Compiler.h revision 630d17566793c7f25a05cd407ab9b79a1756966a
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_attribute 25# define __has_attribute(x) 0 26#endif 27 28#ifndef __has_builtin 29# define __has_builtin(x) 0 30#endif 31 32/// \macro __GNUC_PREREQ 33/// \brief Defines __GNUC_PREREQ if glibc's features.h isn't available. 34#ifndef __GNUC_PREREQ 35# if defined(__GNUC__) && defined(__GNUC_MINOR__) 36# define __GNUC_PREREQ(maj, min) \ 37 ((__GNUC__ << 16) + __GNUC_MINOR__ >= ((maj) << 16) + (min)) 38# else 39# define __GNUC_PREREQ(maj, min) 0 40# endif 41#endif 42 43/// \brief Does the compiler support r-value references? 44/// This implies that <utility> provides the one-argument std::move; it 45/// does not imply the existence of any other C++ library features. 46#if (__has_feature(cxx_rvalue_references) \ 47 || defined(__GXX_EXPERIMENTAL_CXX0X__) \ 48 || (defined(_MSC_VER) && _MSC_VER >= 1600)) 49#define LLVM_HAS_RVALUE_REFERENCES 1 50#else 51#define LLVM_HAS_RVALUE_REFERENCES 0 52#endif 53 54/// \brief Does the compiler support r-value reference *this? 55/// 56/// Sadly, this is separate from just r-value reference support because GCC 57/// implemented everything but this thus far. No release of GCC yet has support 58/// for this feature so it is enabled with Clang only. 59/// FIXME: This should change to a version check when GCC grows support for it. 60#if __has_feature(cxx_rvalue_references) 61#define LLVM_HAS_RVALUE_REFERENCE_THIS 1 62#else 63#define LLVM_HAS_RVALUE_REFERENCE_THIS 0 64#endif 65 66/// \macro LLVM_HAS_CXX11_TYPETRAITS 67/// \brief Does the compiler have the C++11 type traits. 68/// 69/// #include <type_traits> 70/// 71/// * enable_if 72/// * {true,false}_type 73/// * is_constructible 74/// * etc... 75#if defined(__GXX_EXPERIMENTAL_CXX0X__) \ 76 || (defined(_MSC_VER) && _MSC_VER >= 1700) 77#define LLVM_HAS_CXX11_TYPETRAITS 1 78#else 79#define LLVM_HAS_CXX11_TYPETRAITS 0 80#endif 81 82/// \macro LLVM_HAS_CXX11_STDLIB 83/// \brief Does the compiler have the C++11 standard library. 84/// 85/// Implies LLVM_HAS_RVALUE_REFERENCES, LLVM_HAS_CXX11_TYPETRAITS 86#if defined(__GXX_EXPERIMENTAL_CXX0X__) \ 87 || (defined(_MSC_VER) && _MSC_VER >= 1700) 88#define LLVM_HAS_CXX11_STDLIB 1 89#else 90#define LLVM_HAS_CXX11_STDLIB 0 91#endif 92 93/// \macro LLVM_HAS_VARIADIC_TEMPLATES 94/// \brief Does this compiler support variadic templates. 95/// 96/// Implies LLVM_HAS_RVALUE_REFERENCES and the existence of std::forward. 97#if __has_feature(cxx_variadic_templates) 98# define LLVM_HAS_VARIADIC_TEMPLATES 1 99#else 100# define LLVM_HAS_VARIADIC_TEMPLATES 0 101#endif 102 103/// llvm_move - Expands to ::std::move if the compiler supports 104/// r-value references; otherwise, expands to the argument. 105#if LLVM_HAS_RVALUE_REFERENCES 106#define llvm_move(value) (::std::move(value)) 107#else 108#define llvm_move(value) (value) 109#endif 110 111/// Expands to '&' if r-value references are supported. 112/// 113/// This can be used to provide l-value/r-value overrides of member functions. 114/// The r-value override should be guarded by LLVM_HAS_RVALUE_REFERENCE_THIS 115#if LLVM_HAS_RVALUE_REFERENCE_THIS 116#define LLVM_LVALUE_FUNCTION & 117#else 118#define LLVM_LVALUE_FUNCTION 119#endif 120 121/// LLVM_DELETED_FUNCTION - Expands to = delete if the compiler supports it. 122/// Use to mark functions as uncallable. Member functions with this should 123/// be declared private so that some behavior is kept in C++03 mode. 124/// 125/// class DontCopy { 126/// private: 127/// DontCopy(const DontCopy&) LLVM_DELETED_FUNCTION; 128/// DontCopy &operator =(const DontCopy&) LLVM_DELETED_FUNCTION; 129/// public: 130/// ... 131/// }; 132#if (__has_feature(cxx_deleted_functions) \ 133 || defined(__GXX_EXPERIMENTAL_CXX0X__)) 134 // No version of MSVC currently supports this. 135#define LLVM_DELETED_FUNCTION = delete 136#else 137#define LLVM_DELETED_FUNCTION 138#endif 139 140/// LLVM_FINAL - Expands to 'final' if the compiler supports it. 141/// Use to mark classes or virtual methods as final. 142#if __has_feature(cxx_override_control) \ 143 || (defined(_MSC_VER) && _MSC_VER >= 1700) 144#define LLVM_FINAL final 145#else 146#define LLVM_FINAL 147#endif 148 149/// LLVM_OVERRIDE - Expands to 'override' if the compiler supports it. 150/// Use to mark virtual methods as overriding a base class method. 151#if __has_feature(cxx_override_control) \ 152 || (defined(_MSC_VER) && _MSC_VER >= 1700) 153#define LLVM_OVERRIDE override 154#else 155#define LLVM_OVERRIDE 156#endif 157 158#if __has_feature(cxx_constexpr) || defined(__GXX_EXPERIMENTAL_CXX0X__) 159# define LLVM_CONSTEXPR constexpr 160#else 161# define LLVM_CONSTEXPR 162#endif 163 164/// LLVM_LIBRARY_VISIBILITY - If a class marked with this attribute is linked 165/// into a shared library, then the class should be private to the library and 166/// not accessible from outside it. Can also be used to mark variables and 167/// functions, making them private to any shared library they are linked into. 168/// On PE/COFF targets, library visibility is the default, so this isn't needed. 169#if (__has_attribute(visibility) || __GNUC_PREREQ(4, 0)) && \ 170 !defined(__MINGW32__) && !defined(__CYGWIN__) && !defined(LLVM_ON_WIN32) 171#define LLVM_LIBRARY_VISIBILITY __attribute__ ((visibility("hidden"))) 172#else 173#define LLVM_LIBRARY_VISIBILITY 174#endif 175 176#if __has_attribute(used) || __GNUC_PREREQ(3, 1) 177#define LLVM_ATTRIBUTE_USED __attribute__((__used__)) 178#else 179#define LLVM_ATTRIBUTE_USED 180#endif 181 182#if __has_attribute(warn_unused_result) || __GNUC_PREREQ(3, 4) 183#define LLVM_ATTRIBUTE_UNUSED_RESULT __attribute__((__warn_unused_result__)) 184#else 185#define LLVM_ATTRIBUTE_UNUSED_RESULT 186#endif 187 188// Some compilers warn about unused functions. When a function is sometimes 189// used or not depending on build settings (e.g. a function only called from 190// within "assert"), this attribute can be used to suppress such warnings. 191// 192// However, it shouldn't be used for unused *variables*, as those have a much 193// more portable solution: 194// (void)unused_var_name; 195// Prefer cast-to-void wherever it is sufficient. 196#if __has_attribute(unused) || __GNUC_PREREQ(3, 1) 197#define LLVM_ATTRIBUTE_UNUSED __attribute__((__unused__)) 198#else 199#define LLVM_ATTRIBUTE_UNUSED 200#endif 201 202// FIXME: Provide this for PE/COFF targets. 203#if (__has_attribute(weak) || __GNUC_PREREQ(4, 0)) && \ 204 (!defined(__MINGW32__) && !defined(__CYGWIN__) && !defined(LLVM_ON_WIN32)) 205#define LLVM_ATTRIBUTE_WEAK __attribute__((__weak__)) 206#else 207#define LLVM_ATTRIBUTE_WEAK 208#endif 209 210// Prior to clang 3.2, clang did not accept any spelling of 211// __has_attribute(const), so assume it is supported. 212#if defined(__clang__) || defined(__GNUC__) 213// aka 'CONST' but following LLVM Conventions. 214#define LLVM_READNONE __attribute__((__const__)) 215#else 216#define LLVM_READNONE 217#endif 218 219#if __has_attribute(pure) || defined(__GNUC__) 220// aka 'PURE' but following LLVM Conventions. 221#define LLVM_READONLY __attribute__((__pure__)) 222#else 223#define LLVM_READONLY 224#endif 225 226#if __has_builtin(__builtin_expect) || __GNUC_PREREQ(4, 0) 227#define LLVM_LIKELY(EXPR) __builtin_expect((bool)(EXPR), true) 228#define LLVM_UNLIKELY(EXPR) __builtin_expect((bool)(EXPR), false) 229#else 230#define LLVM_LIKELY(EXPR) (EXPR) 231#define LLVM_UNLIKELY(EXPR) (EXPR) 232#endif 233 234// C++ doesn't support 'extern template' of template specializations. GCC does, 235// but requires __extension__ before it. In the header, use this: 236// EXTERN_TEMPLATE_INSTANTIATION(class foo<bar>); 237// in the .cpp file, use this: 238// TEMPLATE_INSTANTIATION(class foo<bar>); 239#ifdef __GNUC__ 240#define EXTERN_TEMPLATE_INSTANTIATION(X) __extension__ extern template X 241#define TEMPLATE_INSTANTIATION(X) template X 242#else 243#define EXTERN_TEMPLATE_INSTANTIATION(X) 244#define TEMPLATE_INSTANTIATION(X) 245#endif 246 247/// LLVM_ATTRIBUTE_NOINLINE - On compilers where we have a directive to do so, 248/// mark a method "not for inlining". 249#if __has_attribute(noinline) || __GNUC_PREREQ(3, 4) 250#define LLVM_ATTRIBUTE_NOINLINE __attribute__((noinline)) 251#elif defined(_MSC_VER) 252#define LLVM_ATTRIBUTE_NOINLINE __declspec(noinline) 253#else 254#define LLVM_ATTRIBUTE_NOINLINE 255#endif 256 257/// LLVM_ATTRIBUTE_ALWAYS_INLINE - On compilers where we have a directive to do 258/// so, mark a method "always inline" because it is performance sensitive. GCC 259/// 3.4 supported this but is buggy in various cases and produces unimplemented 260/// errors, just use it in GCC 4.0 and later. 261#if __has_attribute(always_inline) || __GNUC_PREREQ(4, 0) 262#define LLVM_ATTRIBUTE_ALWAYS_INLINE inline __attribute__((always_inline)) 263#elif defined(_MSC_VER) 264#define LLVM_ATTRIBUTE_ALWAYS_INLINE __forceinline 265#else 266#define LLVM_ATTRIBUTE_ALWAYS_INLINE 267#endif 268 269#ifdef __GNUC__ 270#define LLVM_ATTRIBUTE_NORETURN __attribute__((noreturn)) 271#elif defined(_MSC_VER) 272#define LLVM_ATTRIBUTE_NORETURN __declspec(noreturn) 273#else 274#define LLVM_ATTRIBUTE_NORETURN 275#endif 276 277/// LLVM_EXTENSION - Support compilers where we have a keyword to suppress 278/// pedantic diagnostics. 279#ifdef __GNUC__ 280#define LLVM_EXTENSION __extension__ 281#else 282#define LLVM_EXTENSION 283#endif 284 285// LLVM_ATTRIBUTE_DEPRECATED(decl, "message") 286#if __has_feature(attribute_deprecated_with_message) 287# define LLVM_ATTRIBUTE_DEPRECATED(decl, message) \ 288 decl __attribute__((deprecated(message))) 289#elif defined(__GNUC__) 290# define LLVM_ATTRIBUTE_DEPRECATED(decl, message) \ 291 decl __attribute__((deprecated)) 292#elif defined(_MSC_VER) 293# define LLVM_ATTRIBUTE_DEPRECATED(decl, message) \ 294 __declspec(deprecated(message)) decl 295#else 296# define LLVM_ATTRIBUTE_DEPRECATED(decl, message) \ 297 decl 298#endif 299 300/// LLVM_BUILTIN_UNREACHABLE - On compilers which support it, expands 301/// to an expression which states that it is undefined behavior for the 302/// compiler to reach this point. Otherwise is not defined. 303#if __has_builtin(__builtin_unreachable) || __GNUC_PREREQ(4, 5) 304# define LLVM_BUILTIN_UNREACHABLE __builtin_unreachable() 305#elif defined(_MSC_VER) 306# define LLVM_BUILTIN_UNREACHABLE __assume(false) 307#endif 308 309/// LLVM_BUILTIN_TRAP - On compilers which support it, expands to an expression 310/// which causes the program to exit abnormally. 311#if __has_builtin(__builtin_trap) || __GNUC_PREREQ(4, 3) 312# define LLVM_BUILTIN_TRAP __builtin_trap() 313#else 314# define LLVM_BUILTIN_TRAP *(volatile int*)0x11 = 0 315#endif 316 317/// \macro LLVM_ASSUME_ALIGNED 318/// \brief Returns a pointer with an assumed alignment. 319#if __has_builtin(__builtin_assume_aligned) && __GNUC_PREREQ(4, 7) 320# define LLVM_ASSUME_ALIGNED(p, a) __builtin_assume_aligned(p, a) 321#elif defined(LLVM_BUILTIN_UNREACHABLE) 322// As of today, clang does not support __builtin_assume_aligned. 323# define LLVM_ASSUME_ALIGNED(p, a) \ 324 (((uintptr_t(p) % (a)) == 0) ? (p) : (LLVM_BUILTIN_UNREACHABLE, (p))) 325#else 326# define LLVM_ASSUME_ALIGNED(p, a) (p) 327#endif 328 329/// \macro LLVM_FUNCTION_NAME 330/// \brief Expands to __func__ on compilers which support it. Otherwise, 331/// expands to a compiler-dependent replacement. 332#if defined(_MSC_VER) 333# define LLVM_FUNCTION_NAME __FUNCTION__ 334#else 335# define LLVM_FUNCTION_NAME __func__ 336#endif 337 338#if defined(HAVE_SANITIZER_MSAN_INTERFACE_H) 339# include <sanitizer/msan_interface.h> 340#else 341# define __msan_allocated_memory(p, size) 342# define __msan_unpoison(p, size) 343#endif 344 345/// \macro LLVM_MEMORY_SANITIZER_BUILD 346/// \brief Whether LLVM itself is built with MemorySanitizer instrumentation. 347#if __has_feature(memory_sanitizer) 348# define LLVM_MEMORY_SANITIZER_BUILD 1 349#else 350# define LLVM_MEMORY_SANITIZER_BUILD 0 351#endif 352 353/// \macro LLVM_ADDRESS_SANITIZER_BUILD 354/// \brief Whether LLVM itself is built with AddressSanitizer instrumentation. 355#if __has_feature(address_sanitizer) || defined(__SANITIZE_ADDRESS__) 356# define LLVM_ADDRESS_SANITIZER_BUILD 1 357#else 358# define LLVM_ADDRESS_SANITIZER_BUILD 0 359#endif 360 361/// \macro LLVM_IS_UNALIGNED_ACCESS_FAST 362/// \brief Is unaligned memory access fast on the host machine. 363/// 364/// Don't specialize on alignment for platforms where unaligned memory accesses 365/// generates the same code as aligned memory accesses for common types. 366#if defined(_M_AMD64) || defined(_M_IX86) || defined(__amd64) || \ 367 defined(__amd64__) || defined(__x86_64) || defined(__x86_64__) || \ 368 defined(_X86_) || defined(__i386) || defined(__i386__) 369# define LLVM_IS_UNALIGNED_ACCESS_FAST 1 370#else 371# define LLVM_IS_UNALIGNED_ACCESS_FAST 0 372#endif 373 374/// \macro LLVM_EXPLICIT 375/// \brief Expands to explicit on compilers which support explicit conversion 376/// operators. Otherwise expands to nothing. 377#if (__has_feature(cxx_explicit_conversions) \ 378 || defined(__GXX_EXPERIMENTAL_CXX0X__)) 379#define LLVM_EXPLICIT explicit 380#else 381#define LLVM_EXPLICIT 382#endif 383 384/// \macro LLVM_STATIC_ASSERT 385/// \brief Expands to C/C++'s static_assert on compilers which support it. 386#if __has_feature(cxx_static_assert) 387# define LLVM_STATIC_ASSERT(expr, msg) static_assert(expr, msg) 388#elif __has_feature(c_static_assert) 389# define LLVM_STATIC_ASSERT(expr, msg) _Static_assert(expr, msg) 390#else 391# define LLVM_STATIC_ASSERT(expr, msg) 392#endif 393 394#endif 395