gcc/testsuite/gcc.dg/tree-ssa/calloc-5.c

   1 /* PR tree-optimization/83821 - local aggregate initialization defeats
   2    strlen optimization
   3    Verify that with DSE disabled, a memset() call to zero out a subregion
   4    of memory allocated by calloc() is not eliminated after a non-zero byte
   5    is written into it using memset() in between the two calls.
   6    { dg-do compile }
   7    { dg-options "-O2 -fno-tree-dse -fdump-tree-optimized" } */
   8
   9 char* keep_memset_calls (void)
  10 {
  11   char *p = __builtin_calloc (12, 1);
  12
  13   __builtin_memset (p + 5, 1, 2);   /* dead store (not eliminated) */
  14
  15   __builtin_memset (p, 0, 12);      /* must not be eliminated */
  16
  17   return p;
  18 }
  19
  20 /* { dg-final { scan-tree-dump-not "malloc" "optimized" } }
  21    { dg-final { scan-tree-dump-times "_calloc \\\(" 1 "optimized" } }
  22    { dg-final { scan-tree-dump-times "_memset \\\(" 2 "optimized" } } */