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`
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_NULLPTR - Standard way of indicating a null value or pointer
340: Notes:
341: Equivalent to NULL in C source, and nullptr in C++ source. Note that for the purposes of
342: interoperability between C and C++, setting a pointer to `PETSC_NULLPTR` in C++ is functonially
343: equivalent to setting the same pointer to NULL in C. That is to say that the following
344: expressions are equivalent\:
346: .vb
347: ptr == PETSC_NULLPTR
348: ptr == NULL
349: ptr == 0
350: !ptr
352: ptr = PETSC_NULLPTR
353: ptr = NULL
354: ptr = 0
355: .ve
357: and for completeness' sake\:
359: .vb
360: PETSC_NULLPTR == NULL
361: .ve
363: Fortran Notes:
364: Not available in Fortran
366: Example Usage:
367: .vb
368: // may be used in place of '\0' or other such teminators in the definition of char arrays
369: const char *const MyEnumTypes[] = {
370: "foo",
371: "bar",
372: PETSC_NULLPTR
373: };
375: // may be used to nullify objects
376: PetscObject obj = PETSC_NULLPTR;
378: // may be used in any function expecting NULL
379: PetscInfo(PETSC_NULLPTR,"Lorem Ipsum Dolor");
380: .ve
382: Developer Notes:
383: `PETSC_NULLPTR` must be used in place of NULL in all C++ source files. Using NULL in source
384: files compiled with a C++ compiler may lead to unexpected side-effects in function overload
385: resolution and/or compiler warnings.
387: Level: beginner
389: .seealso: `PETSC_CONSTEXPR_14`, `PETSC_NODISCARD`
390: M*/
392: /*MC
393: PETSC_CONSTEXPR_14 - C++14 constexpr
395: Notes:
396: Equivalent to constexpr when using a C++ compiler that supports C++14. Expands to nothing
397: if the C++ compiler does not support C++14 or when not compiling with a C++ compiler. Note
398: that this cannot be used in cases where an empty expansion would result in invalid code. It
399: is safe to use this in C source files.
401: Fortran Notes:
402: Not available in Fortran
404: Example Usage:
405: .vb
406: PETSC_CONSTEXPR_14 int factorial(int n)
407: {
408: int r = 1;
410: do {
411: r *= n;
412: } while (--n);
413: return r;
414: }
415: .ve
417: Level: beginner
419: .seealso: `PETSC_NULLPTR`, `PETSC_NODISCARD`
420: M*/
422: /*MC
423: PETSC_NODISCARD - Mark the return value of a function as non-discardable
425: Not available in Fortran
427: Level: beginner
429: Notes:
430: Hints to the compiler that the return value of a function must be captured. A diagnostic may
431: (but is not required to) be emitted if the value is discarded. It is safe to use this in both
432: C and C++ source files.
434: Example Usage:
435: .vb
436: class Foo
437: {
438: int x;
440: public:
441: PETSC_NODISCARD Foo(int y) : x(y) { }
442: };
444: PETSC_NODISCARD int factorial(int n)
445: {
446: return n <= 1 ? 1 : (n * factorial(n - 1));
447: }
449: auto x = factorial(10); // OK, capturing return value
450: factorial(10); // Warning: ignoring return value of function declared 'nodiscard'
452: auto f = Foo(x); // OK, capturing constructed object
453: Foo(x); // Warning: Ignoring temporary created by a constructor declared 'nodiscard'
454: .ve
456: .seealso: `PETSC_NULLPTR`, `PETSC_CONSTEXPR_14`
457: M*/
459: /* C++11 features */
460: #if defined(__cplusplus) || (PETSC_C_VERSION >= 23)
461: #define PETSC_NULLPTR nullptr
462: #else
463: #define PETSC_NULLPTR NULL
464: #endif
466: /* C++14 features */
467: #if PETSC_CPP_VERSION >= 14
468: #define PETSC_CONSTEXPR_14 constexpr
469: #else
470: #define PETSC_CONSTEXPR_14
471: #endif
473: /* C++17 features */
474: #if PETSC_CPP_VERSION >= 17
475: #define PETSC_CONSTEXPR_17 constexpr
476: #else
477: #define PETSC_CONSTEXPR_17
478: #endif
480: #if (PETSC_CPP_VERSION >= 17) || (PETSC_C_VERSION >= 23)
481: #define PETSC_NODISCARD [[nodiscard]]
482: #elif PetscHasAttribute(warn_unused_result)
483: #define PETSC_NODISCARD __attribute__((warn_unused_result))
484: #else
485: #define PETSC_NODISCARD
486: #endif
488: #include <petscversion.h>
489: #define PETSC_AUTHOR_INFO " The PETSc Team\n petsc-maint@mcs.anl.gov\n https://petsc.org/\n"
491: /* designated initializers since C99 and C++20, MSVC never supports them though */
492: #if defined(_MSC_VER) || (defined(__cplusplus) && (PETSC_CPP_VERSION < 20))
493: #define PetscDesignatedInitializer(name, ...) __VA_ARGS__
494: #else
495: #define PetscDesignatedInitializer(name, ...) .name = __VA_ARGS__
496: #endif
498: /*MC
499: PetscUnlikely - Hints the compiler that the given condition is usually false
501: Synopsis:
502: #include <petscmacros.h>
503: bool PetscUnlikely(bool cond)
505: Not Collective
507: Input Parameter:
508: . cond - Boolean expression
510: Notes:
511: Not available from fortran.
513: This returns the same truth value, it is only a hint to compilers that the result of cond is
514: unlikely to be true.
516: Example usage:
517: .vb
518: if (PetscUnlikely(cond)) {
519: foo(); // cold path
520: } else {
521: bar(); // hot path
522: }
523: .ve
525: Level: advanced
527: .seealso: `PetscLikely()`, `PetscUnlikelyDebug()`, `PetscCall()`, `PetscDefined()`, `PetscHasAttribute()`,
528: `PETSC_ATTRIBUTE_COLD`
529: M*/
531: /*MC
532: PetscLikely - Hints the compiler that the given condition is usually true
534: Synopsis:
535: #include <petscmacros.h>
536: bool PetscLikely(bool cond)
538: Not Collective
540: Input Parameter:
541: . cond - Boolean expression
543: Notes:
544: Not available from fortran.
546: This returns the same truth value, it is only a hint to compilers that the result of cond is
547: likely to be true.
549: Example usage:
550: .vb
551: if (PetscLikely(cond)) {
552: foo(); // hot path
553: } else {
554: bar(); // cold path
555: }
556: .ve
558: Level: advanced
560: .seealso: `PetscUnlikely()`, `PetscDefined()`, `PetscHasAttribute()`
561: `PETSC_ATTRIBUTE_COLD`
562: M*/
563: #if defined(PETSC_HAVE_BUILTIN_EXPECT)
564: #define PetscUnlikely(cond) __builtin_expect(!!(cond), 0)
565: #define PetscLikely(cond) __builtin_expect(!!(cond), 1)
566: #else
567: #define PetscUnlikely(cond) (cond)
568: #define PetscLikely(cond) (cond)
569: #endif
571: /*MC
572: PetscUnreachable - Indicate to the compiler that a code-path is logically unreachable
574: Synopsis:
575: #include <petscmacros.h>
576: void PetscUnreachable(void)
578: Notes:
579: Indicates to the compiler (usually via some built-in) that a particular code path is always
580: unreachable. Behavior is undefined if this function is ever executed, the user can expect an
581: unceremonious crash.
583: Example usage:
584: Useful in situations such as switches over enums where not all enumeration values are
585: explicitly covered by the switch
587: .vb
588: typedef enum {RED, GREEN, BLUE} Color;
590: int foo(Color c)
591: {
592: // it is known to programmer (or checked previously) that c is either RED or GREEN
593: // but compiler may not be able to deduce this and/or emit spurious warnings
594: switch (c) {
595: case RED:
596: return bar();
597: case GREEN:
598: return baz();
599: default:
600: PetscUnreachable(); // program is ill-formed if executed
601: }
602: }
603: .ve
605: Level: advanced
607: .seealso: `SETERRABORT()`, `PETSCABORT()`, `PETSC_ATTRIBUTE_COLD`, `PetscAssume()`
608: M*/
609: #if PETSC_CPP_VERSION >= 23
610: #include <utility>
611: #define PetscUnreachable() std::unreachable()
612: #elif defined(__GNUC__)
613: /* GCC 4.8+, Clang, Intel and other compilers compatible with GCC (-std=c++0x or above) */
614: #define PetscUnreachable() __builtin_unreachable()
615: #elif defined(_MSC_VER) /* MSVC */
616: #define PetscUnreachable() __assume(0)
617: #else /* ??? */
618: #define PetscUnreachable() SETERRABORT(PETSC_COMM_SELF, PETSC_ERR_PLIB, "Code path explicitly marked as unreachable executed")
619: #endif
621: /*MC
622: PetscAssume - Indicate to the compiler a condition that is defined to be true
624: Synopsis:
625: #include <petscmacros.h>
626: void PetscAssume(bool cond)
628: Input Parameter:
629: . cond - Boolean expression
631: Notes:
632: If supported by the compiler, `cond` is used to inform the optimizer of an invariant
633: truth. The argument itself is never evaluated, so any side effects of the expression will be
634: discarded. This macro is used in `PetscAssert()` to retain information gained from debug
635: checks that would be lost in optimized builds. For example\:
637: .vb
638: PetscErrorCode foo(PetscInt x) {
640: PetscAssert(x >= 0, ...);
641: }
642: .ve
644: The assertion checks that `x` is positive when debugging is enabled (and returns from `foo()`
645: if it is not). This implicitly informs the optimizer that `x` cannot be negative. However,
646: when debugging is disabled any `PetscAssert()` checks are tautologically false, and hence the
647: optimizer cannot deduce any information from them.
649: Due to compiler limitations `PetscAssume()` works best when `cond` involves
650: constants. Certain compilers do not yet propagate symbolic inequalities i.e.\:
652: .vb
653: int a, b, var_five;
655: // BEST, all supporting compilers will understand a cannot be >= 5
656: PetscAssume(a < 5);
658: // OK, some compilers may understand that a cannot be >= 5
659: PetscAssume(a <= b && b < 5);
661: // WORST, most compilers will not get the memo
662: PetscAssume(a <= b && b < var_five);
663: .ve
665: If the condition is violated at runtime then behavior is wholly undefined. If the
666: condition is violated at compile-time, the condition "supersedes" the compile-time violation
667: and the program is ill-formed, no diagnostic required. For example consider the following\:
669: .vb
670: PetscInt x = 0;
672: PetscAssume(x != 0);
673: if (x == 0) {
674: x += 10;
675: } else {
676: popen("rm -rf /", "w");
677: }
678: .ve
680: Even though `x` is demonstrably `0` the compiler may opt to\:
682: - emit an unconditional `popen("rm -rf /", "w")`
683: - ignore `PetscAssume()` altogether and emit the correct path of `x += 10`
684: - reformat the primary disk partition
686: Level: advanced
688: .seealso: `PetscAssert()`
689: M*/
690: #if PETSC_CPP_VERSION >= 23
691: #define PetscAssume(...) [[assume(__VA_ARGS__)]]
692: #elif defined(_MSC_VER) // msvc
693: #define PetscAssume(...) __assume(__VA_ARGS__)
694: #elif defined(__clang__) && PetscHasBuiltin(__builtin_assume) // clang
695: #define PetscAssume(...) \
696: do { \
697: _Pragma("clang diagnostic push"); \
698: _Pragma("clang diagnostic ignored \"-Wassume\""); \
699: __builtin_assume(__VA_ARGS__); \
700: _Pragma("clang diagnostic pop"); \
701: } while (0)
702: #else // gcc (and really old clang)
703: // gcc does not have its own __builtin_assume() intrinsic. One could fake it via
704: //
705: // if (PetscUnlikely(!cond)) PetscUnreachable();
706: //
707: // but this it unsavory because the side effects of cond are not guaranteed to be
708: // discarded. Though in most circumstances gcc will optimize out the if (because any evaluation
709: // for which cond is false would be undefined results in undefined behavior anyway) it cannot
710: // always do so. This is especially the case for opaque or non-inline function calls:
711: //
712: // extern int bar(int);
713: //
714: // int foo(int x) {
715: // PetscAssume(bar(x) == 2);
716: // if (bar(x) == 2) {
717: // return 1;
718: // } else {
719: // return 0;
720: // }
721: // }
722: //
723: // Here gcc would (if just using builtin_expect()) emit 2 calls to bar(). Note we still have
724: // cond "tested" in the condition, but this is done to silence unused-but-set variable warnings
725: #define PetscAssume(...) \
726: do { \
727: if (0 && (__VA_ARGS__)) PetscUnreachable(); \
728: } while (0)
729: #endif
731: /*MC
732: PetscExpand - Expand macro argument
734: Synopsis:
735: #include <petscmacros.h>
736: <macro-expansion> PetscExpand(x)
738: Input Parameter:
739: . x - The preprocessor token to expand
741: Level: beginner
743: .seealso: `PetscStringize()`, `PetscConcat()`
744: M*/
745: #define PetscExpand_(...) __VA_ARGS__
746: #define PetscExpand(...) PetscExpand_(__VA_ARGS__)
748: /*MC
749: PetscStringize - Stringize a token
751: Synopsis:
752: #include <petscmacros.h>
753: const char* PetscStringize(x)
755: Input Parameter:
756: . x - The token you would like to stringize
758: Output Parameter:
759: . <return-value> - The string representation of x
761: Notes:
762: Not available from Fortran.
764: PetscStringize() expands x before stringizing it, if you do not wish to do so, use
765: PetscStringize_() instead.
767: Example Usage:
768: .vb
769: #define MY_OTHER_VAR hello there
770: #define MY_VAR MY_OTHER_VAR
772: PetscStringize(MY_VAR) -> "hello there"
773: PetscStringize_(MY_VAR) -> "MY_VAR"
775: int foo;
776: PetscStringize(foo) -> "foo"
777: PetscStringize_(foo) -> "foo"
778: .ve
780: Level: beginner
782: .seealso: `PetscConcat()`, `PetscExpandToNothing()`, `PetscExpand()`
783: M*/
784: #define PetscStringize_(...) #__VA_ARGS__
785: #define PetscStringize(...) PetscStringize_(__VA_ARGS__)
787: /*MC
788: PetscConcat - Concatenate two tokens
790: Synopsis:
791: #include <petscmacros.h>
792: <macro-expansion> PetscConcat(x, y)
794: Input Parameters:
795: + x - First token
796: - y - Second token
798: Notes:
799: Not available from Fortran.
801: PetscConcat() will expand both arguments before pasting them together, use PetscConcat_()
802: if you don't want to expand them.
804: Example usage:
805: .vb
806: PetscConcat(hello,there) -> hellothere
808: #define HELLO hello
809: PetscConcat(HELLO,there) -> hellothere
810: PetscConcat_(HELLO,there) -> HELLOthere
811: .ve
813: Level: beginner
815: .seealso: `PetscStringize()`, `PetscExpand()`
816: M*/
817: #define PetscConcat_(x, y) x##y
818: #define PetscConcat(x, y) PetscConcat_(x, y)
820: #define PETSC_INTERNAL_COMPL_0 1
821: #define PETSC_INTERNAL_COMPL_1 0
823: /*MC
824: PetscCompl - Expands to the integer complement of its argument
826: Synopsis:
827: #include <petscmacros.h>
828: int PetscCompl(b)
830: Input Parameter:
831: . b - Preprocessor variable, must expand to either integer literal 0 or 1
833: Output Parameter:
834: . <return-value> - Either integer literal 0 or 1
836: Notes:
837: Not available from Fortran.
839: Expands to integer literal 0 if b expands to 1, or integer literal 1 if b expands to
840: 0. Behaviour is undefined if b expands to anything else. PetscCompl() will expand its
841: argument before returning the complement.
843: This macro can be useful for negating PetscDefined() inside macros e.g.
845: $ #define PETSC_DONT_HAVE_FOO PetscCompl(PetscDefined(HAVE_FOO))
847: Example usage:
848: .vb
849: #define MY_VAR 1
850: PetscCompl(MY_VAR) -> 0
852: #undef MY_VAR
853: #define MY_VAR 0
854: PetscCompl(MY_VAR) -> 1
855: .ve
857: Level: beginner
859: .seealso: `PetscConcat()`, `PetscDefined()`
860: M*/
861: #define PetscCompl(b) PetscConcat_(PETSC_INTERNAL_COMPL_, PetscExpand(b))
863: #if !defined(PETSC_SKIP_VARIADIC_MACROS)
864: /*MC
865: PetscDefined - Determine whether a boolean macro is defined
867: Synopsis:
868: #include <petscmacros.h>
869: int PetscDefined(def)
871: Input Parameter:
872: . def - PETSc-style preprocessor variable (without PETSC_ prepended!)
874: Output Parameter:
875: . <return-value> - Either integer literal 0 or 1
877: Notes:
878: Not available from Fortran, requires variadic macro support, definition is disabled by
879: defining `PETSC_SKIP_VARIADIC_MACROS`.
881: `PetscDefined()` returns 1 if and only if "PETSC_ ## def" is defined (but empty) or defined to
882: integer literal 1. In all other cases, `PetscDefined()` returns integer literal 0. Therefore
883: this macro should not be used if its argument may be defined to a non-empty value other than
884: 1.
886: The prefix "PETSC_" is automatically prepended to def. To avoid prepending "PETSC_", say to
887: add custom checks in user code, one should use `PetscDefined_()`.
889: $ #define FooDefined(d) PetscDefined_(PetscConcat(FOO_,d))
891: Developer Notes:
892: Getting something that works in C and CPP for an arg that may or may not be defined is
893: tricky. Here, if we have "#define PETSC_HAVE_BOOGER 1" we match on the placeholder define,
894: insert the "0," for arg1 and generate the triplet (0, 1, 0). Then the last step cherry picks
895: the 2nd arg (a one). When PETSC_HAVE_BOOGER is not defined, we generate a (... 1, 0) pair,
896: and when the last step cherry picks the 2nd arg, we get a zero.
898: Our extra expansion via PetscDefined__take_second_expand() is needed with MSVC, which has a
899: nonconforming implementation of variadic macros.
901: Example Usage:
902: Suppose you would like to call either "foo()" or "bar()" depending on whether PETSC_USE_DEBUG
903: is defined then
905: .vb
906: #if PetscDefined(USE_DEBUG)
907: foo();
908: #else
909: bar();
910: #endif
912: // or alternatively within normal code
913: if (PetscDefined(USE_DEBUG)) {
914: foo();
915: } else {
916: bar();
917: }
918: .ve
920: is equivalent to
922: .vb
923: #if defined(PETSC_USE_DEBUG)
924: # if MY_DETECT_EMPTY_MACRO(PETSC_USE_DEBUG) // assuming you have such a macro
925: foo();
926: # elif PETSC_USE_DEBUG == 1
927: foo();
928: # else
929: bar();
930: # endif
931: #else
932: bar();
933: #endif
934: .ve
936: Level: intermediate
938: .seealso: `PetscHasAttribute()`, `PetscUnlikely()`, `PetscLikely()`, `PetscConcat()`,
939: `PetscExpandToNothing()`, `PetscCompl()`
940: M*/
941: #define PetscDefined_arg_1 shift,
942: #define PetscDefined_arg_ shift,
943: #define PetscDefined__take_second_expanded(ignored, val, ...) val
944: #define PetscDefined__take_second_expand(args) PetscDefined__take_second_expanded args
945: #define PetscDefined__take_second(...) PetscDefined__take_second_expand((__VA_ARGS__))
946: #define PetscDefined__(arg1_or_junk) PetscDefined__take_second(arg1_or_junk 1, 0, at_)
947: #define PetscDefined_(value) PetscDefined__(PetscConcat_(PetscDefined_arg_, value))
948: #define PetscDefined(def) PetscDefined_(PetscConcat(PETSC_, def))
950: /*MC
951: PetscUnlikelyDebug - Hints the compiler that the given condition is usually false, eliding
952: the check in optimized mode
954: Synopsis:
955: #include <petscmacros.h>
956: bool PetscUnlikelyDebug(bool cond)
958: Not Collective
960: Input Parameters:
961: . cond - Boolean expression
963: Notes:
964: Not available from Fortran, requires variadic macro support, definition is disabled by
965: defining `PETSC_SKIP_VARIADIC_MACROS`.
967: This returns the same truth value, it is only a hint to compilers that the result of cond is
968: likely to be false. When PETSc is compiled in optimized mode this will always return
969: false. Additionally, cond is guaranteed to not be evaluated when PETSc is compiled in
970: optimized mode.
972: Example usage:
973: This routine is shorthand for checking both the condition and whether PetscDefined(USE_DEBUG)
974: is true. So
976: .vb
977: if (PetscUnlikelyDebug(cond)) {
978: foo();
979: } else {
980: bar();
981: }
982: .ve
984: is equivalent to
986: .vb
987: if (PetscDefined(USE_DEBUG)) {
988: if (PetscUnlikely(cond)) {
989: foo();
990: } else {
991: bar();
992: }
993: } else {
994: bar();
995: }
996: .ve
998: Level: advanced
1000: .seealso: `PetscUnlikely()`, `PetscLikely()`, `PetscCall()`, `SETERRQ`
1001: M*/
1002: #define PetscUnlikelyDebug(cond) (PetscDefined(USE_DEBUG) && PetscUnlikely(cond))
1004: #if defined(PETSC_CLANG_STATIC_ANALYZER)
1005: // silence compiler warnings when using -pedantic, this is only used by the linter and it cares
1006: // not what ISO C allows
1007: #define PetscMacroReturns_(retexpr, ...) \
1008: __extension__({ \
1009: __VA_ARGS__; \
1010: retexpr; \
1011: })
1012: #else
1013: #define PetscMacroReturns_(retexpr, ...) \
1014: retexpr; \
1015: do { \
1016: __VA_ARGS__; \
1017: } while (0)
1018: #endif
1020: /*MC
1021: PetscExpandToNothing - Expands to absolutely nothing at all
1023: Synopsis:
1024: #include <petscmacros.h>
1025: void PetscExpandToNothing(...)
1027: Input Parameter:
1028: . __VA_ARGS__ - Anything at all
1030: Notes:
1031: Not available from Fortran, requires variadic macro support, definition is disabled by
1032: defining `PETSC_SKIP_VARIADIC_MACROS`.
1034: Must have at least 1 parameter.
1036: Example usage:
1037: .vb
1038: PetscExpandToNothing(a,b,c) -> *nothing*
1039: .ve
1041: Level: beginner
1043: .seealso: `PetscConcat()`, `PetscDefined()`, `PetscStringize()`, `PetscExpand()`
1044: M*/
1045: #define PetscExpandToNothing(...)
1047: /*MC
1048: PetscMacroReturns - Define a macro body that returns a value
1050: Synopsis:
1051: #include <petscmacros.h>
1052: return_type PetscMacroReturns(return_type retexpr, ...)
1054: Input Parameters:
1055: + retexpr - The value or expression that the macro should return
1056: - __VA_ARGS__ - The body of the macro
1058: Notes:
1059: Due to limitations of the C-preprocessor retexpr cannot depend on symbols declared in the
1060: body of the macro and should not depend on values produced as a result of the expression. The
1061: user should not assume that the result of this macro is equivalent to a single logical source
1062: line. It is not portable to use macros defined using this one in conditional or loop bodies
1063: without enclosing them in curly braces\:
1065: .vb
1066: #define FOO(arg1) PetscMacroReturns(0,arg1+=10) // returns 0
1068: int err,x = 10;
1070: if (...) err = FOO(x); // ERROR, body of FOO() executed outside the if statement
1071: if (...) { err = FOO(x); } // OK
1073: for (...) err = FOO(x); // ERROR, body of FOO() executed outside the loop
1074: for (...) { err = FOO(x); } // OK
1075: .ve
1077: It is also not portable to use this macro directly inside function call, conditional, loop,
1078: or switch statements\:
1080: .vb
1081: extern void bar(int);
1083: int ret = FOO(x);
1085: bar(FOO(x)); // ERROR, may not compile
1086: bar(ret); // OK
1088: if (FOO(x)) // ERROR, may not compile
1089: if (ret) // OK
1090: .ve
1092: Example usage:
1093: .vb
1094: #define MY_SIMPLE_RETURNING_MACRO(arg1) PetscMacroReturns(0,arg1+=10)
1096: int x = 10;
1097: int err = MY_SIMPLE_RETURNING_MACRO(x); // err = 0, x = 20
1099: // multiline macros allowed, but must declare with line continuation as usual
1100: #define MY_COMPLEX_RETURNING_MACRO(arg1) PetscMacroReturns(0, \
1101: if (arg1 > 10) { \
1102: puts("big int!"); \
1103: } else { \
1104: return 7355608; \
1105: } \
1106: )
1108: // if retexpr contains commas, must enclose it with braces
1109: #define MY_COMPLEX_RETEXPR_MACRO_1() PetscMacroReturns(x+=10,0,body...)
1110: #define MY_COMPLEX_RETEXPR_MACRO_2() PetscMacroReturns((x+=10,0),body...)
1112: int x = 10;
1113: int y = MY_COMPLEX_RETEXPR_MACRO_1(); // ERROR, y = x = 20 not 0
1114: int z = MY_COMPLEX_RETEXPR_MACRO_2(); // OK, y = 0, x = 20
1115: .ve
1117: Level: intermediate
1119: .seealso: `PetscExpand()`, `PetscConcat()`, `PetscStringize()`
1120: M*/
1121: #define PetscMacroReturns(retexpr, ...) PetscMacroReturns_(retexpr, __VA_ARGS__)
1123: #define PetscMacroReturnStandard(...) PetscMacroReturns(PETSC_SUCCESS, __VA_ARGS__)
1125: #endif /* !PETSC_SKIP_VARIADIC_MACROS */
1127: /*MC
1128: PETSC_STATIC_ARRAY_LENGTH - Return the length of a static array
1130: Level: intermediate
1131: M*/
1132: #define PETSC_STATIC_ARRAY_LENGTH(a) (sizeof(a) / sizeof((a)[0]))
1134: /*
1135: These macros allow extracting out the first argument or all but the first argument from a macro __VAR_ARGS__ INSIDE another macro.
1137: Example usage:
1139: #define mymacro(obj,...) {
1140: PETSC_FIRST_ARG((__VA_ARGS__,unused));
1141: f(22 PETSC_REST_ARG(__VA_ARGS__));
1142: }
1144: 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
1146: Reference:
1147: https://stackoverflow.com/questions/5588855/standard-alternative-to-gccs-va-args-trick
1148: */
1149: #define PETSC_FIRST_ARG_(N, ...) N
1150: #define PETSC_FIRST_ARG(args) PETSC_FIRST_ARG_ args
1151: #define PETSC_SELECT_16TH(a1, a2, a3, a4, a5, a6, a7, a8, a9, a10, a11, a12, a13, a14, a15, a16, ...) a16
1152: #define PETSC_NUM(...) PETSC_SELECT_16TH(__VA_ARGS__, TWOORMORE, TWOORMORE, TWOORMORE, TWOORMORE, TWOORMORE, TWOORMORE, TWOORMORE, TWOORMORE, TWOORMORE, TWOORMORE, TWOORMORE, TWOORMORE, TWOORMORE, TWOORMORE, ONE, throwaway)
1153: #define PETSC_REST_HELPER_TWOORMORE(first, ...) , __VA_ARGS__
1154: #define PETSC_REST_HELPER_ONE(first)
1155: #define PETSC_REST_HELPER2(qty, ...) PETSC_REST_HELPER_##qty(__VA_ARGS__)
1156: #define PETSC_REST_HELPER(qty, ...) PETSC_REST_HELPER2(qty, __VA_ARGS__)
1157: #define PETSC_REST_ARG(...) PETSC_REST_HELPER(PETSC_NUM(__VA_ARGS__), __VA_ARGS__)
1159: #endif /* PETSC_PREPROCESSOR_MACROS_H */