compiler-rt/test/tsan/mop1.c

   1 // RUN: %clang_tsan -O1 %s -o %t && %deflake %run %t | FileCheck %s
   2 #include "test.h"
   3
   4 // We want to establish the following sequence of accesses to X:
   5 // - main thread writes X
   6 // - thread2 reads X, this read happens-before the write in main thread
   7 // - thread1 reads X, this read is concurrent with the write in main thread
   8 // Write in main thread and read in thread1 should be detected as a race.
   9 // Previously tsan replaced write by main thread with read by thread1,
  10 // as the result the race was not detected.
  11
  12 volatile long X, Y, Z;
  13
  14 void *Thread1(void *x) {
  15   barrier_wait(&barrier);
  16   barrier_wait(&barrier);
  17   Y = X;
  18   return NULL;
  19 }
  20
  21 void *Thread2(void *x) {
  22   Z = X;
  23   barrier_wait(&barrier);
  24   return NULL;
  25 }
  26
  27 int main() {
  28   barrier_init(&barrier, 2);
  29   pthread_t t[2];
  30   pthread_create(&t[0], 0, Thread1, 0);
  31   X = 42;
  32   barrier_wait(&barrier);
  33   pthread_create(&t[1], 0, Thread2, 0);
  34   pthread_join(t[0], 0);
  35   pthread_join(t[1], 0);
  36   return 0;
  37 }
  38
  39 // CHECK: WARNING: ThreadSanitizer: data race
  40