[Bug tree-optimization/86203] duplicate non-constant call to strlen() not folded

[msebor at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=86203

--- Comment #4 from Martin Sebor <msebor at gcc dot gnu.org> ---
You're right, a strict reading of the standard does imply that the pointer
argument to strlen could point to the integer.  I keep forgetting about this
unfortunate loophole.  Ironically, the equivalent code using snprintf could be
optimized because the argument to %s "shall be a pointer to the initial element
of an array of character type."  I.e., it cannot point to an int object:

  int n;

  int f (char *s)
  {
    n = __builtin_snprintf (0, 0, "%s", s);
    return __builtin_snprintf (0, 0, "%s", s);   // could be replaced by return
n;
  }