gnu/dist/gcc4/gcc/testsuite/gcc.c-torture/execute/20011126-2.c

   1 /* Problem originally visible on ia64.
   2
   3    There is a partial redundancy of "in + 1" that makes GCSE want to
   4    transform the final while loop to
   5
   6      p = in + 1;
   7      tmp = p;
   8      ...
   9      goto start;
  10    top:
  11      tmp = tmp + 1;
  12    start:
  13      in = tmp;
  14      if (in < p) goto top;
  15
  16    We miscalculate the number of loop iterations as (p - tmp) = 0
  17    instead of (p - in) = 1, which results in overflow in the doloop
  18    optimization.  */
  19
  20 static const char *
  21 test (const char *in, char *out)
  22 {
  23   while (1)
  24     {
  25       if (*in == 'a')
  26         {
  27           const char *p = in + 1;
  28           while (*p == 'x')
  29             ++p;
  30           if (*p == 'b')
  31             return p;
  32           while (in < p)
  33             *out++ = *in++;
  34         }
  35     }
  36 }
  37
  38 int main ()
  39 {
  40   char out[4];
  41   test ("aab", out);
  42   return 0;
  43 }