kProfiler2/tstlongjmp.c

   1
   2 #include <setjmp.h>
   3 #include <time.h>
   4
   5 /* just try trick the compiler into not optimizing stuff by
   6    making it "uncertain" which path to take. */
   7 int always_true(void)
   8 {
   9     time_t t = time(NULL);
  10     if (t == time(NULL))
  11         return 1;
  12     if (t != time(NULL))
  13         return 1;
  14     if (t == time(NULL))
  15         return 1;
  16     if (t != time(NULL))
  17         return 1;
  18     return 0;
  19 }
  20
  21 jmp_buf g_JmpBuf;
  22
  23 int onelevel(void)
  24 {
  25     if (always_true())
  26         longjmp(g_JmpBuf, 1);
  27     return 0;
  28 }
  29
  30
  31 int twolevels_inner(void)
  32 {
  33     if (always_true())
  34         longjmp(g_JmpBuf, 1);
  35     return 0;
  36 }
  37
  38 int twolevels_outer(void)
  39 {
  40     int rc;
  41     always_true();
  42     rc = twolevels_inner();
  43     always_true();
  44     return rc;
  45 }
  46
  47
  48 int main()
  49 {
  50     int rc = 1;
  51
  52     /* first */
  53     if (!setjmp(g_JmpBuf))
  54         rc = onelevel();
  55
  56     /* second */
  57     if (!setjmp(g_JmpBuf))
  58         rc = twolevels_outer();
  59
  60     return rc != 1;
  61 }
  62