gcc/testsuite/gcc.dg/strlenopt-86.c

   1 /* PR tree-optimization/83821 - local aggregate initialization defeats
   2    strlen optimization
   3    Verify that a strlen() call is not eliminated for a pointer to a region
   4    of memory allocated by calloc() if a byte is written into the region
   5    that isn't known to be nul.
   6    { dg-do compile }
   7    { dg-options "-O2 -fdump-tree-optimized" } */
   8
   9 unsigned n0, n1;
  10
  11 void*
  12 keep_strlen_calloc_store_cst_memset (int i, unsigned a, unsigned b)
  13 {
  14   char *p = __builtin_calloc (a, 1);
  15
  16   p[i] = 'x';
  17
  18   __builtin_memset (p, 0, b);
  19
  20   n0 = __builtin_strlen (p);
  21
  22   return p;
  23 }
  24
  25 void*
  26 keep_strlen_calloc_store_var_memset (int i, int x, unsigned a, unsigned b)
  27 {
  28   char *p = __builtin_calloc (a, 1);
  29
  30   p[i] = x;
  31
  32   __builtin_memset (p, 0, b);
  33
  34   n0 = __builtin_strlen (p);
  35
  36   return p;
  37 }
  38
  39 void*
  40 keep_strlen_calloc_store_memset_2 (int i, int x, unsigned a, unsigned b, unsigned c)
  41 {
  42   char *p = __builtin_calloc (a, 1);
  43
  44   p[i] = x;
  45   __builtin_memset (p, 0, b);
  46
  47   n0 = __builtin_strlen (p);
  48
  49   p[3] = x;
  50   __builtin_memset (p, 0, c);
  51
  52   n1 = __builtin_strlen (p);
  53
  54   return p;
  55 }
  56
  57 /* { dg-final { scan-tree-dump-times "__builtin_strlen" 4 "optimized" } } */