func arrayElementSize(t types.T) int32 {
	ret := t.Size()
	if t.RegSizeAlign() {
		return types.RegSizeAlignUp(ret)
	}
	return ret
}

func buildCast(b *builder, from *ref, t types.T) *ref {
	srcType := from.Type()
	ret := b.newTemp(t)

	if types.IsNil(srcType) {
		size := t.Size()
		if size == arch8.RegSize {
			return newRef(t, ir.Num(0))
		}
		if _, ok := t.(*types.Slice); !ok {
			panic("bug")
		}
		ret := b.newTemp(t)
		b.b.Zero(ret.IR())
		return ret
	}

	if c, ok := srcType.(*types.Const); ok {
		if v, ok := types.NumConst(srcType); ok && types.IsInteger(t) {
			return newRef(t, constNumIr(v, t))
		}
		// TODO: we do not support typed const right?
		// so why need this line?
		srcType = c.Type // using the underlying type
	}

	if types.IsInteger(t) && types.IsInteger(srcType) {
		b.b.Arith(ret.IR(), nil, "cast", from.IR())
		return ret
	}
	if regSizeCastable(t, srcType) {
		b.b.Arith(ret.IR(), nil, "", from.IR())
		return ret
	}
	panic("bug")
}

func (b *builder) newGlobalVar(t types.T, name string) ir.Ref {
	name = b.anonyName(name)
	return b.p.NewGlobalVar(t.Size(), name, types.IsByte(t), t.RegSizeAlign())
}

func (b *builder) newLocal(t types.T, name string) ir.Ref {
	return b.f.NewLocal(t.Size(), name,
		types.IsByte(t), t.RegSizeAlign(),
	)
}

func (b *builder) newTempIR(t types.T) ir.Ref {
	return b.f.NewTemp(t.Size(), types.IsByte(t), t.RegSizeAlign())
}