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