Nested pattern matching on an enum with niche optimization generates multiple switches

enum E1 {
	A,
	B,
	C,
	D,
	E,
}

enum E2 {
	E1(E1),
	AA,
	BB,
}

#[unsafe(no_mangle)]
pub fn xx(e2: E2) -> i32 {
	match e2 {
		E2::E1(E1::A) => 999,
		E2::E1(E1::B) => 888,
		E2::E1(E1::C) => 422,
        E2::E1(E1::D) => 483,
        E2::E1(_) => std::hint::black_box(213),
		E2::AA => 123,
		E2::BB => 456,
	}
}

rustc generates 2 switch instructions, first on tag - 4, then on tag. LLVM fails to merge the 2 switches. Ideally there should be only 1 single switch:

switch i8 %0, label %bb1 [
    i8 0, label %bb10
    i8 1, label %bb8
    i8 2, label %bb7
    i8 3, label %bb6
    i8 4, label %bb5
    i8 5, label %bb2
    i8 6, label %bb10
    i8 7, label %bb3
  ]

Godbolt link: https://godbolt.org/z/jzxa3osGo.