1 //===------- dlwrap.h - Convenience wrapper around dlopen/dlsym -- C++ -*-===// 2 // 3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions. 4 // See https://llvm.org/LICENSE.txt for license information. 5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception 6 // 7 //===----------------------------------------------------------------------===// 8 // 9 // The openmp plugins depend on extern libraries. These can be used via: 10 // - bitcode file statically linked 11 // - (relocatable) object file statically linked 12 // - static library 13 // - dynamic library, linked at build time 14 // - dynamic library, loaded at application run time by dlopen 15 // 16 // This file factors out most boilerplate for using a dlopened library. 17 // - Function symbols are generated that are statically linked against 18 // - The dlopen can be done implicitly when initializing the library 19 // - dlsym lookups are done once and cached 20 // - The abstraction is very thin to permit varied uses of the library 21 // 22 // Given int foo(char, double, void*);, writing DLWRAP(foo, 3) will expand to: 23 // int foo(char x0, double x1, void* x2) { 24 // constexpr size_t index = id(); 25 // void * dlsymResult = pointer(index); 26 // return ((int (*)(char, double, void*))dlsymResult)(x0, x1, x2); 27 // } 28 // 29 // Multiple calls to DLWRAP(symbol_name, arity) with bespoke 30 // initialization code that can use the thin abstraction: 31 // namespace dlwrap { 32 // static size_t size(); 33 // static const char *symbol(size_t); 34 // static void **pointer(size_t); 35 // } 36 // will compile to an object file that only exposes the symbols that the 37 // dynamic library would do, with the right function types. 38 // 39 //===----------------------------------------------------------------------===// 40 41 #ifndef DLWRAP_H_INCLUDED 42 #define DLWRAP_H_INCLUDED 43 44 #include <array> 45 #include <cstddef> 46 #include <tuple> 47 #include <type_traits> 48 49 // Where symbol is a function, these expand to some book keeping and an 50 // implementation of that function 51 #define DLWRAP(SYMBOL, ARITY) DLWRAP_IMPL(SYMBOL, ARITY) 52 #define DLWRAP_INTERNAL(SYMBOL, ARITY) DLWRAP_INTERNAL_IMPL(SYMBOL, ARITY) 53 54 // For example, given a prototype: 55 // int foo(char, double); 56 // 57 // DLWRAP(foo, 2) expands to: 58 // 59 // namespace dlwrap { 60 // struct foo_Trait : public dlwrap::trait<decltype(&foo)> { 61 // using T = dlwrap::trait<decltype(&foo)>; 62 // static T::FunctionType get() { 63 // constexpr size_t Index = getIndex(); 64 // void *P = *dlwrap::pointer(Index); 65 // return reinterpret_cast<T::FunctionType>(P); 66 // } 67 // }; 68 // } 69 // int foo(char x0, double x1) { return dlwrap::foo_Trait::get()(x0, x1); } 70 // 71 // DLWRAP_INTERNAL is similar, except the function it expands to is: 72 // static int dlwrap_foo(char x0, double x1) { ... } 73 // so that the function pointer call can be wrapped in library-specific code 74 75 // DLWRAP_FINALIZE() expands to definitions of: 76 #define DLWRAP_FINALIZE() DLWRAP_FINALIZE_IMPL() 77 namespace dlwrap { 78 static size_t size(); 79 static const char *symbol(size_t); // get symbol name in [0, size()) 80 static void **pointer(size_t); // get pointer to function pointer in [0, size()) 81 } // namespace dlwrap 82 83 // Implementation details follow. 84 85 namespace dlwrap { 86 87 // Extract return / argument types from address of function symbol 88 template <typename F> struct trait; 89 template <typename R, typename... Ts> struct trait<R (*)(Ts...)> { 90 constexpr static const size_t nargs = sizeof...(Ts); 91 typedef R ReturnType; 92 template <size_t i> struct arg { 93 typedef typename std::tuple_element<i, std::tuple<Ts...>>::type type; 94 }; 95 96 typedef R (*FunctionType)(Ts...); 97 }; 98 99 namespace type { 100 // Book keeping is by type specialization 101 102 template <size_t S> struct count { 103 static constexpr size_t N = count<S - 1>::N; 104 }; 105 106 template <> struct count<0> { static constexpr size_t N = 0; }; 107 108 // Get a constexpr size_t ID, starts at zero 109 #define DLWRAP_ID() (dlwrap::type::count<__LINE__>::N) 110 111 // Increment value returned by DLWRAP_ID 112 #define DLWRAP_INC() \ 113 template <> struct dlwrap::type::count<__LINE__> { \ 114 static constexpr size_t N = 1 + dlwrap::type::count<__LINE__ - 1>::N; \ 115 } 116 117 template <size_t N> struct symbol; 118 #define DLWRAP_SYMBOL(SYMBOL, ID) \ 119 template <> struct dlwrap::type::symbol<ID> { \ 120 static constexpr const char *call() { return #SYMBOL; } \ 121 } 122 } // namespace type 123 124 template <size_t N, size_t... Is> 125 constexpr std::array<const char *, N> static getSymbolArray( 126 std::index_sequence<Is...>) { 127 return {{dlwrap::type::symbol<Is>::call()...}}; 128 } 129 130 template <size_t Requested, size_t Required> constexpr void verboseAssert() { 131 static_assert(Requested == Required, "Arity Error"); 132 } 133 134 } // namespace dlwrap 135 136 #define DLWRAP_INSTANTIATE(SYM_USE, SYM_DEF, ARITY) \ 137 DLWRAP_INSTANTIATE_##ARITY(SYM_USE, SYM_DEF, \ 138 dlwrap::trait<decltype(&SYM_USE)>) 139 140 #define DLWRAP_FINALIZE_IMPL() \ 141 static size_t dlwrap::size() { return DLWRAP_ID(); } \ 142 static const char *dlwrap::symbol(size_t i) { \ 143 static constexpr const std::array<const char *, DLWRAP_ID()> \ 144 dlwrap_symbols = getSymbolArray<DLWRAP_ID()>( \ 145 std::make_index_sequence<DLWRAP_ID()>()); \ 146 return dlwrap_symbols[i]; \ 147 } \ 148 static void **dlwrap::pointer(size_t i) { \ 149 static std::array<void *, DLWRAP_ID()> dlwrap_pointers; \ 150 return &dlwrap_pointers.data()[i]; \ 151 } 152 153 #define DLWRAP_COMMON(SYMBOL, ARITY) \ 154 DLWRAP_INC(); \ 155 DLWRAP_SYMBOL(SYMBOL, DLWRAP_ID() - 1); \ 156 namespace dlwrap { \ 157 struct SYMBOL##_Trait : public dlwrap::trait<decltype(&SYMBOL)> { \ 158 using T = dlwrap::trait<decltype(&SYMBOL)>; \ 159 static T::FunctionType get() { \ 160 verboseAssert<ARITY, trait<decltype(&SYMBOL)>::nargs>(); \ 161 constexpr size_t Index = DLWRAP_ID() - 1; \ 162 void *P = *dlwrap::pointer(Index); \ 163 return reinterpret_cast<T::FunctionType>(P); \ 164 } \ 165 }; \ 166 } 167 168 #define DLWRAP_IMPL(SYMBOL, ARITY) \ 169 DLWRAP_COMMON(SYMBOL, ARITY); \ 170 DLWRAP_INSTANTIATE(SYMBOL, SYMBOL, ARITY) 171 172 #define DLWRAP_INTERNAL_IMPL(SYMBOL, ARITY) \ 173 DLWRAP_COMMON(SYMBOL, ARITY); \ 174 static DLWRAP_INSTANTIATE(SYMBOL, dlwrap_##SYMBOL, ARITY) 175 176 #define DLWRAP_INSTANTIATE_0(SYM_USE, SYM_DEF, T) \ 177 T::ReturnType SYM_DEF() { return dlwrap::SYM_USE##_Trait::get()(); } 178 #define DLWRAP_INSTANTIATE_1(SYM_USE, SYM_DEF, T) \ 179 T::ReturnType SYM_DEF(typename T::template arg<0>::type x0) { \ 180 return dlwrap::SYM_USE##_Trait::get()(x0); \ 181 } 182 #define DLWRAP_INSTANTIATE_2(SYM_USE, SYM_DEF, T) \ 183 T::ReturnType SYM_DEF(typename T::template arg<0>::type x0, \ 184 typename T::template arg<1>::type x1) { \ 185 return dlwrap::SYM_USE##_Trait::get()(x0, x1); \ 186 } 187 #define DLWRAP_INSTANTIATE_3(SYM_USE, SYM_DEF, T) \ 188 T::ReturnType SYM_DEF(typename T::template arg<0>::type x0, \ 189 typename T::template arg<1>::type x1, \ 190 typename T::template arg<2>::type x2) { \ 191 return dlwrap::SYM_USE##_Trait::get()(x0, x1, x2); \ 192 } 193 #define DLWRAP_INSTANTIATE_4(SYM_USE, SYM_DEF, T) \ 194 T::ReturnType SYM_DEF(typename T::template arg<0>::type x0, \ 195 typename T::template arg<1>::type x1, \ 196 typename T::template arg<2>::type x2, \ 197 typename T::template arg<3>::type x3) { \ 198 return dlwrap::SYM_USE##_Trait::get()(x0, x1, x2, x3); \ 199 } 200 #define DLWRAP_INSTANTIATE_5(SYM_USE, SYM_DEF, T) \ 201 T::ReturnType SYM_DEF(typename T::template arg<0>::type x0, \ 202 typename T::template arg<1>::type x1, \ 203 typename T::template arg<2>::type x2, \ 204 typename T::template arg<3>::type x3, \ 205 typename T::template arg<4>::type x4) { \ 206 return dlwrap::SYM_USE##_Trait::get()(x0, x1, x2, x3, x4); \ 207 } 208 #define DLWRAP_INSTANTIATE_6(SYM_USE, SYM_DEF, T) \ 209 T::ReturnType SYM_DEF(typename T::template arg<0>::type x0, \ 210 typename T::template arg<1>::type x1, \ 211 typename T::template arg<2>::type x2, \ 212 typename T::template arg<3>::type x3, \ 213 typename T::template arg<4>::type x4, \ 214 typename T::template arg<5>::type x5) { \ 215 return dlwrap::SYM_USE##_Trait::get()(x0, x1, x2, x3, x4, x5); \ 216 } 217 218 #define DLWRAP_INSTANTIATE_7(SYM_USE, SYM_DEF, T) \ 219 T::ReturnType SYM_DEF(typename T::template arg<0>::type x0, \ 220 typename T::template arg<1>::type x1, \ 221 typename T::template arg<2>::type x2, \ 222 typename T::template arg<3>::type x3, \ 223 typename T::template arg<4>::type x4, \ 224 typename T::template arg<5>::type x5, \ 225 typename T::template arg<6>::type x6) { \ 226 return dlwrap::SYM_USE##_Trait::get()(x0, x1, x2, x3, x4, x5, x6); \ 227 } 228 229 #define DLWRAP_INSTANTIATE_8(SYM_USE, SYM_DEF, T) \ 230 T::ReturnType SYM_DEF(typename T::template arg<0>::type x0, \ 231 typename T::template arg<1>::type x1, \ 232 typename T::template arg<2>::type x2, \ 233 typename T::template arg<3>::type x3, \ 234 typename T::template arg<4>::type x4, \ 235 typename T::template arg<5>::type x5, \ 236 typename T::template arg<6>::type x6, \ 237 typename T::template arg<7>::type x7) { \ 238 return dlwrap::SYM_USE##_Trait::get()(x0, x1, x2, x3, x4, x5, x6, x7); \ 239 } 240 #define DLWRAP_INSTANTIATE_9(SYM_USE, SYM_DEF, T) \ 241 T::ReturnType SYM_DEF(typename T::template arg<0>::type x0, \ 242 typename T::template arg<1>::type x1, \ 243 typename T::template arg<2>::type x2, \ 244 typename T::template arg<3>::type x3, \ 245 typename T::template arg<4>::type x4, \ 246 typename T::template arg<5>::type x5, \ 247 typename T::template arg<6>::type x6, \ 248 typename T::template arg<7>::type x7, \ 249 typename T::template arg<8>::type x8) { \ 250 return dlwrap::SYM_USE##_Trait::get()(x0, x1, x2, x3, x4, x5, x6, x7, x8); \ 251 } 252 #define DLWRAP_INSTANTIATE_10(SYM_USE, SYM_DEF, T) \ 253 T::ReturnType SYM_DEF(typename T::template arg<0>::type x0, \ 254 typename T::template arg<1>::type x1, \ 255 typename T::template arg<2>::type x2, \ 256 typename T::template arg<3>::type x3, \ 257 typename T::template arg<4>::type x4, \ 258 typename T::template arg<5>::type x5, \ 259 typename T::template arg<6>::type x6, \ 260 typename T::template arg<7>::type x7, \ 261 typename T::template arg<8>::type x8, \ 262 typename T::template arg<9>::type x9) { \ 263 return dlwrap::SYM_USE##_Trait::get()(x0, x1, x2, x3, x4, x5, x6, x7, x8, \ 264 x9); \ 265 } 266 #define DLWRAP_INSTANTIATE_11(SYM_USE, SYM_DEF, T) \ 267 T::ReturnType SYM_DEF(typename T::template arg<0>::type x0, \ 268 typename T::template arg<1>::type x1, \ 269 typename T::template arg<2>::type x2, \ 270 typename T::template arg<3>::type x3, \ 271 typename T::template arg<4>::type x4, \ 272 typename T::template arg<5>::type x5, \ 273 typename T::template arg<6>::type x6, \ 274 typename T::template arg<7>::type x7, \ 275 typename T::template arg<8>::type x8, \ 276 typename T::template arg<9>::type x9, \ 277 typename T::template arg<10>::type x10) { \ 278 return dlwrap::SYM_USE##_Trait::get()(x0, x1, x2, x3, x4, x5, x6, x7, x8, \ 279 x9, x10); \ 280 } 281 282 #endif 283