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