+#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
+
+/// 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))
+#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))
+#define LLVM_OVERRIDE override
+#else
+#define LLVM_OVERRIDE
+#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__))