[Bug tree-optimization/110176] wrong code at -Os and above on x86_64-linux-gnu

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

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=110176

--- Comment #1 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
Fre turns:
  b.2_4 = b;
  _5 = b.2_4 == 0;
  _6 = (int) _5;
  _7 = _6 <= i_19;
  _8 = (int) _7;
  b = _8;

Into:
  b.2_4 = b;
  _5 = b.2_4 == 0;
  _6 = (int) _5;
  b = 1;

Which is wrong as _6 <= -1 is always 0.

(simplify
(cmp (convert@0 @00) (convert?@1 @10))

...

tree min = lower_bound_in_type (TREE_TYPE (@10), TREE_TYPE (@00));
tree max = upper_bound_in_type (TREE_TYPE (@10), TREE_TYPE (@00));
bool above = integer_nonzerop (const_binop (LT_EXPR, type, max, @10));
bool below = integer_nonzerop (const_binop (LT_EXPR, type, @10, min));
...
(if (above || below)
...
{ constant_boolean_node (above ? true : false, type); }