[Bug tree-optimization/120929] [16 Regression] file-5.45 triggers _FORTIFY_SOURCE false positives since r16-1905-g7165ca43caf470

[siddhesh at gcc dot gnu.org via Gcc-bugs]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=120929

Siddhesh Poyarekar <siddhesh at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |siddhesh at gcc dot gnu.org

--- Comment #13 from Siddhesh Poyarekar <siddhesh at gcc dot gnu.org> ---
Here's a super-minimal test case:

typedef __SIZE_TYPE__ size_t;

extern void pin_pointer(void *);
extern int some_value(void);

struct magic_ {
        char unused[9]; // at least 9
};

struct magic_map {
        struct magic_ *magic;
};

static int
coalesce_entries(struct magic_ **ma)
{
  size_t slen;

  slen = sizeof (**ma);
  *ma = __builtin_malloc (slen);

  for (unsigned i = 0; i < 1; i++)
    {
      char b[1024] = {};
      struct magic_ *ptr = *ma;
      (void) __builtin___memcpy_chk (ptr, b, sizeof (*ptr),
                                     __builtin_dynamic_object_size (ptr, 0));
    }
  return 0;
}

struct magic_map *
apprentice_load(void)
{
  char buf[128]; // did not shrink, but needs to be more than 100
  struct magic_map *map2;

  map2 = __builtin_malloc (sizeof (*map2));

  pin_pointer(&buf);
  coalesce_entries(&map2->magic);
  pin_pointer(map2);
}

$ gcc/cc1 -quiet -fdump-tree-objsz-details -O1 ../countedby.c -o /dev/null