[Bug tree-optimization/90917] Propagate constants into loads if dominated by str(n)cmp/memcmp

[david.bolvansky at gmail dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=90917

--- Comment #1 from Dávid Bolvanský <david.bolvansky at gmail dot com> ---
char f(void) {
  char* s = ... ;
  if (strcmp(global_s, s) == 0) return global_s[0];
  return '-';
}

------>

char f2(void) {
  char* s = ... ;
  if (strcmp(global_s, s) == 0) return s[0];
  return '-';
}