github.com/axw/llgo@v0.0.0-20160805011314-95b5fe4dca20/third_party/gofrontend/libbacktrace/atomic.c (about)

     1  /* atomic.c -- Support for atomic functions if not present.
     2     Copyright (C) 2013-2015 Free Software Foundation, Inc.
     3     Written by Ian Lance Taylor, Google.
     4  
     5  Redistribution and use in source and binary forms, with or without
     6  modification, are permitted provided that the following conditions are
     7  met:
     8  
     9      (1) Redistributions of source code must retain the above copyright
    10      notice, this list of conditions and the following disclaimer. 
    11  
    12      (2) Redistributions in binary form must reproduce the above copyright
    13      notice, this list of conditions and the following disclaimer in
    14      the documentation and/or other materials provided with the
    15      distribution.  
    16      
    17      (3) The name of the author may not be used to
    18      endorse or promote products derived from this software without
    19      specific prior written permission.
    20  
    21  THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
    22  IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
    23  WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
    24  DISCLAIMED. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT,
    25  INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
    26  (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
    27  SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
    28  HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
    29  STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING
    30  IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
    31  POSSIBILITY OF SUCH DAMAGE.  */
    32  
    33  #include "config.h"
    34  
    35  #include <sys/types.h>
    36  
    37  #include "backtrace.h"
    38  #include "backtrace-supported.h"
    39  #include "internal.h"
    40  
    41  /* This file holds implementations of the atomic functions that are
    42     used if the host compiler has the sync functions but not the atomic
    43     functions, as is true of versions of GCC before 4.7.  */
    44  
    45  #if !defined (HAVE_ATOMIC_FUNCTIONS) && defined (HAVE_SYNC_FUNCTIONS)
    46  
    47  /* Do an atomic load of a pointer.  */
    48  
    49  void *
    50  backtrace_atomic_load_pointer (void *arg)
    51  {
    52    void **pp;
    53    void *p;
    54  
    55    pp = (void **) arg;
    56    p = *pp;
    57    while (!__sync_bool_compare_and_swap (pp, p, p))
    58      p = *pp;
    59    return p;
    60  }
    61  
    62  /* Do an atomic load of an int.  */
    63  
    64  int
    65  backtrace_atomic_load_int (int *p)
    66  {
    67    int i;
    68  
    69    i = *p;
    70    while (!__sync_bool_compare_and_swap (p, i, i))
    71      i = *p;
    72    return i;
    73  }
    74  
    75  /* Do an atomic store of a pointer.  */
    76  
    77  void
    78  backtrace_atomic_store_pointer (void *arg, void *p)
    79  {
    80    void **pp;
    81    void *old;
    82  
    83    pp = (void **) arg;
    84    old = *pp;
    85    while (!__sync_bool_compare_and_swap (pp, old, p))
    86      old = *pp;
    87  }
    88  
    89  /* Do an atomic store of a size_t value.  */
    90  
    91  void
    92  backtrace_atomic_store_size_t (size_t *p, size_t v)
    93  {
    94    size_t old;
    95  
    96    old = *p;
    97    while (!__sync_bool_compare_and_swap (p, old, v))
    98      old = *p;
    99  }
   100  
   101  /* Do an atomic store of a int value.  */
   102  
   103  void
   104  backtrace_atomic_store_int (int *p, int v)
   105  {
   106    size_t old;
   107  
   108    old = *p;
   109    while (!__sync_bool_compare_and_swap (p, old, v))
   110      old = *p;
   111  }
   112  
   113  #endif