clang/test/seqlock_raw_unannotated.c

   1 #include <stdio.h>
   2 #include <threads.h>
   3 #include "libinterface.h"
   4
   5 /*atomic_*/ int _seq;
   6 /*atomic_*/ int _data;
   7
   8 void seqlock_init() {
   9         store_32(&_seq, 0);
  10         store_32(&_data, 0);
  11 }
  12
  13 int seqlock_read() {
  14         while (true) {
  15                 int old_seq = load_32(&_seq);
  16
  17                 if (old_seq % 2 == 1) {
  18                 } else {
  19                         int res = load_32(&_data);
  20                         int seq = load_32(&_seq);
  21
  22                         if (seq == old_seq) { // relaxed
  23                                 return res;
  24                         }
  25                 }
  26         }
  27 }
  28
  29 void seqlock_write(int new_data) {
  30         while (true) {
  31                 int old_seq = load_32(&_seq);
  32                 if (old_seq % 2 == 1) {
  33                 } else {
  34                         int new_seq = old_seq + 1;
  35                         int cas_value = rmw_32(CAS, &_seq, old_seq, new_seq);
  36                         if (old_seq == cas_value) {
  37                                 break;
  38                         }
  39                 }
  40         }
  41         store_32(&_data, new_data);
  42
  43         rmw_32(ADD, &_seq, /*dummy */0, 1);
  44 }
  45
  46 static void a(void *obj) {
  47         seqlock_write(3);
  48 }
  49
  50 static void b(void *obj) {
  51         seqlock_write(2);
  52 }
  53
  54 static void c(void *obj) {
  55         int r1 = seqlock_read();
  56 }
  57
  58 int user_main(int argc, char **argv) {
  59         thrd_t t1, t2, t3;
  60         seqlock_init();
  61
  62         thrd_create(&t1, (thrd_start_t)&a, NULL);
  63         thrd_create(&t2, (thrd_start_t)&b, NULL);
  64         thrd_create(&t3, (thrd_start_t)&c, NULL);
  65
  66         thrd_join(t1);
  67         thrd_join(t2);
  68         thrd_join(t3);
  69         return 0;
  70 }