include/llvm/Support/Compiler.h

   1 //===-- llvm/Support/Compiler.h - Compiler abstraction support --*- C++ -*-===//
   2 //
   3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
   4 // See https://llvm.org/LICENSE.txt for license information.
   5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
   6 //
   7 //===----------------------------------------------------------------------===//
   8 //
   9 // This file defines several macros, based on the current compiler.  This allows
  10 // use of compiler-specific features in a way that remains portable. This header
  11 // can be included from either C or C++.
  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 #ifdef __cplusplus
  21 #include <new>
  22 #endif
  23 #include <stddef.h>
  24
  25 #if defined(_MSC_VER)
  26 #include <sal.h>
  27 #endif
  28
  29 #ifndef __has_feature
  30 # define __has_feature(x) 0
  31 #endif
  32
  33 #ifndef __has_extension
  34 # define __has_extension(x) 0
  35 #endif
  36
  37 #ifndef __has_attribute
  38 # define __has_attribute(x) 0
  39 #endif
  40
  41 #ifndef __has_builtin
  42 # define __has_builtin(x) 0
  43 #endif
  44
  45 // Only use __has_cpp_attribute in C++ mode. GCC defines __has_cpp_attribute in
  46 // C mode, but the :: in __has_cpp_attribute(scoped::attribute) is invalid.
  47 #ifndef LLVM_HAS_CPP_ATTRIBUTE
  48 #if defined(__cplusplus) && defined(__has_cpp_attribute)
  49 # define LLVM_HAS_CPP_ATTRIBUTE(x) __has_cpp_attribute(x)
  50 #else
  51 # define LLVM_HAS_CPP_ATTRIBUTE(x) 0
  52 #endif
  53 #endif
  54
  55 /// \macro LLVM_GNUC_PREREQ
  56 /// Extend the default __GNUC_PREREQ even if glibc's features.h isn't
  57 /// available.
  58 #ifndef LLVM_GNUC_PREREQ
  59 # if defined(__GNUC__) && defined(__GNUC_MINOR__) && defined(__GNUC_PATCHLEVEL__)
  60 #  define LLVM_GNUC_PREREQ(maj, min, patch) \
  61     ((__GNUC__ << 20) + (__GNUC_MINOR__ << 10) + __GNUC_PATCHLEVEL__ >= \
  62      ((maj) << 20) + ((min) << 10) + (patch))
  63 # elif defined(__GNUC__) && defined(__GNUC_MINOR__)
  64 #  define LLVM_GNUC_PREREQ(maj, min, patch) \
  65     ((__GNUC__ << 20) + (__GNUC_MINOR__ << 10) >= ((maj) << 20) + ((min) << 10))
  66 # else
  67 #  define LLVM_GNUC_PREREQ(maj, min, patch) 0
  68 # endif
  69 #endif
  70
  71 /// \macro LLVM_MSC_PREREQ
  72 /// Is the compiler MSVC of at least the specified version?
  73 /// The common \param version values to check for are:
  74 /// * 1910: VS2017, version 15.1 & 15.2
  75 /// * 1911: VS2017, version 15.3 & 15.4
  76 /// * 1912: VS2017, version 15.5
  77 /// * 1913: VS2017, version 15.6
  78 /// * 1914: VS2017, version 15.7
  79 /// * 1915: VS2017, version 15.8
  80 /// * 1916: VS2017, version 15.9
  81 /// * 1920: VS2019, version 16.0
  82 /// * 1921: VS2019, version 16.1
  83 #ifdef _MSC_VER
  84 #define LLVM_MSC_PREREQ(version) (_MSC_VER >= (version))
  85
  86 // We require at least MSVC 2017.
  87 #if !LLVM_MSC_PREREQ(1910)
  88 #error LLVM requires at least MSVC 2017.
  89 #endif
  90
  91 #else
  92 #define LLVM_MSC_PREREQ(version) 0
  93 #endif
  94
  95 /// Does the compiler support ref-qualifiers for *this?
  96 ///
  97 /// Sadly, this is separate from just rvalue reference support because GCC
  98 /// and MSVC implemented this later than everything else.
  99 #if __has_feature(cxx_rvalue_references) || LLVM_GNUC_PREREQ(4, 8, 1)
 100 #define LLVM_HAS_RVALUE_REFERENCE_THIS 1
 101 #else
 102 #define LLVM_HAS_RVALUE_REFERENCE_THIS 0
 103 #endif
 104
 105 /// Expands to '&' if ref-qualifiers for *this are supported.
 106 ///
 107 /// This can be used to provide lvalue/rvalue overrides of member functions.
 108 /// The rvalue override should be guarded by LLVM_HAS_RVALUE_REFERENCE_THIS
 109 #if LLVM_HAS_RVALUE_REFERENCE_THIS
 110 #define LLVM_LVALUE_FUNCTION &
 111 #else
 112 #define LLVM_LVALUE_FUNCTION
 113 #endif
 114
 115 /// LLVM_LIBRARY_VISIBILITY - If a class marked with this attribute is linked
 116 /// into a shared library, then the class should be private to the library and
 117 /// not accessible from outside it.  Can also be used to mark variables and
 118 /// functions, making them private to any shared library they are linked into.
 119 /// On PE/COFF targets, library visibility is the default, so this isn't needed.
 120 #if (__has_attribute(visibility) || LLVM_GNUC_PREREQ(4, 0, 0)) &&              \
 121     !defined(__MINGW32__) && !defined(__CYGWIN__) && !defined(_WIN32)
 122 #define LLVM_LIBRARY_VISIBILITY __attribute__ ((visibility("hidden")))
 123 #else
 124 #define LLVM_LIBRARY_VISIBILITY
 125 #endif
 126
 127 #if defined(__GNUC__)
 128 #define LLVM_PREFETCH(addr, rw, locality) __builtin_prefetch(addr, rw, locality)
 129 #else
 130 #define LLVM_PREFETCH(addr, rw, locality)
 131 #endif
 132
 133 #if __has_attribute(used) || LLVM_GNUC_PREREQ(3, 1, 0)
 134 #define LLVM_ATTRIBUTE_USED __attribute__((__used__))
 135 #else
 136 #define LLVM_ATTRIBUTE_USED
 137 #endif
 138
 139 /// LLVM_NODISCARD - Warn if a type or return value is discarded.
 140
 141 // Use the 'nodiscard' attribute in C++17 or newer mode.
 142 #if __cplusplus > 201402L && LLVM_HAS_CPP_ATTRIBUTE(nodiscard)
 143 #define LLVM_NODISCARD [[nodiscard]]
 144 #elif LLVM_HAS_CPP_ATTRIBUTE(clang::warn_unused_result)
 145 #define LLVM_NODISCARD [[clang::warn_unused_result]]
 146 // Clang in C++14 mode claims that it has the 'nodiscard' attribute, but also
 147 // warns in the pedantic mode that 'nodiscard' is a C++17 extension (PR33518).
 148 // Use the 'nodiscard' attribute in C++14 mode only with GCC.
 149 // TODO: remove this workaround when PR33518 is resolved.
 150 #elif defined(__GNUC__) && LLVM_HAS_CPP_ATTRIBUTE(nodiscard)
 151 #define LLVM_NODISCARD [[nodiscard]]
 152 #else
 153 #define LLVM_NODISCARD
 154 #endif
 155
 156 // Indicate that a non-static, non-const C++ member function reinitializes
 157 // the entire object to a known state, independent of the previous state of
 158 // the object.
 159 //
 160 // The clang-tidy check bugprone-use-after-move recognizes this attribute as a
 161 // marker that a moved-from object has left the indeterminate state and can be
 162 // reused.
 163 #if LLVM_HAS_CPP_ATTRIBUTE(clang::reinitializes)
 164 #define LLVM_ATTRIBUTE_REINITIALIZES [[clang::reinitializes]]
 165 #else
 166 #define LLVM_ATTRIBUTE_REINITIALIZES
 167 #endif
 168
 169 // Some compilers warn about unused functions. When a function is sometimes
 170 // used or not depending on build settings (e.g. a function only called from
 171 // within "assert"), this attribute can be used to suppress such warnings.
 172 //
 173 // However, it shouldn't be used for unused *variables*, as those have a much
 174 // more portable solution:
 175 //   (void)unused_var_name;
 176 // Prefer cast-to-void wherever it is sufficient.
 177 #if __has_attribute(unused) || LLVM_GNUC_PREREQ(3, 1, 0)
 178 #define LLVM_ATTRIBUTE_UNUSED __attribute__((__unused__))
 179 #else
 180 #define LLVM_ATTRIBUTE_UNUSED
 181 #endif
 182
 183 // FIXME: Provide this for PE/COFF targets.
 184 #if (__has_attribute(weak) || LLVM_GNUC_PREREQ(4, 0, 0)) &&                    \
 185     (!defined(__MINGW32__) && !defined(__CYGWIN__) && !defined(_WIN32))
 186 #define LLVM_ATTRIBUTE_WEAK __attribute__((__weak__))
 187 #else
 188 #define LLVM_ATTRIBUTE_WEAK
 189 #endif
 190
 191 // Prior to clang 3.2, clang did not accept any spelling of
 192 // __has_attribute(const), so assume it is supported.
 193 #if defined(__clang__) || defined(__GNUC__)
 194 // aka 'CONST' but following LLVM Conventions.
 195 #define LLVM_READNONE __attribute__((__const__))
 196 #else
 197 #define LLVM_READNONE
 198 #endif
 199
 200 #if __has_attribute(pure) || defined(__GNUC__)
 201 // aka 'PURE' but following LLVM Conventions.
 202 #define LLVM_READONLY __attribute__((__pure__))
 203 #else
 204 #define LLVM_READONLY
 205 #endif
 206
 207 #if __has_builtin(__builtin_expect) || LLVM_GNUC_PREREQ(4, 0, 0)
 208 #define LLVM_LIKELY(EXPR) __builtin_expect((bool)(EXPR), true)
 209 #define LLVM_UNLIKELY(EXPR) __builtin_expect((bool)(EXPR), false)
 210 #else
 211 #define LLVM_LIKELY(EXPR) (EXPR)
 212 #define LLVM_UNLIKELY(EXPR) (EXPR)
 213 #endif
 214
 215 /// LLVM_ATTRIBUTE_NOINLINE - On compilers where we have a directive to do so,
 216 /// mark a method "not for inlining".
 217 #if __has_attribute(noinline) || LLVM_GNUC_PREREQ(3, 4, 0)
 218 #define LLVM_ATTRIBUTE_NOINLINE __attribute__((noinline))
 219 #elif defined(_MSC_VER)
 220 #define LLVM_ATTRIBUTE_NOINLINE __declspec(noinline)
 221 #else
 222 #define LLVM_ATTRIBUTE_NOINLINE
 223 #endif
 224
 225 /// LLVM_ATTRIBUTE_ALWAYS_INLINE - On compilers where we have a directive to do
 226 /// so, mark a method "always inline" because it is performance sensitive. GCC
 227 /// 3.4 supported this but is buggy in various cases and produces unimplemented
 228 /// errors, just use it in GCC 4.0 and later.
 229 #if __has_attribute(always_inline) || LLVM_GNUC_PREREQ(4, 0, 0)
 230 #define LLVM_ATTRIBUTE_ALWAYS_INLINE __attribute__((always_inline))
 231 #elif defined(_MSC_VER)
 232 #define LLVM_ATTRIBUTE_ALWAYS_INLINE __forceinline
 233 #else
 234 #define LLVM_ATTRIBUTE_ALWAYS_INLINE
 235 #endif
 236
 237 #ifdef __GNUC__
 238 #define LLVM_ATTRIBUTE_NORETURN __attribute__((noreturn))
 239 #elif defined(_MSC_VER)
 240 #define LLVM_ATTRIBUTE_NORETURN __declspec(noreturn)
 241 #else
 242 #define LLVM_ATTRIBUTE_NORETURN
 243 #endif
 244
 245 #if __has_attribute(returns_nonnull) || LLVM_GNUC_PREREQ(4, 9, 0)
 246 #define LLVM_ATTRIBUTE_RETURNS_NONNULL __attribute__((returns_nonnull))
 247 #elif defined(_MSC_VER)
 248 #define LLVM_ATTRIBUTE_RETURNS_NONNULL _Ret_notnull_
 249 #else
 250 #define LLVM_ATTRIBUTE_RETURNS_NONNULL
 251 #endif
 252
 253 /// \macro LLVM_ATTRIBUTE_RETURNS_NOALIAS Used to mark a function as returning a
 254 /// pointer that does not alias any other valid pointer.
 255 #ifdef __GNUC__
 256 #define LLVM_ATTRIBUTE_RETURNS_NOALIAS __attribute__((__malloc__))
 257 #elif defined(_MSC_VER)
 258 #define LLVM_ATTRIBUTE_RETURNS_NOALIAS __declspec(restrict)
 259 #else
 260 #define LLVM_ATTRIBUTE_RETURNS_NOALIAS
 261 #endif
 262
 263 /// LLVM_FALLTHROUGH - Mark fallthrough cases in switch statements.
 264 #if __cplusplus > 201402L && LLVM_HAS_CPP_ATTRIBUTE(fallthrough)
 265 #define LLVM_FALLTHROUGH [[fallthrough]]
 266 #elif LLVM_HAS_CPP_ATTRIBUTE(gnu::fallthrough)
 267 #define LLVM_FALLTHROUGH [[gnu::fallthrough]]
 268 #elif __has_attribute(fallthrough)
 269 #define LLVM_FALLTHROUGH __attribute__((fallthrough))
 270 #elif LLVM_HAS_CPP_ATTRIBUTE(clang::fallthrough)
 271 #define LLVM_FALLTHROUGH [[clang::fallthrough]]
 272 #else
 273 #define LLVM_FALLTHROUGH
 274 #endif
 275
 276 /// LLVM_REQUIRE_CONSTANT_INITIALIZATION - Apply this to globals to ensure that
 277 /// they are constant initialized.
 278 #if LLVM_HAS_CPP_ATTRIBUTE(clang::require_constant_initialization)
 279 #define LLVM_REQUIRE_CONSTANT_INITIALIZATION                                   \
 280   [[clang::require_constant_initialization]]
 281 #else
 282 #define LLVM_REQUIRE_CONSTANT_INITIALIZATION
 283 #endif
 284
 285 /// LLVM_EXTENSION - Support compilers where we have a keyword to suppress
 286 /// pedantic diagnostics.
 287 #ifdef __GNUC__
 288 #define LLVM_EXTENSION __extension__
 289 #else
 290 #define LLVM_EXTENSION
 291 #endif
 292
 293 // LLVM_ATTRIBUTE_DEPRECATED(decl, "message")
 294 #if __has_feature(attribute_deprecated_with_message)
 295 # define LLVM_ATTRIBUTE_DEPRECATED(decl, message) \
 296   decl __attribute__((deprecated(message)))
 297 #elif defined(__GNUC__)
 298 # define LLVM_ATTRIBUTE_DEPRECATED(decl, message) \
 299   decl __attribute__((deprecated))
 300 #elif defined(_MSC_VER)
 301 # define LLVM_ATTRIBUTE_DEPRECATED(decl, message) \
 302   __declspec(deprecated(message)) decl
 303 #else
 304 # define LLVM_ATTRIBUTE_DEPRECATED(decl, message) \
 305   decl
 306 #endif
 307
 308 /// LLVM_BUILTIN_UNREACHABLE - On compilers which support it, expands
 309 /// to an expression which states that it is undefined behavior for the
 310 /// compiler to reach this point.  Otherwise is not defined.
 311 #if __has_builtin(__builtin_unreachable) || LLVM_GNUC_PREREQ(4, 5, 0)
 312 # define LLVM_BUILTIN_UNREACHABLE __builtin_unreachable()
 313 #elif defined(_MSC_VER)
 314 # define LLVM_BUILTIN_UNREACHABLE __assume(false)
 315 #endif
 316
 317 /// LLVM_BUILTIN_TRAP - On compilers which support it, expands to an expression
 318 /// which causes the program to exit abnormally.
 319 #if __has_builtin(__builtin_trap) || LLVM_GNUC_PREREQ(4, 3, 0)
 320 # define LLVM_BUILTIN_TRAP __builtin_trap()
 321 #elif defined(_MSC_VER)
 322 // The __debugbreak intrinsic is supported by MSVC, does not require forward
 323 // declarations involving platform-specific typedefs (unlike RaiseException),
 324 // results in a call to vectored exception handlers, and encodes to a short
 325 // instruction that still causes the trapping behavior we want.
 326 # define LLVM_BUILTIN_TRAP __debugbreak()
 327 #else
 328 # define LLVM_BUILTIN_TRAP *(volatile int*)0x11 = 0
 329 #endif
 330
 331 /// LLVM_BUILTIN_DEBUGTRAP - On compilers which support it, expands to
 332 /// an expression which causes the program to break while running
 333 /// under a debugger.
 334 #if __has_builtin(__builtin_debugtrap)
 335 # define LLVM_BUILTIN_DEBUGTRAP __builtin_debugtrap()
 336 #elif defined(_MSC_VER)
 337 // The __debugbreak intrinsic is supported by MSVC and breaks while
 338 // running under the debugger, and also supports invoking a debugger
 339 // when the OS is configured appropriately.
 340 # define LLVM_BUILTIN_DEBUGTRAP __debugbreak()
 341 #else
 342 // Just continue execution when built with compilers that have no
 343 // support. This is a debugging aid and not intended to force the
 344 // program to abort if encountered.
 345 # define LLVM_BUILTIN_DEBUGTRAP
 346 #endif
 347
 348 /// \macro LLVM_ASSUME_ALIGNED
 349 /// Returns a pointer with an assumed alignment.
 350 #if __has_builtin(__builtin_assume_aligned) || LLVM_GNUC_PREREQ(4, 7, 0)
 351 # define LLVM_ASSUME_ALIGNED(p, a) __builtin_assume_aligned(p, a)
 352 #elif defined(LLVM_BUILTIN_UNREACHABLE)
 353 // As of today, clang does not support __builtin_assume_aligned.
 354 # define LLVM_ASSUME_ALIGNED(p, a) \
 355            (((uintptr_t(p) % (a)) == 0) ? (p) : (LLVM_BUILTIN_UNREACHABLE, (p)))
 356 #else
 357 # define LLVM_ASSUME_ALIGNED(p, a) (p)
 358 #endif
 359
 360 /// \macro LLVM_PACKED
 361 /// Used to specify a packed structure.
 362 /// LLVM_PACKED(
 363 ///    struct A {
 364 ///      int i;
 365 ///      int j;
 366 ///      int k;
 367 ///      long long l;
 368 ///   });
 369 ///
 370 /// LLVM_PACKED_START
 371 /// struct B {
 372 ///   int i;
 373 ///   int j;
 374 ///   int k;
 375 ///   long long l;
 376 /// };
 377 /// LLVM_PACKED_END
 378 #ifdef _MSC_VER
 379 # define LLVM_PACKED(d) __pragma(pack(push, 1)) d __pragma(pack(pop))
 380 # define LLVM_PACKED_START __pragma(pack(push, 1))
 381 # define LLVM_PACKED_END   __pragma(pack(pop))
 382 #else
 383 # define LLVM_PACKED(d) d __attribute__((packed))
 384 # define LLVM_PACKED_START _Pragma("pack(push, 1)")
 385 # define LLVM_PACKED_END   _Pragma("pack(pop)")
 386 #endif
 387
 388 /// \macro LLVM_PTR_SIZE
 389 /// A constant integer equivalent to the value of sizeof(void*).
 390 /// Generally used in combination with alignas or when doing computation in the
 391 /// preprocessor.
 392 #ifdef __SIZEOF_POINTER__
 393 # define LLVM_PTR_SIZE __SIZEOF_POINTER__
 394 #elif defined(_WIN64)
 395 # define LLVM_PTR_SIZE 8
 396 #elif defined(_WIN32)
 397 # define LLVM_PTR_SIZE 4
 398 #elif defined(_MSC_VER)
 399 # error "could not determine LLVM_PTR_SIZE as a constant int for MSVC"
 400 #else
 401 # define LLVM_PTR_SIZE sizeof(void *)
 402 #endif
 403
 404 /// \macro LLVM_MEMORY_SANITIZER_BUILD
 405 /// Whether LLVM itself is built with MemorySanitizer instrumentation.
 406 #if __has_feature(memory_sanitizer)
 407 # define LLVM_MEMORY_SANITIZER_BUILD 1
 408 # include <sanitizer/msan_interface.h>
 409 #else
 410 # define LLVM_MEMORY_SANITIZER_BUILD 0
 411 # define __msan_allocated_memory(p, size)
 412 # define __msan_unpoison(p, size)
 413 #endif
 414
 415 /// \macro LLVM_ADDRESS_SANITIZER_BUILD
 416 /// Whether LLVM itself is built with AddressSanitizer instrumentation.
 417 #if __has_feature(address_sanitizer) || defined(__SANITIZE_ADDRESS__)
 418 # define LLVM_ADDRESS_SANITIZER_BUILD 1
 419 # include <sanitizer/asan_interface.h>
 420 #else
 421 # define LLVM_ADDRESS_SANITIZER_BUILD 0
 422 # define __asan_poison_memory_region(p, size)
 423 # define __asan_unpoison_memory_region(p, size)
 424 #endif
 425
 426 /// \macro LLVM_THREAD_SANITIZER_BUILD
 427 /// Whether LLVM itself is built with ThreadSanitizer instrumentation.
 428 #if __has_feature(thread_sanitizer) || defined(__SANITIZE_THREAD__)
 429 # define LLVM_THREAD_SANITIZER_BUILD 1
 430 #else
 431 # define LLVM_THREAD_SANITIZER_BUILD 0
 432 #endif
 433
 434 #if LLVM_THREAD_SANITIZER_BUILD
 435 // Thread Sanitizer is a tool that finds races in code.
 436 // See http://code.google.com/p/data-race-test/wiki/DynamicAnnotations .
 437 // tsan detects these exact functions by name.
 438 #ifdef __cplusplus
 439 extern "C" {
 440 #endif
 441 void AnnotateHappensAfter(const char *file, int line, const volatile void *cv);
 442 void AnnotateHappensBefore(const char *file, int line, const volatile void *cv);
 443 void AnnotateIgnoreWritesBegin(const char *file, int line);
 444 void AnnotateIgnoreWritesEnd(const char *file, int line);
 445 #ifdef __cplusplus
 446 }
 447 #endif
 448
 449 // This marker is used to define a happens-before arc. The race detector will
 450 // infer an arc from the begin to the end when they share the same pointer
 451 // argument.
 452 # define TsanHappensBefore(cv) AnnotateHappensBefore(__FILE__, __LINE__, cv)
 453
 454 // This marker defines the destination of a happens-before arc.
 455 # define TsanHappensAfter(cv) AnnotateHappensAfter(__FILE__, __LINE__, cv)
 456
 457 // Ignore any races on writes between here and the next TsanIgnoreWritesEnd.
 458 # define TsanIgnoreWritesBegin() AnnotateIgnoreWritesBegin(__FILE__, __LINE__)
 459
 460 // Resume checking for racy writes.
 461 # define TsanIgnoreWritesEnd() AnnotateIgnoreWritesEnd(__FILE__, __LINE__)
 462 #else
 463 # define TsanHappensBefore(cv)
 464 # define TsanHappensAfter(cv)
 465 # define TsanIgnoreWritesBegin()
 466 # define TsanIgnoreWritesEnd()
 467 #endif
 468
 469 /// \macro LLVM_NO_SANITIZE
 470 /// Disable a particular sanitizer for a function.
 471 #if __has_attribute(no_sanitize)
 472 #define LLVM_NO_SANITIZE(KIND) __attribute__((no_sanitize(KIND)))
 473 #else
 474 #define LLVM_NO_SANITIZE(KIND)
 475 #endif
 476
 477 /// Mark debug helper function definitions like dump() that should not be
 478 /// stripped from debug builds.
 479 /// Note that you should also surround dump() functions with
 480 /// `#if !defined(NDEBUG) || defined(LLVM_ENABLE_DUMP)` so they do always
 481 /// get stripped in release builds.
 482 // FIXME: Move this to a private config.h as it's not usable in public headers.
 483 #if !defined(NDEBUG) || defined(LLVM_ENABLE_DUMP)
 484 #define LLVM_DUMP_METHOD LLVM_ATTRIBUTE_NOINLINE LLVM_ATTRIBUTE_USED
 485 #else
 486 #define LLVM_DUMP_METHOD LLVM_ATTRIBUTE_NOINLINE
 487 #endif
 488
 489 /// \macro LLVM_PRETTY_FUNCTION
 490 /// Gets a user-friendly looking function signature for the current scope
 491 /// using the best available method on each platform.  The exact format of the
 492 /// resulting string is implementation specific and non-portable, so this should
 493 /// only be used, for example, for logging or diagnostics.
 494 #if defined(_MSC_VER)
 495 #define LLVM_PRETTY_FUNCTION __FUNCSIG__
 496 #elif defined(__GNUC__) || defined(__clang__)
 497 #define LLVM_PRETTY_FUNCTION __PRETTY_FUNCTION__
 498 #else
 499 #define LLVM_PRETTY_FUNCTION __func__
 500 #endif
 501
 502 /// \macro LLVM_THREAD_LOCAL
 503 /// A thread-local storage specifier which can be used with globals,
 504 /// extern globals, and static globals.
 505 ///
 506 /// This is essentially an extremely restricted analog to C++11's thread_local
 507 /// support, and uses that when available. However, it falls back on
 508 /// platform-specific or vendor-provided extensions when necessary. These
 509 /// extensions don't support many of the C++11 thread_local's features. You
 510 /// should only use this for PODs that you can statically initialize to
 511 /// some constant value. In almost all circumstances this is most appropriate
 512 /// for use with a pointer, integer, or small aggregation of pointers and
 513 /// integers.
 514 #if LLVM_ENABLE_THREADS
 515 #if __has_feature(cxx_thread_local)
 516 #define LLVM_THREAD_LOCAL thread_local
 517 #elif defined(_MSC_VER)
 518 // MSVC supports this with a __declspec.
 519 #define LLVM_THREAD_LOCAL __declspec(thread)
 520 #else
 521 // Clang, GCC, and other compatible compilers used __thread prior to C++11 and
 522 // we only need the restricted functionality that provides.
 523 #define LLVM_THREAD_LOCAL __thread
 524 #endif
 525 #else // !LLVM_ENABLE_THREADS
 526 // If threading is disabled entirely, this compiles to nothing and you get
 527 // a normal global variable.
 528 #define LLVM_THREAD_LOCAL
 529 #endif
 530
 531 /// \macro LLVM_ENABLE_EXCEPTIONS
 532 /// Whether LLVM is built with exception support.
 533 #if __has_feature(cxx_exceptions)
 534 #define LLVM_ENABLE_EXCEPTIONS 1
 535 #elif defined(__GNUC__) && defined(__EXCEPTIONS)
 536 #define LLVM_ENABLE_EXCEPTIONS 1
 537 #elif defined(_MSC_VER) && defined(_CPPUNWIND)
 538 #define LLVM_ENABLE_EXCEPTIONS 1
 539 #endif
 540
 541 #ifdef __cplusplus
 542 namespace llvm {
 543
 544 /// Allocate a buffer of memory with the given size and alignment.
 545 ///
 546 /// When the compiler supports aligned operator new, this will use it to to
 547 /// handle even over-aligned allocations.
 548 ///
 549 /// However, this doesn't make any attempt to leverage the fancier techniques
 550 /// like posix_memalign due to portability. It is mostly intended to allow
 551 /// compatibility with platforms that, after aligned allocation was added, use
 552 /// reduced default alignment.
 553 inline void *allocate_buffer(size_t Size, size_t Alignment) {
 554   return ::operator new(Size
 555 #ifdef __cpp_aligned_new
 556                         ,
 557                         std::align_val_t(Alignment)
 558 #endif
 559   );
 560 }
 561
 562 /// Deallocate a buffer of memory with the given size and alignment.
 563 ///
 564 /// If supported, this will used the sized delete operator. Also if supported,
 565 /// this will pass the alignment to the delete operator.
 566 ///
 567 /// The pointer must have been allocated with the corresponding new operator,
 568 /// most likely using the above helper.
 569 inline void deallocate_buffer(void *Ptr, size_t Size, size_t Alignment) {
 570   ::operator delete(Ptr
 571 #ifdef __cpp_sized_deallocation
 572                     ,
 573                     Size
 574 #endif
 575 #ifdef __cpp_aligned_new
 576                     ,
 577                     std::align_val_t(Alignment)
 578 #endif
 579   );
 580 }
 581
 582 } // End namespace llvm
 583
 584 #endif // __cplusplus
 585 #endif