Eminem just went nuclear on Donald Trump ... dropping a freestyle at The BET Hip-Hop Awards that ripped The Prez apart.
The nearly 5 minute-long segment touched on everything from Trump's criticism of NFL players taking a knee to his proposed border wall.
Among some of Em's highlight lyrics ...
-"Racism's the only thing he's fantastic for."
-"I'm throwing that piece of s*** against the wall til it sticks."
-And giving a big "F*** YOU" to any of the rapper's fans who support 45.