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_xchg(v, i) __atomic_exchange_n((v), (i), __ATOMIC_ACQ_REL)
  52 #define PIPE_NATIVE_ATOMIC_XCHG
  53
  54 #else
  55
  56 #define p_atomic_set(_v, _i) (*(_v) = (_i))
  57 #define p_atomic_read(_v) (*(_v))
  58 #define p_atomic_dec_zero(v) (__sync_sub_and_fetch((v), 1) == 0)
  59 #define p_atomic_inc(v) (void) __sync_add_and_fetch((v), 1)
  60 #define p_atomic_dec(v) (void) __sync_sub_and_fetch((v), 1)
  61 #define p_atomic_add(v, i) (void) __sync_add_and_fetch((v), (i))
  62 #define p_atomic_inc_return(v) __sync_add_and_fetch((v), 1)
  63 #define p_atomic_dec_return(v) __sync_sub_and_fetch((v), 1)
  64
  65 #endif
  66
  67 /* There is no __atomic_* compare and exchange that returns the current value.
  68  * Also, GCC 5.4 seems unable to optimize a compound statement expression that
  69  * uses an additional stack variable with __atomic_compare_exchange[_n].
  70  */
  71 #define p_atomic_cmpxchg(v, old, _new) \
  72    __sync_val_compare_and_swap((v), (old), (_new))
  73
  74 #endif
  75
  76
  77
  78 /* Unlocked version for single threaded environments, such as some
  79  * windows kernel modules.
  80  */
  81 #if defined(PIPE_ATOMIC_OS_UNLOCKED)
  82
  83 #define PIPE_ATOMIC "Unlocked"
  84
  85 #define p_atomic_set(_v, _i) (*(_v) = (_i))
  86 #define p_atomic_read(_v) (*(_v))
  87 #define p_atomic_dec_zero(_v) (p_atomic_dec_return(_v) == 0)
  88 #define p_atomic_inc(_v) ((void) p_atomic_inc_return(_v))
  89 #define p_atomic_dec(_v) ((void) p_atomic_dec_return(_v))
  90 #define p_atomic_add(_v, _i) (*(_v) = *(_v) + (_i))
  91 #define p_atomic_inc_return(_v) (++(*(_v)))
  92 #define p_atomic_dec_return(_v) (--(*(_v)))
  93 #define p_atomic_cmpxchg(_v, _old, _new) (*(_v) == (_old) ? (*(_v) = (_new), (_old)) : *(_v))
  94
  95 #endif
  96
  97
  98 #if defined(PIPE_ATOMIC_MSVC_INTRINSIC)
  99
 100 #define PIPE_ATOMIC "MSVC Intrinsics"
 101
 102 /* We use the Windows header's Interlocked*64 functions instead of the
 103  * _Interlocked*64 intrinsics wherever we can, as support for the latter varies
 104  * with target CPU, whereas Windows headers take care of all portability
 105  * issues: using intrinsics where available, falling back to library
 106  * implementations where not.
 107  */
 108 #ifndef WIN32_LEAN_AND_MEAN
 109 #define WIN32_LEAN_AND_MEAN 1
 110 #endif
 111 #include <windows.h>
 112 #include <intrin.h>
 113 #include <assert.h>
 114
 115 /* MSVC supports decltype keyword, but it's only supported on C++ and doesn't
 116  * quite work here; and if a C++-only solution is worthwhile, then it would be
 117  * better to use templates / function overloading, instead of decltype magic.
 118  * Therefore, we rely on implicit casting to LONGLONG for the functions that return
 119  */
 120
 121 #define p_atomic_set(_v, _i) (*(_v) = (_i))
 122 #define p_atomic_read(_v) (*(_v))
 123
 124 #define p_atomic_dec_zero(_v) \
 125    (p_atomic_dec_return(_v) == 0)
 126
 127 #define p_atomic_inc(_v) \
 128    ((void) p_atomic_inc_return(_v))
 129
 130 #define p_atomic_inc_return(_v) (\
 131    sizeof *(_v) == sizeof(short)   ? _InterlockedIncrement16((short *)  (_v)) : \
 132    sizeof *(_v) == sizeof(long)    ? _InterlockedIncrement  ((long *)   (_v)) : \
 133    sizeof *(_v) == sizeof(__int64) ? InterlockedIncrement64 ((__int64 *)(_v)) : \
 134                                      (assert(!"should not get here"), 0))
 135
 136 #define p_atomic_dec(_v) \
 137    ((void) p_atomic_dec_return(_v))
 138
 139 #define p_atomic_dec_return(_v) (\
 140    sizeof *(_v) == sizeof(short)   ? _InterlockedDecrement16((short *)  (_v)) : \
 141    sizeof *(_v) == sizeof(long)    ? _InterlockedDecrement  ((long *)   (_v)) : \
 142    sizeof *(_v) == sizeof(__int64) ? InterlockedDecrement64 ((__int64 *)(_v)) : \
 143                                      (assert(!"should not get here"), 0))
 144
 145 #define p_atomic_add(_v, _i) (\
 146    sizeof *(_v) == sizeof(char)    ? _InterlockedExchangeAdd8 ((char *)   (_v), (_i)) : \
 147    sizeof *(_v) == sizeof(short)   ? _InterlockedExchangeAdd16((short *)  (_v), (_i)) : \
 148    sizeof *(_v) == sizeof(long)    ? _InterlockedExchangeAdd  ((long *)   (_v), (_i)) : \
 149    sizeof *(_v) == sizeof(__int64) ? InterlockedExchangeAdd64((__int64 *)(_v), (_i)) : \
 150                                      (assert(!"should not get here"), 0))
 151
 152 #define p_atomic_cmpxchg(_v, _old, _new) (\
 153    sizeof *(_v) == sizeof(char)    ? _InterlockedCompareExchange8 ((char *)   (_v), (char)   (_new), (char)   (_old)) : \
 154    sizeof *(_v) == sizeof(short)   ? _InterlockedCompareExchange16((short *)  (_v), (short)  (_new), (short)  (_old)) : \
 155    sizeof *(_v) == sizeof(long)    ? _InterlockedCompareExchange  ((long *)   (_v), (long)   (_new), (long)   (_old)) : \
 156    sizeof *(_v) == sizeof(__int64) ? InterlockedCompareExchange64 ((__int64 *)(_v), (__int64)(_new), (__int64)(_old)) : \
 157                                      (assert(!"should not get here"), 0))
 158
 159 #endif
 160
 161 #if defined(PIPE_ATOMIC_OS_SOLARIS)
 162
 163 #define PIPE_ATOMIC "Solaris OS atomic functions"
 164
 165 #include <atomic.h>
 166 #include <assert.h>
 167
 168 #define p_atomic_set(_v, _i) (*(_v) = (_i))
 169 #define p_atomic_read(_v) (*(_v))
 170
 171 #define p_atomic_dec_zero(v) (\
 172    sizeof(*v) == sizeof(uint8_t)  ? atomic_dec_8_nv ((uint8_t  *)(v)) == 0 : \
 173    sizeof(*v) == sizeof(uint16_t) ? atomic_dec_16_nv((uint16_t *)(v)) == 0 : \
 174    sizeof(*v) == sizeof(uint32_t) ? atomic_dec_32_nv((uint32_t *)(v)) == 0 : \
 175    sizeof(*v) == sizeof(uint64_t) ? atomic_dec_64_nv((uint64_t *)(v)) == 0 : \
 176                                     (assert(!"should not get here"), 0))
 177
 178 #define p_atomic_inc(v) (void) (\
 179    sizeof(*v) == sizeof(uint8_t)  ? atomic_inc_8 ((uint8_t  *)(v)) : \
 180    sizeof(*v) == sizeof(uint16_t) ? atomic_inc_16((uint16_t *)(v)) : \
 181    sizeof(*v) == sizeof(uint32_t) ? atomic_inc_32((uint32_t *)(v)) : \
 182    sizeof(*v) == sizeof(uint64_t) ? atomic_inc_64((uint64_t *)(v)) : \
 183                                     (assert(!"should not get here"), 0))
 184
 185 #define p_atomic_inc_return(v) ((__typeof(*v)) \
 186    sizeof(*v) == sizeof(uint8_t)  ? atomic_inc_8_nv ((uint8_t  *)(v)) : \
 187    sizeof(*v) == sizeof(uint16_t) ? atomic_inc_16_nv((uint16_t *)(v)) : \
 188    sizeof(*v) == sizeof(uint32_t) ? atomic_inc_32_nv((uint32_t *)(v)) : \
 189    sizeof(*v) == sizeof(uint64_t) ? atomic_inc_64_nv((uint64_t *)(v)) : \
 190                                     (assert(!"should not get here"), 0))
 191
 192 #define p_atomic_dec(v) ((void) \
 193    sizeof(*v) == sizeof(uint8_t)  ? atomic_dec_8 ((uint8_t  *)(v)) : \
 194    sizeof(*v) == sizeof(uint16_t) ? atomic_dec_16((uint16_t *)(v)) : \
 195    sizeof(*v) == sizeof(uint32_t) ? atomic_dec_32((uint32_t *)(v)) : \
 196    sizeof(*v) == sizeof(uint64_t) ? atomic_dec_64((uint64_t *)(v)) : \
 197                                     (assert(!"should not get here"), 0))
 198
 199 #define p_atomic_dec_return(v) ((__typeof(*v)) \
 200    sizeof(*v) == sizeof(uint8_t)  ? atomic_dec_8_nv ((uint8_t  *)(v)) : \
 201    sizeof(*v) == sizeof(uint16_t) ? atomic_dec_16_nv((uint16_t *)(v)) : \
 202    sizeof(*v) == sizeof(uint32_t) ? atomic_dec_32_nv((uint32_t *)(v)) : \
 203    sizeof(*v) == sizeof(uint64_t) ? atomic_dec_64_nv((uint64_t *)(v)) : \
 204                                     (assert(!"should not get here"), 0))
 205
 206 #define p_atomic_add(v, i) ((void)                                   \
 207    sizeof(*v) == sizeof(uint8_t)  ? atomic_add_8 ((uint8_t  *)(v), (i)) : \
 208    sizeof(*v) == sizeof(uint16_t) ? atomic_add_16((uint16_t *)(v), (i)) : \
 209    sizeof(*v) == sizeof(uint32_t) ? atomic_add_32((uint32_t *)(v), (i)) : \
 210    sizeof(*v) == sizeof(uint64_t) ? atomic_add_64((uint64_t *)(v), (i)) : \
 211                                     (assert(!"should not get here"), 0))
 212
 213 #define p_atomic_cmpxchg(v, old, _new) ((__typeof(*v)) \
 214    sizeof(*v) == sizeof(uint8_t)  ? atomic_cas_8 ((uint8_t  *)(v), (uint8_t )(old), (uint8_t )(_new)) : \
 215    sizeof(*v) == sizeof(uint16_t) ? atomic_cas_16((uint16_t *)(v), (uint16_t)(old), (uint16_t)(_new)) : \
 216    sizeof(*v) == sizeof(uint32_t) ? atomic_cas_32((uint32_t *)(v), (uint32_t)(old), (uint32_t)(_new)) : \
 217    sizeof(*v) == sizeof(uint64_t) ? atomic_cas_64((uint64_t *)(v), (uint64_t)(old), (uint64_t)(_new)) : \
 218                                     (assert(!"should not get here"), 0))
 219
 220 #endif
 221
 222 #ifndef PIPE_ATOMIC
 223 #error "No pipe_atomic implementation selected"
 224 #endif
 225
 226 #ifndef PIPE_NATIVE_ATOMIC_XCHG
 227 static inline uint32_t p_atomic_xchg_32(uint32_t *v, uint32_t i)
 228 {
 229    uint32_t actual = p_atomic_read(v);
 230    uint32_t expected;
 231    do {
 232       expected = actual;
 233       actual = p_atomic_cmpxchg(v, expected, i);
 234    } while (expected != actual);
 235    return actual;
 236 }
 237
 238 static inline uint64_t p_atomic_xchg_64(uint64_t *v, uint64_t i)
 239 {
 240    uint64_t actual = p_atomic_read(v);
 241    uint64_t expected;
 242    do {
 243       expected = actual;
 244       actual = p_atomic_cmpxchg(v, expected, i);
 245    } while (expected != actual);
 246    return actual;
 247 }
 248
 249 #define p_atomic_xchg(v, i) ((__typeof(*(v))) \
 250    sizeof(*(v)) == sizeof(uint32_t) ? p_atomic_xchg_32((uint32_t *)(v), (uint32_t)(i)) : \
 251    sizeof(*(v)) == sizeof(uint64_t) ? p_atomic_xchg_64((uint64_t *)(v), (uint64_t)(i)) : \
 252                                       (assert(!"should not get here"), 0))
 253 #endif
 254
 255 #endif /* U_ATOMIC_H */