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//===------- dlwrap.h - Convenience wrapper around dlopen/dlsym -- C++ -*-===//
//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See https://llvm.org/LICENSE.txt for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
//
//===----------------------------------------------------------------------===//
//
// The openmp plugins depend on extern libraries. These can be used via:
// - bitcode file statically linked
// - (relocatable) object file statically linked
// - static library
// - dynamic library, linked at build time
// - dynamic library, loaded at application run time by dlopen
//
// This file factors out most boilerplate for using a dlopened library.
// - Function symbols are generated that are statically linked against
// - The dlopen can be done implicitly when initializing the library
// - dlsym lookups are done once and cached
// - The abstraction is very thin to permit varied uses of the library
//
// Given int foo(char, double, void*);, writing DLWRAP(foo, 3) will expand to:
// int foo(char x0, double x1, void* x2) {
// constexpr size_t index = id();
// void * dlsymResult = pointer(index);
// return ((int (*)(char, double, void*))dlsymResult)(x0, x1, x2);
// }
//
// Multiple calls to DLWRAP(symbol_name, arity) with bespoke
// initialization code that can use the thin abstraction:
// namespace dlwrap {
// static size_t size();
// static const char *symbol(size_t);
// static void **pointer(size_t);
// }
// will compile to an object file that only exposes the symbols that the
// dynamic library would do, with the right function types.
//
//===----------------------------------------------------------------------===//
#ifndef DLWRAP_H_INCLUDED
#define DLWRAP_H_INCLUDED
#include <array>
#include <cstddef>
#include <tuple>
#include <type_traits>
// Where symbol is a function, these expand to some book keeping and an
// implementation of that function
#define DLWRAP(SYMBOL, ARITY) DLWRAP_IMPL(SYMBOL, ARITY)
#define DLWRAP_INTERNAL(SYMBOL, ARITY) DLWRAP_INTERNAL_IMPL(SYMBOL, ARITY)
// For example, given a prototype:
// int foo(char, double);
//
// DLWRAP(foo, 2) expands to:
//
// namespace dlwrap {
// struct foo_Trait : public dlwrap::trait<decltype(&foo)> {
// using T = dlwrap::trait<decltype(&foo)>;
// static T::FunctionType get() {
// constexpr size_t Index = getIndex();
// void *P = *dlwrap::pointer(Index);
// return reinterpret_cast<T::FunctionType>(P);
// }
// };
// }
// int foo(char x0, double x1) { return dlwrap::foo_Trait::get()(x0, x1); }
//
// DLWRAP_INTERNAL is similar, except the function it expands to is:
// static int dlwrap_foo(char x0, double x1) { ... }
// so that the function pointer call can be wrapped in library-specific code
//
// DLWRAP_INITIALIZE() declares static functions:
#define DLWRAP_INITIALIZE() \
namespace dlwrap { \
static size_t size(); \
static const char *symbol(size_t); /* get symbol name in [0, size()) */ \
static void ** \
pointer(size_t); /* get pointer to function pointer in [0, size()) */ \
}
// DLWRAP_FINALIZE() implements the functions from DLWRAP_INITIALIZE
#define DLWRAP_FINALIZE() DLWRAP_FINALIZE_IMPL()
// Implementation details follow.
namespace dlwrap {
// Extract return / argument types from address of function symbol
template <typename F> struct trait;
template <typename R, typename... Ts> struct trait<R (*)(Ts...)> {
constexpr static const size_t nargs = sizeof...(Ts);
typedef R ReturnType;
template <size_t i> struct arg {
typedef typename std::tuple_element<i, std::tuple<Ts...>>::type type;
};
typedef R (*FunctionType)(Ts...);
};
namespace type {
// Book keeping is by type specialization
template <size_t S> struct count {
static constexpr size_t N = count<S - 1>::N;
};
template <> struct count<0> { static constexpr size_t N = 0; };
// Get a constexpr size_t ID, starts at zero
#define DLWRAP_ID() (dlwrap::type::count<__LINE__>::N)
// Increment value returned by DLWRAP_ID
#define DLWRAP_INC() \
template <> struct dlwrap::type::count<__LINE__> { \
static constexpr size_t N = 1 + dlwrap::type::count<__LINE__ - 1>::N; \
}
template <size_t N> struct symbol;
#define DLWRAP_SYMBOL(SYMBOL, ID) \
template <> struct dlwrap::type::symbol<ID> { \
static constexpr const char *call() { return #SYMBOL; } \
}
} // namespace type
template <size_t N, size_t... Is>
constexpr std::array<const char *, N> static getSymbolArray(
std::index_sequence<Is...>) {
return {{dlwrap::type::symbol<Is>::call()...}};
}
template <size_t Requested, size_t Required> constexpr void verboseAssert() {
static_assert(Requested == Required, "Arity Error");
}
} // namespace dlwrap
#define DLWRAP_INSTANTIATE(SYM_DEF, SYM_USE, ARITY) \
DLWRAP_INSTANTIATE_##ARITY(SYM_DEF, SYM_USE, \
dlwrap::trait<decltype(&SYM_USE)>)
#define DLWRAP_FINALIZE_IMPL() \
static size_t dlwrap::size() { return DLWRAP_ID(); } \
static const char *dlwrap::symbol(size_t i) { \
static constexpr const std::array<const char *, DLWRAP_ID()> \
dlwrap_symbols = getSymbolArray<DLWRAP_ID()>( \
std::make_index_sequence<DLWRAP_ID()>()); \
return dlwrap_symbols[i]; \
} \
static void **dlwrap::pointer(size_t i) { \
static std::array<void *, DLWRAP_ID()> dlwrap_pointers; \
return &dlwrap_pointers.data()[i]; \
}
#define DLWRAP_COMMON(SYMBOL, ARITY) \
DLWRAP_INC(); \
DLWRAP_SYMBOL(SYMBOL, DLWRAP_ID() - 1); \
namespace dlwrap { \
struct SYMBOL##_Trait : public dlwrap::trait<decltype(&SYMBOL)> { \
using T = dlwrap::trait<decltype(&SYMBOL)>; \
static T::FunctionType get() { \
verboseAssert<ARITY, trait<decltype(&SYMBOL)>::nargs>(); \
constexpr size_t Index = DLWRAP_ID() - 1; \
void *P = *dlwrap::pointer(Index); \
return reinterpret_cast<T::FunctionType>(P); \
} \
}; \
}
#define DLWRAP_IMPL(SYMBOL, ARITY) \
DLWRAP_COMMON(SYMBOL, ARITY); \
DLWRAP_INSTANTIATE(SYMBOL, SYMBOL, ARITY)
#define DLWRAP_INTERNAL_IMPL(SYMBOL, ARITY) \
DLWRAP_COMMON(SYMBOL, ARITY); \
static DLWRAP_INSTANTIATE(dlwrap_##SYMBOL, SYMBOL, ARITY)
#define DLWRAP_INSTANTIATE_0(SYM_DEF, SYM_USE, T) \
T::ReturnType SYM_DEF() { return dlwrap::SYM_USE##_Trait::get()(); }
#define DLWRAP_INSTANTIATE_1(SYM_DEF, SYM_USE, T) \
T::ReturnType SYM_DEF(typename T::template arg<0>::type x0) { \
return dlwrap::SYM_USE##_Trait::get()(x0); \
}
#define DLWRAP_INSTANTIATE_2(SYM_DEF, SYM_USE, T) \
T::ReturnType SYM_DEF(typename T::template arg<0>::type x0, \
typename T::template arg<1>::type x1) { \
return dlwrap::SYM_USE##_Trait::get()(x0, x1); \
}
#define DLWRAP_INSTANTIATE_3(SYM_DEF, SYM_USE, T) \
T::ReturnType SYM_DEF(typename T::template arg<0>::type x0, \
typename T::template arg<1>::type x1, \
typename T::template arg<2>::type x2) { \
return dlwrap::SYM_USE##_Trait::get()(x0, x1, x2); \
}
#define DLWRAP_INSTANTIATE_4(SYM_DEF, SYM_USE, T) \
T::ReturnType SYM_DEF(typename T::template arg<0>::type x0, \
typename T::template arg<1>::type x1, \
typename T::template arg<2>::type x2, \
typename T::template arg<3>::type x3) { \
return dlwrap::SYM_USE##_Trait::get()(x0, x1, x2, x3); \
}
#define DLWRAP_INSTANTIATE_5(SYM_DEF, SYM_USE, T) \
T::ReturnType SYM_DEF(typename T::template arg<0>::type x0, \
typename T::template arg<1>::type x1, \
typename T::template arg<2>::type x2, \
typename T::template arg<3>::type x3, \
typename T::template arg<4>::type x4) { \
return dlwrap::SYM_USE##_Trait::get()(x0, x1, x2, x3, x4); \
}
#define DLWRAP_INSTANTIATE_6(SYM_DEF, SYM_USE, T) \
T::ReturnType SYM_DEF(typename T::template arg<0>::type x0, \
typename T::template arg<1>::type x1, \
typename T::template arg<2>::type x2, \
typename T::template arg<3>::type x3, \
typename T::template arg<4>::type x4, \
typename T::template arg<5>::type x5) { \
return dlwrap::SYM_USE##_Trait::get()(x0, x1, x2, x3, x4, x5); \
}
#define DLWRAP_INSTANTIATE_7(SYM_DEF, SYM_USE, T) \
T::ReturnType SYM_DEF(typename T::template arg<0>::type x0, \
typename T::template arg<1>::type x1, \
typename T::template arg<2>::type x2, \
typename T::template arg<3>::type x3, \
typename T::template arg<4>::type x4, \
typename T::template arg<5>::type x5, \
typename T::template arg<6>::type x6) { \
return dlwrap::SYM_USE##_Trait::get()(x0, x1, x2, x3, x4, x5, x6); \
}
#define DLWRAP_INSTANTIATE_8(SYM_DEF, SYM_USE, T) \
T::ReturnType SYM_DEF(typename T::template arg<0>::type x0, \
typename T::template arg<1>::type x1, \
typename T::template arg<2>::type x2, \
typename T::template arg<3>::type x3, \
typename T::template arg<4>::type x4, \
typename T::template arg<5>::type x5, \
typename T::template arg<6>::type x6, \
typename T::template arg<7>::type x7) { \
return dlwrap::SYM_USE##_Trait::get()(x0, x1, x2, x3, x4, x5, x6, x7); \
}
#define DLWRAP_INSTANTIATE_9(SYM_DEF, SYM_USE, T) \
T::ReturnType SYM_DEF(typename T::template arg<0>::type x0, \
typename T::template arg<1>::type x1, \
typename T::template arg<2>::type x2, \
typename T::template arg<3>::type x3, \
typename T::template arg<4>::type x4, \
typename T::template arg<5>::type x5, \
typename T::template arg<6>::type x6, \
typename T::template arg<7>::type x7, \
typename T::template arg<8>::type x8) { \
return dlwrap::SYM_USE##_Trait::get()(x0, x1, x2, x3, x4, x5, x6, x7, x8); \
}
#define DLWRAP_INSTANTIATE_10(SYM_DEF, SYM_USE, T) \
T::ReturnType SYM_DEF(typename T::template arg<0>::type x0, \
typename T::template arg<1>::type x1, \
typename T::template arg<2>::type x2, \
typename T::template arg<3>::type x3, \
typename T::template arg<4>::type x4, \
typename T::template arg<5>::type x5, \
typename T::template arg<6>::type x6, \
typename T::template arg<7>::type x7, \
typename T::template arg<8>::type x8, \
typename T::template arg<9>::type x9) { \
return dlwrap::SYM_USE##_Trait::get()(x0, x1, x2, x3, x4, x5, x6, x7, x8, \
x9); \
}
#define DLWRAP_INSTANTIATE_11(SYM_DEF, SYM_USE, T) \
T::ReturnType SYM_DEF(typename T::template arg<0>::type x0, \
typename T::template arg<1>::type x1, \
typename T::template arg<2>::type x2, \
typename T::template arg<3>::type x3, \
typename T::template arg<4>::type x4, \
typename T::template arg<5>::type x5, \
typename T::template arg<6>::type x6, \
typename T::template arg<7>::type x7, \
typename T::template arg<8>::type x8, \
typename T::template arg<9>::type x9, \
typename T::template arg<10>::type x10) { \
return dlwrap::SYM_USE##_Trait::get()(x0, x1, x2, x3, x4, x5, x6, x7, x8, \
x9, x10); \
}
#endif
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