test verifier

function %test() -> i32 {   ; Ok
ebb0:
    v0 = iconst.i32 0
    v1 = iconst.i32 0
    jump ebb2

ebb2:
    jump ebb4

ebb4:
    jump ebb2

ebb3(v2: i32):
    v4 = iadd.i32 v1, v2
    jump ebb9(v4)

ebb9(v7: i32):
    v9 = iadd.i32 v2, v7
    return v9

}

; Using a function argument in an unreachable block is ok.
function %arg(i32) -> i32 {
ebb0(v0: i32):
    v1 = iadd_imm v0, 1
    return v1

ebb1:
    v10 = iadd_imm v0, 10
    return v10
}

; Using an EBB argument from an unreachable block is not ok.
function %arg2(i32) -> i32 {
ebb0(v0: i32):
    v1 = iadd v0, v10   ; error: uses value arg from non-dominating
    return v1

ebb1(v10: i32):
    v11 = iadd v0, v10
    return v11
}