// number of bytes between the start of the struct and the start of the field.
func Offsetof(x ArbitraryType) uintptr
-// Alignof takes an expression x of any type and returns the alignment
+// Alignof takes an expression x of any type and returns the required alignment
// of a hypothetical variable v as if v was declared via var v = x.
-// It is the largest value m such that the address of v is zero mod m.
+// It is the largest value m such that the address of v is always zero mod m.
+// It is the same as the value returned by reflect.TypeOf(x).Align().
+// As a special case, if s has a struct type and f is a field within that
+// struct, then Alignof(s.f) will return the required alignment of a field
+// of that type within a struct. This case is the same as the value returned
+// by reflect.TypeOf(s.f).FieldAlign().
func Alignof(x ArbitraryType) uintptr