kernel_t kernel, arg_ts &&args, arg_ts &&shadow_args)
{
auto arg_indices =
std::make_index_sequence<std::tuple_size_v<std::remove_reference_t<arg_ts>>> {};
auto enzyme_args = create_enzyme_args(args, shadow_args, arg_indices);
using kf_return_t = typename create_function_signature<
decltype(&kernel_t::operator())>::type::return_t;
std::cout << "args is " << get_type_name<decltype(args)>() << "\n\n";
std::cout << "enzyme_args type is " << get_type_name<decltype(enzyme_args)>() <<
"\n\n";
std::cout << "return type is " << get_type_name<decltype(kf_return_t{})>() <<
"\n\n";
return std::apply([&](auto &&...args)
{
return enzyme::get<0>(
enzyme::autodiff<enzyme::Forward>
(+kernel, args...));
},
enzyme_args);
}
int main()
{
auto func = [](const double &x)
{
return x*x;
};
using kf_param_ts = typename create_function_signature<
decltype(&decltype(func)::operator())>::type::parameter_ts;
using kf_output_t = typename create_function_signature<
decltype(&decltype(func)::operator())>::type::return_t;
auto kernel_args = decay_tuple<kf_param_ts> {};
auto kernel_shadow_args = decay_tuple<kf_param_ts> {};
std::get<0>(kernel_args) = 3;
std::get<0>(kernel_shadow_args) = 1;
const auto res = fwddiff_apply_enzyme(func, kernel_args, kernel_shadow_args);
std::cout << res << " == 6\n";
return 0;
}