lib/compiler.h

   1 /*
   2  * Copyright (c) 2015-2017  David Lamparter, for NetDEF, Inc.
   3  *
   4  * Permission to use, copy, modify, and distribute this software for any
   5  * purpose with or without fee is hereby granted, provided that the above
   6  * copyright notice and this permission notice appear in all copies.
   7  *
   8  * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
   9  * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
  10  * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
  11  * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
  12  * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
  13  * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
  14  * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
  15  */
  16
  17 #ifndef _FRR_COMPILER_H
  18 #define _FRR_COMPILER_H
  19
  20 #ifdef __cplusplus
  21 extern "C" {
  22 #endif
  23
  24 #ifdef __cplusplus
  25 # if __cplusplus < 201103L
  26 #  error FRRouting headers must be compiled in C++11 mode or newer
  27 # endif
  28 /* C++ defines static_assert(), but not _Static_assert().  C defines
  29  * _Static_assert() and has static_assert() in <assert.h>.  However, we mess
  30  * with assert() in zassert.h so let's not include <assert.h> here.
  31  */
  32 # define _Static_assert static_assert
  33 #else
  34 # if !defined(__STDC_VERSION__) || __STDC_VERSION__ < 201112L
  35 #  error FRRouting must be compiled with min. -std=gnu11 (GNU ISO C11 dialect)
  36 # endif
  37 #endif
  38
  39 /* function attributes, use like
  40  *   void prototype(void) __attribute__((_CONSTRUCTOR(100)));
  41  */
  42 #if defined(__clang__)
  43 #if __clang_major__ > 3 || (__clang_major__ == 3 && __clang_minor__ >= 5)
  44 #  define _RET_NONNULL    , returns_nonnull
  45 #endif
  46 #if __has_attribute(fallthrough)
  47 #  define _FALLTHROUGH __attribute__((fallthrough));
  48 #endif
  49 # define _CONSTRUCTOR(x)  constructor(x)
  50 # define _DEPRECATED(x) deprecated(x)
  51 # if __has_builtin(assume)
  52 #  define assume(x) __builtin_assume(x)
  53 # endif
  54 #elif defined(__GNUC__)
  55 #if __GNUC__ > 4 || (__GNUC__ == 4 && __GNUC_MINOR__ >= 9)
  56 #  define _RET_NONNULL    , returns_nonnull
  57 #endif
  58 #if __GNUC__ > 4 || (__GNUC__ == 4 && __GNUC_MINOR__ >= 3)
  59 #  define _CONSTRUCTOR(x) constructor(x)
  60 #  define _DESTRUCTOR(x)  destructor(x)
  61 #  define _ALLOC_SIZE(x)  alloc_size(x)
  62 #endif
  63 #if __GNUC__ > 4 || (__GNUC__ == 4 && __GNUC_MINOR__ >= 5)
  64 #  define _DEPRECATED(x) deprecated(x)
  65 #  define assume(x) do { if (!(x)) __builtin_unreachable(); } while (0)
  66 #endif
  67 #if __GNUC__ < 5
  68 #  define __has_attribute(x) 0
  69 #endif
  70 #if __GNUC__ >= 7
  71 #  define _FALLTHROUGH __attribute__((fallthrough));
  72 #endif
  73 #endif
  74
  75 #if __has_attribute(hot)
  76 #  define _OPTIMIZE_HOT __attribute__((hot))
  77 #else
  78 #  define _OPTIMIZE_HOT
  79 #endif
  80 #if __has_attribute(optimize)
  81 #  define _OPTIMIZE_O3 __attribute__((optimize("3")))
  82 #else
  83 #  define _OPTIMIZE_O3
  84 #endif
  85 #define OPTIMIZE _OPTIMIZE_O3 _OPTIMIZE_HOT
  86
  87 #if !defined(__GNUC__)
  88 #error module code needs GCC visibility extensions
  89 #elif __GNUC__ < 4
  90 #error module code needs GCC visibility extensions
  91 #else
  92 # define DSO_PUBLIC __attribute__ ((visibility ("default")))
  93 # define DSO_SELF   __attribute__ ((visibility ("protected")))
  94 # define DSO_LOCAL  __attribute__ ((visibility ("hidden")))
  95 #endif
  96
  97 #ifdef __sun
  98 /* Solaris doesn't do constructor priorities due to linker restrictions */
  99 #undef _CONSTRUCTOR
 100 #undef _DESTRUCTOR
 101 #endif
 102
 103 /* fallback versions */
 104 #ifndef _RET_NONNULL
 105 # define _RET_NONNULL
 106 #endif
 107 #ifndef _CONSTRUCTOR
 108 # define _CONSTRUCTOR(x) constructor
 109 #endif
 110 #ifndef _DESTRUCTOR
 111 # define _DESTRUCTOR(x) destructor
 112 #endif
 113 #ifndef _ALLOC_SIZE
 114 # define _ALLOC_SIZE(x)
 115 #endif
 116 #ifndef _FALLTHROUGH
 117 #define _FALLTHROUGH
 118 #endif
 119 #ifndef _DEPRECATED
 120 #define _DEPRECATED(x) deprecated
 121 #endif
 122 #ifndef assume
 123 #define assume(x)
 124 #endif
 125
 126 /* pure = function does not modify memory & return value is the same if
 127  * memory hasn't changed (=> allows compiler to optimize)
 128  *
 129  * Mostly autodetected by the compiler if function body is available (i.e.
 130  * static inline functions in headers).  Since that implies it should only be
 131  * used in headers for non-inline functions, the "extern" is included here.
 132  */
 133 #define ext_pure        extern __attribute__((pure))
 134
 135 /* for helper functions defined inside macros */
 136 #define macro_inline    static inline __attribute__((unused))
 137 #define macro_pure      static inline __attribute__((unused, pure))
 138
 139 /* if the macro ends with a function definition */
 140 #define MACRO_REQUIRE_SEMICOLON() \
 141         _Static_assert(1, "please add a semicolon after this macro")
 142
 143 #if CONFDATE < 20210601
 144 #ifdef ENABLE_BGP_VNC
 145 /* temporarily disabled for transition for LabN CI
 146  * NB: it's not possible to generate a deprecation warning for this, hence
 147  * the shortened transition period (since otherwise new uses of the old syntax
 148  * may creep in without errors)
 149  */
 150 #undef MACRO_REQUIRE_SEMICOLON
 151 #define MACRO_REQUIRE_SEMICOLON() \
 152         /* nothing */
 153 #endif /* ENABLE_BGP_VNC */
 154 #else /* CONFDATE >= 20210601 */
 155 CPP_NOTICE("time to remove this CONFDATE block")
 156 #endif
 157
 158 /* variadic macros, use like:
 159  * #define V_0()  ...
 160  * #define V_1(x) ...
 161  * #define V(...) MACRO_VARIANT(V, ##__VA_ARGS__)(__VA_ARGS__)
 162  */
 163 #define _MACRO_VARIANT(A0,A1,A2,A3,A4,A5,A6,A7,A8,A9,A10, N, ...) N
 164
 165 #define _CONCAT2(a, b) a ## b
 166 #define _CONCAT(a, b) _CONCAT2(a,b)
 167
 168 #define MACRO_VARIANT(NAME, ...) \
 169         _CONCAT(NAME, _MACRO_VARIANT(0, ##__VA_ARGS__, \
 170                         _10, _9, _8, _7, _6, _5, _4, _3, _2, _1, _0))
 171
 172 #define NAMECTR(name) _CONCAT(name, __COUNTER__)
 173
 174 /* per-arg repeat macros, use like:
 175  * #define PERARG(n) ...n...
 176  * #define FOO(...) MACRO_REPEAT(PERARG, ##__VA_ARGS__)
 177  */
 178
 179 #define _MACRO_REPEAT_0(NAME)
 180 #define _MACRO_REPEAT_1(NAME, A1) \
 181         NAME(A1)
 182 #define _MACRO_REPEAT_2(NAME, A1, A2) \
 183         NAME(A1) NAME(A2)
 184 #define _MACRO_REPEAT_3(NAME, A1, A2, A3) \
 185         NAME(A1) NAME(A2) NAME(A3)
 186 #define _MACRO_REPEAT_4(NAME, A1, A2, A3, A4) \
 187         NAME(A1) NAME(A2) NAME(A3) NAME(A4)
 188 #define _MACRO_REPEAT_5(NAME, A1, A2, A3, A4, A5) \
 189         NAME(A1) NAME(A2) NAME(A3) NAME(A4) NAME(A5)
 190 #define _MACRO_REPEAT_6(NAME, A1, A2, A3, A4, A5, A6) \
 191         NAME(A1) NAME(A2) NAME(A3) NAME(A4) NAME(A5) NAME(A6)
 192 #define _MACRO_REPEAT_7(NAME, A1, A2, A3, A4, A5, A6, A7) \
 193         NAME(A1) NAME(A2) NAME(A3) NAME(A4) NAME(A5) NAME(A6) NAME(A7)
 194 #define _MACRO_REPEAT_8(NAME, A1, A2, A3, A4, A5, A6, A7, A8) \
 195         NAME(A1) NAME(A2) NAME(A3) NAME(A4) NAME(A5) NAME(A6) NAME(A7) NAME(A8)
 196
 197 #define MACRO_REPEAT(NAME, ...) \
 198         MACRO_VARIANT(_MACRO_REPEAT, ##__VA_ARGS__)(NAME, ##__VA_ARGS__)
 199
 200 /*
 201  * for warnings on macros, put in the macro content like this:
 202  *   #define MACRO BLA CPP_WARN("MACRO has been deprecated")
 203  */
 204 #define CPP_STR(X) #X
 205
 206 #if defined(__ICC)
 207 #define CPP_NOTICE(text) _Pragma(CPP_STR(message __FILE__ ": " text))
 208 #define CPP_WARN(text) CPP_NOTICE(text)
 209
 210 #elif (defined(__GNUC__)                                                       \
 211        && (__GNUC__ >= 5 || (__GNUC__ == 4 && __GNUC_MINOR__ >= 8)))           \
 212         || (defined(__clang__)                                                 \
 213             && (__clang_major__ >= 4                                           \
 214                 || (__clang_major__ == 3 && __clang_minor__ >= 5)))
 215 #define CPP_WARN(text) _Pragma(CPP_STR(GCC warning text))
 216 #define CPP_NOTICE(text) _Pragma(CPP_STR(message text))
 217
 218 #else
 219 #define CPP_WARN(text)
 220 #define CPP_NOTICE(text)
 221 #endif
 222
 223 /* MAX / MIN are not commonly defined, but useful */
 224 /* note: glibc sys/param.h has #define MIN(a,b) (((a)<(b))?(a):(b)) */
 225 #ifdef MAX
 226 #undef MAX
 227 #endif
 228 #define MAX(a, b)                                                              \
 229         ({                                                                     \
 230                 typeof(a) _max_a = (a);                                        \
 231                 typeof(b) _max_b = (b);                                        \
 232                 _max_a > _max_b ? _max_a : _max_b;                             \
 233         })
 234 #ifdef MIN
 235 #undef MIN
 236 #endif
 237 #define MIN(a, b)                                                              \
 238         ({                                                                     \
 239                 typeof(a) _min_a = (a);                                        \
 240                 typeof(b) _min_b = (b);                                        \
 241                 _min_a < _min_b ? _min_a : _min_b;                             \
 242         })
 243
 244 #define numcmp(a, b)                                                           \
 245         ({                                                                     \
 246                 typeof(a) _cmp_a = (a);                                        \
 247                 typeof(b) _cmp_b = (b);                                        \
 248                 (_cmp_a < _cmp_b) ? -1 : ((_cmp_a > _cmp_b) ? 1 : 0);          \
 249         })
 250
 251 #ifndef offsetof
 252 #ifdef __compiler_offsetof
 253 #define offsetof(TYPE, MEMBER) __compiler_offsetof(TYPE,MEMBER)
 254 #else
 255 #define offsetof(TYPE, MEMBER) ((size_t) &((TYPE *)0)->MEMBER)
 256 #endif
 257 #endif
 258
 259 #ifdef container_of
 260 #undef container_of
 261 #endif
 262
 263 #if !(defined(__cplusplus) || defined(test__cplusplus))
 264 /* this variant of container_of() retains 'const' on pointers without needing
 265  * to be told to do so.  The following will all work without warning:
 266  *
 267  * struct member *p;
 268  * const struct member *cp;
 269  *
 270  * const struct cont *x = container_of(cp, struct cont, member);
 271  * const struct cont *x = container_of(cp, const struct cont, member);
 272  * const struct cont *x = container_of(p,  struct cont, member);
 273  * const struct cont *x = container_of(p,  const struct cont, member);
 274  * struct cont *x       = container_of(p,  struct cont, member);
 275  *
 276  * but the following will generate warnings about stripping const:
 277  *
 278  * struct cont *x       = container_of(cp, struct cont, member);
 279  * struct cont *x       = container_of(cp, const struct cont, member);
 280  * struct cont *x       = container_of(p,  const struct cont, member);
 281  */
 282 #define container_of(ptr, type, member)                                        \
 283         (__builtin_choose_expr(                                                \
 284                 __builtin_types_compatible_p(typeof(&((type *)0)->member),     \
 285                         typeof(ptr))                                           \
 286                     ||  __builtin_types_compatible_p(void *, typeof(ptr)),     \
 287                 ({                                                             \
 288                         typeof(((type *)0)->member) *__mptr = (void *)(ptr);   \
 289                         (type *)((char *)__mptr - offsetof(type, member));     \
 290                 }),                                                            \
 291                 ({                                                             \
 292                         typeof(((const type *)0)->member) *__mptr = (ptr);     \
 293                         (const type *)((const char *)__mptr -                  \
 294                                         offsetof(type, member));               \
 295                 })                                                             \
 296         ))
 297 #else
 298 /* current C++ compilers don't have the builtins used above; so this version
 299  * of the macro doesn't do the const check. */
 300 #define container_of(ptr, type, member)                                        \
 301                 ({                                                             \
 302                         const typeof(((type *)0)->member) *__mptr = (ptr);     \
 303                         (type *)((char *)__mptr - offsetof(type, member));     \
 304                 })
 305 #endif
 306
 307 #define container_of_null(ptr, type, member)                                   \
 308         ({                                                                     \
 309                 typeof(ptr) _tmp = (ptr);                                      \
 310                 _tmp ? container_of(_tmp, type, member) : NULL;                \
 311         })
 312
 313 #define array_size(ar) (sizeof(ar) / sizeof(ar[0]))
 314
 315 /* Some insane macros to count number of varargs to a functionlike macro */
 316 #define PP_ARG_N( \
 317           _1,  _2,  _3,  _4,  _5,  _6,  _7,  _8,  _9, _10, \
 318          _11, _12, _13, _14, _15, _16, _17, _18, _19, _20, \
 319          _21, _22, _23, _24, _25, _26, _27, _28, _29, _30, \
 320          _31, _32, _33, _34, _35, _36, _37, _38, _39, _40, \
 321          _41, _42, _43, _44, _45, _46, _47, _48, _49, _50, \
 322          _51, _52, _53, _54, _55, _56, _57, _58, _59, _60, \
 323          _61, _62, _63, N, ...) N
 324
 325 #define PP_RSEQ_N()                                        \
 326          62, 61, 60,                                       \
 327          59, 58, 57, 56, 55, 54, 53, 52, 51, 50,           \
 328          49, 48, 47, 46, 45, 44, 43, 42, 41, 40,           \
 329          39, 38, 37, 36, 35, 34, 33, 32, 31, 30,           \
 330          29, 28, 27, 26, 25, 24, 23, 22, 21, 20,           \
 331          19, 18, 17, 16, 15, 14, 13, 12, 11, 10,           \
 332           9,  8,  7,  6,  5,  4,  3,  2,  1,  0
 333
 334 #define PP_NARG_(...)    PP_ARG_N(__VA_ARGS__)
 335 #define PP_NARG(...)     PP_NARG_(_, ##__VA_ARGS__, PP_RSEQ_N())
 336
 337
 338 /* sigh. this is so ugly, it overflows and wraps to being nice again.
 339  *
 340  * printfrr() supports "%Ld" for <int64_t>, whatever that is typedef'd to.
 341  * However, gcc & clang think that "%Ld" is <long long>, which doesn't quite
 342  * match up since int64_t is <long> on a lot of 64-bit systems.
 343  *
 344  * If we have _FRR_ATTRIBUTE_PRINTFRR, we loaded a compiler plugin that
 345  * replaces the whole format checking bits with a custom version that
 346  * understands "%Ld" (along with "%pI4" and co.), so we don't need to do
 347  * anything.
 348  *
 349  * If we don't have that attribute...  we still want -Wformat to work.  So,
 350  * this is the "f*ck it" approach and we just redefine int64_t to always be
 351  * <long long>.  This should work until such a time that <long long> is
 352  * something else (e.g. 128-bit integer)...  let's just guard against that
 353  * with the _Static_assert below and work with the world we have right now,
 354  * where <long long> is always 64-bit.
 355  */
 356
 357 /* these need to be included before any of the following, so we can
 358  * "overwrite" things.
 359  */
 360 #include <stdint.h>
 361 #include <inttypes.h>
 362
 363 #ifdef _FRR_ATTRIBUTE_PRINTFRR
 364 #define PRINTFRR(a, b) __attribute__((frr_format("frr_printf", a, b)))
 365
 366 #undef PRIu64
 367 #undef PRId64
 368 #undef PRIx64
 369 #define PRIu64 "Lu"
 370 #define PRId64 "Ld"
 371 #define PRIx64 "Lx"
 372
 373 #else /* !_FRR_ATTRIBUTE_PRINTFRR */
 374 #define PRINTFRR(a, b) __attribute__((format(printf, a, b)))
 375
 376 /* frr-format plugin is C-only for now, so no point in doing these shenanigans
 377  * for C++...  (also they can break some C++ stuff...)
 378  */
 379 #ifndef __cplusplus
 380 /* these should be typedefs, but might also be #define */
 381 #ifdef uint64_t
 382 #undef uint64_t
 383 #endif
 384 #ifdef int64_t
 385 #undef int64_t
 386 #endif
 387
 388 /* can't overwrite the typedef, but we can replace int64_t with _int64_t */
 389 typedef unsigned long long _uint64_t;
 390 #define uint64_t _uint64_t
 391 typedef signed long long _int64_t;
 392 #define int64_t _int64_t
 393
 394 /* if this breaks, 128-bit machines may have entered reality (or <long long>
 395  * is something weird)
 396  */
 397 _Static_assert(sizeof(_uint64_t) == 8 && sizeof(_int64_t) == 8,
 398                "nobody expects the spanish intquisition");
 399
 400 /* since we redefined int64_t, we also need to redefine PRI*64 */
 401 #undef PRIu64
 402 #undef PRId64
 403 #undef PRIx64
 404 #define PRIu64 "llu"
 405 #define PRId64 "lld"
 406 #define PRIx64 "llx"
 407
 408 #endif /* !__cplusplus */
 409 #endif /* !_FRR_ATTRIBUTE_PRINTFRR */
 410
 411 #ifdef __cplusplus
 412 }
 413 #endif
 414
 415 #endif /* _FRR_COMPILER_H */