src/util/u_atomic.h

   1 /**
   2  * Many similar implementations exist. See for example libwsbm
   3  * or the linux kernel include/atomic.h
   4  *
   5  * No copyright claimed on this file.
   6  *
   7  */
   8
   9 #include "no_extern_c.h"
  10
  11 #ifndef U_ATOMIC_H
  12 #define U_ATOMIC_H
  13
  14 #include <stdbool.h>
  15 #include <stdint.h>
  16
  17 /* Favor OS-provided implementations.
  18  *
  19  * Where no OS-provided implementation is available, fall back to
  20  * locally coded assembly, compiler intrinsic or ultimately a
  21  * mutex-based implementation.
  22  */
  23 #if defined(__sun)
  24 #define PIPE_ATOMIC_OS_SOLARIS
  25 #elif defined(_MSC_VER)
  26 #define PIPE_ATOMIC_MSVC_INTRINSIC
  27 #elif defined(__GNUC__)
  28 #define PIPE_ATOMIC_GCC_INTRINSIC
  29 #else
  30 #error "Unsupported platform"
  31 #endif
  32
  33
  34 /* Implementation using GCC-provided synchronization intrinsics
  35  */
  36 #if defined(PIPE_ATOMIC_GCC_INTRINSIC)
  37
  38 #define PIPE_ATOMIC "GCC Sync Intrinsics"
  39
  40 #if defined(USE_GCC_ATOMIC_BUILTINS)
  41
  42 /* The builtins with explicit memory model are available since GCC 4.7. */
  43 #define p_atomic_set(_v, _i) __atomic_store_n((_v), (_i), __ATOMIC_RELEASE)
  44 #define p_atomic_read(_v) __atomic_load_n((_v), __ATOMIC_ACQUIRE)
  45 #define p_atomic_dec_zero(v) (__atomic_sub_fetch((v), 1, __ATOMIC_ACQ_REL) == 0)
  46 #define p_atomic_inc(v) (void) __atomic_add_fetch((v), 1, __ATOMIC_ACQ_REL)
  47 #define p_atomic_dec(v) (void) __atomic_sub_fetch((v), 1, __ATOMIC_ACQ_REL)
  48 #define p_atomic_add(v, i) (void) __atomic_add_fetch((v), (i), __ATOMIC_ACQ_REL)
  49 #define p_atomic_inc_return(v) __atomic_add_fetch((v), 1, __ATOMIC_ACQ_REL)
  50 #define p_atomic_dec_return(v) __atomic_sub_fetch((v), 1, __ATOMIC_ACQ_REL)
  51 #define p_atomic_add_return(v, i) __atomic_add_fetch((v), (i), __ATOMIC_ACQ_REL)
  52 #define p_atomic_xchg(v, i) __atomic_exchange_n((v), (i), __ATOMIC_ACQ_REL)
  53 #define PIPE_NATIVE_ATOMIC_XCHG
  54
  55 #else
  56
  57 #define p_atomic_set(_v, _i) (*(_v) = (_i))
  58 #define p_atomic_read(_v) (*(_v))
  59 #define p_atomic_dec_zero(v) (__sync_sub_and_fetch((v), 1) == 0)
  60 #define p_atomic_inc(v) (void) __sync_add_and_fetch((v), 1)
  61 #define p_atomic_dec(v) (void) __sync_sub_and_fetch((v), 1)
  62 #define p_atomic_add(v, i) (void) __sync_add_and_fetch((v), (i))
  63 #define p_atomic_inc_return(v) __sync_add_and_fetch((v), 1)
  64 #define p_atomic_dec_return(v) __sync_sub_and_fetch((v), 1)
  65 #define p_atomic_add_return(v, i) __sync_add_and_fetch((v), (i))
  66
  67 #endif
  68
  69 /* There is no __atomic_* compare and exchange that returns the current value.
  70  * Also, GCC 5.4 seems unable to optimize a compound statement expression that
  71  * uses an additional stack variable with __atomic_compare_exchange[_n].
  72  */
  73 #define p_atomic_cmpxchg(v, old, _new) \
  74    __sync_val_compare_and_swap((v), (old), (_new))
  75
  76 #endif
  77
  78
  79
  80 /* Unlocked version for single threaded environments, such as some
  81  * windows kernel modules.
  82  */
  83 #if defined(PIPE_ATOMIC_OS_UNLOCKED)
  84
  85 #define PIPE_ATOMIC "Unlocked"
  86
  87 #define p_atomic_set(_v, _i) (*(_v) = (_i))
  88 #define p_atomic_read(_v) (*(_v))
  89 #define p_atomic_dec_zero(_v) (p_atomic_dec_return(_v) == 0)
  90 #define p_atomic_inc(_v) ((void) p_atomic_inc_return(_v))
  91 #define p_atomic_dec(_v) ((void) p_atomic_dec_return(_v))
  92 #define p_atomic_add(_v, _i) ((void) p_atomic_add_return((_v), (_i)))
  93 #define p_atomic_inc_return(_v) (++(*(_v)))
  94 #define p_atomic_dec_return(_v) (--(*(_v)))
  95 #define p_atomic_add_return(_v, _i) (*(_v) = *(_v) + (_i))
  96 #define p_atomic_cmpxchg(_v, _old, _new) (*(_v) == (_old) ? (*(_v) = (_new), (_old)) : *(_v))
  97
  98 #endif
  99
 100
 101 #if defined(PIPE_ATOMIC_MSVC_INTRINSIC)
 102
 103 #define PIPE_ATOMIC "MSVC Intrinsics"
 104
 105 /* We use the Windows header's Interlocked*64 functions instead of the
 106  * _Interlocked*64 intrinsics wherever we can, as support for the latter varies
 107  * with target CPU, whereas Windows headers take care of all portability
 108  * issues: using intrinsics where available, falling back to library
 109  * implementations where not.
 110  */
 111 #ifndef WIN32_LEAN_AND_MEAN
 112 #define WIN32_LEAN_AND_MEAN 1
 113 #endif
 114 #include <windows.h>
 115 #include <intrin.h>
 116 #include <assert.h>
 117
 118 /* MSVC supports decltype keyword, but it's only supported on C++ and doesn't
 119  * quite work here; and if a C++-only solution is worthwhile, then it would be
 120  * better to use templates / function overloading, instead of decltype magic.
 121  * Therefore, we rely on implicit casting to LONGLONG for the functions that return
 122  */
 123
 124 #define p_atomic_set(_v, _i) (*(_v) = (_i))
 125 #define p_atomic_read(_v) (*(_v))
 126
 127 #define p_atomic_dec_zero(_v) \
 128    (p_atomic_dec_return(_v) == 0)
 129
 130 #define p_atomic_inc(_v) \
 131    ((void) p_atomic_inc_return(_v))
 132
 133 #define p_atomic_inc_return(_v) (\
 134    sizeof *(_v) == sizeof(short)   ? _InterlockedIncrement16((short *)  (_v)) : \
 135    sizeof *(_v) == sizeof(long)    ? _InterlockedIncrement  ((long *)   (_v)) : \
 136    sizeof *(_v) == sizeof(__int64) ? InterlockedIncrement64 ((__int64 *)(_v)) : \
 137                                      (assert(!"should not get here"), 0))
 138
 139 #define p_atomic_dec(_v) \
 140    ((void) p_atomic_dec_return(_v))
 141
 142 #define p_atomic_dec_return(_v) (\
 143    sizeof *(_v) == sizeof(short)   ? _InterlockedDecrement16((short *)  (_v)) : \
 144    sizeof *(_v) == sizeof(long)    ? _InterlockedDecrement  ((long *)   (_v)) : \
 145    sizeof *(_v) == sizeof(__int64) ? InterlockedDecrement64 ((__int64 *)(_v)) : \
 146                                      (assert(!"should not get here"), 0))
 147
 148 #define p_atomic_add(_v, _i) \
 149    ((void) p_atomic_add_return((_v), (_i)))
 150
 151 #define p_atomic_add_return(_v, _i) (\
 152    sizeof *(_v) == sizeof(char)    ? _InterlockedExchangeAdd8 ((char *)   (_v), (_i)) : \
 153    sizeof *(_v) == sizeof(short)   ? _InterlockedExchangeAdd16((short *)  (_v), (_i)) : \
 154    sizeof *(_v) == sizeof(long)    ? _InterlockedExchangeAdd  ((long *)   (_v), (_i)) : \
 155    sizeof *(_v) == sizeof(__int64) ? InterlockedExchangeAdd64((__int64 *)(_v), (_i)) : \
 156                                      (assert(!"should not get here"), 0))
 157
 158 #define p_atomic_cmpxchg(_v, _old, _new) (\
 159    sizeof *(_v) == sizeof(char)    ? _InterlockedCompareExchange8 ((char *)   (_v), (char)   (_new), (char)   (_old)) : \
 160    sizeof *(_v) == sizeof(short)   ? _InterlockedCompareExchange16((short *)  (_v), (short)  (_new), (short)  (_old)) : \
 161    sizeof *(_v) == sizeof(long)    ? _InterlockedCompareExchange  ((long *)   (_v), (long)   (_new), (long)   (_old)) : \
 162    sizeof *(_v) == sizeof(__int64) ? InterlockedCompareExchange64 ((__int64 *)(_v), (__int64)(_new), (__int64)(_old)) : \
 163                                      (assert(!"should not get here"), 0))
 164
 165 #endif
 166
 167 #if defined(PIPE_ATOMIC_OS_SOLARIS)
 168
 169 #define PIPE_ATOMIC "Solaris OS atomic functions"
 170
 171 #include <atomic.h>
 172 #include <assert.h>
 173
 174 #define p_atomic_set(_v, _i) (*(_v) = (_i))
 175 #define p_atomic_read(_v) (*(_v))
 176
 177 #define p_atomic_dec_zero(v) (\
 178    sizeof(*v) == sizeof(uint8_t)  ? atomic_dec_8_nv ((uint8_t  *)(v)) == 0 : \
 179    sizeof(*v) == sizeof(uint16_t) ? atomic_dec_16_nv((uint16_t *)(v)) == 0 : \
 180    sizeof(*v) == sizeof(uint32_t) ? atomic_dec_32_nv((uint32_t *)(v)) == 0 : \
 181    sizeof(*v) == sizeof(uint64_t) ? atomic_dec_64_nv((uint64_t *)(v)) == 0 : \
 182                                     (assert(!"should not get here"), 0))
 183
 184 #define p_atomic_inc(v) (void) (\
 185    sizeof(*v) == sizeof(uint8_t)  ? atomic_inc_8 ((uint8_t  *)(v)) : \
 186    sizeof(*v) == sizeof(uint16_t) ? atomic_inc_16((uint16_t *)(v)) : \
 187    sizeof(*v) == sizeof(uint32_t) ? atomic_inc_32((uint32_t *)(v)) : \
 188    sizeof(*v) == sizeof(uint64_t) ? atomic_inc_64((uint64_t *)(v)) : \
 189                                     (assert(!"should not get here"), 0))
 190
 191 #define p_atomic_inc_return(v) (__typeof(*v))( \
 192    sizeof(*v) == sizeof(uint8_t)  ? atomic_inc_8_nv ((uint8_t  *)(v)) : \
 193    sizeof(*v) == sizeof(uint16_t) ? atomic_inc_16_nv((uint16_t *)(v)) : \
 194    sizeof(*v) == sizeof(uint32_t) ? atomic_inc_32_nv((uint32_t *)(v)) : \
 195    sizeof(*v) == sizeof(uint64_t) ? atomic_inc_64_nv((uint64_t *)(v)) : \
 196                                     (assert(!"should not get here"), 0))
 197
 198 #define p_atomic_dec(v) (void) ( \
 199    sizeof(*v) == sizeof(uint8_t)  ? atomic_dec_8 ((uint8_t  *)(v)) : \
 200    sizeof(*v) == sizeof(uint16_t) ? atomic_dec_16((uint16_t *)(v)) : \
 201    sizeof(*v) == sizeof(uint32_t) ? atomic_dec_32((uint32_t *)(v)) : \
 202    sizeof(*v) == sizeof(uint64_t) ? atomic_dec_64((uint64_t *)(v)) : \
 203                                     (assert(!"should not get here"), 0))
 204
 205 #define p_atomic_dec_return(v) (__typeof(*v))( \
 206    sizeof(*v) == sizeof(uint8_t)  ? atomic_dec_8_nv ((uint8_t  *)(v)) : \
 207    sizeof(*v) == sizeof(uint16_t) ? atomic_dec_16_nv((uint16_t *)(v)) : \
 208    sizeof(*v) == sizeof(uint32_t) ? atomic_dec_32_nv((uint32_t *)(v)) : \
 209    sizeof(*v) == sizeof(uint64_t) ? atomic_dec_64_nv((uint64_t *)(v)) : \
 210                                     (assert(!"should not get here"), 0))
 211
 212 #define p_atomic_add(v, i) (void) ( \
 213    sizeof(*v) == sizeof(uint8_t)  ? atomic_add_8 ((uint8_t  *)(v), (i)) : \
 214    sizeof(*v) == sizeof(uint16_t) ? atomic_add_16((uint16_t *)(v), (i)) : \
 215    sizeof(*v) == sizeof(uint32_t) ? atomic_add_32((uint32_t *)(v), (i)) : \
 216    sizeof(*v) == sizeof(uint64_t) ? atomic_add_64((uint64_t *)(v), (i)) : \
 217                                     (assert(!"should not get here"), 0))
 218
 219 #define p_atomic_add_return(v, i) (__typeof(*v)) ( \
 220    sizeof(*v) == sizeof(uint8_t)  ? atomic_add_8_nv ((uint8_t  *)(v), (i)) : \
 221    sizeof(*v) == sizeof(uint16_t) ? atomic_add_16_nv((uint16_t *)(v), (i)) : \
 222    sizeof(*v) == sizeof(uint32_t) ? atomic_add_32_nv((uint32_t *)(v), (i)) : \
 223    sizeof(*v) == sizeof(uint64_t) ? atomic_add_64_nv((uint64_t *)(v), (i)) : \
 224                                     (assert(!"should not get here"), 0))
 225
 226 #define p_atomic_cmpxchg(v, old, _new) (__typeof(*v))( \
 227    sizeof(*v) == sizeof(uint8_t)  ? atomic_cas_8 ((uint8_t  *)(v), (uint8_t )(old), (uint8_t )(_new)) : \
 228    sizeof(*v) == sizeof(uint16_t) ? atomic_cas_16((uint16_t *)(v), (uint16_t)(old), (uint16_t)(_new)) : \
 229    sizeof(*v) == sizeof(uint32_t) ? atomic_cas_32((uint32_t *)(v), (uint32_t)(old), (uint32_t)(_new)) : \
 230    sizeof(*v) == sizeof(uint64_t) ? atomic_cas_64((uint64_t *)(v), (uint64_t)(old), (uint64_t)(_new)) : \
 231                                     (assert(!"should not get here"), 0))
 232
 233 #endif
 234
 235 #ifndef PIPE_ATOMIC
 236 #error "No pipe_atomic implementation selected"
 237 #endif
 238
 239 #ifndef PIPE_NATIVE_ATOMIC_XCHG
 240 static inline uint32_t p_atomic_xchg_32(uint32_t *v, uint32_t i)
 241 {
 242    uint32_t actual = p_atomic_read(v);
 243    uint32_t expected;
 244    do {
 245       expected = actual;
 246       actual = p_atomic_cmpxchg(v, expected, i);
 247    } while (expected != actual);
 248    return actual;
 249 }
 250
 251 static inline uint64_t p_atomic_xchg_64(uint64_t *v, uint64_t i)
 252 {
 253    uint64_t actual = p_atomic_read(v);
 254    uint64_t expected;
 255    do {
 256       expected = actual;
 257       actual = p_atomic_cmpxchg(v, expected, i);
 258    } while (expected != actual);
 259    return actual;
 260 }
 261
 262 #define p_atomic_xchg(v, i) (__typeof(*(v)))( \
 263    sizeof(*(v)) == sizeof(uint32_t) ? p_atomic_xchg_32((uint32_t *)(v), (uint32_t)(i)) : \
 264    sizeof(*(v)) == sizeof(uint64_t) ? p_atomic_xchg_64((uint64_t *)(v), (uint64_t)(i)) : \
 265                                       (assert(!"should not get here"), 0))
 266 #endif
 267
 268 #endif /* U_ATOMIC_H */