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 #if defined(_MSC_VER) 21 #include <sal.h> 22 #endif 23 24 #ifndef __has_feature 25 # define __has_feature(x) 0 26 #endif 27 28 #ifndef __has_extension 29 # define __has_extension(x) 0 30 #endif 31 32 #ifndef __has_attribute 33 # define __has_attribute(x) 0 34 #endif 35 36 #ifndef __has_cpp_attribute 37 # define __has_cpp_attribute(x) 0 38 #endif 39 40 #ifndef __has_builtin 41 # define __has_builtin(x) 0 42 #endif 43 44 /// \macro LLVM_GNUC_PREREQ 45 /// \brief Extend the default __GNUC_PREREQ even if glibc's features.h isn't 46 /// available. 47 #ifndef LLVM_GNUC_PREREQ 48 # if defined(__GNUC__) && defined(__GNUC_MINOR__) && defined(__GNUC_PATCHLEVEL__) 49 # define LLVM_GNUC_PREREQ(maj, min, patch) \ 50 ((__GNUC__ << 20) + (__GNUC_MINOR__ << 10) + __GNUC_PATCHLEVEL__ >= \ 51 ((maj) << 20) + ((min) << 10) + (patch)) 52 # elif defined(__GNUC__) && defined(__GNUC_MINOR__) 53 # define LLVM_GNUC_PREREQ(maj, min, patch) \ 54 ((__GNUC__ << 20) + (__GNUC_MINOR__ << 10) >= ((maj) << 20) + ((min) << 10)) 55 # else 56 # define LLVM_GNUC_PREREQ(maj, min, patch) 0 57 # endif 58 #endif 59 60 /// \macro LLVM_MSC_PREREQ 61 /// \brief Is the compiler MSVC of at least the specified version? 62 /// The common \param version values to check for are: 63 /// * 1900: Microsoft Visual Studio 2015 / 14.0 64 #ifdef _MSC_VER 65 #define LLVM_MSC_PREREQ(version) (_MSC_VER >= (version)) 66 67 // We require at least MSVC 2015. 68 #if !LLVM_MSC_PREREQ(1900) 69 #error LLVM requires at least MSVC 2015. 70 #endif 71 72 #else 73 #define LLVM_MSC_PREREQ(version) 0 74 #endif 75 76 /// \brief Does the compiler support ref-qualifiers for *this? 77 /// 78 /// Sadly, this is separate from just rvalue reference support because GCC 79 /// and MSVC implemented this later than everything else. 80 #if __has_feature(cxx_rvalue_references) || LLVM_GNUC_PREREQ(4, 8, 1) 81 #define LLVM_HAS_RVALUE_REFERENCE_THIS 1 82 #else 83 #define LLVM_HAS_RVALUE_REFERENCE_THIS 0 84 #endif 85 86 /// Expands to '&' if ref-qualifiers for *this are supported. 87 /// 88 /// This can be used to provide lvalue/rvalue overrides of member functions. 89 /// The rvalue override should be guarded by LLVM_HAS_RVALUE_REFERENCE_THIS 90 #if LLVM_HAS_RVALUE_REFERENCE_THIS 91 #define LLVM_LVALUE_FUNCTION & 92 #else 93 #define LLVM_LVALUE_FUNCTION 94 #endif 95 96 /// LLVM_LIBRARY_VISIBILITY - If a class marked with this attribute is linked 97 /// into a shared library, then the class should be private to the library and 98 /// not accessible from outside it. Can also be used to mark variables and 99 /// functions, making them private to any shared library they are linked into. 100 /// On PE/COFF targets, library visibility is the default, so this isn't needed. 101 #if (__has_attribute(visibility) || LLVM_GNUC_PREREQ(4, 0, 0)) && \ 102 !defined(__MINGW32__) && !defined(__CYGWIN__) && !defined(LLVM_ON_WIN32) 103 #define LLVM_LIBRARY_VISIBILITY __attribute__ ((visibility("hidden"))) 104 #else 105 #define LLVM_LIBRARY_VISIBILITY 106 #endif 107 108 #if defined(__GNUC__) 109 #define LLVM_PREFETCH(addr, rw, locality) __builtin_prefetch(addr, rw, locality) 110 #else 111 #define LLVM_PREFETCH(addr, rw, locality) 112 #endif 113 114 #if __has_attribute(used) || LLVM_GNUC_PREREQ(3, 1, 0) 115 #define LLVM_ATTRIBUTE_USED __attribute__((__used__)) 116 #else 117 #define LLVM_ATTRIBUTE_USED 118 #endif 119 120 /// LLVM_NODISCARD - Warn if a type or return value is discarded. 121 #if __cplusplus > 201402L && __has_cpp_attribute(nodiscard) 122 #define LLVM_NODISCARD [[nodiscard]] 123 #elif !__cplusplus 124 // Workaround for llvm.org/PR23435, since clang 3.6 and below emit a spurious 125 // error when __has_cpp_attribute is given a scoped attribute in C mode. 126 #define LLVM_NODISCARD 127 #elif __has_cpp_attribute(clang::warn_unused_result) 128 #define LLVM_NODISCARD [[clang::warn_unused_result]] 129 #else 130 #define LLVM_NODISCARD 131 #endif 132 133 // Some compilers warn about unused functions. When a function is sometimes 134 // used or not depending on build settings (e.g. a function only called from 135 // within "assert"), this attribute can be used to suppress such warnings. 136 // 137 // However, it shouldn't be used for unused *variables*, as those have a much 138 // more portable solution: 139 // (void)unused_var_name; 140 // Prefer cast-to-void wherever it is sufficient. 141 #if __has_attribute(unused) || LLVM_GNUC_PREREQ(3, 1, 0) 142 #define LLVM_ATTRIBUTE_UNUSED __attribute__((__unused__)) 143 #else 144 #define LLVM_ATTRIBUTE_UNUSED 145 #endif 146 147 // FIXME: Provide this for PE/COFF targets. 148 #if (__has_attribute(weak) || LLVM_GNUC_PREREQ(4, 0, 0)) && \ 149 (!defined(__MINGW32__) && !defined(__CYGWIN__) && !defined(LLVM_ON_WIN32)) 150 #define LLVM_ATTRIBUTE_WEAK __attribute__((__weak__)) 151 #else 152 #define LLVM_ATTRIBUTE_WEAK 153 #endif 154 155 // Prior to clang 3.2, clang did not accept any spelling of 156 // __has_attribute(const), so assume it is supported. 157 #if defined(__clang__) || defined(__GNUC__) 158 // aka 'CONST' but following LLVM Conventions. 159 #define LLVM_READNONE __attribute__((__const__)) 160 #else 161 #define LLVM_READNONE 162 #endif 163 164 #if __has_attribute(pure) || defined(__GNUC__) 165 // aka 'PURE' but following LLVM Conventions. 166 #define LLVM_READONLY __attribute__((__pure__)) 167 #else 168 #define LLVM_READONLY 169 #endif 170 171 #if __has_builtin(__builtin_expect) || LLVM_GNUC_PREREQ(4, 0, 0) 172 #define LLVM_LIKELY(EXPR) __builtin_expect((bool)(EXPR), true) 173 #define LLVM_UNLIKELY(EXPR) __builtin_expect((bool)(EXPR), false) 174 #else 175 #define LLVM_LIKELY(EXPR) (EXPR) 176 #define LLVM_UNLIKELY(EXPR) (EXPR) 177 #endif 178 179 /// LLVM_ATTRIBUTE_NOINLINE - On compilers where we have a directive to do so, 180 /// mark a method "not for inlining". 181 #if __has_attribute(noinline) || LLVM_GNUC_PREREQ(3, 4, 0) 182 #define LLVM_ATTRIBUTE_NOINLINE __attribute__((noinline)) 183 #elif defined(_MSC_VER) 184 #define LLVM_ATTRIBUTE_NOINLINE __declspec(noinline) 185 #else 186 #define LLVM_ATTRIBUTE_NOINLINE 187 #endif 188 189 /// LLVM_ATTRIBUTE_ALWAYS_INLINE - On compilers where we have a directive to do 190 /// so, mark a method "always inline" because it is performance sensitive. GCC 191 /// 3.4 supported this but is buggy in various cases and produces unimplemented 192 /// errors, just use it in GCC 4.0 and later. 193 #if __has_attribute(always_inline) || LLVM_GNUC_PREREQ(4, 0, 0) 194 #define LLVM_ATTRIBUTE_ALWAYS_INLINE __attribute__((always_inline)) 195 #elif defined(_MSC_VER) 196 #define LLVM_ATTRIBUTE_ALWAYS_INLINE __forceinline 197 #else 198 #define LLVM_ATTRIBUTE_ALWAYS_INLINE 199 #endif 200 201 #ifdef __GNUC__ 202 #define LLVM_ATTRIBUTE_NORETURN __attribute__((noreturn)) 203 #elif defined(_MSC_VER) 204 #define LLVM_ATTRIBUTE_NORETURN __declspec(noreturn) 205 #else 206 #define LLVM_ATTRIBUTE_NORETURN 207 #endif 208 209 #if __has_attribute(returns_nonnull) || LLVM_GNUC_PREREQ(4, 9, 0) 210 #define LLVM_ATTRIBUTE_RETURNS_NONNULL __attribute__((returns_nonnull)) 211 #elif defined(_MSC_VER) 212 #define LLVM_ATTRIBUTE_RETURNS_NONNULL _Ret_notnull_ 213 #else 214 #define LLVM_ATTRIBUTE_RETURNS_NONNULL 215 #endif 216 217 /// \macro LLVM_ATTRIBUTE_RETURNS_NOALIAS Used to mark a function as returning a 218 /// pointer that does not alias any other valid pointer. 219 #ifdef __GNUC__ 220 #define LLVM_ATTRIBUTE_RETURNS_NOALIAS __attribute__((__malloc__)) 221 #elif defined(_MSC_VER) 222 #define LLVM_ATTRIBUTE_RETURNS_NOALIAS __declspec(restrict) 223 #else 224 #define LLVM_ATTRIBUTE_RETURNS_NOALIAS 225 #endif 226 227 /// LLVM_FALLTHROUGH - Mark fallthrough cases in switch statements. 228 #if __cplusplus > 201402L && __has_cpp_attribute(fallthrough) 229 #define LLVM_FALLTHROUGH [[fallthrough]] 230 #elif __has_cpp_attribute(gnu::fallthrough) 231 #define LLVM_FALLTHROUGH [[gnu::fallthrough]] 232 #elif !__cplusplus 233 // Workaround for llvm.org/PR23435, since clang 3.6 and below emit a spurious 234 // error when __has_cpp_attribute is given a scoped attribute in C mode. 235 #define LLVM_FALLTHROUGH 236 #elif __has_cpp_attribute(clang::fallthrough) 237 #define LLVM_FALLTHROUGH [[clang::fallthrough]] 238 #else 239 #define LLVM_FALLTHROUGH 240 #endif 241 242 /// LLVM_EXTENSION - Support compilers where we have a keyword to suppress 243 /// pedantic diagnostics. 244 #ifdef __GNUC__ 245 #define LLVM_EXTENSION __extension__ 246 #else 247 #define LLVM_EXTENSION 248 #endif 249 250 // LLVM_ATTRIBUTE_DEPRECATED(decl, "message") 251 #if __has_feature(attribute_deprecated_with_message) 252 # define LLVM_ATTRIBUTE_DEPRECATED(decl, message) \ 253 decl __attribute__((deprecated(message))) 254 #elif defined(__GNUC__) 255 # define LLVM_ATTRIBUTE_DEPRECATED(decl, message) \ 256 decl __attribute__((deprecated)) 257 #elif defined(_MSC_VER) 258 # define LLVM_ATTRIBUTE_DEPRECATED(decl, message) \ 259 __declspec(deprecated(message)) decl 260 #else 261 # define LLVM_ATTRIBUTE_DEPRECATED(decl, message) \ 262 decl 263 #endif 264 265 /// LLVM_BUILTIN_UNREACHABLE - On compilers which support it, expands 266 /// to an expression which states that it is undefined behavior for the 267 /// compiler to reach this point. Otherwise is not defined. 268 #if __has_builtin(__builtin_unreachable) || LLVM_GNUC_PREREQ(4, 5, 0) 269 # define LLVM_BUILTIN_UNREACHABLE __builtin_unreachable() 270 #elif defined(_MSC_VER) 271 # define LLVM_BUILTIN_UNREACHABLE __assume(false) 272 #endif 273 274 /// LLVM_BUILTIN_TRAP - On compilers which support it, expands to an expression 275 /// which causes the program to exit abnormally. 276 #if __has_builtin(__builtin_trap) || LLVM_GNUC_PREREQ(4, 3, 0) 277 # define LLVM_BUILTIN_TRAP __builtin_trap() 278 #elif defined(_MSC_VER) 279 // The __debugbreak intrinsic is supported by MSVC, does not require forward 280 // declarations involving platform-specific typedefs (unlike RaiseException), 281 // results in a call to vectored exception handlers, and encodes to a short 282 // instruction that still causes the trapping behavior we want. 283 # define LLVM_BUILTIN_TRAP __debugbreak() 284 #else 285 # define LLVM_BUILTIN_TRAP *(volatile int*)0x11 = 0 286 #endif 287 288 /// LLVM_BUILTIN_DEBUGTRAP - On compilers which support it, expands to 289 /// an expression which causes the program to break while running 290 /// under a debugger. 291 #if __has_builtin(__builtin_debugtrap) 292 # define LLVM_BUILTIN_DEBUGTRAP __builtin_debugtrap() 293 #elif defined(_MSC_VER) 294 // The __debugbreak intrinsic is supported by MSVC and breaks while 295 // running under the debugger, and also supports invoking a debugger 296 // when the OS is configured appropriately. 297 # define LLVM_BUILTIN_DEBUGTRAP __debugbreak() 298 #else 299 // Just continue execution when built with compilers that have no 300 // support. This is a debugging aid and not intended to force the 301 // program to abort if encountered. 302 # define LLVM_BUILTIN_DEBUGTRAP 303 #endif 304 305 /// \macro LLVM_ASSUME_ALIGNED 306 /// \brief Returns a pointer with an assumed alignment. 307 #if __has_builtin(__builtin_assume_aligned) || LLVM_GNUC_PREREQ(4, 7, 0) 308 # define LLVM_ASSUME_ALIGNED(p, a) __builtin_assume_aligned(p, a) 309 #elif defined(LLVM_BUILTIN_UNREACHABLE) 310 // As of today, clang does not support __builtin_assume_aligned. 311 # define LLVM_ASSUME_ALIGNED(p, a) \ 312 (((uintptr_t(p) % (a)) == 0) ? (p) : (LLVM_BUILTIN_UNREACHABLE, (p))) 313 #else 314 # define LLVM_ASSUME_ALIGNED(p, a) (p) 315 #endif 316 317 /// \macro LLVM_ALIGNAS 318 /// \brief Used to specify a minimum alignment for a structure or variable. 319 #if __GNUC__ && !__has_feature(cxx_alignas) && !LLVM_GNUC_PREREQ(4, 8, 1) 320 # define LLVM_ALIGNAS(x) __attribute__((aligned(x))) 321 #else 322 # define LLVM_ALIGNAS(x) alignas(x) 323 #endif 324 325 /// \macro LLVM_PACKED 326 /// \brief Used to specify a packed structure. 327 /// LLVM_PACKED( 328 /// struct A { 329 /// int i; 330 /// int j; 331 /// int k; 332 /// long long l; 333 /// }); 334 /// 335 /// LLVM_PACKED_START 336 /// struct B { 337 /// int i; 338 /// int j; 339 /// int k; 340 /// long long l; 341 /// }; 342 /// LLVM_PACKED_END 343 #ifdef _MSC_VER 344 # define LLVM_PACKED(d) __pragma(pack(push, 1)) d __pragma(pack(pop)) 345 # define LLVM_PACKED_START __pragma(pack(push, 1)) 346 # define LLVM_PACKED_END __pragma(pack(pop)) 347 #else 348 # define LLVM_PACKED(d) d __attribute__((packed)) 349 # define LLVM_PACKED_START _Pragma("pack(push, 1)") 350 # define LLVM_PACKED_END _Pragma("pack(pop)") 351 #endif 352 353 /// \macro LLVM_PTR_SIZE 354 /// \brief A constant integer equivalent to the value of sizeof(void*). 355 /// Generally used in combination with LLVM_ALIGNAS or when doing computation in 356 /// the preprocessor. 357 #ifdef __SIZEOF_POINTER__ 358 # define LLVM_PTR_SIZE __SIZEOF_POINTER__ 359 #elif defined(_WIN64) 360 # define LLVM_PTR_SIZE 8 361 #elif defined(_WIN32) 362 # define LLVM_PTR_SIZE 4 363 #elif defined(_MSC_VER) 364 # error "could not determine LLVM_PTR_SIZE as a constant int for MSVC" 365 #else 366 # define LLVM_PTR_SIZE sizeof(void *) 367 #endif 368 369 /// \macro LLVM_MEMORY_SANITIZER_BUILD 370 /// \brief Whether LLVM itself is built with MemorySanitizer instrumentation. 371 #if __has_feature(memory_sanitizer) 372 # define LLVM_MEMORY_SANITIZER_BUILD 1 373 # include <sanitizer/msan_interface.h> 374 #else 375 # define LLVM_MEMORY_SANITIZER_BUILD 0 376 # define __msan_allocated_memory(p, size) 377 # define __msan_unpoison(p, size) 378 #endif 379 380 /// \macro LLVM_ADDRESS_SANITIZER_BUILD 381 /// \brief Whether LLVM itself is built with AddressSanitizer instrumentation. 382 #if __has_feature(address_sanitizer) || defined(__SANITIZE_ADDRESS__) 383 # define LLVM_ADDRESS_SANITIZER_BUILD 1 384 # include <sanitizer/asan_interface.h> 385 #else 386 # define LLVM_ADDRESS_SANITIZER_BUILD 0 387 # define __asan_poison_memory_region(p, size) 388 # define __asan_unpoison_memory_region(p, size) 389 #endif 390 391 /// \macro LLVM_THREAD_SANITIZER_BUILD 392 /// \brief Whether LLVM itself is built with ThreadSanitizer instrumentation. 393 #if __has_feature(thread_sanitizer) || defined(__SANITIZE_THREAD__) 394 # define LLVM_THREAD_SANITIZER_BUILD 1 395 #else 396 # define LLVM_THREAD_SANITIZER_BUILD 0 397 #endif 398 399 #if LLVM_THREAD_SANITIZER_BUILD 400 // Thread Sanitizer is a tool that finds races in code. 401 // See http://code.google.com/p/data-race-test/wiki/DynamicAnnotations . 402 // tsan detects these exact functions by name. 403 #ifdef __cplusplus 404 extern "C" { 405 #endif 406 void AnnotateHappensAfter(const char *file, int line, const volatile void *cv); 407 void AnnotateHappensBefore(const char *file, int line, const volatile void *cv); 408 void AnnotateIgnoreWritesBegin(const char *file, int line); 409 void AnnotateIgnoreWritesEnd(const char *file, int line); 410 #ifdef __cplusplus 411 } 412 #endif 413 414 // This marker is used to define a happens-before arc. The race detector will 415 // infer an arc from the begin to the end when they share the same pointer 416 // argument. 417 # define TsanHappensBefore(cv) AnnotateHappensBefore(__FILE__, __LINE__, cv) 418 419 // This marker defines the destination of a happens-before arc. 420 # define TsanHappensAfter(cv) AnnotateHappensAfter(__FILE__, __LINE__, cv) 421 422 // Ignore any races on writes between here and the next TsanIgnoreWritesEnd. 423 # define TsanIgnoreWritesBegin() AnnotateIgnoreWritesBegin(__FILE__, __LINE__) 424 425 // Resume checking for racy writes. 426 # define TsanIgnoreWritesEnd() AnnotateIgnoreWritesEnd(__FILE__, __LINE__) 427 #else 428 # define TsanHappensBefore(cv) 429 # define TsanHappensAfter(cv) 430 # define TsanIgnoreWritesBegin() 431 # define TsanIgnoreWritesEnd() 432 #endif 433 434 /// \macro LLVM_NO_SANITIZE 435 /// \brief Disable a particular sanitizer for a function. 436 #if __has_attribute(no_sanitize) 437 #define LLVM_NO_SANITIZE(KIND) __attribute__((no_sanitize(KIND))) 438 #else 439 #define LLVM_NO_SANITIZE(KIND) 440 #endif 441 442 /// \brief Mark debug helper function definitions like dump() that should not be 443 /// stripped from debug builds. 444 /// Note that you should also surround dump() functions with 445 /// `#if !defined(NDEBUG) || defined(LLVM_ENABLE_DUMP)` so they do always 446 /// get stripped in release builds. 447 // FIXME: Move this to a private config.h as it's not usable in public headers. 448 #if !defined(NDEBUG) || defined(LLVM_ENABLE_DUMP) 449 #define LLVM_DUMP_METHOD LLVM_ATTRIBUTE_NOINLINE LLVM_ATTRIBUTE_USED 450 #else 451 #define LLVM_DUMP_METHOD LLVM_ATTRIBUTE_NOINLINE 452 #endif 453 454 /// \macro LLVM_PRETTY_FUNCTION 455 /// \brief Gets a user-friendly looking function signature for the current scope 456 /// using the best available method on each platform. The exact format of the 457 /// resulting string is implementation specific and non-portable, so this should 458 /// only be used, for example, for logging or diagnostics. 459 #if defined(_MSC_VER) 460 #define LLVM_PRETTY_FUNCTION __FUNCSIG__ 461 #elif defined(__GNUC__) || defined(__clang__) 462 #define LLVM_PRETTY_FUNCTION __PRETTY_FUNCTION__ 463 #else 464 #define LLVM_PRETTY_FUNCTION __func__ 465 #endif 466 467 /// \macro LLVM_THREAD_LOCAL 468 /// \brief A thread-local storage specifier which can be used with globals, 469 /// extern globals, and static globals. 470 /// 471 /// This is essentially an extremely restricted analog to C++11's thread_local 472 /// support, and uses that when available. However, it falls back on 473 /// platform-specific or vendor-provided extensions when necessary. These 474 /// extensions don't support many of the C++11 thread_local's features. You 475 /// should only use this for PODs that you can statically initialize to 476 /// some constant value. In almost all circumstances this is most appropriate 477 /// for use with a pointer, integer, or small aggregation of pointers and 478 /// integers. 479 #if LLVM_ENABLE_THREADS 480 #if __has_feature(cxx_thread_local) 481 #define LLVM_THREAD_LOCAL thread_local 482 #elif defined(_MSC_VER) 483 // MSVC supports this with a __declspec. 484 #define LLVM_THREAD_LOCAL __declspec(thread) 485 #else 486 // Clang, GCC, and other compatible compilers used __thread prior to C++11 and 487 // we only need the restricted functionality that provides. 488 #define LLVM_THREAD_LOCAL __thread 489 #endif 490 #else // !LLVM_ENABLE_THREADS 491 // If threading is disabled entirely, this compiles to nothing and you get 492 // a normal global variable. 493 #define LLVM_THREAD_LOCAL 494 #endif 495 496 /// \macro LLVM_ENABLE_EXCEPTIONS 497 /// \brief Whether LLVM is built with exception support. 498 #if __has_feature(cxx_exceptions) 499 #define LLVM_ENABLE_EXCEPTIONS 1 500 #elif defined(__GNUC__) && defined(__EXCEPTIONS) 501 #define LLVM_ENABLE_EXCEPTIONS 1 502 #elif defined(_MSC_VER) && defined(_CPPUNWIND) 503 #define LLVM_ENABLE_EXCEPTIONS 1 504 #endif 505 506 #endif 507
