This patch is mainly to deal with folding `truncf`, as follows: `truncf(extf(a))` -> `a`, if `a` has the same bitwidth as the result `truncf(extf(a))` -> `truncf(a)`, if `a` has larger bitwidth than the result
This patch is mainly to deal with folding `truncf`, as follows: `truncf(extf(a))` -> `a`, if `a` has the same bitwidth as the result `truncf(extf(a))` -> `truncf(a)`, if `a` has larger bitwidth than the result