Compiler.h revision 309124
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_builtin 37# define __has_builtin(x) 0 38#endif 39 40/// \macro LLVM_GNUC_PREREQ 41/// \brief Extend the default __GNUC_PREREQ even if glibc's features.h isn't 42/// available. 43#ifndef LLVM_GNUC_PREREQ 44# if defined(__GNUC__) && defined(__GNUC_MINOR__) && defined(__GNUC_PATCHLEVEL__) 45# define LLVM_GNUC_PREREQ(maj, min, patch) \ 46 ((__GNUC__ << 20) + (__GNUC_MINOR__ << 10) + __GNUC_PATCHLEVEL__ >= \ 47 ((maj) << 20) + ((min) << 10) + (patch)) 48# elif defined(__GNUC__) && defined(__GNUC_MINOR__) 49# define LLVM_GNUC_PREREQ(maj, min, patch) \ 50 ((__GNUC__ << 20) + (__GNUC_MINOR__ << 10) >= ((maj) << 20) + ((min) << 10)) 51# else 52# define LLVM_GNUC_PREREQ(maj, min, patch) 0 53# endif 54#endif 55 56/// \macro LLVM_MSC_PREREQ 57/// \brief Is the compiler MSVC of at least the specified version? 58/// The common \param version values to check for are: 59/// * 1800: Microsoft Visual Studio 2013 / 12.0 60/// * 1900: Microsoft Visual Studio 2015 / 14.0 61#ifdef _MSC_VER 62#define LLVM_MSC_PREREQ(version) (_MSC_VER >= (version)) 63 64// We require at least MSVC 2013. 65#if !LLVM_MSC_PREREQ(1800) 66#error LLVM requires at least MSVC 2013. 67#endif 68 69#else 70#define LLVM_MSC_PREREQ(version) 0 71#endif 72 73#if !defined(_MSC_VER) || defined(__clang__) || LLVM_MSC_PREREQ(1900) 74#define LLVM_NOEXCEPT noexcept 75#else 76#define LLVM_NOEXCEPT throw() 77#endif 78 79/// \brief Does the compiler support ref-qualifiers for *this? 80/// 81/// Sadly, this is separate from just rvalue reference support because GCC 82/// and MSVC implemented this later than everything else. 83#if __has_feature(cxx_rvalue_references) || LLVM_GNUC_PREREQ(4, 8, 1) 84#define LLVM_HAS_RVALUE_REFERENCE_THIS 1 85#else 86#define LLVM_HAS_RVALUE_REFERENCE_THIS 0 87#endif 88 89/// Expands to '&' if ref-qualifiers for *this are supported. 90/// 91/// This can be used to provide lvalue/rvalue overrides of member functions. 92/// The rvalue override should be guarded by LLVM_HAS_RVALUE_REFERENCE_THIS 93#if LLVM_HAS_RVALUE_REFERENCE_THIS 94#define LLVM_LVALUE_FUNCTION & 95#else 96#define LLVM_LVALUE_FUNCTION 97#endif 98 99#if __has_feature(cxx_constexpr) || defined(__GXX_EXPERIMENTAL_CXX0X__) || LLVM_MSC_PREREQ(1900) 100# define LLVM_CONSTEXPR constexpr 101#else 102# define LLVM_CONSTEXPR 103#endif 104 105/// LLVM_LIBRARY_VISIBILITY - If a class marked with this attribute is linked 106/// into a shared library, then the class should be private to the library and 107/// not accessible from outside it. Can also be used to mark variables and 108/// functions, making them private to any shared library they are linked into. 109/// On PE/COFF targets, library visibility is the default, so this isn't needed. 110#if (__has_attribute(visibility) || LLVM_GNUC_PREREQ(4, 0, 0)) && \ 111 !defined(__MINGW32__) && !defined(__CYGWIN__) && !defined(LLVM_ON_WIN32) 112#define LLVM_LIBRARY_VISIBILITY __attribute__ ((visibility("hidden"))) 113#else 114#define LLVM_LIBRARY_VISIBILITY 115#endif 116 117#if __has_attribute(sentinel) || LLVM_GNUC_PREREQ(3, 0, 0) 118#define LLVM_END_WITH_NULL __attribute__((sentinel)) 119#else 120#define LLVM_END_WITH_NULL 121#endif 122 123#if __has_attribute(used) || LLVM_GNUC_PREREQ(3, 1, 0) 124#define LLVM_ATTRIBUTE_USED __attribute__((__used__)) 125#else 126#define LLVM_ATTRIBUTE_USED 127#endif 128 129#if __has_attribute(warn_unused_result) || LLVM_GNUC_PREREQ(3, 4, 0) 130#define LLVM_ATTRIBUTE_UNUSED_RESULT __attribute__((__warn_unused_result__)) 131#elif defined(_MSC_VER) 132#define LLVM_ATTRIBUTE_UNUSED_RESULT _Check_return_ 133#else 134#define LLVM_ATTRIBUTE_UNUSED_RESULT 135#endif 136 137// Some compilers warn about unused functions. When a function is sometimes 138// used or not depending on build settings (e.g. a function only called from 139// within "assert"), this attribute can be used to suppress such warnings. 140// 141// However, it shouldn't be used for unused *variables*, as those have a much 142// more portable solution: 143// (void)unused_var_name; 144// Prefer cast-to-void wherever it is sufficient. 145#if __has_attribute(unused) || LLVM_GNUC_PREREQ(3, 1, 0) 146#define LLVM_ATTRIBUTE_UNUSED __attribute__((__unused__)) 147#else 148#define LLVM_ATTRIBUTE_UNUSED 149#endif 150 151// FIXME: Provide this for PE/COFF targets. 152#if (__has_attribute(weak) || LLVM_GNUC_PREREQ(4, 0, 0)) && \ 153 (!defined(__MINGW32__) && !defined(__CYGWIN__) && !defined(LLVM_ON_WIN32)) 154#define LLVM_ATTRIBUTE_WEAK __attribute__((__weak__)) 155#else 156#define LLVM_ATTRIBUTE_WEAK 157#endif 158 159// Prior to clang 3.2, clang did not accept any spelling of 160// __has_attribute(const), so assume it is supported. 161#if defined(__clang__) || defined(__GNUC__) 162// aka 'CONST' but following LLVM Conventions. 163#define LLVM_READNONE __attribute__((__const__)) 164#else 165#define LLVM_READNONE 166#endif 167 168#if __has_attribute(pure) || defined(__GNUC__) 169// aka 'PURE' but following LLVM Conventions. 170#define LLVM_READONLY __attribute__((__pure__)) 171#else 172#define LLVM_READONLY 173#endif 174 175#if __has_builtin(__builtin_expect) || LLVM_GNUC_PREREQ(4, 0, 0) 176#define LLVM_LIKELY(EXPR) __builtin_expect((bool)(EXPR), true) 177#define LLVM_UNLIKELY(EXPR) __builtin_expect((bool)(EXPR), false) 178#else 179#define LLVM_LIKELY(EXPR) (EXPR) 180#define LLVM_UNLIKELY(EXPR) (EXPR) 181#endif 182 183/// LLVM_ATTRIBUTE_NOINLINE - On compilers where we have a directive to do so, 184/// mark a method "not for inlining". 185#if __has_attribute(noinline) || LLVM_GNUC_PREREQ(3, 4, 0) 186#define LLVM_ATTRIBUTE_NOINLINE __attribute__((noinline)) 187#elif defined(_MSC_VER) 188#define LLVM_ATTRIBUTE_NOINLINE __declspec(noinline) 189#else 190#define LLVM_ATTRIBUTE_NOINLINE 191#endif 192 193/// LLVM_ATTRIBUTE_ALWAYS_INLINE - On compilers where we have a directive to do 194/// so, mark a method "always inline" because it is performance sensitive. GCC 195/// 3.4 supported this but is buggy in various cases and produces unimplemented 196/// errors, just use it in GCC 4.0 and later. 197#if __has_attribute(always_inline) || LLVM_GNUC_PREREQ(4, 0, 0) 198#define LLVM_ATTRIBUTE_ALWAYS_INLINE __attribute__((always_inline)) 199#elif defined(_MSC_VER) 200#define LLVM_ATTRIBUTE_ALWAYS_INLINE __forceinline 201#else 202#define LLVM_ATTRIBUTE_ALWAYS_INLINE 203#endif 204 205#ifdef __GNUC__ 206#define LLVM_ATTRIBUTE_NORETURN __attribute__((noreturn)) 207#elif defined(_MSC_VER) 208#define LLVM_ATTRIBUTE_NORETURN __declspec(noreturn) 209#else 210#define LLVM_ATTRIBUTE_NORETURN 211#endif 212 213#if __has_attribute(returns_nonnull) || LLVM_GNUC_PREREQ(4, 9, 0) 214#define LLVM_ATTRIBUTE_RETURNS_NONNULL __attribute__((returns_nonnull)) 215#elif defined(_MSC_VER) 216#define LLVM_ATTRIBUTE_RETURNS_NONNULL _Ret_notnull_ 217#else 218#define LLVM_ATTRIBUTE_RETURNS_NONNULL 219#endif 220 221/// \macro LLVM_ATTRIBUTE_RETURNS_NOALIAS Used to mark a function as returning a 222/// pointer that does not alias any other valid pointer. 223#ifdef __GNUC__ 224#define LLVM_ATTRIBUTE_RETURNS_NOALIAS __attribute__((__malloc__)) 225#elif defined(_MSC_VER) 226#define LLVM_ATTRIBUTE_RETURNS_NOALIAS __declspec(restrict) 227#else 228#define LLVM_ATTRIBUTE_RETURNS_NOALIAS 229#endif 230 231/// LLVM_EXTENSION - Support compilers where we have a keyword to suppress 232/// pedantic diagnostics. 233#ifdef __GNUC__ 234#define LLVM_EXTENSION __extension__ 235#else 236#define LLVM_EXTENSION 237#endif 238 239// LLVM_ATTRIBUTE_DEPRECATED(decl, "message") 240#if __has_feature(attribute_deprecated_with_message) 241# define LLVM_ATTRIBUTE_DEPRECATED(decl, message) \ 242 decl __attribute__((deprecated(message))) 243#elif defined(__GNUC__) 244# define LLVM_ATTRIBUTE_DEPRECATED(decl, message) \ 245 decl __attribute__((deprecated)) 246#elif defined(_MSC_VER) 247# define LLVM_ATTRIBUTE_DEPRECATED(decl, message) \ 248 __declspec(deprecated(message)) decl 249#else 250# define LLVM_ATTRIBUTE_DEPRECATED(decl, message) \ 251 decl 252#endif 253 254/// LLVM_BUILTIN_UNREACHABLE - On compilers which support it, expands 255/// to an expression which states that it is undefined behavior for the 256/// compiler to reach this point. Otherwise is not defined. 257#if __has_builtin(__builtin_unreachable) || LLVM_GNUC_PREREQ(4, 5, 0) 258# define LLVM_BUILTIN_UNREACHABLE __builtin_unreachable() 259#elif defined(_MSC_VER) 260# define LLVM_BUILTIN_UNREACHABLE __assume(false) 261#endif 262 263/// LLVM_BUILTIN_TRAP - On compilers which support it, expands to an expression 264/// which causes the program to exit abnormally. 265#if __has_builtin(__builtin_trap) || LLVM_GNUC_PREREQ(4, 3, 0) 266# define LLVM_BUILTIN_TRAP __builtin_trap() 267#elif defined(_MSC_VER) 268// The __debugbreak intrinsic is supported by MSVC, does not require forward 269// declarations involving platform-specific typedefs (unlike RaiseException), 270// results in a call to vectored exception handlers, and encodes to a short 271// instruction that still causes the trapping behavior we want. 272# define LLVM_BUILTIN_TRAP __debugbreak() 273#else 274# define LLVM_BUILTIN_TRAP *(volatile int*)0x11 = 0 275#endif 276 277/// LLVM_BUILTIN_DEBUGTRAP - On compilers which support it, expands to 278/// an expression which causes the program to break while running 279/// under a debugger. 280#if __has_builtin(__builtin_debugtrap) 281# define LLVM_BUILTIN_DEBUGTRAP __builtin_debugtrap() 282#elif defined(_MSC_VER) 283// The __debugbreak intrinsic is supported by MSVC and breaks while 284// running under the debugger, and also supports invoking a debugger 285// when the OS is configured appropriately. 286# define LLVM_BUILTIN_DEBUGTRAP __debugbreak() 287#else 288// Just continue execution when built with compilers that have no 289// support. This is a debugging aid and not intended to force the 290// program to abort if encountered. 291# define LLVM_BUILTIN_DEBUGTRAP 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_ALIGNAS 307/// \brief Used to specify a minimum alignment for a structure or variable. The 308/// alignment must be a constant integer. Use LLVM_PTR_SIZE to compute 309/// alignments in terms of the size of a pointer. 310/// 311/// Note that __declspec(align) has special quirks, it's not legal to pass a 312/// structure with __declspec(align) as a formal parameter. 313#ifdef _MSC_VER 314# define LLVM_ALIGNAS(x) __declspec(align(x)) 315#elif __GNUC__ && !__has_feature(cxx_alignas) && !LLVM_GNUC_PREREQ(4, 8, 0) 316# define LLVM_ALIGNAS(x) __attribute__((aligned(x))) 317#else 318# define LLVM_ALIGNAS(x) alignas(x) 319#endif 320 321/// \macro LLVM_PACKED 322/// \brief Used to specify a packed structure. 323/// LLVM_PACKED( 324/// struct A { 325/// int i; 326/// int j; 327/// int k; 328/// long long l; 329/// }); 330/// 331/// LLVM_PACKED_START 332/// struct B { 333/// int i; 334/// int j; 335/// int k; 336/// long long l; 337/// }; 338/// LLVM_PACKED_END 339#ifdef _MSC_VER 340# define LLVM_PACKED(d) __pragma(pack(push, 1)) d __pragma(pack(pop)) 341# define LLVM_PACKED_START __pragma(pack(push, 1)) 342# define LLVM_PACKED_END __pragma(pack(pop)) 343#else 344# define LLVM_PACKED(d) d __attribute__((packed)) 345# define LLVM_PACKED_START _Pragma("pack(push, 1)") 346# define LLVM_PACKED_END _Pragma("pack(pop)") 347#endif 348 349/// \macro LLVM_PTR_SIZE 350/// \brief A constant integer equivalent to the value of sizeof(void*). 351/// Generally used in combination with LLVM_ALIGNAS or when doing computation in 352/// the preprocessor. 353#ifdef __SIZEOF_POINTER__ 354# define LLVM_PTR_SIZE __SIZEOF_POINTER__ 355#elif defined(_WIN64) 356# define LLVM_PTR_SIZE 8 357#elif defined(_WIN32) 358# define LLVM_PTR_SIZE 4 359#elif defined(_MSC_VER) 360# error "could not determine LLVM_PTR_SIZE as a constant int for MSVC" 361#else 362# define LLVM_PTR_SIZE sizeof(void *) 363#endif 364 365/// \macro LLVM_FUNCTION_NAME 366/// \brief Expands to __func__ on compilers which support it. Otherwise, 367/// expands to a compiler-dependent replacement. 368#if defined(_MSC_VER) 369# define LLVM_FUNCTION_NAME __FUNCTION__ 370#else 371# define LLVM_FUNCTION_NAME __func__ 372#endif 373 374/// \macro LLVM_MEMORY_SANITIZER_BUILD 375/// \brief Whether LLVM itself is built with MemorySanitizer instrumentation. 376#if __has_feature(memory_sanitizer) 377# define LLVM_MEMORY_SANITIZER_BUILD 1 378# include <sanitizer/msan_interface.h> 379#else 380# define LLVM_MEMORY_SANITIZER_BUILD 0 381# define __msan_allocated_memory(p, size) 382# define __msan_unpoison(p, size) 383#endif 384 385/// \macro LLVM_ADDRESS_SANITIZER_BUILD 386/// \brief Whether LLVM itself is built with AddressSanitizer instrumentation. 387#if __has_feature(address_sanitizer) || defined(__SANITIZE_ADDRESS__) 388# define LLVM_ADDRESS_SANITIZER_BUILD 1 389# include <sanitizer/asan_interface.h> 390#else 391# define LLVM_ADDRESS_SANITIZER_BUILD 0 392# define __asan_poison_memory_region(p, size) 393# define __asan_unpoison_memory_region(p, size) 394#endif 395 396/// \macro LLVM_THREAD_SANITIZER_BUILD 397/// \brief Whether LLVM itself is built with ThreadSanitizer instrumentation. 398#if __has_feature(thread_sanitizer) || defined(__SANITIZE_THREAD__) 399# define LLVM_THREAD_SANITIZER_BUILD 1 400#else 401# define LLVM_THREAD_SANITIZER_BUILD 0 402#endif 403 404#if LLVM_THREAD_SANITIZER_BUILD 405// Thread Sanitizer is a tool that finds races in code. 406// See http://code.google.com/p/data-race-test/wiki/DynamicAnnotations . 407// tsan detects these exact functions by name. 408extern "C" { 409void AnnotateHappensAfter(const char *file, int line, const volatile void *cv); 410void AnnotateHappensBefore(const char *file, int line, const volatile void *cv); 411void AnnotateIgnoreWritesBegin(const char *file, int line); 412void AnnotateIgnoreWritesEnd(const char *file, int line); 413} 414 415// This marker is used to define a happens-before arc. The race detector will 416// infer an arc from the begin to the end when they share the same pointer 417// argument. 418# define TsanHappensBefore(cv) AnnotateHappensBefore(__FILE__, __LINE__, cv) 419 420// This marker defines the destination of a happens-before arc. 421# define TsanHappensAfter(cv) AnnotateHappensAfter(__FILE__, __LINE__, cv) 422 423// Ignore any races on writes between here and the next TsanIgnoreWritesEnd. 424# define TsanIgnoreWritesBegin() AnnotateIgnoreWritesBegin(__FILE__, __LINE__) 425 426// Resume checking for racy writes. 427# define TsanIgnoreWritesEnd() AnnotateIgnoreWritesEnd(__FILE__, __LINE__) 428#else 429# define TsanHappensBefore(cv) 430# define TsanHappensAfter(cv) 431# define TsanIgnoreWritesBegin() 432# define TsanIgnoreWritesEnd() 433#endif 434 435/// \macro LLVM_NO_SANITIZE 436/// \brief Disable a particular sanitizer for a function. 437#if __has_attribute(no_sanitize) 438#define LLVM_NO_SANITIZE(KIND) __attribute__((no_sanitize(KIND))) 439#else 440#define LLVM_NO_SANITIZE(KIND) 441#endif 442 443/// \brief Mark debug helper function definitions like dump() that should not be 444/// stripped from debug builds. 445// FIXME: Move this to a private config.h as it's not usable in public headers. 446#if !defined(NDEBUG) || defined(LLVM_ENABLE_DUMP) 447#define LLVM_DUMP_METHOD LLVM_ATTRIBUTE_NOINLINE LLVM_ATTRIBUTE_USED 448#else 449#define LLVM_DUMP_METHOD LLVM_ATTRIBUTE_NOINLINE 450#endif 451 452/// \macro LLVM_THREAD_LOCAL 453/// \brief A thread-local storage specifier which can be used with globals, 454/// extern globals, and static globals. 455/// 456/// This is essentially an extremely restricted analog to C++11's thread_local 457/// support, and uses that when available. However, it falls back on 458/// platform-specific or vendor-provided extensions when necessary. These 459/// extensions don't support many of the C++11 thread_local's features. You 460/// should only use this for PODs that you can statically initialize to 461/// some constant value. In almost all circumstances this is most appropriate 462/// for use with a pointer, integer, or small aggregation of pointers and 463/// integers. 464#if LLVM_ENABLE_THREADS 465#if __has_feature(cxx_thread_local) 466#define LLVM_THREAD_LOCAL thread_local 467#elif defined(_MSC_VER) 468// MSVC supports this with a __declspec. 469#define LLVM_THREAD_LOCAL __declspec(thread) 470#else 471// Clang, GCC, and other compatible compilers used __thread prior to C++11 and 472// we only need the restricted functionality that provides. 473#define LLVM_THREAD_LOCAL __thread 474#endif 475#else // !LLVM_ENABLE_THREADS 476// If threading is disabled entirely, this compiles to nothing and you get 477// a normal global variable. 478#define LLVM_THREAD_LOCAL 479#endif 480 481#endif 482