2.35

/* Determine whether arguments can be multiplied without overflow */
int tmult_ok(int x, int y) {
    int p = x * y;
    return !x || p/x == y;
}

For x and y such that $TMin \le x,y \le TMax$: $x y = U2T(( x y ) mod 2^w) = p + t * 2^w$, if positive overflow, $ t = -1$, else if negative overflow, $t = 1$.
$r$ is remainder.
if $q$ equal $y$, then $xy - t2^w = x y + r$, then $r + tw^ = 0$, And $|r|< |x| < 2^w$, so $t=0$, then $r=0$.