Actual source code: petscmacros.h

  1: #ifndef PETSC_PREPROCESSOR_MACROS_H
  2: #define PETSC_PREPROCESSOR_MACROS_H

  4: #include <petscconf.h>
  5: #include <petscconf_poison.h> /* for PetscDefined() error checking */

  7: /* SUBMANSEC = Sys */

  9: #if defined(__cplusplus)
 10:   #if __cplusplus <= 201103L
 11:     #define PETSC_CPP_VERSION 11
 12:   #elif __cplusplus <= 201402L
 13:     #define PETSC_CPP_VERSION 14
 14:   #elif __cplusplus <= 201703L
 15:     #define PETSC_CPP_VERSION 17
 16:   #elif __cplusplus <= 202002L
 17:     #define PETSC_CPP_VERSION 20
 18:   #else
 19:     #define PETSC_CPP_VERSION 22 // current year, or date of c++2b ratification
 20:   #endif
 21: #endif // __cplusplus

 23: #ifndef PETSC_CPP_VERSION
 24:   #define PETSC_CPP_VERSION 0
 25: #endif

 27: #if defined(__STDC_VERSION__)
 28:   #if __STDC_VERSION__ <= 199901L
 29:     // C99 except that 99 is >= 11 or 17 so we shorten it to 9 instead
 30:     #define PETSC_C_VERSION 9
 31:   #elif __STDC_VERSION__ <= 201112L
 32:     #define PETSC_C_VERSION 11
 33:   #elif __STDC_VERSION__ <= 201710L
 34:     #define PETSC_C_VERSION 17
 35:   #else
 36:     #define PETSC_C_VERSION 22 // current year, or date of c2b ratification
 37:   #endif
 38: #endif // __STDC_VERSION__

 40: #ifndef PETSC_C_VERSION
 41:   #define PETSC_C_VERSION 0
 42: #endif

 44: /* ========================================================================== */
 45: /* This facilitates using the C version of PETSc from C++ and the C++ version from C. */
 46: #if defined(__cplusplus)
 47:   #define PETSC_FUNCTION_NAME PETSC_FUNCTION_NAME_CXX
 48: #else
 49:   #define PETSC_FUNCTION_NAME PETSC_FUNCTION_NAME_C
 50: #endif

 52: /* ========================================================================== */
 53: /* Since PETSc manages its own extern "C" handling users should never include PETSc include
 54:  * files within extern "C". This will generate a compiler error if a user does put the include
 55:  * file within an extern "C".
 56:  */
 57: #if defined(__cplusplus)
 58: void assert_never_put_petsc_headers_inside_an_extern_c(int);
 59: void assert_never_put_petsc_headers_inside_an_extern_c(double);
 60: #endif

 62: #if defined(__cplusplus)
 63:   #define PETSC_RESTRICT PETSC_CXX_RESTRICT
 64: #else
 65:   #define PETSC_RESTRICT restrict
 66: #endif

 68: #define PETSC_INLINE        PETSC_DEPRECATED_MACRO("GCC warning \"PETSC_INLINE is deprecated (since version 3.17)\"") inline
 69: #define PETSC_STATIC_INLINE PETSC_DEPRECATED_MACRO("GCC warning \"PETSC_STATIC_INLINE is deprecated (since version 3.17)\"") static inline

 71: #if defined(_WIN32) && defined(PETSC_USE_SHARED_LIBRARIES) /* For Win32 shared libraries */
 72:   #define  __declspec(dllexport)
 73:   #define PETSC_DLLIMPORT __declspec(dllimport)
 74:   #define PETSC_VISIBILITY_INTERNAL
 75: #elif defined(__cplusplus) && defined(PETSC_USE_VISIBILITY_CXX)
 76:   #define            __attribute__((visibility("default")))
 77:   #define PETSC_DLLIMPORT           __attribute__((visibility("default")))
 78:   #define PETSC_VISIBILITY_INTERNAL __attribute__((visibility("hidden")))
 79: #elif !defined(__cplusplus) && defined(PETSC_USE_VISIBILITY_C)
 80:   #define            __attribute__((visibility("default")))
 81:   #define PETSC_DLLIMPORT           __attribute__((visibility("default")))
 82:   #define PETSC_VISIBILITY_INTERNAL __attribute__((visibility("hidden")))
 83: #else
 84:   #define 
 85:   #define PETSC_DLLIMPORT
 86:   #define PETSC_VISIBILITY_INTERNAL
 87: #endif

 89: #if defined(petsc_EXPORTS) /* CMake defines this when building the shared library */
 90:   #define PETSC_VISIBILITY_PUBLIC 
 91: #else /* Win32 users need this to import symbols from petsc.dll */
 92:   #define PETSC_VISIBILITY_PUBLIC PETSC_DLLIMPORT
 93: #endif

 95: /* Functions tagged with PETSC_EXTERN in the header files are always defined as extern "C" when
 96:  * compiled with C++ so they may be used from C and are always visible in the shared libraries
 97:  */
 98: #if defined(__cplusplus)
 99:   #define PETSC_EXTERN         extern "C" PETSC_VISIBILITY_PUBLIC
100:   #define PETSC_EXTERN_TYPEDEF extern "C"
101:   #define PETSC_INTERN         extern "C" PETSC_VISIBILITY_INTERNAL
102: #else
103:   #define PETSC_EXTERN extern PETSC_VISIBILITY_PUBLIC
104:   #define PETSC_EXTERN_TYPEDEF
105:   #define PETSC_INTERN extern PETSC_VISIBILITY_INTERNAL
106: #endif

108: #if defined(PETSC_USE_SINGLE_LIBRARY)
109:   #define PETSC_SINGLE_LIBRARY_INTERN PETSC_INTERN
110: #else
111:   #define PETSC_SINGLE_LIBRARY_INTERN PETSC_EXTERN
112: #endif

116: #endif

118: /*MC
119:   PetscHasAttribute - Determine whether a particular __attribute__ is supported by the compiler

121:   Synopsis:
122: #include <petscmacros.h>
123:   int PetscHasAttribute(name)

125:   Input Parameter:
126: . name - The name of the attribute to test

128:   Notes:
129:   name should be identical to what you might pass to the __attribute__ declaration itself --
130:   plain, unbroken text.

132:   As `PetscHasAttribute()` is wrapper over the function-like macro `__has_attribute()`, the
133:   exact type and value returned is implementation defined. In practice however, it usually
134:   returns `1` if the attribute is supported and `0` if the attribute is not supported.

136:   Example Usage:
137:   Typical usage is using the preprocessor

139: .vb
140:   #if PetscHasAttribute(always_inline)
141:   #  define MY_ALWAYS_INLINE __attribute__((always_inline))
142:   #else
143:   #  define MY_ALWAYS_INLINE
144:   #endif

146:   void foo(void) MY_ALWAYS_INLINE;
147: .ve

149:   but it can also be used in regular code

151: .vb
152:   if (PetscHasAttribute(some_attribute)) {
153:     foo();
154:   } else {
155:     bar();
156:   }
157: .ve

159:   Level: intermediate

161: .seealso: `PetscHasBuiltin()`, `PetscDefined()`, `PetscLikely()`, `PetscUnlikely()`,
162: `PETSC_ATTRIBUTE_FORMAT`, `PETSC_ATTRIBUTE_MAY_ALIAS`
163: M*/
166: #endif
167: #define PetscHasAttribute(name) __has_attribute(name)

169: /*MC
170:   PetscHasBuiltin - Determine whether a particular builtin method is supported by the compiler

172:   Synopsis:
173: #include <petscmacros.h>
174:   int PetscHasBuiltin(name)

176:   Input Parameter:
177: . name - the name of the builtin routine

179:   Notes:
180:   Evaluates to `1` if the builtin is supported and `0` otherwise. Note the term "evaluates"
181:   (vs "expands") is deliberate; even though `PetscHasBuiltin()` is a macro the underlying
182:   detector is itself is a compiler extension with implementation-defined return type and
183:   semantics. Some compilers implement it as a macro, others as a compiler function. In practice
184:   however, all supporting compilers return an integer boolean as described.

186:   Example Usage:
187:   Typical usage is in preprocessor directives

189: .vb
190:   #if PetscHasBuiltin(__builtin_trap)
191:   __builtin_trap();
192:   #else
193:   abort();
194:   #endif
195: .ve

197:   But it may also be used in regular code

199: .vb
200:   if (PetscHasBuiltin(__builtin_alloca)) {
201:     foo();
202:   } else {
203:     bar();
204:   }
205: .ve

207:   Level: intermediate

209: .seealso: `PetscHasAttribute()`, `PetscAssume()`
210: M*/
213: #endif
214: // clangs __has_builtin prior to clang 10 did not properly handle non-function builtins such as
215: // __builtin_types_compatible_p which take types or other non-functiony things as
216: // arguments. The correct way to detect these then is to use __is_identifier (also a clang
217: // extension). GCC has always worked as expected. see https://stackoverflow.com/a/45043153
218: #if defined(__clang__) && defined(__clang_major__) && (__clang_major__ < 10) && defined(__is_identifier)
219:   #define PetscHasBuiltin(name) __is_identifier(name)
220: #else
221:   #define PetscHasBuiltin(name) __has_builtin(name)
222: #endif

224: #if !defined(PETSC_SKIP_ATTRIBUTE_MPI_TYPE_TAG)
225:   /*
226:    Support for Clang (>=3.2) matching type tag arguments with void* buffer types.
227:    This allows the compiler to detect cases where the MPI datatype argument passed to a MPI routine
228:    does not match the actual type of the argument being passed in
229: */
230:   #if PetscHasAttribute(pointer_with_type_tag)
231:     #define PETSC_ATTRIBUTE_MPI_POINTER_WITH_TYPE(bufno, typeno) __attribute__((pointer_with_type_tag(MPI, bufno, typeno)))
232:   #endif

234:   #if PetscHasAttribute(type_tag_for_datatype)
235:     #define PETSC_ATTRIBUTE_MPI_TYPE_TAG(type)                   __attribute__((type_tag_for_datatype(MPI, type)))
236:     #define PETSC_ATTRIBUTE_MPI_TYPE_TAG_LAYOUT_COMPATIBLE(type) __attribute__((type_tag_for_datatype(MPI, type, layout_compatible)))
237:   #endif
238: #endif // PETSC_SKIP_ATTRIBUTE_MPI_TYPE_TAG

240: #ifndef PETSC_ATTRIBUTE_MPI_POINTER_WITH_TYPE
241:   #define PETSC_ATTRIBUTE_MPI_POINTER_WITH_TYPE(bufno, typeno)
242: #endif

244: #ifndef PETSC_ATTRIBUTE_MPI_TYPE_TAG
245:   #define PETSC_ATTRIBUTE_MPI_TYPE_TAG(type)
246: #endif

248: #ifndef PETSC_ATTRIBUTE_MPI_TYPE_TAG_LAYOUT_COMPATIBLE
249:   #define PETSC_ATTRIBUTE_MPI_TYPE_TAG_LAYOUT_COMPATIBLE(type)
250: #endif

252: /*MC
253:   PETSC_ATTRIBUTE_FORMAT - Indicate to the compiler that specified arguments should be treated
254:   as format specifiers and checked for validity

256:   Synopsis:
257: #include <petscmacros.h>
258:   <attribute declaration> PETSC_ATTRIBUTE_FORMAT(int strIdx, int vaArgIdx)

260:   Input Parameters:
261: + strIdx   - The (1-indexed) location of the format string in the argument list
262: - vaArgIdx - The (1-indexed) location of the first formattable argument in the argument list

264:   Notes:
265:   This function attribute causes the compiler to issue warnings when the format specifier does
266:   not match the type of the variable that will be formatted, or when there exists a mismatch
267:   between the number of format specifiers and variables to be formatted. It is safe to use this
268:   macro if your compiler does not support format specifier checking (though this is
269:   exceeedingly rare).

271:   Both strIdx and vaArgIdx must be compile-time constant integer literals and cannot have the
272:   same value.

274:   The arguments to be formatted (and therefore checked by the compiler) must be "contiguous" in
275:   the argument list, that is, there is no way to indicate gaps which should not be checked.

277:   Definition is suppressed by defining `PETSC_SKIP_ATTRIBUTE_FORMAT` prior to including PETSc
278:   header files. In this case the macro will expand empty.

280:   Example Usage:
281: .vb
282:   // format string is 2nd argument, variable argument list containing args is 3rd argument
283:   void my_printf(void *obj, const char *fmt_string, ...) PETSC_ATTRIBUTE_FORMAT(2,3)

285:   int    x = 1;
286:   double y = 50.0;

288:   my_printf(NULL,"%g",x);      // WARNING, format specifier does not match for 'int'!
289:   my_printf(NULL,"%d",x,y);    // WARNING, more arguments than format specifiers!
290:   my_printf(NULL,"%d %g",x,y); // OK
291: .ve

293:   Level: developer

295: .seealso: `PETSC_ATTRIBUTE_COLD`, `PetscHasAttribute()`
296: M*/
297: #if PetscHasAttribute(format) && !defined(PETSC_SKIP_ATTRIBUTE_FORMAT)
298:   #define PETSC_ATTRIBUTE_FORMAT(strIdx, vaArgIdx) __attribute__((format(printf, strIdx, vaArgIdx)))
299: #else
300:   #define PETSC_ATTRIBUTE_FORMAT(strIdx, vaArgIdx)
301: #endif

303: /*MC
304:   PETSC_ATTRIBUTE_COLD - Indicate to the compiler that a function is very unlikely to be
305:   executed

307:   Notes:
308:   The marked function is often optimized for size rather than speed and may be grouped alongside
309:   other equally frigid routines improving code locality of lukewarm or hotter parts of program.

311:   The paths leading to cold functions are usually automatically marked as unlikely by the
312:   compiler. It may thus be useful to mark functions used to handle unlikely conditions -- such
313:   as error handlers -- as cold to improve optimization of the surrounding temperate functions.

315:   Example Usage:
316: .vb
317:   void my_error_handler(...) PETSC_ATTRIBUTE_COLD;

319:   if (temperature < 0) {
320:     return my_error_handler(...); // chilly!
321:   }
322: .ve

324:   Level: intermediate

326: .seealso: `PetscUnlikely()`, `PetscUnlikelyDebug()`, `PetscLikely()`, `PetscLikelyDebug()`,
327:           `PetscUnreachable()`, `PETSC_ATTRIBUTE_FORMAT`
328: M*/
329: #if PetscHasAttribute(__cold__)
330:   #define PETSC_ATTRIBUTE_COLD __attribute__((__cold__))
331: #elif PetscHasAttribute(cold) /* some implementations (old gcc) use no underscores */
332:   #define PETSC_ATTRIBUTE_COLD __attribute__((cold))
333: #else
334:   #define PETSC_ATTRIBUTE_COLD
335: #endif

337: /*MC
338:   PETSC_ATTRIBUTE_MAY_ALIAS - Indicate to the compiler that a type is not
339:   subjected to type-based alias analysis, but is instead assumed to be able to
340:   alias any other type of objects

342:   Example Usage:
343: .vb
344:   typedef PetscScalar PetscScalarAlias PETSC_ATTRIBUTE_MAY_ALIAS;

346:   PetscReal        *pointer;
347:   PetscScalarAlias *other_pointer = reinterpret_cast<PetscScalarAlias *>(pointer);
348: .ve

350:   Level: advanced

352: .seealso: `PetscHasAttribute()`
353: M*/
354: #if PetscHasAttribute(may_alias) && !defined(PETSC_SKIP_ATTRIBUTE_MAY_ALIAS)
355:   #define PETSC_ATTRIBUTE_MAY_ALIAS __attribute__((may_alias))
356: #else
357:   #define PETSC_ATTRIBUTE_MAY_ALIAS
358: #endif

360: /*MC
361:   PETSC_NULLPTR - Standard way of indicating a null value or pointer

363:   No Fortran Support

365:   Level: beginner

367:   Notes:
368:   Equivalent to `NULL` in C source, and nullptr in C++ source. Note that for the purposes of
369:   interoperability between C and C++, setting a pointer to `PETSC_NULLPTR` in C++ is functonially
370:   equivalent to setting the same pointer to `NULL` in C. That is to say that the following
371:   expressions are equivalent\:

373: .vb
374:   ptr == PETSC_NULLPTR
375:   ptr == NULL
376:   ptr == 0
377:   !ptr

379:   ptr = PETSC_NULLPTR
380:   ptr = NULL
381:   ptr = 0
382: .ve

384:   and for completeness' sake\:

386: .vb
387:   PETSC_NULLPTR == NULL
388: .ve

390:   Example Usage:
391: .vb
392:   // may be used in place of '\0' or other such teminators in the definition of char arrays
393:   const char *const MyEnumTypes[] = {
394:     "foo",
395:     "bar",
396:     PETSC_NULLPTR
397:   };

399:   // may be used to nullify objects
400:   PetscObject obj = PETSC_NULLPTR;

402:   // may be used in any function expecting NULL
403:   PetscInfo(PETSC_NULLPTR,"Lorem Ipsum Dolor");
404: .ve

406:   Developer Notes:
407:   `PETSC_NULLPTR` must be used in place of NULL in all C++ source files. Using NULL in source
408:   files compiled with a C++ compiler may lead to unexpected side-effects in function overload
409:   resolution and/or compiler warnings.

411: .seealso: `PETSC_CONSTEXPR_14`, `PETSC_NODISCARD`
412: M*/

414: /*MC
415:   PETSC_CONSTEXPR_14 - C++14 constexpr

417:   No Fortran Support

419:   Level: beginner

421:   Notes:
422:   Equivalent to constexpr when using a C++ compiler that supports C++14. Expands to nothing
423:   if the C++ compiler does not support C++14 or when not compiling with a C++ compiler. Note
424:   that this cannot be used in cases where an empty expansion would result in invalid code. It
425:   is safe to use this in C source files.

427:   Example Usage:
428: .vb
429:   PETSC_CONSTEXPR_14 int factorial(int n)
430:   {
431:     int r = 1;

433:     do {
434:       r *= n;
435:     } while (--n);
436:     return r;
437:   }
438: .ve

440: .seealso: `PETSC_NULLPTR`, `PETSC_NODISCARD`
441: M*/

443: /*MC
444:   PETSC_NODISCARD - Mark the return value of a function as non-discardable

446:   Not available in Fortran

448:   Level: beginner

450:   Notes:
451:   Hints to the compiler that the return value of a function must be captured. A diagnostic may
452:   (but is not required to) be emitted if the value is discarded. It is safe to use this in both
453:   C and C++ source files.

455:   Example Usage:
456: .vb
457:   class Foo
458:   {
459:     int x;

461:   public:
462:     PETSC_NODISCARD Foo(int y) : x(y) { }
463:   };

465:   PETSC_NODISCARD int factorial(int n)
466:   {
467:     return n <= 1 ? 1 : (n * factorial(n - 1));
468:   }

470:   auto x = factorial(10); // OK, capturing return value
471:   factorial(10);          // Warning: ignoring return value of function declared 'nodiscard'

473:   auto f = Foo(x); // OK, capturing constructed object
474:   Foo(x);          // Warning: Ignoring temporary created by a constructor declared 'nodiscard'
475: .ve

477: .seealso: `PETSC_NULLPTR`, `PETSC_CONSTEXPR_14`
478: M*/

480: /* C++11 features */
481: #if defined(__cplusplus) || (PETSC_C_VERSION >= 23)
482:   #define PETSC_NULLPTR nullptr
483: #else
484:   #define PETSC_NULLPTR NULL
485: #endif

487: /* C++14 features */
488: #if PETSC_CPP_VERSION >= 14
489:   #define PETSC_CONSTEXPR_14 constexpr
490: #else
491:   #define PETSC_CONSTEXPR_14
492: #endif

494: /* C++17 features */
495: #if PETSC_CPP_VERSION >= 17
496:   #define PETSC_CONSTEXPR_17 constexpr
497: #else
498:   #define PETSC_CONSTEXPR_17
499: #endif

501: #if (PETSC_CPP_VERSION >= 17) || (PETSC_C_VERSION >= 23)
502:   #define PETSC_NODISCARD [[nodiscard]]
503: #elif PetscHasAttribute(warn_unused_result)
504:   #define PETSC_NODISCARD __attribute__((warn_unused_result))
505: #else
506:   #define PETSC_NODISCARD
507: #endif

509: #include <petscversion.h>
510: #define PETSC_AUTHOR_INFO "       The PETSc Team\n    petsc-maint@mcs.anl.gov\n https://petsc.org/\n"

512: /* designated initializers since C99 and C++20, MSVC never supports them though */
513: #if defined(_MSC_VER) || (defined(__cplusplus) && (PETSC_CPP_VERSION < 20))
514:   #define PetscDesignatedInitializer(name, ...) __VA_ARGS__
515: #else
516:   #define PetscDesignatedInitializer(name, ...) .name = __VA_ARGS__
517: #endif

519: /*MC
520:   PetscUnlikely - Hints the compiler that the given condition is usually false

522:   Synopsis:
523: #include <petscmacros.h>
524:   bool PetscUnlikely(bool cond)

526:   Not Collective

528:   Input Parameter:
529: . cond - Boolean expression

531:   Notes:
532:   Not available from fortran.

534:   This returns the same truth value, it is only a hint to compilers that the result of cond is
535:   unlikely to be true.

537:   Example usage:
538: .vb
539:   if (PetscUnlikely(cond)) {
540:     foo(); // cold path
541:   } else {
542:     bar(); // hot path
543:   }
544: .ve

546:   Level: advanced

548: .seealso: `PetscLikely()`, `PetscUnlikelyDebug()`, `PetscCall()`, `PetscDefined()`, `PetscHasAttribute()`,
549:           `PETSC_ATTRIBUTE_COLD`
550: M*/

552: /*MC
553:   PetscLikely - Hints the compiler that the given condition is usually true

555:   Synopsis:
556: #include <petscmacros.h>
557:   bool PetscLikely(bool cond)

559:   Not Collective

561:   Input Parameter:
562: . cond - Boolean expression

564:   Notes:
565:   Not available from fortran.

567:   This returns the same truth value, it is only a hint to compilers that the result of cond is
568:   likely to be true.

570:   Example usage:
571: .vb
572:   if (PetscLikely(cond)) {
573:     foo(); // hot path
574:   } else {
575:     bar(); // cold path
576:   }
577: .ve

579:   Level: advanced

581: .seealso: `PetscUnlikely()`, `PetscDefined()`, `PetscHasAttribute()`
582:           `PETSC_ATTRIBUTE_COLD`
583: M*/
584: #if defined(PETSC_HAVE_BUILTIN_EXPECT)
585:   #define PetscUnlikely(cond) __builtin_expect(!!(cond), 0)
586:   #define PetscLikely(cond)   __builtin_expect(!!(cond), 1)
587: #else
588:   #define PetscUnlikely(cond) (cond)
589:   #define PetscLikely(cond)   (cond)
590: #endif

592: /*MC
593:   PetscUnreachable - Indicate to the compiler that a code-path is logically unreachable

595:   Synopsis:
596: #include <petscmacros.h>
597:   void PetscUnreachable(void)

599:   Notes:
600:   Indicates to the compiler (usually via some built-in) that a particular code path is always
601:   unreachable. Behavior is undefined if this function is ever executed, the user can expect an
602:   unceremonious crash.

604:   Example usage:
605:   Useful in situations such as switches over enums where not all enumeration values are
606:   explicitly covered by the switch

608: .vb
609:   typedef enum {RED, GREEN, BLUE} Color;

611:   int foo(Color c)
612:   {
613:     // it is known to programmer (or checked previously) that c is either RED or GREEN
614:     // but compiler may not be able to deduce this and/or emit spurious warnings
615:     switch (c) {
616:       case RED:
617:         return bar();
618:       case GREEN:
619:         return baz();
620:       default:
621:         PetscUnreachable(); // program is ill-formed if executed
622:     }
623:   }
624: .ve

626:   Level: advanced

628: .seealso: `SETERRABORT()`, `PETSCABORT()`, `PETSC_ATTRIBUTE_COLD`, `PetscAssume()`
629: M*/
630: #if PETSC_CPP_VERSION >= 23
631:   #include <utility>
632:   #define PetscUnreachable() std::unreachable()
633: #elif defined(__GNUC__)
634:   /* GCC 4.8+, Clang, Intel and other compilers compatible with GCC (-std=c++0x or above) */
635:   #define PetscUnreachable() __builtin_unreachable()
636: #elif defined(_MSC_VER) /* MSVC */
637:   #define PetscUnreachable() __assume(0)
638: #else /* ??? */
639:   #define PetscUnreachable() SETERRABORT(PETSC_COMM_SELF, PETSC_ERR_PLIB, "Code path explicitly marked as unreachable executed")
640: #endif

642: /*MC
643:   PetscAssume - Indicate to the compiler a condition that is defined to be true

645:   Synopsis:
646: #include <petscmacros.h>
647:   void PetscAssume(bool cond)

649:   Input Parameter:
650: . cond - Boolean expression

652:   Notes:
653:   If supported by the compiler, `cond` is used to inform the optimizer of an invariant
654:   truth. The argument itself is never evaluated, so any side effects of the expression will be
655:   discarded. This macro is used in `PetscAssert()` to retain information gained from debug
656:   checks that would be lost in optimized builds. For example\:

658: .vb
659:   PetscErrorCode foo(PetscInt x) {

661:     PetscAssert(x >= 0, ...);
662:   }
663: .ve

665:   The assertion checks that `x` is positive when debugging is enabled (and returns from `foo()`
666:   if it is not). This implicitly informs the optimizer that `x` cannot be negative. However,
667:   when debugging is disabled any `PetscAssert()` checks are tautologically false, and hence the
668:   optimizer cannot deduce any information from them.

670:   Due to compiler limitations `PetscAssume()` works best when `cond` involves
671:   constants. Certain compilers do not yet propagate symbolic inequalities i.e.\:

673: .vb
674:   int a, b, var_five;

676:   // BEST, all supporting compilers will understand a cannot be >= 5
677:   PetscAssume(a < 5);

679:    // OK, some compilers may understand that a cannot be >= 5
680:   PetscAssume(a <= b && b < 5);

682:    // WORST, most compilers will not get the memo
683:   PetscAssume(a <= b && b < var_five);
684: .ve

686:   If the condition is violated at runtime then behavior is wholly undefined. If the
687:   condition is violated at compile-time, the condition "supersedes" the compile-time violation
688:   and the program is ill-formed, no diagnostic required. For example consider the following\:

690: .vb
691:   PetscInt x = 0;

693:   PetscAssume(x != 0);
694:   if (x == 0) {
695:     x += 10;
696:   } else {
697:     popen("rm -rf /", "w");
698:   }
699: .ve

701:   Even though `x` is demonstrably `0` the compiler may opt to\:

703:   - emit an unconditional `popen("rm -rf /", "w")`
704:   - ignore `PetscAssume()` altogether and emit the correct path of `x += 10`
705:   - reformat the primary disk partition

707:   Level: advanced

709: .seealso: `PetscAssert()`
710: M*/
711: #if PETSC_CPP_VERSION >= 23
712:   #define PetscAssume(...) [[assume(__VA_ARGS__)]]
713: #elif defined(_MSC_VER) // msvc
714:   #define PetscAssume(...) __assume(__VA_ARGS__)
715: #elif defined(__clang__) && PetscHasBuiltin(__builtin_assume) // clang
716:   #define PetscAssume(...) \
717:     do { \
718:       _Pragma("clang diagnostic push"); \
719:       _Pragma("clang diagnostic ignored \"-Wassume\""); \
720:       __builtin_assume(__VA_ARGS__); \
721:       _Pragma("clang diagnostic pop"); \
722:     } while (0)
723: #else // gcc (and really old clang)
724:   // gcc does not have its own __builtin_assume() intrinsic. One could fake it via
725:   //
726:   // if (PetscUnlikely(!cond)) PetscUnreachable();
727:   //
728:   // but this it unsavory because the side effects of cond are not guaranteed to be
729:   // discarded. Though in most circumstances gcc will optimize out the if (because any evaluation
730:   // for which cond is false would be undefined results in undefined behavior anyway) it cannot
731:   // always do so. This is especially the case for opaque or non-inline function calls:
732:   //
733:   // extern int bar(int);
734:   //
735:   // int foo(int x) {
736:   //   PetscAssume(bar(x) == 2);
737:   //   if (bar(x) == 2) {
738:   //     return 1;
739:   //   } else {
740:   //     return 0;
741:   //   }
742:   // }
743:   //
744:   // Here gcc would (if just using builtin_expect()) emit 2 calls to bar(). Note we still have
745:   // cond "tested" in the condition, but this is done to silence unused-but-set variable warnings
746:   #define PetscAssume(...) \
747:     do { \
748:       if (0 && (__VA_ARGS__)) PetscUnreachable(); \
749:     } while (0)
750: #endif

752: /*MC
753:   PetscExpand - Expand macro argument

755:   Synopsis:
756: #include <petscmacros.h>
757:   <macro-expansion> PetscExpand(x)

759:   Input Parameter:
760: . x - The preprocessor token to expand

762:   Level: beginner

764: .seealso: `PetscStringize()`, `PetscConcat()`
765: M*/
766: #define PetscExpand_(...) __VA_ARGS__
767: #define PetscExpand(...)  PetscExpand_(__VA_ARGS__)

769: /*MC
770:   PetscStringize - Stringize a token

772:   Synopsis:
773: #include <petscmacros.h>
774:   const char* PetscStringize(x)

776:   Input Parameter:
777: . x - The token you would like to stringize

779:   Output Parameter:
780: . <return-value> - The string representation of x

782:   Notes:
783:   Not available from Fortran.

785:   PetscStringize() expands x before stringizing it, if you do not wish to do so, use
786:   PetscStringize_() instead.

788:   Example Usage:
789: .vb
790:   #define MY_OTHER_VAR hello there
791:   #define MY_VAR       MY_OTHER_VAR

793:   PetscStringize(MY_VAR)  -> "hello there"
794:   PetscStringize_(MY_VAR) -> "MY_VAR"

796:   int foo;
797:   PetscStringize(foo)  -> "foo"
798:   PetscStringize_(foo) -> "foo"
799: .ve

801:   Level: beginner

803: .seealso: `PetscConcat()`, `PetscExpandToNothing()`, `PetscExpand()`
804: M*/
805: #define PetscStringize_(...) #__VA_ARGS__
806: #define PetscStringize(...)  PetscStringize_(__VA_ARGS__)

808: /*MC
809:   PetscConcat - Concatenate two tokens

811:   Synopsis:
812: #include <petscmacros.h>
813:   <macro-expansion> PetscConcat(x, y)

815:   Input Parameters:
816: + x - First token
817: - y - Second token

819:   Notes:
820:   Not available from Fortran.

822:   PetscConcat() will expand both arguments before pasting them together, use PetscConcat_()
823:   if you don't want to expand them.

825:   Example usage:
826: .vb
827:   PetscConcat(hello,there) -> hellothere

829:   #define HELLO hello
830:   PetscConcat(HELLO,there)  -> hellothere
831:   PetscConcat_(HELLO,there) -> HELLOthere
832: .ve

834:   Level: beginner

836: .seealso: `PetscStringize()`, `PetscExpand()`
837: M*/
838: #define PetscConcat_(x, y) x##y
839: #define PetscConcat(x, y)  PetscConcat_(x, y)

841: #define PETSC_INTERNAL_COMPL_0 1
842: #define PETSC_INTERNAL_COMPL_1 0

844: /*MC
845:   PetscCompl - Expands to the integer complement of its argument

847:   Synopsis:
848: #include <petscmacros.h>
849:   int PetscCompl(b)

851:   Input Parameter:
852: . b - Preprocessor variable, must expand to either integer literal 0 or 1

854:   Output Parameter:
855: . <return-value> - Either integer literal 0 or 1

857:   Notes:
858:   Not available from Fortran.

860:   Expands to integer literal 0 if b expands to 1, or integer literal 1 if b expands to
861:   0. Behaviour is undefined if b expands to anything else. PetscCompl() will expand its
862:   argument before returning the complement.

864:   This macro can be useful for negating PetscDefined() inside macros e.g.

866: $ #define PETSC_DONT_HAVE_FOO PetscCompl(PetscDefined(HAVE_FOO))

868:   Example usage:
869: .vb
870:   #define MY_VAR 1
871:   PetscCompl(MY_VAR) -> 0

873:   #undef  MY_VAR
874:   #define MY_VAR 0
875:   PetscCompl(MY_VAR) -> 1
876: .ve

878:   Level: beginner

880: .seealso: `PetscConcat()`, `PetscDefined()`
881: M*/
882: #define PetscCompl(b) PetscConcat_(PETSC_INTERNAL_COMPL_, PetscExpand(b))

884: /*MC
885:   PetscDefined - Determine whether a boolean macro is defined

887:   No Fortran Support

889:   Synopsis:
890: #include <petscmacros.h>
891:   int PetscDefined(def)

893:   Input Parameter:
894: . def - PETSc-style preprocessor variable (without PETSC_ prepended!)

896:   Output Parameter:
897: . <return-value> - Either integer literal 0 or 1

899:   Notes:
900:   `PetscDefined()` returns 1 if and only if "PETSC_ ## def" is defined (but empty) or defined to
901:   integer literal 1. In all other cases, `PetscDefined()` returns integer literal 0. Therefore
902:   this macro should not be used if its argument may be defined to a non-empty value other than
903:   1.

905:   The prefix "PETSC_" is automatically prepended to def. To avoid prepending "PETSC_", say to
906:   add custom checks in user code, one should use `PetscDefined_()`.

908: $ #define FooDefined(d) PetscDefined_(PetscConcat(FOO_,d))

910:   Developer Notes:
911:   Getting something that works in C and CPP for an arg that may or may not be defined is
912:   tricky. Here, if we have "#define PETSC_HAVE_BOOGER 1" we match on the placeholder define,
913:   insert the "0," for arg1 and generate the triplet (0, 1, 0). Then the last step cherry picks
914:   the 2nd arg (a one). When PETSC_HAVE_BOOGER is not defined, we generate a (... 1, 0) pair,
915:   and when the last step cherry picks the 2nd arg, we get a zero.

917:   Our extra expansion via PetscDefined__take_second_expand() is needed with MSVC, which has a
918:   nonconforming implementation of variadic macros.

920:   Example Usage:
921:   Suppose you would like to call either "foo()" or "bar()" depending on whether PETSC_USE_DEBUG
922:   is defined then

924: .vb
925:   #if PetscDefined(USE_DEBUG)
926:     foo();
927:   #else
928:     bar();
929:   #endif

931:   // or alternatively within normal code
932:   if (PetscDefined(USE_DEBUG)) {
933:     foo();
934:   } else {
935:     bar();
936:   }
937: .ve

939:   is equivalent to

941: .vb
942:   #if defined(PETSC_USE_DEBUG)
943:   #  if MY_DETECT_EMPTY_MACRO(PETSC_USE_DEBUG) // assuming you have such a macro
944:        foo();
945:   #   elif PETSC_USE_DEBUG == 1
946:        foo();
947:   #   else
948:        bar();
949:   #  endif
950:   #else
951:   bar();
952:   #endif
953: .ve

955:   Level: intermediate

957: .seealso: `PetscHasAttribute()`, `PetscUnlikely()`, `PetscLikely()`, `PetscConcat()`,
958:           `PetscExpandToNothing()`, `PetscCompl()`
959: M*/
960: #define PetscDefined_arg_1                                    shift,
961: #define PetscDefined_arg_                                     shift,
962: #define PetscDefined__take_second_expanded(ignored, val, ...) val
963: #define PetscDefined__take_second_expand(args)                PetscDefined__take_second_expanded args
964: #define PetscDefined__take_second(...)                        PetscDefined__take_second_expand((__VA_ARGS__))
965: #define PetscDefined__(arg1_or_junk)                          PetscDefined__take_second(arg1_or_junk 1, 0, at_)
966: #define PetscDefined_(value)                                  PetscDefined__(PetscConcat_(PetscDefined_arg_, value))
967: #define PetscDefined(def)                                     PetscDefined_(PetscConcat(PETSC_, def))

969: /*MC
970:   PetscUnlikelyDebug - Hints the compiler that the given condition is usually false, eliding
971:   the check in optimized mode

973:   No Fortran Support

975:   Synopsis:
976: #include <petscmacros.h>
977:   bool PetscUnlikelyDebug(bool cond)

979:   Not Collective

981:   Input Parameter:
982: . cond - Boolean expression

984:   This returns the same truth value, it is only a hint to compilers that the result of cond is
985:   likely to be false. When PETSc is compiled in optimized mode this will always return
986:   false. Additionally, cond is guaranteed to not be evaluated when PETSc is compiled in
987:   optimized mode.

989:   Example usage:
990:   This routine is shorthand for checking both the condition and whether PetscDefined(USE_DEBUG)
991:   is true. So

993: .vb
994:   if (PetscUnlikelyDebug(cond)) {
995:     foo();
996:   } else {
997:     bar();
998:   }
999: .ve

1001:   is equivalent to

1003: .vb
1004:   if (PetscDefined(USE_DEBUG)) {
1005:     if (PetscUnlikely(cond)) {
1006:       foo();
1007:     } else {
1008:       bar();
1009:     }
1010:   } else {
1011:     bar();
1012:   }
1013: .ve

1015:   Level: advanced

1017: .seealso: `PetscUnlikely()`, `PetscLikely()`, `PetscCall()`, `SETERRQ`
1018: M*/
1019: #define PetscUnlikelyDebug(cond) (PetscDefined(USE_DEBUG) && PetscUnlikely(cond))

1021: #if defined(PETSC_CLANG_STATIC_ANALYZER)
1022:   // silence compiler warnings when using -pedantic, this is only used by the linter and it cares
1023:   // not what ISO C allows
1024:   #define PetscMacroReturns_(retexpr, ...) \
1025:     __extension__({ \
1026:       __VA_ARGS__; \
1027:       retexpr; \
1028:     })
1029: #else
1030:   #define PetscMacroReturns_(retexpr, ...) \
1031:     retexpr; \
1032:     do { \
1033:       __VA_ARGS__; \
1034:     } while (0)
1035: #endif

1037: /*MC
1038:   PetscExpandToNothing - Expands to absolutely nothing at all

1040:   No Fortran Support

1042:   Synopsis:
1043: #include <petscmacros.h>
1044:   void PetscExpandToNothing(...)

1046:   Input Parameter:
1047: . __VA_ARGS__ - Anything at all

1049:   Notes:
1050:   Must have at least 1 parameter.

1052:   Example usage:
1053: .vb
1054:   PetscExpandToNothing(a,b,c) -> *nothing*
1055: .ve

1057:   Level: beginner

1059: .seealso: `PetscConcat()`, `PetscDefined()`, `PetscStringize()`, `PetscExpand()`
1060: M*/
1061: #define PetscExpandToNothing(...)

1063: /*MC
1064:   PetscMacroReturns - Define a macro body that returns a value

1066:   Synopsis:
1067: #include <petscmacros.h>
1068:   return_type PetscMacroReturns(return_type retexpr, ...)

1070:   Input Parameters:
1071: + retexpr     - The value or expression that the macro should return
1072: - __VA_ARGS__ - The body of the macro

1074:   Notes:
1075:   Due to limitations of the C-preprocessor retexpr cannot depend on symbols declared in the
1076:   body of the macro and should not depend on values produced as a result of the expression. The
1077:   user should not assume that the result of this macro is equivalent to a single logical source
1078:   line. It is not portable to use macros defined using this one in conditional or loop bodies
1079:   without enclosing them in curly braces\:

1081: .vb
1082:   #define FOO(arg1) PetscMacroReturns(0,arg1+=10) // returns 0

1084:   int err,x = 10;

1086:   if (...) err = FOO(x);      // ERROR, body of FOO() executed outside the if statement
1087:   if (...) { err = FOO(x); }  // OK

1089:   for (...) err = FOO(x);     // ERROR, body of FOO() executed outside the loop
1090:   for (...) { err = FOO(x); } // OK
1091: .ve

1093:   It is also not portable to use this macro directly inside function call, conditional, loop,
1094:   or switch statements\:

1096: .vb
1097:   extern void bar(int);

1099:   int ret = FOO(x);

1101:   bar(FOO(x)); // ERROR, may not compile
1102:   bar(ret);    // OK

1104:   if (FOO(x))  // ERROR, may not compile
1105:   if (ret)     // OK
1106: .ve

1108:   Example usage:
1109: .vb
1110:   #define MY_SIMPLE_RETURNING_MACRO(arg1) PetscMacroReturns(0,arg1+=10)

1112:   int x = 10;
1113:   int err = MY_SIMPLE_RETURNING_MACRO(x); // err = 0, x = 20

1115:   // multiline macros allowed, but must declare with line continuation as usual
1116:   #define MY_COMPLEX_RETURNING_MACRO(arg1) PetscMacroReturns(0, \
1117:     if (arg1 > 10) {                                            \
1118:       puts("big int!");                                         \
1119:     } else {                                                    \
1120:       return 7355608;                                           \
1121:     }                                                           \
1122:   )

1124:   // if retexpr contains commas, must enclose it with braces
1125:   #define MY_COMPLEX_RETEXPR_MACRO_1() PetscMacroReturns(x+=10,0,body...)
1126:   #define MY_COMPLEX_RETEXPR_MACRO_2() PetscMacroReturns((x+=10,0),body...)

1128:   int x = 10;
1129:   int y = MY_COMPLEX_RETEXPR_MACRO_1(); // ERROR, y = x = 20 not 0
1130:   int z = MY_COMPLEX_RETEXPR_MACRO_2(); // OK, y = 0, x = 20
1131: .ve

1133:   Level: intermediate

1135: .seealso: `PetscExpand()`, `PetscConcat()`, `PetscStringize()`
1136: M*/
1137: #define PetscMacroReturns(retexpr, ...) PetscMacroReturns_(retexpr, __VA_ARGS__)

1139: #define PetscMacroReturnStandard(...) PetscMacroReturns(PETSC_SUCCESS, __VA_ARGS__)

1141: /*MC
1142:   PETSC_STATIC_ARRAY_LENGTH - Return the length of a static array

1144:   Level: intermediate
1145: M*/
1146: #define PETSC_STATIC_ARRAY_LENGTH(a) (sizeof(a) / sizeof((a)[0]))

1148: /*
1149:   These macros allow extracting out the first argument or all but the first argument from a macro __VAR_ARGS__ INSIDE another macro.

1151:   Example usage:

1153:   #define mymacro(obj,...) {
1154:     PETSC_FIRST_ARG((__VA_ARGS__,unused));
1155:     f(22 PETSC_REST_ARG(__VA_ARGS__));
1156:   }

1158:   Note you add a dummy extra argument to __VA_ARGS__ and enclose them in an extra set of () for PETSC_FIRST_ARG() and PETSC_REST_ARG(__VA_ARGS__) automatically adds a leading comma only if there are additional arguments

1160:   Reference:
1161:   https://stackoverflow.com/questions/5588855/standard-alternative-to-gccs-va-args-trick
1162: */
1163: #define PETSC_FIRST_ARG_(N, ...)                                                                      N
1164: #define PETSC_FIRST_ARG(args)                                                                         PETSC_FIRST_ARG_ args
1165: #define PETSC_SELECT_16TH(a1, a2, a3, a4, a5, a6, a7, a8, a9, a10, a11, a12, a13, a14, a15, a16, ...) a16
1166: #define PETSC_NUM(...)                                                                                PETSC_SELECT_16TH(__VA_ARGS__, TWOORMORE, TWOORMORE, TWOORMORE, TWOORMORE, TWOORMORE, TWOORMORE, TWOORMORE, TWOORMORE, TWOORMORE, TWOORMORE, TWOORMORE, TWOORMORE, TWOORMORE, TWOORMORE, ONE, throwaway)
1167: #define PETSC_REST_HELPER_TWOORMORE(first, ...)                                                       , __VA_ARGS__
1168: #define PETSC_REST_HELPER_ONE(first)
1169: #define PETSC_REST_HELPER2(qty, ...) PETSC_REST_HELPER_##qty(__VA_ARGS__)
1170: #define PETSC_REST_HELPER(qty, ...)  PETSC_REST_HELPER2(qty, __VA_ARGS__)
1171: #define PETSC_REST_ARG(...)          PETSC_REST_HELPER(PETSC_NUM(__VA_ARGS__), __VA_ARGS__)

1173: #define PETSC_PRAGMA_DIAGNOSTIC_IGNORED_BEGIN_(name, ...) \
1174:   _Pragma(PetscStringize(name diagnostic push)) \
1175:   _Pragma(PetscStringize(name diagnostic ignored __VA_ARGS__))

1177: #define PETSC_PRAGMA_DIAGNOSTIC_IGNORED_END_(name) _Pragma(PetscStringize(name diagnostic pop))

1179: #if defined(__clang__)
1180:   #define PETSC_PRAGMA_DIAGNOSTIC_IGNORED_BEGIN(...) PETSC_PRAGMA_DIAGNOSTIC_IGNORED_BEGIN_(clang, __VA_ARGS__)
1181:   #define PETSC_PRAGMA_DIAGNOSTIC_IGNORED_END()      PETSC_PRAGMA_DIAGNOSTIC_IGNORED_END_(clang)
1182: #elif defined(__GNUC__) || defined(__GNUG__)
1183:   #define PETSC_PRAGMA_DIAGNOSTIC_IGNORED_BEGIN(...) PETSC_PRAGMA_DIAGNOSTIC_IGNORED_BEGIN_(GCC, __VA_ARGS__)
1184:   #define PETSC_PRAGMA_DIAGNOSTIC_IGNORED_END()      PETSC_PRAGMA_DIAGNOSTIC_IGNORED_END_(GCC)
1185: #endif

1187: #ifndef PETSC_PRAGMA_DIAGNOSTIC_IGNORED_BEGIN
1188:   #define PETSC_PRAGMA_DIAGNOSTIC_IGNORED_BEGIN(...)
1189:   #define PETSC_PRAGMA_DIAGNOSTIC_IGNORED_END(...)
1190:   // only undefine these if they are not used
1191:   #undef PETSC_PRAGMA_DIAGNOSTIC_IGNORED_BEGIN_
1192:   #undef PETSC_PRAGMA_DIAGNOSTIC_IGNORED_END_
1193: #endif

1195: /* OpenMP support */
1196: #if defined(_OPENMP)
1197:   #if defined(_MSC_VER)
1198:     #define PetscPragmaOMP(...) __pragma(__VA_ARGS__)
1199:   #else
1200:     #define PetscPragmaOMP(...) _Pragma(PetscStringize(omp __VA_ARGS__))
1201:   #endif
1202: #endif

1204: #ifndef PetscPragmaOMP
1205:   #define PetscPragmaOMP(...)
1206: #endif

1208: /* PetscPragmaSIMD - from CeedPragmaSIMD */
1209: #if defined(__NEC__)
1210:   #define PetscPragmaSIMD _Pragma("_NEC ivdep")
1211: #elif defined(__INTEL_COMPILER) && !defined(_WIN32)
1212:   #define PetscPragmaSIMD _Pragma("vector")
1213: #elif defined(__GNUC__)
1214:   #if __GNUC__ >= 5 && !defined(__PGI)
1215:     #define PetscPragmaSIMD _Pragma("GCC ivdep")
1216:   #endif
1217: #elif defined(_OPENMP) && _OPENMP >= 201307
1218:   #define PetscPragmaSIMD PetscPragmaOMP(simd)
1219: #elif defined(PETSC_HAVE_CRAY_VECTOR)
1220:   #define PetscPragmaSIMD _Pragma("_CRI ivdep")
1221: #endif

1223: #ifndef PetscPragmaSIMD
1224:   #define PetscPragmaSIMD
1225: #endif

1227: #endif /* PETSC_PREPROCESSOR_MACROS_H */