A child of an amaleki and a bas yisrael would be a yisroel. end of that discussion.
Actually, that is not so certain. If you have a look at ?????? ??????? ?? ??: ?”? ?’ ??????, Tosfos says that the product of a union between a Bas Yisroel and Oived Kochavim would actually be a GOY.
(See :??”? ?”? and ???”? in ?????? ???; see also ????”? on the tosfos cited above)