// into equivalence classes (Types that compare CMPeq) matters.
func (t *Type) Compare(x *Type) Cmp {
	if x == t {
		return CMPeq
	}
	return t.cmp(x)
}

func cmpForNe(x bool) Cmp {
	if x {
		return CMPlt
	}
	return CMPgt
}

func (r *Sym) cmpsym(s *Sym) Cmp {
	if r == s {
		return CMPeq
	}
	if r == nil {
		return CMPlt
	}
	if s == nil {

			// the spill location.
			var name LocalSlot
			if v.Op == OpStoreReg {
				name = names[v.Args[0].ID]
			} else {
				name = names[v.ID]
			}
			if name.N != nil && v.Type.Compare(name.Type) == types.CMPeq {
				for _, id := range s.interfere[v.ID] {
					h := f.getHome(id)
					if h != nil && h.(LocalSlot).N == name.N && h.(LocalSlot).Off == name.Off {
						// A variable can interfere with itself.

	// The goal here is stability in the face
	// of unrelated changes elsewhere in the compiler.
	if c := x.AuxInt - y.AuxInt; c != 0 {
		return c < 0
	}
	if cmp := x.Type.Compare(y.Type); cmp != types.CMPeq {
		return cmp == types.CMPlt
	}
	return x.ID < y.ID
}

func (op Op) isLoweredGetClosurePtr() bool {
	switch op {

(Load <t1> p1 (Store {t2} p2 x _))
	&& isSamePtr(p1, p2)
	&& t1.Compare(x.Type) == types.CMPeq
	&& t1.Size() == t2.Size()
	=> x
(Load <t1> p1 (Store {t2} p2 _ (Store {t3} p3 x _)))
	&& isSamePtr(p1, p3)
	&& t1.Compare(x.Type) == types.CMPeq
	&& t1.Size() == t2.Size()
	&& disjoint(p3, t3.Size(), p2, t2.Size())
	=> x

(Eq32 x y) => (SGTU (MOVVconst [1]) (XOR (ZeroExt32to64 x) (ZeroExt32to64 y)))
(Eq64 x y) => (SGTU (MOVVconst [1]) (XOR x y))
(EqPtr x y) => (SGTU (MOVVconst [1]) (XOR x y))
(Eq(32|64)F x y) => (FPFlagTrue (CMPEQ(F|D) x y))

(Neq8 x y)  => (SGTU (XOR (ZeroExt8to64 x) (ZeroExt8to64 y)) (MOVVconst [0]))
(Neq16 x y) => (SGTU (XOR (ZeroExt16to32 x) (ZeroExt16to64 y)) (MOVVconst [0]))

(Eq32 x y) => (SGTU (MOVVconst [1]) (XOR (ZeroExt32to64 x) (ZeroExt32to64 y)))
(Eq64 x y) => (SGTU (MOVVconst [1]) (XOR x y))
(EqPtr x y) => (SGTU (MOVVconst [1]) (XOR x y))
(Eq(32|64)F x y) => (FPFlagTrue (CMPEQ(F|D) x y))

(Neq8 x y)  => (SGTU (XOR (ZeroExt8to64 x) (ZeroExt8to64 y)) (MOVVconst [0]))
(Neq16 x y) => (SGTU (XOR (ZeroExt16to32 x) (ZeroExt16to64 y)) (MOVVconst [0]))

	SCASD:     "scas",
	SCASQ:     "scas",
	SCASW:     "scas",
	STOSB:     "stos",
	STOSD:     "stos",
	STOSQ:     "stos",
	STOSW:     "stos",
	XLATB:     "xlat",
}

var cmppsOps = []string{
	"cmpeq",
	"cmplt",
	"cmple",
	"cmpunord",
	"cmpneq",
	"cmpnlt",
	"cmpnle",
	"cmpord",
}

var pclmulqOps = []string{
	"pclmullqlqdq",
	"pclmulhqlqdq",
	"pclmullqhqdq",
	"pclmulhqhqdq",

	if f.constants == nil {
		f.constants = make(map[int64][]*Value)
	}
	vv := f.constants[c]
	for _, v := range vv {
		if v.Op == op && v.Type.Compare(t) == types.CMPeq {
			if setAuxInt && v.AuxInt != c {
				panic(fmt.Sprintf("cached const %s should have AuxInt of %d", v.LongString(), c))
			}
			return v
		}
	}
	var v *Value
	if setAuxInt {

	// cond: isSamePtr(p1, p2) && t1.Compare(x.Type) == types.CMPeq && t1.Size() == t2.Size()
	// result: x
	for {
		t1 := v.Type
		p1 := v_0
		if v_1.Op != OpStore {
			break
		}
		t2 := auxToType(v_1.Aux)
		x := v_1.Args[1]
		p2 := v_1.Args[0]
		if !(isSamePtr(p1, p2) && t1.Compare(x.Type) == types.CMPeq && t1.Size() == t2.Size()) {
			break
		}
		v.copyOf(x)