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 /// * 1800: Microsoft Visual Studio 2013 / 12.0 56 /// * 1900: Microsoft Visual Studio 2015 / 14.0 57 #ifdef _MSC_VER 58 #define LLVM_MSC_PREREQ(version) (_MSC_VER >= (version)) 59 60 // We require at least MSVC 2013. 61 #if !LLVM_MSC_PREREQ(1800) 62 #error LLVM requires at least MSVC 2013. 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 ref-qualifiers for *this? 76 /// 77 /// Sadly, this is separate from just rvalue reference support because GCC 78 /// and MSVC 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 /// Expands to '&' if ref-qualifiers for *this are supported. 86 /// 87 /// This can be used to provide lvalue/rvalue overrides of member functions. 88 /// The rvalue override should be guarded by LLVM_HAS_RVALUE_REFERENCE_THIS 89 #if LLVM_HAS_RVALUE_REFERENCE_THIS 90 #define LLVM_LVALUE_FUNCTION & 91 #else 92 #define LLVM_LVALUE_FUNCTION 93 #endif 94 95 #if __has_feature(cxx_constexpr) || defined(__GXX_EXPERIMENTAL_CXX0X__) 96 # define LLVM_CONSTEXPR constexpr 97 #else 98 # define LLVM_CONSTEXPR 99 #endif 100 101 /// LLVM_LIBRARY_VISIBILITY - If a class marked with this attribute is linked 102 /// into a shared library, then the class should be private to the library and 103 /// not accessible from outside it. Can also be used to mark variables and 104 /// functions, making them private to any shared library they are linked into. 105 /// On PE/COFF targets, library visibility is the default, so this isn't needed. 106 #if (__has_attribute(visibility) || LLVM_GNUC_PREREQ(4, 0, 0)) && \ 107 !defined(__MINGW32__) && !defined(__CYGWIN__) && !defined(LLVM_ON_WIN32) 108 #define LLVM_LIBRARY_VISIBILITY __attribute__ ((visibility("hidden"))) 109 #else 110 #define LLVM_LIBRARY_VISIBILITY 111 #endif 112 113 #if __has_attribute(sentinel) || LLVM_GNUC_PREREQ(3, 0, 0) 114 #define LLVM_END_WITH_NULL __attribute__((sentinel)) 115 #else 116 #define LLVM_END_WITH_NULL 117 #endif 118 119 #if __has_attribute(used) || LLVM_GNUC_PREREQ(3, 1, 0) 120 #define LLVM_ATTRIBUTE_USED __attribute__((__used__)) 121 #else 122 #define LLVM_ATTRIBUTE_USED 123 #endif 124 125 #if __has_attribute(warn_unused_result) || LLVM_GNUC_PREREQ(3, 4, 0) 126 #define LLVM_ATTRIBUTE_UNUSED_RESULT __attribute__((__warn_unused_result__)) 127 #else 128 #define LLVM_ATTRIBUTE_UNUSED_RESULT 129 #endif 130 131 // Some compilers warn about unused functions. When a function is sometimes 132 // used or not depending on build settings (e.g. a function only called from 133 // within "assert"), this attribute can be used to suppress such warnings. 134 // 135 // However, it shouldn't be used for unused *variables*, as those have a much 136 // more portable solution: 137 // (void)unused_var_name; 138 // Prefer cast-to-void wherever it is sufficient. 139 #if __has_attribute(unused) || LLVM_GNUC_PREREQ(3, 1, 0) 140 #define LLVM_ATTRIBUTE_UNUSED __attribute__((__unused__)) 141 #else 142 #define LLVM_ATTRIBUTE_UNUSED 143 #endif 144 145 // FIXME: Provide this for PE/COFF targets. 146 #if (__has_attribute(weak) || LLVM_GNUC_PREREQ(4, 0, 0)) && \ 147 (!defined(__MINGW32__) && !defined(__CYGWIN__) && !defined(LLVM_ON_WIN32)) 148 #define LLVM_ATTRIBUTE_WEAK __attribute__((__weak__)) 149 #else 150 #define LLVM_ATTRIBUTE_WEAK 151 #endif 152 153 // Prior to clang 3.2, clang did not accept any spelling of 154 // __has_attribute(const), so assume it is supported. 155 #if defined(__clang__) || defined(__GNUC__) 156 // aka 'CONST' but following LLVM Conventions. 157 #define LLVM_READNONE __attribute__((__const__)) 158 #else 159 #define LLVM_READNONE 160 #endif 161 162 #if __has_attribute(pure) || defined(__GNUC__) 163 // aka 'PURE' but following LLVM Conventions. 164 #define LLVM_READONLY __attribute__((__pure__)) 165 #else 166 #define LLVM_READONLY 167 #endif 168 169 #if __has_builtin(__builtin_expect) || LLVM_GNUC_PREREQ(4, 0, 0) 170 #define LLVM_LIKELY(EXPR) __builtin_expect((bool)(EXPR), true) 171 #define LLVM_UNLIKELY(EXPR) __builtin_expect((bool)(EXPR), false) 172 #else 173 #define LLVM_LIKELY(EXPR) (EXPR) 174 #define LLVM_UNLIKELY(EXPR) (EXPR) 175 #endif 176 177 // C++ doesn't support 'extern template' of template specializations. GCC does, 178 // but requires __extension__ before it. In the header, use this: 179 // EXTERN_TEMPLATE_INSTANTIATION(class foo<bar>); 180 // in the .cpp file, use this: 181 // TEMPLATE_INSTANTIATION(class foo<bar>); 182 #ifdef __GNUC__ 183 #define EXTERN_TEMPLATE_INSTANTIATION(X) __extension__ extern template X 184 #define TEMPLATE_INSTANTIATION(X) template X 185 #else 186 #define EXTERN_TEMPLATE_INSTANTIATION(X) 187 #define TEMPLATE_INSTANTIATION(X) 188 #endif 189 190 /// LLVM_ATTRIBUTE_NOINLINE - On compilers where we have a directive to do so, 191 /// mark a method "not for inlining". 192 #if __has_attribute(noinline) || LLVM_GNUC_PREREQ(3, 4, 0) 193 #define LLVM_ATTRIBUTE_NOINLINE __attribute__((noinline)) 194 #elif defined(_MSC_VER) 195 #define LLVM_ATTRIBUTE_NOINLINE __declspec(noinline) 196 #else 197 #define LLVM_ATTRIBUTE_NOINLINE 198 #endif 199 200 /// LLVM_ATTRIBUTE_ALWAYS_INLINE - On compilers where we have a directive to do 201 /// so, mark a method "always inline" because it is performance sensitive. GCC 202 /// 3.4 supported this but is buggy in various cases and produces unimplemented 203 /// errors, just use it in GCC 4.0 and later. 204 #if __has_attribute(always_inline) || LLVM_GNUC_PREREQ(4, 0, 0) 205 #define LLVM_ATTRIBUTE_ALWAYS_INLINE inline __attribute__((always_inline)) 206 #elif defined(_MSC_VER) 207 #define LLVM_ATTRIBUTE_ALWAYS_INLINE __forceinline 208 #else 209 #define LLVM_ATTRIBUTE_ALWAYS_INLINE 210 #endif 211 212 #ifdef __GNUC__ 213 #define LLVM_ATTRIBUTE_NORETURN __attribute__((noreturn)) 214 #elif defined(_MSC_VER) 215 #define LLVM_ATTRIBUTE_NORETURN __declspec(noreturn) 216 #else 217 #define LLVM_ATTRIBUTE_NORETURN 218 #endif 219 220 #if __has_attribute(returns_nonnull) || LLVM_GNUC_PREREQ(4, 9, 0) 221 #define LLVM_ATTRIBUTE_RETURNS_NONNULL __attribute__((returns_nonnull)) 222 #else 223 #define LLVM_ATTRIBUTE_RETURNS_NONNULL 224 #endif 225 226 /// \macro LLVM_ATTRIBUTE_RETURNS_NOALIAS Used to mark a function as returning a 227 /// pointer that does not alias any other valid pointer. 228 #ifdef __GNUC__ 229 #define LLVM_ATTRIBUTE_RETURNS_NOALIAS __attribute__((__malloc__)) 230 #elif defined(_MSC_VER) 231 #define LLVM_ATTRIBUTE_RETURNS_NOALIAS __declspec(restrict) 232 #else 233 #define LLVM_ATTRIBUTE_RETURNS_NOALIAS 234 #endif 235 236 /// LLVM_EXTENSION - Support compilers where we have a keyword to suppress 237 /// pedantic diagnostics. 238 #ifdef __GNUC__ 239 #define LLVM_EXTENSION __extension__ 240 #else 241 #define LLVM_EXTENSION 242 #endif 243 244 // LLVM_ATTRIBUTE_DEPRECATED(decl, "message") 245 #if __has_feature(attribute_deprecated_with_message) 246 # define LLVM_ATTRIBUTE_DEPRECATED(decl, message) \ 247 decl __attribute__((deprecated(message))) 248 #elif defined(__GNUC__) 249 # define LLVM_ATTRIBUTE_DEPRECATED(decl, message) \ 250 decl __attribute__((deprecated)) 251 #elif defined(_MSC_VER) 252 # define LLVM_ATTRIBUTE_DEPRECATED(decl, message) \ 253 __declspec(deprecated(message)) decl 254 #else 255 # define LLVM_ATTRIBUTE_DEPRECATED(decl, message) \ 256 decl 257 #endif 258 259 /// LLVM_BUILTIN_UNREACHABLE - On compilers which support it, expands 260 /// to an expression which states that it is undefined behavior for the 261 /// compiler to reach this point. Otherwise is not defined. 262 #if __has_builtin(__builtin_unreachable) || LLVM_GNUC_PREREQ(4, 5, 0) 263 # define LLVM_BUILTIN_UNREACHABLE __builtin_unreachable() 264 #elif defined(_MSC_VER) 265 # define LLVM_BUILTIN_UNREACHABLE __assume(false) 266 #endif 267 268 /// LLVM_BUILTIN_TRAP - On compilers which support it, expands to an expression 269 /// which causes the program to exit abnormally. 270 #if __has_builtin(__builtin_trap) || LLVM_GNUC_PREREQ(4, 3, 0) 271 # define LLVM_BUILTIN_TRAP __builtin_trap() 272 #elif defined(_MSC_VER) 273 // The __debugbreak intrinsic is supported by MSVC, does not require forward 274 // declarations involving platform-specific typedefs (unlike RaiseException), 275 // results in a call to vectored exception handlers, and encodes to a short 276 // instruction that still causes the trapping behavior we want. 277 # define LLVM_BUILTIN_TRAP __debugbreak() 278 #else 279 # define LLVM_BUILTIN_TRAP *(volatile int*)0x11 = 0 280 #endif 281 282 /// \macro LLVM_ASSUME_ALIGNED 283 /// \brief Returns a pointer with an assumed alignment. 284 #if __has_builtin(__builtin_assume_aligned) || LLVM_GNUC_PREREQ(4, 7, 0) 285 # define LLVM_ASSUME_ALIGNED(p, a) __builtin_assume_aligned(p, a) 286 #elif defined(LLVM_BUILTIN_UNREACHABLE) 287 // As of today, clang does not support __builtin_assume_aligned. 288 # define LLVM_ASSUME_ALIGNED(p, a) \ 289 (((uintptr_t(p) % (a)) == 0) ? (p) : (LLVM_BUILTIN_UNREACHABLE, (p))) 290 #else 291 # define LLVM_ASSUME_ALIGNED(p, a) (p) 292 #endif 293 294 /// \macro LLVM_ALIGNAS 295 /// \brief Used to specify a minimum alignment for a structure or variable. The 296 /// alignment must be a constant integer. Use LLVM_PTR_SIZE to compute 297 /// alignments in terms of the size of a pointer. 298 /// 299 /// Note that __declspec(align) has special quirks, it's not legal to pass a 300 /// structure with __declspec(align) as a formal parameter. 301 #ifdef _MSC_VER 302 # define LLVM_ALIGNAS(x) __declspec(align(x)) 303 #elif __GNUC__ && !__has_feature(cxx_alignas) && !LLVM_GNUC_PREREQ(4, 8, 0) 304 # define LLVM_ALIGNAS(x) __attribute__((aligned(x))) 305 #else 306 # define LLVM_ALIGNAS(x) alignas(x) 307 #endif 308 309 /// \macro LLVM_PTR_SIZE 310 /// \brief A constant integer equivalent to the value of sizeof(void*). 311 /// Generally used in combination with LLVM_ALIGNAS or when doing computation in 312 /// the preprocessor. 313 #ifdef __SIZEOF_POINTER__ 314 # define LLVM_PTR_SIZE __SIZEOF_POINTER__ 315 #elif defined(_WIN64) 316 # define LLVM_PTR_SIZE 8 317 #elif defined(_WIN32) 318 # define LLVM_PTR_SIZE 4 319 #elif defined(_MSC_VER) 320 # error "could not determine LLVM_PTR_SIZE as a constant int for MSVC" 321 #else 322 # define LLVM_PTR_SIZE sizeof(void *) 323 #endif 324 325 /// \macro LLVM_FUNCTION_NAME 326 /// \brief Expands to __func__ on compilers which support it. Otherwise, 327 /// expands to a compiler-dependent replacement. 328 #if defined(_MSC_VER) 329 # define LLVM_FUNCTION_NAME __FUNCTION__ 330 #else 331 # define LLVM_FUNCTION_NAME __func__ 332 #endif 333 334 /// \macro LLVM_MEMORY_SANITIZER_BUILD 335 /// \brief Whether LLVM itself is built with MemorySanitizer instrumentation. 336 #if __has_feature(memory_sanitizer) 337 # define LLVM_MEMORY_SANITIZER_BUILD 1 338 # include <sanitizer/msan_interface.h> 339 #else 340 # define LLVM_MEMORY_SANITIZER_BUILD 0 341 # define __msan_allocated_memory(p, size) 342 # define __msan_unpoison(p, size) 343 #endif 344 345 /// \macro LLVM_ADDRESS_SANITIZER_BUILD 346 /// \brief Whether LLVM itself is built with AddressSanitizer instrumentation. 347 #if __has_feature(address_sanitizer) || defined(__SANITIZE_ADDRESS__) 348 # define LLVM_ADDRESS_SANITIZER_BUILD 1 349 #else 350 # define LLVM_ADDRESS_SANITIZER_BUILD 0 351 #endif 352 353 /// \macro LLVM_IS_UNALIGNED_ACCESS_FAST 354 /// \brief Is unaligned memory access fast on the host machine. 355 /// 356 /// Don't specialize on alignment for platforms where unaligned memory accesses 357 /// generates the same code as aligned memory accesses for common types. 358 #if defined(_M_AMD64) || defined(_M_IX86) || defined(__amd64) || \ 359 defined(__amd64__) || defined(__x86_64) || defined(__x86_64__) || \ 360 defined(_X86_) || defined(__i386) || defined(__i386__) 361 # define LLVM_IS_UNALIGNED_ACCESS_FAST 1 362 #else 363 # define LLVM_IS_UNALIGNED_ACCESS_FAST 0 364 #endif 365 366 /// \brief Mark debug helper function definitions like dump() that should not be 367 /// stripped from debug builds. 368 // FIXME: Move this to a private config.h as it's not usable in public headers. 369 #if !defined(NDEBUG) || defined(LLVM_ENABLE_DUMP) 370 #define LLVM_DUMP_METHOD LLVM_ATTRIBUTE_NOINLINE LLVM_ATTRIBUTE_USED 371 #else 372 #define LLVM_DUMP_METHOD LLVM_ATTRIBUTE_NOINLINE 373 #endif 374 375 /// \macro LLVM_THREAD_LOCAL 376 /// \brief A thread-local storage specifier which can be used with globals, 377 /// extern globals, and static globals. 378 /// 379 /// This is essentially an extremely restricted analog to C++11's thread_local 380 /// support, and uses that when available. However, it falls back on 381 /// platform-specific or vendor-provided extensions when necessary. These 382 /// extensions don't support many of the C++11 thread_local's features. You 383 /// should only use this for PODs that you can statically initialize to 384 /// some constant value. In almost all circumstances this is most appropriate 385 /// for use with a pointer, integer, or small aggregation of pointers and 386 /// integers. 387 #if LLVM_ENABLE_THREADS 388 #if __has_feature(cxx_thread_local) 389 #define LLVM_THREAD_LOCAL thread_local 390 #elif defined(_MSC_VER) 391 // MSVC supports this with a __declspec. 392 #define LLVM_THREAD_LOCAL __declspec(thread) 393 #else 394 // Clang, GCC, and other compatible compilers used __thread prior to C++11 and 395 // we only need the restricted functionality that provides. 396 #define LLVM_THREAD_LOCAL __thread 397 #endif 398 #else // !LLVM_ENABLE_THREADS 399 // If threading is disabled entirely, this compiles to nothing and you get 400 // a normal global variable. 401 #define LLVM_THREAD_LOCAL 402 #endif 403 404 #endif 405
