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 */