include/llvm/Support/Compiler.h - llvm - Git at Google

 //===-- llvm/Support/Compiler.h - Compiler abstraction support --*- C++ -*-===//
 //
 //                     The LLVM Compiler Infrastructure
 //
 // This file is distributed under the University of Illinois Open Source
 // License. See LICENSE.TXT for details.
 //
 //===----------------------------------------------------------------------===//
 //
 // This file defines several macros, based on the current compiler.  This allows
 // use of compiler-specific features in a way that remains portable.
 //
 //===----------------------------------------------------------------------===//

 #ifndef LLVM_SUPPORT_COMPILER_H
 #define LLVM_SUPPORT_COMPILER_H

 #include "llvm/Config/llvm-config.h"

 #ifndef __has_feature
 # define __has_feature(x) 0
 #endif

 /// \brief Does the compiler support r-value references?
 /// This implies that <utility> provides the one-argument std::move;  it
 /// does not imply the existence of any other C++ library features.
 #if (__has_feature(cxx_rvalue_references)   \
      || defined(__GXX_EXPERIMENTAL_CXX0X__) \
      || (defined(_MSC_VER) && _MSC_VER >= 1600))
 #define LLVM_HAS_RVALUE_REFERENCES 1
 #else
 #define LLVM_HAS_RVALUE_REFERENCES 0
 #endif

 /// \brief Does the compiler support r-value reference *this?
 ///
 /// Sadly, this is separate from just r-value reference support because GCC
 /// implemented everything but this thus far. No release of GCC yet has support
 /// for this feature so it is enabled with Clang only.
 /// FIXME: This should change to a version check when GCC grows support for it.
 #if __has_feature(cxx_rvalue_references)
 #define LLVM_HAS_RVALUE_REFERENCE_THIS 1
 #else
 #define LLVM_HAS_RVALUE_REFERENCE_THIS 0
 #endif

 /// \macro LLVM_HAS_CXX11_TYPETRAITS
 /// \brief Does the compiler have the C++11 type traits.
 ///
 /// #include <type_traits>
 ///
 /// * enable_if
 /// * {true,false}_type
 /// * is_constructible
 /// * etc...
 #if defined(__GXX_EXPERIMENTAL_CXX0X__) \
     || (defined(_MSC_VER) && _MSC_VER >= 1700)
 #define LLVM_HAS_CXX11_TYPETRAITS 1
 #else
 #define LLVM_HAS_CXX11_TYPETRAITS 0
 #endif

 /// \macro LLVM_HAS_CXX11_STDLIB
 /// \brief Does the compiler have the C++11 standard library.
 ///
 /// Implies LLVM_HAS_RVALUE_REFERENCES, LLVM_HAS_CXX11_TYPETRAITS
 #if defined(__GXX_EXPERIMENTAL_CXX0X__) \
     || (defined(_MSC_VER) && _MSC_VER >= 1700)
 #define LLVM_HAS_CXX11_STDLIB 1
 #else
 #define LLVM_HAS_CXX11_STDLIB 0
 #endif

 /// \macro LLVM_HAS_VARIADIC_TEMPLATES
 /// \brief Does this compiler support variadic templates.
 ///
 /// Implies LLVM_HAS_RVALUE_REFERENCES and the existence of std::forward.
 #if __has_feature(cxx_variadic_templates)
 # define LLVM_HAS_VARIADIC_TEMPLATES 1
 #else
 # define LLVM_HAS_VARIADIC_TEMPLATES 0
 #endif

 /// llvm_move - Expands to ::std::move if the compiler supports
 /// r-value references; otherwise, expands to the argument.
 #if LLVM_HAS_RVALUE_REFERENCES
 #define llvm_move(value) (::std::move(value))
 #else
 #define llvm_move(value) (value)
 #endif

 /// Expands to '&' if r-value references are supported.
 ///
 /// This can be used to provide l-value/r-value overrides of member functions.
 /// The r-value override should be guarded by LLVM_HAS_RVALUE_REFERENCE_THIS
 #if LLVM_HAS_RVALUE_REFERENCE_THIS
 #define LLVM_LVALUE_FUNCTION &
 #else
 #define LLVM_LVALUE_FUNCTION
 #endif

 /// LLVM_DELETED_FUNCTION - Expands to = delete if the compiler supports it.
 /// Use to mark functions as uncallable. Member functions with this should
 /// be declared private so that some behavior is kept in C++03 mode.
 ///
 /// class DontCopy {
 /// private:
 ///   DontCopy(const DontCopy&) LLVM_DELETED_FUNCTION;
 ///   DontCopy &operator =(const DontCopy&) LLVM_DELETED_FUNCTION;
 /// public:
 ///   ...
 /// };
 #if (__has_feature(cxx_deleted_functions) \
      || defined(__GXX_EXPERIMENTAL_CXX0X__))
      // No version of MSVC currently supports this.
 #define LLVM_DELETED_FUNCTION = delete
 #else
 #define LLVM_DELETED_FUNCTION
 #endif

 /// LLVM_FINAL - Expands to 'final' if the compiler supports it.
 /// Use to mark classes or virtual methods as final.
 #if __has_feature(cxx_override_control) \
     || (defined(_MSC_VER) && _MSC_VER >= 1700)
 #define LLVM_FINAL final
 #else
 #define LLVM_FINAL
 #endif

 /// LLVM_OVERRIDE - Expands to 'override' if the compiler supports it.
 /// Use to mark virtual methods as overriding a base class method.
 #if __has_feature(cxx_override_control) \
     || (defined(_MSC_VER) && _MSC_VER >= 1700)
 #define LLVM_OVERRIDE override
 #else
 #define LLVM_OVERRIDE
 #endif

 #if __has_feature(cxx_constexpr) || defined(__GXX_EXPERIMENTAL_CXX0X__)
 # define LLVM_CONSTEXPR constexpr
 #else
 # define LLVM_CONSTEXPR
 #endif

 /// LLVM_LIBRARY_VISIBILITY - If a class marked with this attribute is linked
 /// into a shared library, then the class should be private to the library and
 /// not accessible from outside it.  Can also be used to mark variables and
 /// functions, making them private to any shared library they are linked into.
 #if (__GNUC__ >= 4) && !defined(__MINGW32__) && !defined(__CYGWIN__)
 #define LLVM_LIBRARY_VISIBILITY __attribute__ ((visibility("hidden")))
 #else
 #define LLVM_LIBRARY_VISIBILITY
 #endif

 #if (__GNUC__ >= 4 || (__GNUC__ == 3 && __GNUC_MINOR__ >= 1))
 #define LLVM_ATTRIBUTE_USED __attribute__((__used__))
 #else
 #define LLVM_ATTRIBUTE_USED
 #endif

 // Some compilers warn about unused functions. When a function is sometimes
 // used or not depending on build settings (e.g. a function only called from
 // within "assert"), this attribute can be used to suppress such warnings.
 //
 // However, it shouldn't be used for unused *variables*, as those have a much
 // more portable solution:
 //   (void)unused_var_name;
 // Prefer cast-to-void wherever it is sufficient.
 #if (__GNUC__ >= 4 || (__GNUC__ == 3 && __GNUC_MINOR__ >= 1))
 #define LLVM_ATTRIBUTE_UNUSED __attribute__((__unused__))
 #else
 #define LLVM_ATTRIBUTE_UNUSED
 #endif

 #if (__GNUC__ >= 4) && !defined(__MINGW32__) && !defined(__CYGWIN__)
 #define LLVM_ATTRIBUTE_WEAK __attribute__((__weak__))
 #else
 #define LLVM_ATTRIBUTE_WEAK
 #endif

 #ifdef __GNUC__ // aka 'CONST' but following LLVM Conventions.
 #define LLVM_READNONE __attribute__((__const__))
 #else
 #define LLVM_READNONE
 #endif

 #ifdef __GNUC__  // aka 'PURE' but following LLVM Conventions.
 #define LLVM_READONLY __attribute__((__pure__))
 #else
 #define LLVM_READONLY
 #endif

 #if (__GNUC__ >= 4)
 #define LLVM_LIKELY(EXPR) __builtin_expect((bool)(EXPR), true)
 #define LLVM_UNLIKELY(EXPR) __builtin_expect((bool)(EXPR), false)
 #else
 #define LLVM_LIKELY(EXPR) (EXPR)
 #define LLVM_UNLIKELY(EXPR) (EXPR)
 #endif

 // C++ doesn't support 'extern template' of template specializations.  GCC does,
 // but requires __extension__ before it.  In the header, use this:
 //   EXTERN_TEMPLATE_INSTANTIATION(class foo<bar>);
 // in the .cpp file, use this:
 //   TEMPLATE_INSTANTIATION(class foo<bar>);
 #ifdef __GNUC__
 #define EXTERN_TEMPLATE_INSTANTIATION(X) __extension__ extern template X
 #define TEMPLATE_INSTANTIATION(X) template X
 #else
 #define EXTERN_TEMPLATE_INSTANTIATION(X)
 #define TEMPLATE_INSTANTIATION(X)
 #endif

 /// LLVM_ATTRIBUTE_NOINLINE - On compilers where we have a directive to do so,
 /// mark a method "not for inlining".
 #if (__GNUC__ > 3 || (__GNUC__ == 3 && __GNUC_MINOR__ >= 4))
 #define LLVM_ATTRIBUTE_NOINLINE __attribute__((noinline))
 #elif defined(_MSC_VER)
 #define LLVM_ATTRIBUTE_NOINLINE __declspec(noinline)
 #else
 #define LLVM_ATTRIBUTE_NOINLINE
 #endif

 /// LLVM_ATTRIBUTE_ALWAYS_INLINE - On compilers where we have a directive to do
 /// so, mark a method "always inline" because it is performance sensitive. GCC
 /// 3.4 supported this but is buggy in various cases and produces unimplemented
 /// errors, just use it in GCC 4.0 and later.
 #if __GNUC__ > 3
 #define LLVM_ATTRIBUTE_ALWAYS_INLINE inline __attribute__((always_inline))
 #elif defined(_MSC_VER)
 #define LLVM_ATTRIBUTE_ALWAYS_INLINE __forceinline
 #else
 #define LLVM_ATTRIBUTE_ALWAYS_INLINE
 #endif

 #ifdef __GNUC__
 #define LLVM_ATTRIBUTE_NORETURN __attribute__((noreturn))
 #elif defined(_MSC_VER)
 #define LLVM_ATTRIBUTE_NORETURN __declspec(noreturn)
 #else
 #define LLVM_ATTRIBUTE_NORETURN
 #endif

 /// LLVM_EXTENSION - Support compilers where we have a keyword to suppress
 /// pedantic diagnostics.
 #ifdef __GNUC__
 #define LLVM_EXTENSION __extension__
 #else
 #define LLVM_EXTENSION
 #endif

 // LLVM_ATTRIBUTE_DEPRECATED(decl, "message")
 #if __has_feature(attribute_deprecated_with_message)
 # define LLVM_ATTRIBUTE_DEPRECATED(decl, message) \
   decl __attribute__((deprecated(message)))
 #elif defined(__GNUC__)
 # define LLVM_ATTRIBUTE_DEPRECATED(decl, message) \
   decl __attribute__((deprecated))
 #elif defined(_MSC_VER)
 # define LLVM_ATTRIBUTE_DEPRECATED(decl, message) \
   __declspec(deprecated(message)) decl
 #else
 # define LLVM_ATTRIBUTE_DEPRECATED(decl, message) \
   decl
 #endif

 /// LLVM_BUILTIN_UNREACHABLE - On compilers which support it, expands
 /// to an expression which states that it is undefined behavior for the
 /// compiler to reach this point.  Otherwise is not defined.
 #if defined(__clang__) || (__GNUC__ > 4) \
  || (__GNUC__ == 4 && __GNUC_MINOR__ >= 5)
 # define LLVM_BUILTIN_UNREACHABLE __builtin_unreachable()
 #elif defined(_MSC_VER)
 # define LLVM_BUILTIN_UNREACHABLE __assume(false)
 #endif

 /// LLVM_BUILTIN_TRAP - On compilers which support it, expands to an expression
 /// which causes the program to exit abnormally.
 #if defined(__clang__) || (__GNUC__ > 4) \
  || (__GNUC__ == 4 && __GNUC_MINOR__ >= 3)
 # define LLVM_BUILTIN_TRAP __builtin_trap()
 #else
 # define LLVM_BUILTIN_TRAP *(volatile int*)0x11 = 0
 #endif

 /// \macro LLVM_ASSUME_ALIGNED
 /// \brief Returns a pointer with an assumed alignment.
 #if !defined(__clang__) && ((__GNUC__ > 4) \
  || (__GNUC__ == 4 && __GNUC_MINOR__ >= 7))
 // FIXME: Enable on clang when it supports it.
 # define LLVM_ASSUME_ALIGNED(p, a) __builtin_assume_aligned(p, a)
 #elif defined(LLVM_BUILTIN_UNREACHABLE)
 # define LLVM_ASSUME_ALIGNED(p, a) \
            (((uintptr_t(p) % (a)) == 0) ? (p) : (LLVM_BUILTIN_UNREACHABLE, (p)))
 #else
 # define LLVM_ASSUME_ALIGNED(p, a) (p)
 #endif

 /// \macro LLVM_FUNCTION_NAME
 /// \brief Expands to __func__ on compilers which support it.  Otherwise,
 /// expands to a compiler-dependent replacement.
 #if defined(_MSC_VER)
 # define LLVM_FUNCTION_NAME __FUNCTION__
 #else
 # define LLVM_FUNCTION_NAME __func__
 #endif

 #if defined(HAVE_SANITIZER_MSAN_INTERFACE_H)
 # include <sanitizer/msan_interface.h>
 #else
 # define __msan_allocated_memory(p, size)
 # define __msan_unpoison(p, size)
 #endif

 /// \macro LLVM_MEMORY_SANITIZER_BUILD
 /// \brief Whether LLVM itself is built with MemorySanitizer instrumentation.
 #if __has_feature(memory_sanitizer)
 # define LLVM_MEMORY_SANITIZER_BUILD 1
 #else
 # define LLVM_MEMORY_SANITIZER_BUILD 0
 #endif

 /// \macro LLVM_ADDRESS_SANITIZER_BUILD
 /// \brief Whether LLVM itself is built with AddressSanitizer instrumentation.
 #if __has_feature(address_sanitizer) || defined(__SANITIZE_ADDRESS__)
 # define LLVM_ADDRESS_SANITIZER_BUILD 1
 #else
 # define LLVM_ADDRESS_SANITIZER_BUILD 0
 #endif

 /// \macro LLVM_IS_UNALIGNED_ACCESS_FAST
 /// \brief Is unaligned memory access fast on the host machine.
 ///
 /// Don't specialize on alignment for platforms where unaligned memory accesses
 /// generates the same code as aligned memory accesses for common types.
 #if defined(_M_AMD64) || defined(_M_IX86) || defined(__amd64) || \
     defined(__amd64__) || defined(__x86_64) || defined(__x86_64__) || \
     defined(_X86_) || defined(__i386) || defined(__i386__)
 # define LLVM_IS_UNALIGNED_ACCESS_FAST 1
 #else
 # define LLVM_IS_UNALIGNED_ACCESS_FAST 0
 #endif

 /// \macro LLVM_EXPLICIT
 /// \brief Expands to explicit on compilers which support explicit conversion
 /// operators. Otherwise expands to nothing.
 #if (__has_feature(cxx_explicit_conversions) \
      || defined(__GXX_EXPERIMENTAL_CXX0X__))
 #define LLVM_EXPLICIT explicit
 #else
 #define LLVM_EXPLICIT
 #endif

 /// \macro LLVM_STATIC_ASSERT
 /// \brief Expands to C/C++'s static_assert on compilers which support it.
 #if __has_feature(cxx_static_assert)
 # define LLVM_STATIC_ASSERT(expr, msg) static_assert(expr, msg)
 #elif __has_feature(c_static_assert)
 # define LLVM_STATIC_ASSERT(expr, msg) _Static_assert(expr, msg)
 #else
 # define LLVM_STATIC_ASSERT(expr, msg)
 #endif

 #endif
	//===-- llvm/Support/Compiler.h - Compiler abstraction support --- C++ --===//
	//
	// The LLVM Compiler Infrastructure
	//
	// This file is distributed under the University of Illinois Open Source
	// License. See LICENSE.TXT for details.
	//
	//===----------------------------------------------------------------------===//
	//
	// This file defines several macros, based on the current compiler. This allows
	// use of compiler-specific features in a way that remains portable.
	//
	//===----------------------------------------------------------------------===//

	#ifndef LLVM_SUPPORT_COMPILER_H
	#define LLVM_SUPPORT_COMPILER_H

	#include "llvm/Config/llvm-config.h"

	#ifndef __has_feature
	# define __has_feature(x) 0
	#endif

	/// \brief Does the compiler support r-value references?
	/// This implies that <utility> provides the one-argument std::move; it
	/// does not imply the existence of any other C++ library features.
	#if (__has_feature(cxx_rvalue_references) \
	\|\| defined(__GXX_EXPERIMENTAL_CXX0X__) \
	\|\| (defined(_MSC_VER) && _MSC_VER >= 1600))
	#define LLVM_HAS_RVALUE_REFERENCES 1
	#else
	#define LLVM_HAS_RVALUE_REFERENCES 0
	#endif

	/// \brief Does the compiler support r-value reference *this?
	///
	/// Sadly, this is separate from just r-value reference support because GCC
	/// implemented everything but this thus far. No release of GCC yet has support
	/// for this feature so it is enabled with Clang only.
	/// FIXME: This should change to a version check when GCC grows support for it.
	#if __has_feature(cxx_rvalue_references)
	#define LLVM_HAS_RVALUE_REFERENCE_THIS 1
	#else
	#define LLVM_HAS_RVALUE_REFERENCE_THIS 0
	#endif

	/// \macro LLVM_HAS_CXX11_TYPETRAITS
	/// \brief Does the compiler have the C++11 type traits.
	///
	/// #include <type_traits>
	///
	/// * enable_if
	/// * {true,false}_type
	/// * is_constructible
	/// * etc...
	#if defined(__GXX_EXPERIMENTAL_CXX0X__) \
	\|\| (defined(_MSC_VER) && _MSC_VER >= 1700)
	#define LLVM_HAS_CXX11_TYPETRAITS 1
	#else
	#define LLVM_HAS_CXX11_TYPETRAITS 0
	#endif

	/// \macro LLVM_HAS_CXX11_STDLIB
	/// \brief Does the compiler have the C++11 standard library.
	///
	/// Implies LLVM_HAS_RVALUE_REFERENCES, LLVM_HAS_CXX11_TYPETRAITS
	#if defined(__GXX_EXPERIMENTAL_CXX0X__) \
	\|\| (defined(_MSC_VER) && _MSC_VER >= 1700)
	#define LLVM_HAS_CXX11_STDLIB 1
	#else
	#define LLVM_HAS_CXX11_STDLIB 0
	#endif

	/// \macro LLVM_HAS_VARIADIC_TEMPLATES
	/// \brief Does this compiler support variadic templates.
	///
	/// Implies LLVM_HAS_RVALUE_REFERENCES and the existence of std::forward.
	#if __has_feature(cxx_variadic_templates)
	# define LLVM_HAS_VARIADIC_TEMPLATES 1
	#else
	# define LLVM_HAS_VARIADIC_TEMPLATES 0
	#endif

	/// llvm_move - Expands to ::std::move if the compiler supports
	/// r-value references; otherwise, expands to the argument.
	#if LLVM_HAS_RVALUE_REFERENCES
	#define llvm_move(value) (::std::move(value))
	#else
	#define llvm_move(value) (value)
	#endif

	/// Expands to '&' if r-value references are supported.
	///
	/// This can be used to provide l-value/r-value overrides of member functions.
	/// The r-value override should be guarded by LLVM_HAS_RVALUE_REFERENCE_THIS
	#if LLVM_HAS_RVALUE_REFERENCE_THIS
	#define LLVM_LVALUE_FUNCTION &
	#else
	#define LLVM_LVALUE_FUNCTION
	#endif

	/// LLVM_DELETED_FUNCTION - Expands to = delete if the compiler supports it.
	/// Use to mark functions as uncallable. Member functions with this should
	/// be declared private so that some behavior is kept in C++03 mode.
	///
	/// class DontCopy {
	/// private:
	/// DontCopy(const DontCopy&) LLVM_DELETED_FUNCTION;
	/// DontCopy &operator =(const DontCopy&) LLVM_DELETED_FUNCTION;
	/// public:
	/// ...
	/// };
	#if (__has_feature(cxx_deleted_functions) \
	\|\| defined(__GXX_EXPERIMENTAL_CXX0X__))
	// No version of MSVC currently supports this.
	#define LLVM_DELETED_FUNCTION = delete
	#else
	#define LLVM_DELETED_FUNCTION
	#endif

	/// LLVM_FINAL - Expands to 'final' if the compiler supports it.
	/// Use to mark classes or virtual methods as final.
	#if __has_feature(cxx_override_control) \
	\|\| (defined(_MSC_VER) && _MSC_VER >= 1700)
	#define LLVM_FINAL final
	#else
	#define LLVM_FINAL
	#endif

	/// LLVM_OVERRIDE - Expands to 'override' if the compiler supports it.
	/// Use to mark virtual methods as overriding a base class method.
	#if __has_feature(cxx_override_control) \
	\|\| (defined(_MSC_VER) && _MSC_VER >= 1700)
	#define LLVM_OVERRIDE override
	#else
	#define LLVM_OVERRIDE
	#endif

	#if __has_feature(cxx_constexpr) \|\| defined(__GXX_EXPERIMENTAL_CXX0X__)
	# define LLVM_CONSTEXPR constexpr
	#else
	# define LLVM_CONSTEXPR
	#endif

	/// LLVM_LIBRARY_VISIBILITY - If a class marked with this attribute is linked
	/// into a shared library, then the class should be private to the library and
	/// not accessible from outside it. Can also be used to mark variables and
	/// functions, making them private to any shared library they are linked into.
	#if (__GNUC__ >= 4) && !defined(__MINGW32__) && !defined(__CYGWIN__)
	#define LLVM_LIBRARY_VISIBILITY __attribute__ ((visibility("hidden")))
	#else
	#define LLVM_LIBRARY_VISIBILITY
	#endif

	#if (__GNUC__ >= 4 \|\| (__GNUC__ == 3 && __GNUC_MINOR__ >= 1))
	#define LLVM_ATTRIBUTE_USED __attribute__((__used__))
	#else
	#define LLVM_ATTRIBUTE_USED
	#endif

	// Some compilers warn about unused functions. When a function is sometimes
	// used or not depending on build settings (e.g. a function only called from
	// within "assert"), this attribute can be used to suppress such warnings.
	//
	// However, it shouldn't be used for unused variables, as those have a much
	// more portable solution:
	// (void)unused_var_name;
	// Prefer cast-to-void wherever it is sufficient.
	#if (__GNUC__ >= 4 \|\| (__GNUC__ == 3 && __GNUC_MINOR__ >= 1))
	#define LLVM_ATTRIBUTE_UNUSED __attribute__((__unused__))
	#else
	#define LLVM_ATTRIBUTE_UNUSED
	#endif

	#if (__GNUC__ >= 4) && !defined(__MINGW32__) && !defined(__CYGWIN__)
	#define LLVM_ATTRIBUTE_WEAK __attribute__((__weak__))
	#else
	#define LLVM_ATTRIBUTE_WEAK
	#endif

	#ifdef __GNUC__ // aka 'CONST' but following LLVM Conventions.
	#define LLVM_READNONE __attribute__((__const__))
	#else
	#define LLVM_READNONE
	#endif

	#ifdef __GNUC__ // aka 'PURE' but following LLVM Conventions.
	#define LLVM_READONLY __attribute__((__pure__))
	#else
	#define LLVM_READONLY
	#endif

	#if (__GNUC__ >= 4)
	#define LLVM_LIKELY(EXPR) __builtin_expect((bool)(EXPR), true)
	#define LLVM_UNLIKELY(EXPR) __builtin_expect((bool)(EXPR), false)
	#else
	#define LLVM_LIKELY(EXPR) (EXPR)
	#define LLVM_UNLIKELY(EXPR) (EXPR)
	#endif

	// C++ doesn't support 'extern template' of template specializations. GCC does,
	// but requires __extension__ before it. In the header, use this:
	// EXTERN_TEMPLATE_INSTANTIATION(class foo<bar>);
	// in the .cpp file, use this:
	// TEMPLATE_INSTANTIATION(class foo<bar>);
	#ifdef __GNUC__
	#define EXTERN_TEMPLATE_INSTANTIATION(X) __extension__ extern template X
	#define TEMPLATE_INSTANTIATION(X) template X
	#else
	#define EXTERN_TEMPLATE_INSTANTIATION(X)
	#define TEMPLATE_INSTANTIATION(X)
	#endif

	/// LLVM_ATTRIBUTE_NOINLINE - On compilers where we have a directive to do so,
	/// mark a method "not for inlining".
	#if (__GNUC__ > 3 \|\| (__GNUC__ == 3 && __GNUC_MINOR__ >= 4))
	#define LLVM_ATTRIBUTE_NOINLINE __attribute__((noinline))
	#elif defined(_MSC_VER)
	#define LLVM_ATTRIBUTE_NOINLINE __declspec(noinline)
	#else
	#define LLVM_ATTRIBUTE_NOINLINE
	#endif

	/// LLVM_ATTRIBUTE_ALWAYS_INLINE - On compilers where we have a directive to do
	/// so, mark a method "always inline" because it is performance sensitive. GCC
	/// 3.4 supported this but is buggy in various cases and produces unimplemented
	/// errors, just use it in GCC 4.0 and later.
	#if __GNUC__ > 3
	#define LLVM_ATTRIBUTE_ALWAYS_INLINE inline __attribute__((always_inline))
	#elif defined(_MSC_VER)
	#define LLVM_ATTRIBUTE_ALWAYS_INLINE __forceinline
	#else
	#define LLVM_ATTRIBUTE_ALWAYS_INLINE
	#endif

	#ifdef __GNUC__
	#define LLVM_ATTRIBUTE_NORETURN __attribute__((noreturn))
	#elif defined(_MSC_VER)
	#define LLVM_ATTRIBUTE_NORETURN __declspec(noreturn)
	#else
	#define LLVM_ATTRIBUTE_NORETURN
	#endif

	/// LLVM_EXTENSION - Support compilers where we have a keyword to suppress
	/// pedantic diagnostics.
	#ifdef __GNUC__
	#define LLVM_EXTENSION __extension__
	#else
	#define LLVM_EXTENSION
	#endif

	// LLVM_ATTRIBUTE_DEPRECATED(decl, "message")
	#if __has_feature(attribute_deprecated_with_message)
	# define LLVM_ATTRIBUTE_DEPRECATED(decl, message) \
	decl __attribute__((deprecated(message)))
	#elif defined(__GNUC__)
	# define LLVM_ATTRIBUTE_DEPRECATED(decl, message) \
	decl __attribute__((deprecated))
	#elif defined(_MSC_VER)
	# define LLVM_ATTRIBUTE_DEPRECATED(decl, message) \
	__declspec(deprecated(message)) decl
	#else
	# define LLVM_ATTRIBUTE_DEPRECATED(decl, message) \
	decl
	#endif

	/// LLVM_BUILTIN_UNREACHABLE - On compilers which support it, expands
	/// to an expression which states that it is undefined behavior for the
	/// compiler to reach this point. Otherwise is not defined.
	#if defined(__clang__) \|\| (__GNUC__ > 4) \
	\|\| (__GNUC__ == 4 && __GNUC_MINOR__ >= 5)
	# define LLVM_BUILTIN_UNREACHABLE __builtin_unreachable()
	#elif defined(_MSC_VER)
	# define LLVM_BUILTIN_UNREACHABLE __assume(false)
	#endif

	/// LLVM_BUILTIN_TRAP - On compilers which support it, expands to an expression
	/// which causes the program to exit abnormally.
	#if defined(__clang__) \|\| (__GNUC__ > 4) \
	\|\| (__GNUC__ == 4 && __GNUC_MINOR__ >= 3)
	# define LLVM_BUILTIN_TRAP __builtin_trap()
	#else
	# define LLVM_BUILTIN_TRAP (volatile int)0x11 = 0
	#endif

	/// \macro LLVM_ASSUME_ALIGNED
	/// \brief Returns a pointer with an assumed alignment.
	#if !defined(__clang__) && ((__GNUC__ > 4) \
	\|\| (__GNUC__ == 4 && __GNUC_MINOR__ >= 7))
	// FIXME: Enable on clang when it supports it.
	# define LLVM_ASSUME_ALIGNED(p, a) __builtin_assume_aligned(p, a)
	#elif defined(LLVM_BUILTIN_UNREACHABLE)
	# define LLVM_ASSUME_ALIGNED(p, a) \
	(((uintptr_t(p) % (a)) == 0) ? (p) : (LLVM_BUILTIN_UNREACHABLE, (p)))
	#else
	# define LLVM_ASSUME_ALIGNED(p, a) (p)
	#endif

	/// \macro LLVM_FUNCTION_NAME
	/// \brief Expands to __func__ on compilers which support it. Otherwise,
	/// expands to a compiler-dependent replacement.
	#if defined(_MSC_VER)
	# define LLVM_FUNCTION_NAME __FUNCTION__
	#else
	# define LLVM_FUNCTION_NAME __func__
	#endif

	#if defined(HAVE_SANITIZER_MSAN_INTERFACE_H)
	# include <sanitizer/msan_interface.h>
	#else
	# define __msan_allocated_memory(p, size)
	# define __msan_unpoison(p, size)
	#endif

	/// \macro LLVM_MEMORY_SANITIZER_BUILD
	/// \brief Whether LLVM itself is built with MemorySanitizer instrumentation.
	#if __has_feature(memory_sanitizer)
	# define LLVM_MEMORY_SANITIZER_BUILD 1
	#else
	# define LLVM_MEMORY_SANITIZER_BUILD 0
	#endif

	/// \macro LLVM_ADDRESS_SANITIZER_BUILD
	/// \brief Whether LLVM itself is built with AddressSanitizer instrumentation.
	#if __has_feature(address_sanitizer) \|\| defined(__SANITIZE_ADDRESS__)
	# define LLVM_ADDRESS_SANITIZER_BUILD 1
	#else
	# define LLVM_ADDRESS_SANITIZER_BUILD 0
	#endif

	/// \macro LLVM_IS_UNALIGNED_ACCESS_FAST
	/// \brief Is unaligned memory access fast on the host machine.
	///
	/// Don't specialize on alignment for platforms where unaligned memory accesses
	/// generates the same code as aligned memory accesses for common types.
	#if defined(_M_AMD64) \|\| defined(_M_IX86) \|\| defined(__amd64) \|\| \
	defined(__amd64__) \|\| defined(__x86_64) \|\| defined(__x86_64__) \|\| \
	defined(_X86_) \|\| defined(__i386) \|\| defined(__i386__)
	# define LLVM_IS_UNALIGNED_ACCESS_FAST 1
	#else
	# define LLVM_IS_UNALIGNED_ACCESS_FAST 0
	#endif

	/// \macro LLVM_EXPLICIT
	/// \brief Expands to explicit on compilers which support explicit conversion
	/// operators. Otherwise expands to nothing.
	#if (__has_feature(cxx_explicit_conversions) \
	\|\| defined(__GXX_EXPERIMENTAL_CXX0X__))
	#define LLVM_EXPLICIT explicit
	#else
	#define LLVM_EXPLICIT
	#endif

	/// \macro LLVM_STATIC_ASSERT
	/// \brief Expands to C/C++'s static_assert on compilers which support it.
	#if __has_feature(cxx_static_assert)
	# define LLVM_STATIC_ASSERT(expr, msg) static_assert(expr, msg)
	#elif __has_feature(c_static_assert)
	# define LLVM_STATIC_ASSERT(expr, msg) _Static_assert(expr, msg)
	#else
	# define LLVM_STATIC_ASSERT(expr, msg)
	#endif

	#endif