[Bug tree-optimization/82911] missing strlen optimization for strncpy with constant strings and constant bound

[pinskia at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=82911

Andrew Pinski <pinskia at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
     Ever confirmed|0                           |1
   Last reconfirmed|                            |2021-09-05
             Status|UNCONFIRMED                 |NEW
           Severity|normal                      |enhancement

--- Comment #1 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
Confirmed.

A related testcase is:
void f1 (char *d, char *e, bool b)
{
  d[2] = 0;

  if (__builtin_strlen (d) > 2)   // not eliminated but could be
    __builtin_abort ();
}

where the strlen's range should be [0,2]. Maybe we can add a class to the
ranger for string and do the optimization that way instead.
so the null store to d[2] the range for the string becomes [0,2].