https://gcc.gnu.org/bugzilla/show_bug.cgi?id=94893
--- Comment #6 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
(In reply to Andrew Pinski from comment #4)
> (In reply to Andrew Pinski from comment #3)
> > Note we also don't optimize:
> >
> > inline int sign1(int x)
> > {
> > return (x < 0 ? -1 : 0) | (x > 0 ? 1 : 0);
> > }
> > bool f1(int x)
> > {
> > return sign1(x) < 1;
> > }
> >
> > To be just `x <= 0`
>
> That is because forwprop leaves assignments that are not used anywhere still.
> after dce7:
> ```
> if (x_2(D) < 0)
> goto <bb 4>; [41.00%]
> else
> goto <bb 3>; [59.00%]
>
> <bb 3> [local count: 633507680]:
> _7 = x_2(D) != 0;
> _8 = (int) _7;
> _5 = _8 ^ 1;
> _10 = (bool) _5;
>
> <bb 4> [local count: 1073741824]:
> # prephitmp_11 = PHI <1(2), _10(3)>
> ```
> After frowprop4:
> ```
> if (x_2(D) < 0)
> goto <bb 4>; [41.00%]
> else
> goto <bb 3>; [59.00%]
>
> <bb 3> [local count: 633507680]:
> _7 = x_2(D) != 0;
> _8 = (int) _7;
> _3 = x_2(D) == 0;
> _5 = (int) _3;
>
> <bb 4> [local count: 1073741824]:
> # prephitmp_11 = PHI <1(2), _3(3)>
> ```
>
> If those statements were removed then phiopt4 would be able to optimize
> prephitmp_11 to: `(x_2(D) < 0) | (x_2(D) == 0)` which simplifies to `x_2(D)
> <= 0` .
>
> Let me look into the forwprop issue here.
That was fixed with r14-3982-g9ea74d235c7e78 .
