x = x + y
	x = x - y
	x = x * y
	x = x / y
	x = x % y
	x = x << y
	x = x >> y

	z = z + 1
	z = z + 1.0
	z = z + 1.1 // ERROR "truncated to int"
	z = z /* ERROR "mismatched types" */ + y
	z = z /* ERROR "mismatched types" */ - y
	z = z /* ERROR "mismatched types" */ * y
	z = z /* ERROR "mismatched types" */ / y
	z = z /* ERROR "mismatched types" */ % y
	z = z << y
	z = z >> y
}

		if y, ok := y.(*Basic); ok {
			return x.kind == y.kind
		}

	case *Array:
		// Two array types are identical if they have identical element types
		// and the same array length.
		if y, ok := y.(*Array); ok {
			// If one or both array lengths are unknown (< 0) due to some error,
			// assume they are the same to avoid spurious follow-on errors.
			return (x.len < 0 || y.len < 0 || x.len == y.len) && c.identical(x.elem, y.elem, p)

				}
				if x <= y {
					fmt.Fprintf(w, "\t\tif !(x <= y) { t.Errorf(\"!(%%d <= %%d)\", x, y) }\n")
				} else {
					fmt.Fprintf(w, "\t\tif x <= y { t.Errorf(\"%%d <= %%d\", x, y) }\n")
				}
				if x >= y {
					fmt.Fprintf(w, "\t\tif !(x >= y) { t.Errorf(\"!(%%d >= %%d)\", x, y) }\n")
				} else {
					fmt.Fprintf(w, "\t\tif x >= y { t.Errorf(\"%%d >= %%d\", x, y) }\n")
				}

	x  Expr
}{
	{"x", tag("x")},
	{"x&&y", and(tag("x"), tag("y"))},
	{"x||y", or(tag("x"), tag("y"))},
	{"(x)", tag("x")},
	{"x||y&&z", or(tag("x"), and(tag("y"), tag("z")))},
	{"x&&y||z", or(and(tag("x"), tag("y")), tag("z"))},
	{"x&&(y||z)", and(tag("x"), or(tag("y"), tag("z")))},
	{"(x||y)&&z", and(or(tag("x"), tag("y")), tag("z"))},
	{"!(x&&y)", not(and(tag("x"), tag("y")))},
}

func TestParseExpr(t *testing.T) {

(Mod8u x y) => (Mod32u (ZeroExt8to32 x) (ZeroExt8to32 y))
(Mod64 x y) && buildcfg.GOPPC64 >=9 => (MODSD x y)
(Mod64 x y) && buildcfg.GOPPC64 <=8 => (SUB x (MULLD y (DIVD x y)))
(Mod64u x y) && buildcfg.GOPPC64 >= 9 => (MODUD x y)
(Mod64u x y) && buildcfg.GOPPC64 <= 8 => (SUB x (MULLD y (DIVDU x y)))
(Mod32 x y) && buildcfg.GOPPC64 >= 9 => (MODSW x y)
(Mod32 x y) && buildcfg.GOPPC64 <= 8 => (SUB x (MULLW y (DIVW x y)))

		return (y-p.Rect.Min.Y)*p.CStride + (x/2 - p.Rect.Min.X/2)
	case YCbCrSubsampleRatio420:
		return (y/2-p.Rect.Min.Y/2)*p.CStride + (x/2 - p.Rect.Min.X/2)
	case YCbCrSubsampleRatio440:
		return (y/2-p.Rect.Min.Y/2)*p.CStride + (x - p.Rect.Min.X)
	case YCbCrSubsampleRatio411:
		return (y-p.Rect.Min.Y)*p.CStride + (x/4 - p.Rect.Min.X/4)
	case YCbCrSubsampleRatio410:
		return (y/2-p.Rect.Min.Y/2)*p.CStride + (x/4 - p.Rect.Min.X/4)
	}

	switch {
	case x == nil && y == nil:
		return nil, nil // ∅ ∪ ∅ == ∅
	case x == nil:
		return y, nil // ∅ ∪ y == y
	case y == nil:
		return x, nil // x ∪ ∅ == x
	case x.typ == nil:
		return x, nil // 𝓤 ∪ y == 𝓤
	case y.typ == nil:
		return y, nil // x ∪ 𝓤 == 𝓤
	}
	// ∅ ⊂ x, y ⊂ 𝓤

	if x.disjoint(y) {
		return x, y // x ∪ y == (x, y) if x ∩ y == ∅
	}
	// x.typ == y.typ

	// ~t ∪ ~t == ~t

	switch {
	case x == nil && y == nil:
		return nil, nil // ∅ ∪ ∅ == ∅
	case x == nil:
		return y, nil // ∅ ∪ y == y
	case y == nil:
		return x, nil // x ∪ ∅ == x
	case x.typ == nil:
		return x, nil // 𝓤 ∪ y == 𝓤
	case y.typ == nil:
		return y, nil // x ∪ 𝓤 == 𝓤
	}
	// ∅ ⊂ x, y ⊂ 𝓤

	if x.disjoint(y) {
		return x, y // x ∪ y == (x, y) if x ∩ y == ∅
	}
	// x.typ == y.typ

	// ~t ∪ ~t == ~t

	switch {
	case x == nil && y == nil:
		return nil, nil // ∅ ∪ ∅ == ∅
	case x == nil:
		return y, nil // ∅ ∪ y == y
	case y == nil:
		return x, nil // x ∪ ∅ == x
	case x.typ == nil:
		return x, nil // 𝓤 ∪ y == 𝓤
	case y.typ == nil:
		return y, nil // x ∪ 𝓤 == 𝓤
	}
	// ∅ ⊂ x, y ⊂ 𝓤

	if x.disjoint(y) {
		return x, y // x ∪ y == (x, y) if x ∩ y == ∅
	}
	// x.typ == y.typ

	// ~t ∪ ~t == ~t

		}
		return Copysign(Pi, y)
	case x == 0:
		return Copysign(Pi/2, y)
	case IsInf(x, 0):
		if IsInf(x, 1) {
			switch {
			case IsInf(y, 0):
				return Copysign(Pi/4, y)
			default:
				return Copysign(0, y)
			}
		}
		switch {
		case IsInf(y, 0):
			return Copysign(3*Pi/4, y)
		default:
			return Copysign(Pi, y)
		}
	case IsInf(y, 0):
		return Copysign(Pi/2, y)
	}