+/// \macro LLVM_ASSUME_ALIGNED
+/// \brief Returns a pointer with an assumed alignment.
+#if __has_builtin(__builtin_assume_aligned) || LLVM_GNUC_PREREQ(4, 7, 0)
+# define LLVM_ASSUME_ALIGNED(p, a) __builtin_assume_aligned(p, a)
+#elif defined(LLVM_BUILTIN_UNREACHABLE)
+// As of today, clang does not support __builtin_assume_aligned.
+# 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_ALIGNAS
+/// \brief Used to specify a minimum alignment for a structure or variable. The
+/// alignment must be a constant integer. Use LLVM_PTR_SIZE to compute
+/// alignments in terms of the size of a pointer.
+///
+/// Note that __declspec(align) has special quirks, it's not legal to pass a
+/// structure with __declspec(align) as a formal parameter.
+#ifdef _MSC_VER
+# define LLVM_ALIGNAS(x) __declspec(align(x))
+#elif __GNUC__ && !__has_feature(cxx_alignas) && !LLVM_GNUC_PREREQ(4, 8, 0)
+# define LLVM_ALIGNAS(x) __attribute__((aligned(x)))
+#else
+# define LLVM_ALIGNAS(x) alignas(x)
+#endif
+
+/// \macro LLVM_PACKED
+/// \brief Used to specify a packed structure.
+/// LLVM_PACKED(
+/// struct A {
+/// int i;
+/// int j;
+/// int k;
+/// long long l;
+/// });
+///
+/// LLVM_PACKED_START
+/// struct B {
+/// int i;
+/// int j;
+/// int k;
+/// long long l;
+/// };
+/// LLVM_PACKED_END
+#ifdef _MSC_VER
+# define LLVM_PACKED(d) __pragma(pack(push, 1)) d __pragma(pack(pop))
+# define LLVM_PACKED_START __pragma(pack(push, 1))
+# define LLVM_PACKED_END __pragma(pack(pop))
+#else
+# define LLVM_PACKED(d) d __attribute__((packed))
+# define LLVM_PACKED_START _Pragma("pack(push, 1)")
+# define LLVM_PACKED_END _Pragma("pack(pop)")
+#endif
+
+/// \macro LLVM_PTR_SIZE
+/// \brief A constant integer equivalent to the value of sizeof(void*).
+/// Generally used in combination with LLVM_ALIGNAS or when doing computation in
+/// the preprocessor.
+#ifdef __SIZEOF_POINTER__
+# define LLVM_PTR_SIZE __SIZEOF_POINTER__
+#elif defined(_WIN64)
+# define LLVM_PTR_SIZE 8
+#elif defined(_WIN32)
+# define LLVM_PTR_SIZE 4
+#elif defined(_MSC_VER)
+# error "could not determine LLVM_PTR_SIZE as a constant int for MSVC"
+#else
+# define LLVM_PTR_SIZE sizeof(void *)
+#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
+
+/// \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
+# include <sanitizer/msan_interface.h>
+#else
+# define LLVM_MEMORY_SANITIZER_BUILD 0
+# define __msan_allocated_memory(p, size)
+# define __msan_unpoison(p, size)
+#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_THREAD_SANITIZER_BUILD
+/// \brief Whether LLVM itself is built with ThreadSanitizer instrumentation.
+#if __has_feature(thread_sanitizer) || defined(__SANITIZE_THREAD__)
+# define LLVM_THREAD_SANITIZER_BUILD 1
+#else
+# define LLVM_THREAD_SANITIZER_BUILD 0
+#endif
+
+#if LLVM_THREAD_SANITIZER_BUILD
+// Thread Sanitizer is a tool that finds races in code.
+// See http://code.google.com/p/data-race-test/wiki/DynamicAnnotations .
+// tsan detects these exact functions by name.
+extern "C" {
+void AnnotateHappensAfter(const char *file, int line, const volatile void *cv);
+void AnnotateHappensBefore(const char *file, int line, const volatile void *cv);
+void AnnotateIgnoreWritesBegin(const char *file, int line);
+void AnnotateIgnoreWritesEnd(const char *file, int line);
+}
+
+// This marker is used to define a happens-before arc. The race detector will
+// infer an arc from the begin to the end when they share the same pointer
+// argument.
+# define TsanHappensBefore(cv) AnnotateHappensBefore(__FILE__, __LINE__, cv)
+
+// This marker defines the destination of a happens-before arc.
+# define TsanHappensAfter(cv) AnnotateHappensAfter(__FILE__, __LINE__, cv)
+
+// Ignore any races on writes between here and the next TsanIgnoreWritesEnd.
+# define TsanIgnoreWritesBegin() AnnotateIgnoreWritesBegin(__FILE__, __LINE__)
+
+// Resume checking for racy writes.
+# define TsanIgnoreWritesEnd() AnnotateIgnoreWritesEnd(__FILE__, __LINE__)
+#else
+# define TsanHappensBefore(cv)
+# define TsanHappensAfter(cv)
+# define TsanIgnoreWritesBegin()
+# define TsanIgnoreWritesEnd()
+#endif
+
+/// \brief Mark debug helper function definitions like dump() that should not be
+/// stripped from debug builds.
+// FIXME: Move this to a private config.h as it's not usable in public headers.
+#if !defined(NDEBUG) || defined(LLVM_ENABLE_DUMP)
+#define LLVM_DUMP_METHOD LLVM_ATTRIBUTE_NOINLINE LLVM_ATTRIBUTE_USED
+#else
+#define LLVM_DUMP_METHOD LLVM_ATTRIBUTE_NOINLINE
+#endif
+
+/// \macro LLVM_THREAD_LOCAL
+/// \brief A thread-local storage specifier which can be used with globals,
+/// extern globals, and static globals.
+///
+/// This is essentially an extremely restricted analog to C++11's thread_local
+/// support, and uses that when available. However, it falls back on
+/// platform-specific or vendor-provided extensions when necessary. These
+/// extensions don't support many of the C++11 thread_local's features. You
+/// should only use this for PODs that you can statically initialize to
+/// some constant value. In almost all circumstances this is most appropriate
+/// for use with a pointer, integer, or small aggregation of pointers and
+/// integers.
+#if LLVM_ENABLE_THREADS
+#if __has_feature(cxx_thread_local)
+#define LLVM_THREAD_LOCAL thread_local
+#elif defined(_MSC_VER)
+// MSVC supports this with a __declspec.
+#define LLVM_THREAD_LOCAL __declspec(thread)
+#else
+// Clang, GCC, and other compatible compilers used __thread prior to C++11 and
+// we only need the restricted functionality that provides.
+#define LLVM_THREAD_LOCAL __thread
+#endif
+#else // !LLVM_ENABLE_THREADS
+// If threading is disabled entirely, this compiles to nothing and you get
+// a normal global variable.
+#define LLVM_THREAD_LOCAL
+#endif
+