1 //===-- llvm/Support/Compiler.h - Compiler abstraction support --*- C++ -*-===// 2 // 3 // The LLVM Compiler Infrastructure 4 // 5 // This file is distributed under the University of Illinois Open Source 6 // License. See LICENSE.TXT for details. 7 // 8 //===----------------------------------------------------------------------===// 9 // 10 // This file defines several macros, based on the current compiler. This allows 11 // use of compiler-specific features in a way that remains portable. 12 // 13 //===----------------------------------------------------------------------===// 14 15 #ifndef LLVM_SUPPORT_COMPILER_H 16 #define LLVM_SUPPORT_COMPILER_H 17 18 #include "llvm/Config/llvm-config.h" 19 20 #ifndef __has_feature 21 # define __has_feature(x) 0 22 #endif 23 24 #ifndef __has_extension 25 # define __has_extension(x) 0 26 #endif 27 28 #ifndef __has_attribute 29 # define __has_attribute(x) 0 30 #endif 31 32 #ifndef __has_builtin 33 # define __has_builtin(x) 0 34 #endif 35 36 /// \macro LLVM_GNUC_PREREQ 37 /// \brief Extend the default __GNUC_PREREQ even if glibc's features.h isn't 38 /// available. 39 #ifndef LLVM_GNUC_PREREQ 40 # if defined(__GNUC__) && defined(__GNUC_MINOR__) && defined(__GNUC_PATCHLEVEL__) 41 # define LLVM_GNUC_PREREQ(maj, min, patch) \ 42 ((__GNUC__ << 20) + (__GNUC_MINOR__ << 10) + __GNUC_PATCHLEVEL__ >= \ 43 ((maj) << 20) + ((min) << 10) + (patch)) 44 # elif defined(__GNUC__) && defined(__GNUC_MINOR__) 45 # define LLVM_GNUC_PREREQ(maj, min, patch) \ 46 ((__GNUC__ << 20) + (__GNUC_MINOR__ << 10) >= ((maj) << 20) + ((min) << 10)) 47 # else 48 # define LLVM_GNUC_PREREQ(maj, min, patch) 0 49 # endif 50 #endif 51 52 /// \macro LLVM_MSC_PREREQ 53 /// \brief Is the compiler MSVC of at least the specified version? 54 /// The common \param version values to check for are: 55 /// * 1700: Microsoft Visual Studio 2012 / 11.0 56 /// * 1800: Microsoft Visual Studio 2013 / 12.0 57 #ifdef _MSC_VER 58 #define LLVM_MSC_PREREQ(version) (_MSC_VER >= (version)) 59 60 // We require at least MSVC 2012. 61 #if !LLVM_MSC_PREREQ(1700) 62 #error LLVM requires at least MSVC 2012. 63 #endif 64 65 #else 66 #define LLVM_MSC_PREREQ(version) 0 67 #endif 68 69 #if !defined(_MSC_VER) || defined(__clang__) || LLVM_MSC_PREREQ(1900) 70 #define LLVM_NOEXCEPT noexcept 71 #else 72 #define LLVM_NOEXCEPT 73 #endif 74 75 /// \brief Does the compiler support r-value reference *this? 76 /// 77 /// Sadly, this is separate from just r-value reference support because GCC 78 /// implemented this later than everything else. 79 #if __has_feature(cxx_rvalue_references) || LLVM_GNUC_PREREQ(4, 8, 1) 80 #define LLVM_HAS_RVALUE_REFERENCE_THIS 1 81 #else 82 #define LLVM_HAS_RVALUE_REFERENCE_THIS 0 83 #endif 84 85 /// \macro LLVM_HAS_VARIADIC_TEMPLATES 86 /// \brief Does this compiler support variadic templates. 87 /// 88 /// Implies LLVM_HAS_RVALUE_REFERENCES and the existence of std::forward. 89 #if __has_feature(cxx_variadic_templates) || LLVM_MSC_PREREQ(1800) 90 # define LLVM_HAS_VARIADIC_TEMPLATES 1 91 #else 92 # define LLVM_HAS_VARIADIC_TEMPLATES 0 93 #endif 94 95 /// Expands to '&' if r-value references are supported. 96 /// 97 /// This can be used to provide l-value/r-value overrides of member functions. 98 /// The r-value override should be guarded by LLVM_HAS_RVALUE_REFERENCE_THIS 99 #if LLVM_HAS_RVALUE_REFERENCE_THIS 100 #define LLVM_LVALUE_FUNCTION & 101 #else 102 #define LLVM_LVALUE_FUNCTION 103 #endif 104 105 /// LLVM_DELETED_FUNCTION - Expands to = delete if the compiler supports it. 106 /// Use to mark functions as uncallable. Member functions with this should 107 /// be declared private so that some behavior is kept in C++03 mode. 108 /// 109 /// class DontCopy { 110 /// private: 111 /// DontCopy(const DontCopy&) LLVM_DELETED_FUNCTION; 112 /// DontCopy &operator =(const DontCopy&) LLVM_DELETED_FUNCTION; 113 /// public: 114 /// ... 115 /// }; 116 #if __has_feature(cxx_deleted_functions) || \ 117 defined(__GXX_EXPERIMENTAL_CXX0X__) || LLVM_MSC_PREREQ(1800) 118 #define LLVM_DELETED_FUNCTION = delete 119 #else 120 #define LLVM_DELETED_FUNCTION 121 #endif 122 123 #if __has_feature(cxx_constexpr) || defined(__GXX_EXPERIMENTAL_CXX0X__) 124 # define LLVM_CONSTEXPR constexpr 125 #else 126 # define LLVM_CONSTEXPR 127 #endif 128 129 /// LLVM_LIBRARY_VISIBILITY - If a class marked with this attribute is linked 130 /// into a shared library, then the class should be private to the library and 131 /// not accessible from outside it. Can also be used to mark variables and 132 /// functions, making them private to any shared library they are linked into. 133 /// On PE/COFF targets, library visibility is the default, so this isn't needed. 134 #if (__has_attribute(visibility) || LLVM_GNUC_PREREQ(4, 0, 0)) && \ 135 !defined(__MINGW32__) && !defined(__CYGWIN__) && !defined(LLVM_ON_WIN32) 136 #define LLVM_LIBRARY_VISIBILITY __attribute__ ((visibility("hidden"))) 137 #else 138 #define LLVM_LIBRARY_VISIBILITY 139 #endif 140 141 #if __has_attribute(sentinel) || LLVM_GNUC_PREREQ(3, 0, 0) 142 #define LLVM_END_WITH_NULL __attribute__((sentinel)) 143 #else 144 #define LLVM_END_WITH_NULL 145 #endif 146 147 #if __has_attribute(used) || LLVM_GNUC_PREREQ(3, 1, 0) 148 #define LLVM_ATTRIBUTE_USED __attribute__((__used__)) 149 #else 150 #define LLVM_ATTRIBUTE_USED 151 #endif 152 153 #if __has_attribute(warn_unused_result) || LLVM_GNUC_PREREQ(3, 4, 0) 154 #define LLVM_ATTRIBUTE_UNUSED_RESULT __attribute__((__warn_unused_result__)) 155 #else 156 #define LLVM_ATTRIBUTE_UNUSED_RESULT 157 #endif 158 159 // Some compilers warn about unused functions. When a function is sometimes 160 // used or not depending on build settings (e.g. a function only called from 161 // within "assert"), this attribute can be used to suppress such warnings. 162 // 163 // However, it shouldn't be used for unused *variables*, as those have a much 164 // more portable solution: 165 // (void)unused_var_name; 166 // Prefer cast-to-void wherever it is sufficient. 167 #if __has_attribute(unused) || LLVM_GNUC_PREREQ(3, 1, 0) 168 #define LLVM_ATTRIBUTE_UNUSED __attribute__((__unused__)) 169 #else 170 #define LLVM_ATTRIBUTE_UNUSED 171 #endif 172 173 // FIXME: Provide this for PE/COFF targets. 174 #if (__has_attribute(weak) || LLVM_GNUC_PREREQ(4, 0, 0)) && \ 175 (!defined(__MINGW32__) && !defined(__CYGWIN__) && !defined(LLVM_ON_WIN32)) 176 #define LLVM_ATTRIBUTE_WEAK __attribute__((__weak__)) 177 #else 178 #define LLVM_ATTRIBUTE_WEAK 179 #endif 180 181 // Prior to clang 3.2, clang did not accept any spelling of 182 // __has_attribute(const), so assume it is supported. 183 #if defined(__clang__) || defined(__GNUC__) 184 // aka 'CONST' but following LLVM Conventions. 185 #define LLVM_READNONE __attribute__((__const__)) 186 #else 187 #define LLVM_READNONE 188 #endif 189 190 #if __has_attribute(pure) || defined(__GNUC__) 191 // aka 'PURE' but following LLVM Conventions. 192 #define LLVM_READONLY __attribute__((__pure__)) 193 #else 194 #define LLVM_READONLY 195 #endif 196 197 #if __has_builtin(__builtin_expect) || LLVM_GNUC_PREREQ(4, 0, 0) 198 #define LLVM_LIKELY(EXPR) __builtin_expect((bool)(EXPR), true) 199 #define LLVM_UNLIKELY(EXPR) __builtin_expect((bool)(EXPR), false) 200 #else 201 #define LLVM_LIKELY(EXPR) (EXPR) 202 #define LLVM_UNLIKELY(EXPR) (EXPR) 203 #endif 204 205 // C++ doesn't support 'extern template' of template specializations. GCC does, 206 // but requires __extension__ before it. In the header, use this: 207 // EXTERN_TEMPLATE_INSTANTIATION(class foo<bar>); 208 // in the .cpp file, use this: 209 // TEMPLATE_INSTANTIATION(class foo<bar>); 210 #ifdef __GNUC__ 211 #define EXTERN_TEMPLATE_INSTANTIATION(X) __extension__ extern template X 212 #define TEMPLATE_INSTANTIATION(X) template X 213 #else 214 #define EXTERN_TEMPLATE_INSTANTIATION(X) 215 #define TEMPLATE_INSTANTIATION(X) 216 #endif 217 218 /// LLVM_ATTRIBUTE_NOINLINE - On compilers where we have a directive to do so, 219 /// mark a method "not for inlining". 220 #if __has_attribute(noinline) || LLVM_GNUC_PREREQ(3, 4, 0) 221 #define LLVM_ATTRIBUTE_NOINLINE __attribute__((noinline)) 222 #elif defined(_MSC_VER) 223 #define LLVM_ATTRIBUTE_NOINLINE __declspec(noinline) 224 #else 225 #define LLVM_ATTRIBUTE_NOINLINE 226 #endif 227 228 /// LLVM_ATTRIBUTE_ALWAYS_INLINE - On compilers where we have a directive to do 229 /// so, mark a method "always inline" because it is performance sensitive. GCC 230 /// 3.4 supported this but is buggy in various cases and produces unimplemented 231 /// errors, just use it in GCC 4.0 and later. 232 #if __has_attribute(always_inline) || LLVM_GNUC_PREREQ(4, 0, 0) 233 #define LLVM_ATTRIBUTE_ALWAYS_INLINE inline __attribute__((always_inline)) 234 #elif defined(_MSC_VER) 235 #define LLVM_ATTRIBUTE_ALWAYS_INLINE __forceinline 236 #else 237 #define LLVM_ATTRIBUTE_ALWAYS_INLINE 238 #endif 239 240 #ifdef __GNUC__ 241 #define LLVM_ATTRIBUTE_NORETURN __attribute__((noreturn)) 242 #elif defined(_MSC_VER) 243 #define LLVM_ATTRIBUTE_NORETURN __declspec(noreturn) 244 #else 245 #define LLVM_ATTRIBUTE_NORETURN 246 #endif 247 248 #if __has_attribute(returns_nonnull) || LLVM_GNUC_PREREQ(4, 9, 0) 249 #define LLVM_ATTRIBUTE_RETURNS_NONNULL __attribute__((returns_nonnull)) 250 #else 251 #define LLVM_ATTRIBUTE_RETURNS_NONNULL 252 #endif 253 254 /// LLVM_EXTENSION - Support compilers where we have a keyword to suppress 255 /// pedantic diagnostics. 256 #ifdef __GNUC__ 257 #define LLVM_EXTENSION __extension__ 258 #else 259 #define LLVM_EXTENSION 260 #endif 261 262 // LLVM_ATTRIBUTE_DEPRECATED(decl, "message") 263 #if __has_feature(attribute_deprecated_with_message) 264 # define LLVM_ATTRIBUTE_DEPRECATED(decl, message) \ 265 decl __attribute__((deprecated(message))) 266 #elif defined(__GNUC__) 267 # define LLVM_ATTRIBUTE_DEPRECATED(decl, message) \ 268 decl __attribute__((deprecated)) 269 #elif defined(_MSC_VER) 270 # define LLVM_ATTRIBUTE_DEPRECATED(decl, message) \ 271 __declspec(deprecated(message)) decl 272 #else 273 # define LLVM_ATTRIBUTE_DEPRECATED(decl, message) \ 274 decl 275 #endif 276 277 /// LLVM_BUILTIN_UNREACHABLE - On compilers which support it, expands 278 /// to an expression which states that it is undefined behavior for the 279 /// compiler to reach this point. Otherwise is not defined. 280 #if __has_builtin(__builtin_unreachable) || LLVM_GNUC_PREREQ(4, 5, 0) 281 # define LLVM_BUILTIN_UNREACHABLE __builtin_unreachable() 282 #elif defined(_MSC_VER) 283 # define LLVM_BUILTIN_UNREACHABLE __assume(false) 284 #endif 285 286 /// LLVM_BUILTIN_TRAP - On compilers which support it, expands to an expression 287 /// which causes the program to exit abnormally. 288 #if __has_builtin(__builtin_trap) || LLVM_GNUC_PREREQ(4, 3, 0) 289 # define LLVM_BUILTIN_TRAP __builtin_trap() 290 #else 291 # define LLVM_BUILTIN_TRAP *(volatile int*)0x11 = 0 292 #endif 293 294 /// \macro LLVM_ASSUME_ALIGNED 295 /// \brief Returns a pointer with an assumed alignment. 296 #if __has_builtin(__builtin_assume_aligned) || LLVM_GNUC_PREREQ(4, 7, 0) 297 # define LLVM_ASSUME_ALIGNED(p, a) __builtin_assume_aligned(p, a) 298 #elif defined(LLVM_BUILTIN_UNREACHABLE) 299 // As of today, clang does not support __builtin_assume_aligned. 300 # define LLVM_ASSUME_ALIGNED(p, a) \ 301 (((uintptr_t(p) % (a)) == 0) ? (p) : (LLVM_BUILTIN_UNREACHABLE, (p))) 302 #else 303 # define LLVM_ASSUME_ALIGNED(p, a) (p) 304 #endif 305 306 /// \macro LLVM_FUNCTION_NAME 307 /// \brief Expands to __func__ on compilers which support it. Otherwise, 308 /// expands to a compiler-dependent replacement. 309 #if defined(_MSC_VER) 310 # define LLVM_FUNCTION_NAME __FUNCTION__ 311 #else 312 # define LLVM_FUNCTION_NAME __func__ 313 #endif 314 315 /// \macro LLVM_MEMORY_SANITIZER_BUILD 316 /// \brief Whether LLVM itself is built with MemorySanitizer instrumentation. 317 #if __has_feature(memory_sanitizer) 318 # define LLVM_MEMORY_SANITIZER_BUILD 1 319 # include <sanitizer/msan_interface.h> 320 #else 321 # define LLVM_MEMORY_SANITIZER_BUILD 0 322 # define __msan_allocated_memory(p, size) 323 # define __msan_unpoison(p, size) 324 #endif 325 326 /// \macro LLVM_ADDRESS_SANITIZER_BUILD 327 /// \brief Whether LLVM itself is built with AddressSanitizer instrumentation. 328 #if __has_feature(address_sanitizer) || defined(__SANITIZE_ADDRESS__) 329 # define LLVM_ADDRESS_SANITIZER_BUILD 1 330 #else 331 # define LLVM_ADDRESS_SANITIZER_BUILD 0 332 #endif 333 334 /// \macro LLVM_IS_UNALIGNED_ACCESS_FAST 335 /// \brief Is unaligned memory access fast on the host machine. 336 /// 337 /// Don't specialize on alignment for platforms where unaligned memory accesses 338 /// generates the same code as aligned memory accesses for common types. 339 #if defined(_M_AMD64) || defined(_M_IX86) || defined(__amd64) || \ 340 defined(__amd64__) || defined(__x86_64) || defined(__x86_64__) || \ 341 defined(_X86_) || defined(__i386) || defined(__i386__) 342 # define LLVM_IS_UNALIGNED_ACCESS_FAST 1 343 #else 344 # define LLVM_IS_UNALIGNED_ACCESS_FAST 0 345 #endif 346 347 /// \macro LLVM_EXPLICIT 348 /// \brief Expands to explicit on compilers which support explicit conversion 349 /// operators. Otherwise expands to nothing. 350 #if __has_feature(cxx_explicit_conversions) || \ 351 defined(__GXX_EXPERIMENTAL_CXX0X__) || LLVM_MSC_PREREQ(1800) 352 #define LLVM_EXPLICIT explicit 353 #else 354 #define LLVM_EXPLICIT 355 #endif 356 357 /// \brief Does the compiler support generalized initializers (using braced 358 /// lists and std::initializer_list). While clang may claim it supports general 359 /// initializers, if we're using MSVC's headers, we might not have a usable 360 /// std::initializer list type from the STL. Disable this for now. 361 #if __has_feature(cxx_generalized_initializers) && !defined(_MSC_VER) 362 #define LLVM_HAS_INITIALIZER_LISTS 1 363 #else 364 #define LLVM_HAS_INITIALIZER_LISTS 0 365 #endif 366 367 /// \brief Mark debug helper function definitions like dump() that should not be 368 /// stripped from debug builds. 369 // FIXME: Move this to a private config.h as it's not usable in public headers. 370 #if !defined(NDEBUG) || defined(LLVM_ENABLE_DUMP) 371 #define LLVM_DUMP_METHOD LLVM_ATTRIBUTE_NOINLINE LLVM_ATTRIBUTE_USED 372 #else 373 #define LLVM_DUMP_METHOD LLVM_ATTRIBUTE_NOINLINE 374 #endif 375 376 #endif 377