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 /* variadic macros, use like:
 144  * #define V_0()  ...
 145  * #define V_1(x) ...
 146  * #define V(...) MACRO_VARIANT(V, ##__VA_ARGS__)(__VA_ARGS__)
 147  */
 148 #define _MACRO_VARIANT(A0,A1,A2,A3,A4,A5,A6,A7,A8,A9,A10, N, ...) N
 149
 150 #define _CONCAT2(a, b) a ## b
 151 #define _CONCAT(a, b) _CONCAT2(a,b)
 152
 153 #define MACRO_VARIANT(NAME, ...) \
 154         _CONCAT(NAME, _MACRO_VARIANT(0, ##__VA_ARGS__, \
 155                         _10, _9, _8, _7, _6, _5, _4, _3, _2, _1, _0))
 156
 157 #define NAMECTR(name) _CONCAT(name, __COUNTER__)
 158
 159 /* per-arg repeat macros, use like:
 160  * #define PERARG(n) ...n...
 161  * #define FOO(...) MACRO_REPEAT(PERARG, ##__VA_ARGS__)
 162  */
 163
 164 #define _MACRO_REPEAT_0(NAME)
 165 #define _MACRO_REPEAT_1(NAME, A1) \
 166         NAME(A1)
 167 #define _MACRO_REPEAT_2(NAME, A1, A2) \
 168         NAME(A1) NAME(A2)
 169 #define _MACRO_REPEAT_3(NAME, A1, A2, A3) \
 170         NAME(A1) NAME(A2) NAME(A3)
 171 #define _MACRO_REPEAT_4(NAME, A1, A2, A3, A4) \
 172         NAME(A1) NAME(A2) NAME(A3) NAME(A4)
 173 #define _MACRO_REPEAT_5(NAME, A1, A2, A3, A4, A5) \
 174         NAME(A1) NAME(A2) NAME(A3) NAME(A4) NAME(A5)
 175 #define _MACRO_REPEAT_6(NAME, A1, A2, A3, A4, A5, A6) \
 176         NAME(A1) NAME(A2) NAME(A3) NAME(A4) NAME(A5) NAME(A6)
 177 #define _MACRO_REPEAT_7(NAME, A1, A2, A3, A4, A5, A6, A7) \
 178         NAME(A1) NAME(A2) NAME(A3) NAME(A4) NAME(A5) NAME(A6) NAME(A7)
 179 #define _MACRO_REPEAT_8(NAME, A1, A2, A3, A4, A5, A6, A7, A8) \
 180         NAME(A1) NAME(A2) NAME(A3) NAME(A4) NAME(A5) NAME(A6) NAME(A7) NAME(A8)
 181
 182 #define MACRO_REPEAT(NAME, ...) \
 183         MACRO_VARIANT(_MACRO_REPEAT, ##__VA_ARGS__)(NAME, ##__VA_ARGS__)
 184
 185 /*
 186  * for warnings on macros, put in the macro content like this:
 187  *   #define MACRO BLA CPP_WARN("MACRO has been deprecated")
 188  */
 189 #define CPP_STR(X) #X
 190
 191 #if defined(__ICC)
 192 #define CPP_NOTICE(text) _Pragma(CPP_STR(message __FILE__ ": " text))
 193 #define CPP_WARN(text) CPP_NOTICE(text)
 194
 195 #elif (defined(__GNUC__)                                                       \
 196        && (__GNUC__ >= 5 || (__GNUC__ == 4 && __GNUC_MINOR__ >= 8)))           \
 197         || (defined(__clang__)                                                 \
 198             && (__clang_major__ >= 4                                           \
 199                 || (__clang_major__ == 3 && __clang_minor__ >= 5)))
 200 #define CPP_WARN(text) _Pragma(CPP_STR(GCC warning text))
 201 #define CPP_NOTICE(text) _Pragma(CPP_STR(message text))
 202
 203 #else
 204 #define CPP_WARN(text)
 205 #define CPP_NOTICE(text)
 206 #endif
 207
 208 /* MAX / MIN are not commonly defined, but useful */
 209 /* note: glibc sys/param.h has #define MIN(a,b) (((a)<(b))?(a):(b)) */
 210 #ifdef MAX
 211 #undef MAX
 212 #endif
 213 #define MAX(a, b)                                                              \
 214         ({                                                                     \
 215                 typeof(a) _max_a = (a);                                        \
 216                 typeof(b) _max_b = (b);                                        \
 217                 _max_a > _max_b ? _max_a : _max_b;                             \
 218         })
 219 #ifdef MIN
 220 #undef MIN
 221 #endif
 222 #define MIN(a, b)                                                              \
 223         ({                                                                     \
 224                 typeof(a) _min_a = (a);                                        \
 225                 typeof(b) _min_b = (b);                                        \
 226                 _min_a < _min_b ? _min_a : _min_b;                             \
 227         })
 228
 229 #define numcmp(a, b)                                                           \
 230         ({                                                                     \
 231                 typeof(a) _cmp_a = (a);                                        \
 232                 typeof(b) _cmp_b = (b);                                        \
 233                 (_cmp_a < _cmp_b) ? -1 : ((_cmp_a > _cmp_b) ? 1 : 0);          \
 234         })
 235
 236 #ifndef offsetof
 237 #ifdef __compiler_offsetof
 238 #define offsetof(TYPE, MEMBER) __compiler_offsetof(TYPE,MEMBER)
 239 #else
 240 #define offsetof(TYPE, MEMBER) ((size_t) &((TYPE *)0)->MEMBER)
 241 #endif
 242 #endif
 243
 244 #ifdef container_of
 245 #undef container_of
 246 #endif
 247
 248 #if !(defined(__cplusplus) || defined(test__cplusplus))
 249 /* this variant of container_of() retains 'const' on pointers without needing
 250  * to be told to do so.  The following will all work without warning:
 251  *
 252  * struct member *p;
 253  * const struct member *cp;
 254  *
 255  * const struct cont *x = container_of(cp, struct cont, member);
 256  * const struct cont *x = container_of(cp, const struct cont, member);
 257  * const struct cont *x = container_of(p,  struct cont, member);
 258  * const struct cont *x = container_of(p,  const struct cont, member);
 259  * struct cont *x       = container_of(p,  struct cont, member);
 260  *
 261  * but the following will generate warnings about stripping const:
 262  *
 263  * struct cont *x       = container_of(cp, struct cont, member);
 264  * struct cont *x       = container_of(cp, const struct cont, member);
 265  * struct cont *x       = container_of(p,  const struct cont, member);
 266  */
 267 #define container_of(ptr, type, member)                                        \
 268         (__builtin_choose_expr(                                                \
 269                 __builtin_types_compatible_p(typeof(&((type *)0)->member),     \
 270                         typeof(ptr))                                           \
 271                     ||  __builtin_types_compatible_p(void *, typeof(ptr)),     \
 272                 ({                                                             \
 273                         typeof(((type *)0)->member) *__mptr = (void *)(ptr);   \
 274                         (type *)((char *)__mptr - offsetof(type, member));     \
 275                 }),                                                            \
 276                 ({                                                             \
 277                         typeof(((const type *)0)->member) *__mptr = (ptr);     \
 278                         (const type *)((const char *)__mptr -                  \
 279                                         offsetof(type, member));               \
 280                 })                                                             \
 281         ))
 282 #else
 283 /* current C++ compilers don't have the builtins used above; so this version
 284  * of the macro doesn't do the const check. */
 285 #define container_of(ptr, type, member)                                        \
 286                 ({                                                             \
 287                         const typeof(((type *)0)->member) *__mptr = (ptr);     \
 288                         (type *)((char *)__mptr - offsetof(type, member));     \
 289                 })
 290 #endif
 291
 292 #define container_of_null(ptr, type, member)                                   \
 293         ({                                                                     \
 294                 typeof(ptr) _tmp = (ptr);                                      \
 295                 _tmp ? container_of(_tmp, type, member) : NULL;                \
 296         })
 297
 298 #define array_size(ar) (sizeof(ar) / sizeof(ar[0]))
 299
 300 /* Some insane macros to count number of varargs to a functionlike macro */
 301 #define PP_ARG_N( \
 302           _1,  _2,  _3,  _4,  _5,  _6,  _7,  _8,  _9, _10, \
 303          _11, _12, _13, _14, _15, _16, _17, _18, _19, _20, \
 304          _21, _22, _23, _24, _25, _26, _27, _28, _29, _30, \
 305          _31, _32, _33, _34, _35, _36, _37, _38, _39, _40, \
 306          _41, _42, _43, _44, _45, _46, _47, _48, _49, _50, \
 307          _51, _52, _53, _54, _55, _56, _57, _58, _59, _60, \
 308          _61, _62, _63, N, ...) N
 309
 310 #define PP_RSEQ_N()                                        \
 311          62, 61, 60,                                       \
 312          59, 58, 57, 56, 55, 54, 53, 52, 51, 50,           \
 313          49, 48, 47, 46, 45, 44, 43, 42, 41, 40,           \
 314          39, 38, 37, 36, 35, 34, 33, 32, 31, 30,           \
 315          29, 28, 27, 26, 25, 24, 23, 22, 21, 20,           \
 316          19, 18, 17, 16, 15, 14, 13, 12, 11, 10,           \
 317           9,  8,  7,  6,  5,  4,  3,  2,  1,  0
 318
 319 #define PP_NARG_(...) PP_ARG_N(__VA_ARGS__)
 320 #define PP_NARG(...)     PP_NARG_(_, ##__VA_ARGS__, PP_RSEQ_N())
 321
 322
 323 /* sigh. this is so ugly, it overflows and wraps to being nice again.
 324  *
 325  * printfrr() supports "%Ld" for <int64_t>, whatever that is typedef'd to.
 326  * However, gcc & clang think that "%Ld" is <long long>, which doesn't quite
 327  * match up since int64_t is <long> on a lot of 64-bit systems.
 328  *
 329  * If we have _FRR_ATTRIBUTE_PRINTFRR, we loaded a compiler plugin that
 330  * replaces the whole format checking bits with a custom version that
 331  * understands "%Ld" (along with "%pI4" and co.), so we don't need to do
 332  * anything.
 333  *
 334  * If we don't have that attribute...  we still want -Wformat to work.  So,
 335  * this is the "f*ck it" approach and we just redefine int64_t to always be
 336  * <long long>.  This should work until such a time that <long long> is
 337  * something else (e.g. 128-bit integer)...  let's just guard against that
 338  * with the _Static_assert below and work with the world we have right now,
 339  * where <long long> is always 64-bit.
 340  */
 341
 342 /* these need to be included before any of the following, so we can
 343  * "overwrite" things.
 344  */
 345 #include <stdint.h>
 346 #include <inttypes.h>
 347
 348 #ifdef _FRR_ATTRIBUTE_PRINTFRR
 349 #define PRINTFRR(a, b) __attribute__((frr_format("frr_printf", a, b)))
 350
 351 #undef PRIu64
 352 #undef PRId64
 353 #undef PRIx64
 354 #define PRIu64 "Lu"
 355 #define PRId64 "Ld"
 356 #define PRIx64 "Lx"
 357
 358 #else /* !_FRR_ATTRIBUTE_PRINTFRR */
 359 #define PRINTFRR(a, b) __attribute__((format(printf, a, b)))
 360
 361 /* frr-format plugin is C-only for now, so no point in doing these shenanigans
 362  * for C++...  (also they can break some C++ stuff...)
 363  */
 364 #ifndef __cplusplus
 365 /* these should be typedefs, but might also be #define */
 366 #ifdef uint64_t
 367 #undef uint64_t
 368 #endif
 369 #ifdef int64_t
 370 #undef int64_t
 371 #endif
 372
 373 /* can't overwrite the typedef, but we can replace int64_t with _int64_t */
 374 typedef unsigned long long _uint64_t;
 375 #define uint64_t _uint64_t
 376 typedef signed long long _int64_t;
 377 #define int64_t _int64_t
 378
 379 /* if this breaks, 128-bit machines may have entered reality (or <long long>
 380  * is something weird)
 381  */
 382 _Static_assert(sizeof(_uint64_t) == 8 && sizeof(_int64_t) == 8,
 383                "nobody expects the spanish intquisition");
 384
 385 /* since we redefined int64_t, we also need to redefine PRI*64 */
 386 #undef PRIu64
 387 #undef PRId64
 388 #undef PRIx64
 389 #define PRIu64 "llu"
 390 #define PRId64 "lld"
 391 #define PRIx64 "llx"
 392
 393 #endif /* !__cplusplus */
 394 #endif /* !_FRR_ATTRIBUTE_PRINTFRR */
 395
 396 #ifdef __cplusplus
 397 }
 398 #endif
 399
 400 #endif /* _FRR_COMPILER_H */