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#include <stddef.h>
21
22#if defined(_MSC_VER)
23#include <sal.h>
24#endif
25
26#ifndef __has_feature
27# define __has_feature(x) 0
28#endif
29
30#ifndef __has_extension
31# define __has_extension(x) 0
32#endif
33
34#ifndef __has_attribute
35# define __has_attribute(x) 0
36#endif
37
38#ifndef __has_builtin
39# define __has_builtin(x) 0
40#endif
41
42#ifndef __has_include
43# define __has_include(x) 0
44#endif
45
46// Only use __has_cpp_attribute in C++ mode. GCC defines __has_cpp_attribute in
47// C mode, but the :: in __has_cpp_attribute(scoped::attribute) is invalid.
48#ifndef LLVM_HAS_CPP_ATTRIBUTE
49#if defined(__cplusplus) && defined(__has_cpp_attribute)
50# define LLVM_HAS_CPP_ATTRIBUTE(x) __has_cpp_attribute(x)
51#else
52# define LLVM_HAS_CPP_ATTRIBUTE(x) 0
53#endif
54#endif
55
56/// \macro LLVM_GNUC_PREREQ
57/// Extend the default __GNUC_PREREQ even if glibc's features.h isn't
58/// available.
59#ifndef LLVM_GNUC_PREREQ
60# if defined(__GNUC__) && defined(__GNUC_MINOR__) && defined(__GNUC_PATCHLEVEL__)
61# define LLVM_GNUC_PREREQ(maj, min, patch) \
62 ((__GNUC__ << 20) + (__GNUC_MINOR__ << 10) + __GNUC_PATCHLEVEL__ >= \
63 ((maj) << 20) + ((min) << 10) + (patch))
64# elif defined(__GNUC__) && defined(__GNUC_MINOR__)
65# define LLVM_GNUC_PREREQ(maj, min, patch) \
66 ((__GNUC__ << 20) + (__GNUC_MINOR__ << 10) >= ((maj) << 20) + ((min) << 10))
67# else
68# define LLVM_GNUC_PREREQ(maj, min, patch) 0
69# endif
70#endif
71
72/// \macro LLVM_MSC_PREREQ
73/// Is the compiler MSVC of at least the specified version?
74/// The common \param version values to check for are:
75/// * 1910: VS2017, version 15.1 & 15.2
76/// * 1911: VS2017, version 15.3 & 15.4
77/// * 1912: VS2017, version 15.5
78/// * 1913: VS2017, version 15.6
79/// * 1914: VS2017, version 15.7
80/// * 1915: VS2017, version 15.8
81/// * 1916: VS2017, version 15.9
82/// * 1920: VS2019, version 16.0
83/// * 1921: VS2019, version 16.1
84/// * 1922: VS2019, version 16.2
85/// * 1923: VS2019, version 16.3
86/// * 1924: VS2019, version 16.4
87/// * 1925: VS2019, version 16.5
88/// * 1926: VS2019, version 16.6
89/// * 1927: VS2019, version 16.7
90/// * 1928: VS2019, version 16.8 + 16.9
91/// * 1929: VS2019, version 16.10 + 16.11
92/// * 1930: VS2022, version 17.0
93#ifdef _MSC_VER
94#define LLVM_MSC_PREREQ(version) (_MSC_VER >= (version))
95
96// We require at least VS 2019.
97#if !defined(LLVM_FORCE_USE_OLD_TOOLCHAIN)
98#if !LLVM_MSC_PREREQ(1920)
99#error LLVM requires at least VS 2019.
100#endif
101#endif
102
103#else
104#define LLVM_MSC_PREREQ(version) 0
105#endif
106
107/// LLVM_LIBRARY_VISIBILITY - If a class marked with this attribute is linked
108/// into a shared library, then the class should be private to the library and
109/// not accessible from outside it. Can also be used to mark variables and
110/// functions, making them private to any shared library they are linked into.
111/// On PE/COFF targets, library visibility is the default, so this isn't needed.
112///
113/// LLVM_EXTERNAL_VISIBILITY - classes, functions, and variables marked with
114/// this attribute will be made public and visible outside of any shared library
115/// they are linked in to.
116#if __has_attribute(visibility) && \
117 (!(defined(_WIN32) || defined(__CYGWIN__)) || \
118 (defined(__MINGW32__) && defined(__clang__)))
119#define LLVM_LIBRARY_VISIBILITY __attribute__ ((visibility("hidden")))
120#if defined(LLVM_BUILD_LLVM_DYLIB) || defined(LLVM_BUILD_SHARED_LIBS)
121#define LLVM_EXTERNAL_VISIBILITY __attribute__((visibility("default")))
122#else
123#define LLVM_EXTERNAL_VISIBILITY
124#endif
125#else
126#define LLVM_LIBRARY_VISIBILITY
127#define LLVM_EXTERNAL_VISIBILITY
128#endif
129
130#if defined(__GNUC__)
131#define LLVM_PREFETCH(addr, rw, locality) __builtin_prefetch(addr, rw, locality)
132#else
133#define LLVM_PREFETCH(addr, rw, locality)
134#endif
135
136#if __has_attribute(used)
137#define LLVM_ATTRIBUTE_USED __attribute__((__used__))
138#else
139#define LLVM_ATTRIBUTE_USED
140#endif
141
142#if defined(__clang__)
143#define LLVM_DEPRECATED(MSG, FIX) __attribute__((deprecated(MSG, FIX)))
144#else
145#define LLVM_DEPRECATED(MSG, FIX) [[deprecated(MSG)]]
146#endif
147
148// Indicate that a non-static, non-const C++ member function reinitializes
149// the entire object to a known state, independent of the previous state of
150// the object.
151//
152// The clang-tidy check bugprone-use-after-move recognizes this attribute as a
153// marker that a moved-from object has left the indeterminate state and can be
154// reused.
155#if LLVM_HAS_CPP_ATTRIBUTE(clang::reinitializes)
156#define LLVM_ATTRIBUTE_REINITIALIZES [[clang::reinitializes]]
157#else
158#define LLVM_ATTRIBUTE_REINITIALIZES
159#endif
160
161// Some compilers warn about unused functions. When a function is sometimes
162// used or not depending on build settings (e.g. a function only called from
163// within "assert"), this attribute can be used to suppress such warnings.
164//
165// However, it shouldn't be used for unused *variables*, as those have a much
166// more portable solution:
167// (void)unused_var_name;
168// Prefer cast-to-void wherever it is sufficient.
169#if __has_attribute(unused)
170#define LLVM_ATTRIBUTE_UNUSED __attribute__((__unused__))
171#else
172#define LLVM_ATTRIBUTE_UNUSED
173#endif
174
175// FIXME: Provide this for PE/COFF targets.
176#if __has_attribute(weak) && !defined(__MINGW32__) && !defined(__CYGWIN__) && \
177 !defined(_WIN32)
178#define LLVM_ATTRIBUTE_WEAK __attribute__((__weak__))
179#else
180#define LLVM_ATTRIBUTE_WEAK
181#endif
182
183// Prior to clang 3.2, clang did not accept any spelling of
184// __has_attribute(const), so assume it is supported.
185#if defined(__clang__) || defined(__GNUC__)
186// aka 'CONST' but following LLVM Conventions.
187#define LLVM_READNONE __attribute__((__const__))
188#else
189#define LLVM_READNONE
190#endif
191
192#if __has_attribute(pure) || defined(__GNUC__)
193// aka 'PURE' but following LLVM Conventions.
194#define LLVM_READONLY __attribute__((__pure__))
195#else
196#define LLVM_READONLY
197#endif
198
199#if __has_attribute(minsize)
200#define LLVM_ATTRIBUTE_MINSIZE __attribute__((minsize))
201#else
202#define LLVM_ATTRIBUTE_MINSIZE
203#endif
204
205#if __has_builtin(__builtin_expect) || defined(__GNUC__)
206#define LLVM_LIKELY(EXPR) __builtin_expect((bool)(EXPR), true)
207#define LLVM_UNLIKELY(EXPR) __builtin_expect((bool)(EXPR), false)
208#else
209#define LLVM_LIKELY(EXPR) (EXPR)
210#define LLVM_UNLIKELY(EXPR) (EXPR)
211#endif
212
213/// LLVM_ATTRIBUTE_NOINLINE - On compilers where we have a directive to do so,
214/// mark a method "not for inlining".
215#if __has_attribute(noinline)
216#define LLVM_ATTRIBUTE_NOINLINE __attribute__((noinline))
217#elif defined(_MSC_VER)
218#define LLVM_ATTRIBUTE_NOINLINE __declspec(noinline)
219#else
220#define LLVM_ATTRIBUTE_NOINLINE
221#endif
222
223/// LLVM_ATTRIBUTE_ALWAYS_INLINE - On compilers where we have a directive to do
224/// so, mark a method "always inline" because it is performance sensitive.
225#if __has_attribute(always_inline)
226#define LLVM_ATTRIBUTE_ALWAYS_INLINE inline __attribute__((always_inline))
227#elif defined(_MSC_VER)
228#define LLVM_ATTRIBUTE_ALWAYS_INLINE __forceinline
229#else
230#define LLVM_ATTRIBUTE_ALWAYS_INLINE inline
231#endif
232
233/// LLVM_ATTRIBUTE_NO_DEBUG - On compilers where we have a directive to do
234/// so, mark a method "no debug" because debug info makes the debugger
235/// experience worse.
236#if __has_attribute(nodebug)
237#define LLVM_ATTRIBUTE_NODEBUG __attribute__((nodebug))
238#else
239#define LLVM_ATTRIBUTE_NODEBUG
240#endif
241
242#if __has_attribute(returns_nonnull)
243#define LLVM_ATTRIBUTE_RETURNS_NONNULL __attribute__((returns_nonnull))
244#elif defined(_MSC_VER)
245#define LLVM_ATTRIBUTE_RETURNS_NONNULL _Ret_notnull_
246#else
247#define LLVM_ATTRIBUTE_RETURNS_NONNULL
248#endif
249
250/// \macro LLVM_ATTRIBUTE_RETURNS_NOALIAS Used to mark a function as returning a
251/// pointer that does not alias any other valid pointer.
252#ifdef __GNUC__
253#define LLVM_ATTRIBUTE_RETURNS_NOALIAS __attribute__((__malloc__))
254#elif defined(_MSC_VER)
255#define LLVM_ATTRIBUTE_RETURNS_NOALIAS __declspec(restrict)
256#else
257#define LLVM_ATTRIBUTE_RETURNS_NOALIAS
258#endif
259
260/// LLVM_FALLTHROUGH - Mark fallthrough cases in switch statements.
261#if defined(__cplusplus) && __cplusplus > 201402L && LLVM_HAS_CPP_ATTRIBUTE(fallthrough)
262#define LLVM_FALLTHROUGH [[fallthrough]]
263#elif LLVM_HAS_CPP_ATTRIBUTE(gnu::fallthrough)
264#define LLVM_FALLTHROUGH [[gnu::fallthrough]]
265#elif __has_attribute(fallthrough)
266#define LLVM_FALLTHROUGH __attribute__((fallthrough))
267#elif LLVM_HAS_CPP_ATTRIBUTE(clang::fallthrough)
268#define LLVM_FALLTHROUGH [[clang::fallthrough]]
269#else
270#define LLVM_FALLTHROUGH
271#endif
272
273/// LLVM_REQUIRE_CONSTANT_INITIALIZATION - Apply this to globals to ensure that
274/// they are constant initialized.
275#if LLVM_HAS_CPP_ATTRIBUTE(clang::require_constant_initialization)
276#define LLVM_REQUIRE_CONSTANT_INITIALIZATION \
277 [[clang::require_constant_initialization]]
278#else
279#define LLVM_REQUIRE_CONSTANT_INITIALIZATION
280#endif
281
282/// LLVM_GSL_OWNER - Apply this to owning classes like SmallVector to enable
283/// lifetime warnings.
284#if LLVM_HAS_CPP_ATTRIBUTE(gsl::Owner)
285#define LLVM_GSL_OWNER [[gsl::Owner]]
286#else
287#define LLVM_GSL_OWNER
288#endif
289
290/// LLVM_GSL_POINTER - Apply this to non-owning classes like
291/// StringRef to enable lifetime warnings.
292#if LLVM_HAS_CPP_ATTRIBUTE(gsl::Pointer)
293#define LLVM_GSL_POINTER [[gsl::Pointer]]
294#else
295#define LLVM_GSL_POINTER
296#endif
297
298/// LLVM_EXTENSION - Support compilers where we have a keyword to suppress
299/// pedantic diagnostics.
300#ifdef __GNUC__
301#define LLVM_EXTENSION __extension__
302#else
303#define LLVM_EXTENSION
304#endif
305
306/// LLVM_BUILTIN_UNREACHABLE - On compilers which support it, expands
307/// to an expression which states that it is undefined behavior for the
308/// compiler to reach this point. Otherwise is not defined.
309///
310/// '#else' is intentionally left out so that other macro logic (e.g.,
311/// LLVM_ASSUME_ALIGNED and llvm_unreachable()) can detect whether
312/// LLVM_BUILTIN_UNREACHABLE has a definition.
313#if __has_builtin(__builtin_unreachable) || defined(__GNUC__)
314# define LLVM_BUILTIN_UNREACHABLE __builtin_unreachable()
315#elif defined(_MSC_VER)
316# define LLVM_BUILTIN_UNREACHABLE __assume(false)
317#endif
318
319/// LLVM_BUILTIN_TRAP - On compilers which support it, expands to an expression
320/// which causes the program to exit abnormally.
321#if __has_builtin(__builtin_trap) || defined(__GNUC__)
322# define LLVM_BUILTIN_TRAP __builtin_trap()
323#elif defined(_MSC_VER)
324// The __debugbreak intrinsic is supported by MSVC, does not require forward
325// declarations involving platform-specific typedefs (unlike RaiseException),
326// results in a call to vectored exception handlers, and encodes to a short
327// instruction that still causes the trapping behavior we want.
328# define LLVM_BUILTIN_TRAP __debugbreak()
329#else
330# define LLVM_BUILTIN_TRAP *(volatile int*)0x11 = 0
331#endif
332
333/// LLVM_BUILTIN_DEBUGTRAP - On compilers which support it, expands to
334/// an expression which causes the program to break while running
335/// under a debugger.
336#if __has_builtin(__builtin_debugtrap)
337# define LLVM_BUILTIN_DEBUGTRAP __builtin_debugtrap()
338#elif defined(_MSC_VER)
339// The __debugbreak intrinsic is supported by MSVC and breaks while
340// running under the debugger, and also supports invoking a debugger
341// when the OS is configured appropriately.
342# define LLVM_BUILTIN_DEBUGTRAP __debugbreak()
343#else
344// Just continue execution when built with compilers that have no
345// support. This is a debugging aid and not intended to force the
346// program to abort if encountered.
347# define LLVM_BUILTIN_DEBUGTRAP
348#endif
349
350/// \macro LLVM_ASSUME_ALIGNED
351/// Returns a pointer with an assumed alignment.
352#if __has_builtin(__builtin_assume_aligned) || defined(__GNUC__)
353# define LLVM_ASSUME_ALIGNED(p, a) __builtin_assume_aligned(p, a)
354#elif defined(LLVM_BUILTIN_UNREACHABLE)
355# define LLVM_ASSUME_ALIGNED(p, a) \
356 (((uintptr_t(p) % (a)) == 0) ? (p) : (LLVM_BUILTIN_UNREACHABLE, (p)))
357#else
358# define LLVM_ASSUME_ALIGNED(p, a) (p)
359#endif
360
361/// \macro LLVM_PACKED
362/// Used to specify a packed structure.
363/// LLVM_PACKED(
364/// struct A {
365/// int i;
366/// int j;
367/// int k;
368/// long long l;
369/// });
370///
371/// LLVM_PACKED_START
372/// struct B {
373/// int i;
374/// int j;
375/// int k;
376/// long long l;
377/// };
378/// LLVM_PACKED_END
379#ifdef _MSC_VER
380# define LLVM_PACKED(d) __pragma(pack(push, 1)) d __pragma(pack(pop))
381# define LLVM_PACKED_START __pragma(pack(push, 1))
382# define LLVM_PACKED_END __pragma(pack(pop))
383#else
384# define LLVM_PACKED(d) d __attribute__((packed))
385# define LLVM_PACKED_START _Pragma("pack(push, 1)")
386# define LLVM_PACKED_END _Pragma("pack(pop)")
387#endif
388
389/// \macro LLVM_MEMORY_SANITIZER_BUILD
390/// Whether LLVM itself is built with MemorySanitizer instrumentation.
391#if __has_feature(memory_sanitizer)
392# define LLVM_MEMORY_SANITIZER_BUILD 1
393# include <sanitizer/msan_interface.h>
394# define LLVM_NO_SANITIZE_MEMORY_ATTRIBUTE __attribute__((no_sanitize_memory))
395#else
396# define LLVM_MEMORY_SANITIZER_BUILD 0
397# define __msan_allocated_memory(p, size)
398# define __msan_unpoison(p, size)
399# define LLVM_NO_SANITIZE_MEMORY_ATTRIBUTE
400#endif
401
402/// \macro LLVM_ADDRESS_SANITIZER_BUILD
403/// Whether LLVM itself is built with AddressSanitizer instrumentation.
404#if __has_feature(address_sanitizer) || defined(__SANITIZE_ADDRESS__)
405# define LLVM_ADDRESS_SANITIZER_BUILD 1
406#if __has_include(<sanitizer/asan_interface.h>)
407# include <sanitizer/asan_interface.h>
408#else
409// These declarations exist to support ASan with MSVC. If MSVC eventually ships
410// asan_interface.h in their headers, then we can remove this.
411#ifdef __cplusplus
412extern "C" {
413#endif
414void __asan_poison_memory_region(void const volatile *addr, size_t size);
415void __asan_unpoison_memory_region(void const volatile *addr, size_t size);
416#ifdef __cplusplus
417} // extern "C"
418#endif
419#endif
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
439extern "C" {
440#endif
441void AnnotateHappensAfter(const char *file, int line, const volatile void *cv);
442void AnnotateHappensBefore(const char *file, int line, const volatile void *cv);
443void AnnotateIgnoreWritesBegin(const char *file, int line);
444void 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. It uses thread_local if available, falling back on gcc __thread
508/// if not. __thread doesn't support many of the C++11 thread_local's
509/// features. You should only use this for PODs that you can statically
510/// initialize to some constant value. In almost all circumstances this is most
511/// appropriate for use with a pointer, integer, or small aggregation of
512/// pointers and integers.
513#if LLVM_ENABLE_THREADS
514#if __has_feature(cxx_thread_local) || defined(_MSC_VER)
515#define LLVM_THREAD_LOCAL thread_local
516#else
517// Clang, GCC, and other compatible compilers used __thread prior to C++11 and
518// we only need the restricted functionality that provides.
519#define LLVM_THREAD_LOCAL __thread
520#endif
521#else // !LLVM_ENABLE_THREADS
522// If threading is disabled entirely, this compiles to nothing and you get
523// a normal global variable.
524#define LLVM_THREAD_LOCAL
525#endif
526
527/// \macro LLVM_ENABLE_EXCEPTIONS
528/// Whether LLVM is built with exception support.
529#if __has_feature(cxx_exceptions)
530#define LLVM_ENABLE_EXCEPTIONS 1
531#elif defined(__GNUC__) && defined(__EXCEPTIONS)
532#define LLVM_ENABLE_EXCEPTIONS 1
533#elif defined(_MSC_VER) && defined(_CPPUNWIND)
534#define LLVM_ENABLE_EXCEPTIONS 1
535#endif
536
537/// \macro LLVM_NO_PROFILE_INSTRUMENT_FUNCTION
538/// Disable the profile instrument for a function.
539#if __has_attribute(no_profile_instrument_function)
540#define LLVM_NO_PROFILE_INSTRUMENT_FUNCTION \
541 __attribute__((no_profile_instrument_function))
542#else
543#define LLVM_NO_PROFILE_INSTRUMENT_FUNCTION
544#endif
545
546#endif
547

source code of llvm/include/llvm/Support/Compiler.h