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