(ConstSlice) && config.PtrSize == 4 =>
  (SliceMake
    (ConstNil <v.Type.Elem().PtrTo()>)
    (Const32 <typ.Int> [0])
    (Const32 <typ.Int> [0]))
(ConstSlice) && config.PtrSize == 8 =>
  (SliceMake
    (ConstNil <v.Type.Elem().PtrTo()>)
    (Const64 <typ.Int> [0])
    (Const64 <typ.Int> [0]))

// interface ops
(ConstInterface) =>
  (IMake
    (ConstNil <typ.Uintptr>)
    (ConstNil <typ.BytePtr>))

// constants
(Const(64|32|16|8) [val]) => (MOVDconst [int64(val)])
(Const(32|64)F    [val]) => (FMOV(S|D)const [float64(val)])
(ConstNil) => (MOVDconst [0])
(ConstBool [t]) => (MOVDconst [b2i(t)])

(Slicemask <t> x) => (SRAconst (NEG <t> x) [63])

// truncations
// Because we ignore high parts of registers, truncates are just copies.