diff --git a/src/cmd/compile/internal/gc/alg.go b/src/cmd/compile/internal/gc/alg.go
index 448986203df..e9b5afe8381 100644
--- a/src/cmd/compile/internal/gc/alg.go
+++ b/src/cmd/compile/internal/gc/alg.go
@@ -122,7 +122,7 @@ func algtype1(t *Type) (AlgKind, *Type) {
 		return ASTRING, nil
 
 	case TINTER:
-		if isnilinter(t) {
+		if t.IsEmptyInterface() {
 			return ANILINTER, nil
 		}
 		return AINTER, nil
diff --git a/src/cmd/compile/internal/gc/bexport.go b/src/cmd/compile/internal/gc/bexport.go
index 15b3118f165..bfa5a501a0a 100644
--- a/src/cmd/compile/internal/gc/bexport.go
+++ b/src/cmd/compile/internal/gc/bexport.go
@@ -356,7 +356,7 @@ func Export(out *obj.Biobuf, trace bool) int {
 func unidealType(typ *Type, val Val) *Type {
 	// Untyped (ideal) constants get their own type. This decouples
 	// the constant type from the encoding of the constant value.
-	if typ == nil || isideal(typ) {
+	if typ == nil || typ.IsUntyped() {
 		typ = untype(val.Ctype())
 	}
 	return typ
diff --git a/src/cmd/compile/internal/gc/bimport.go b/src/cmd/compile/internal/gc/bimport.go
index f0953966d3b..0a51ab037fe 100644
--- a/src/cmd/compile/internal/gc/bimport.go
+++ b/src/cmd/compile/internal/gc/bimport.go
@@ -131,7 +131,7 @@ func Import(in *bufio.Reader) {
 }
 
 func idealType(typ *Type) *Type {
-	if isideal(typ) {
+	if typ.IsUntyped() {
 		// canonicalize ideal types
 		typ = Types[TIDEAL]
 	}
@@ -519,7 +519,7 @@ func (p *importer) value(typ *Type) (x Val) {
 	}
 
 	// verify ideal type
-	if isideal(typ) && untype(x.Ctype()) != typ {
+	if typ.IsUntyped() && untype(x.Ctype()) != typ {
 		Fatalf("importer: value %v and type %v don't match", x, typ)
 	}
 
diff --git a/src/cmd/compile/internal/gc/cgen.go b/src/cmd/compile/internal/gc/cgen.go
index 22cd87b2942..5cab13bc4e0 100644
--- a/src/cmd/compile/internal/gc/cgen.go
+++ b/src/cmd/compile/internal/gc/cgen.go
@@ -174,7 +174,7 @@ func cgen_wb(n, res *Node, wb bool) {
 	// changes if n->left is an escaping local variable.
 	switch n.Op {
 	case OSPTR, OLEN:
-		if n.Left.Type.IsSlice() || Istype(n.Left.Type, TSTRING) {
+		if n.Left.Type.IsSlice() || n.Left.Type.IsString() {
 			n.Addable = n.Left.Addable
 		}
 
@@ -554,7 +554,7 @@ func cgen_wb(n, res *Node, wb bool) {
 		Regfree(&n1)
 
 	case OLEN:
-		if Istype(nl.Type, TMAP) || Istype(nl.Type, TCHAN) {
+		if nl.Type.IsMap() || nl.Type.IsChan() {
 			// map and chan have len in the first int-sized word.
 			// a zero pointer means zero length
 			var n1 Node
@@ -578,7 +578,7 @@ func cgen_wb(n, res *Node, wb bool) {
 			break
 		}
 
-		if Istype(nl.Type, TSTRING) || nl.Type.IsSlice() {
+		if nl.Type.IsString() || nl.Type.IsSlice() {
 			// both slice and string have len one pointer into the struct.
 			// a zero pointer means zero length
 			var n1 Node
@@ -594,7 +594,7 @@ func cgen_wb(n, res *Node, wb bool) {
 		Fatalf("cgen: OLEN: unknown type %v", Tconv(nl.Type, FmtLong))
 
 	case OCAP:
-		if Istype(nl.Type, TCHAN) {
+		if nl.Type.IsChan() {
 			// chan has cap in the second int-sized word.
 			// a zero pointer means zero length
 			var n1 Node
diff --git a/src/cmd/compile/internal/gc/const.go b/src/cmd/compile/internal/gc/const.go
index a9ca129fd9e..160eb66d5e6 100644
--- a/src/cmd/compile/internal/gc/const.go
+++ b/src/cmd/compile/internal/gc/const.go
@@ -117,10 +117,10 @@ func convlit(n *Node, t *Type) *Node {
 // The result of convlit1 MUST be assigned back to n, e.g.
 // 	n.Left = convlit1(n.Left, t, explicit, reuse)
 func convlit1(n *Node, t *Type, explicit bool, reuse canReuseNode) *Node {
-	if n == nil || t == nil || n.Type == nil || isideal(t) || n.Type == t {
+	if n == nil || t == nil || n.Type == nil || t.IsUntyped() || n.Type == t {
 		return n
 	}
-	if !explicit && !isideal(n.Type) {
+	if !explicit && !n.Type.IsUntyped() {
 		return n
 	}
 
@@ -157,7 +157,7 @@ func convlit1(n *Node, t *Type, explicit bool, reuse canReuseNode) *Node {
 		}
 
 	case OLSH, ORSH:
-		n.Left = convlit1(n.Left, t, explicit && isideal(n.Left.Type), noReuse)
+		n.Left = convlit1(n.Left, t, explicit && n.Left.Type.IsUntyped(), noReuse)
 		t = n.Left.Type
 		if t != nil && t.Etype == TIDEAL && n.Val().Ctype() != CTINT {
 			n.SetVal(toint(n.Val()))
@@ -319,7 +319,7 @@ bad:
 		n.Diag = 1
 	}
 
-	if isideal(n.Type) {
+	if n.Type.IsUntyped() {
 		n = defaultlitreuse(n, nil, reuse)
 	}
 	return n
@@ -1189,7 +1189,7 @@ func nodcplxlit(r Val, i Val) *Node {
 // idealkind returns a constant kind like consttype
 // but for an arbitrary "ideal" (untyped constant) expression.
 func idealkind(n *Node) Ctype {
-	if n == nil || !isideal(n.Type) {
+	if n == nil || !n.Type.IsUntyped() {
 		return CTxxx
 	}
 
@@ -1259,7 +1259,7 @@ func defaultlit(n *Node, t *Type) *Node {
 // The result of defaultlitreuse MUST be assigned back to n, e.g.
 // 	n.Left = defaultlitreuse(n.Left, t, reuse)
 func defaultlitreuse(n *Node, t *Type, reuse canReuseNode) *Node {
-	if n == nil || !isideal(n.Type) {
+	if n == nil || !n.Type.IsUntyped() {
 		return n
 	}
 
@@ -1365,12 +1365,12 @@ func defaultlit2(l *Node, r *Node, force bool) (*Node, *Node) {
 	if l.Type == nil || r.Type == nil {
 		return l, r
 	}
-	if !isideal(l.Type) {
+	if !l.Type.IsUntyped() {
 		r = convlit(r, l.Type)
 		return l, r
 	}
 
-	if !isideal(r.Type) {
+	if !r.Type.IsUntyped() {
 		l = convlit(l, r.Type)
 		return l, r
 	}
diff --git a/src/cmd/compile/internal/gc/esc.go b/src/cmd/compile/internal/gc/esc.go
index e6f543f05d0..0346cd41fd2 100644
--- a/src/cmd/compile/internal/gc/esc.go
+++ b/src/cmd/compile/internal/gc/esc.go
@@ -1337,7 +1337,7 @@ func (e *EscState) addDereference(n *Node) *Node {
 	e.nodeEscState(ind).Escloopdepth = e.nodeEscState(n).Escloopdepth
 	ind.Lineno = n.Lineno
 	t := n.Type
-	if Istype(t, Tptr) {
+	if t.IsKind(Tptr) {
 		// This should model our own sloppy use of OIND to encode
 		// decreasing levels of indirection; i.e., "indirecting" an array
 		// might yield the type of an element. To be enhanced...
diff --git a/src/cmd/compile/internal/gc/export.go b/src/cmd/compile/internal/gc/export.go
index 09f048b7580..0a0906c5d17 100644
--- a/src/cmd/compile/internal/gc/export.go
+++ b/src/cmd/compile/internal/gc/export.go
@@ -233,7 +233,7 @@ func dumpexportconst(s *Sym) {
 	t := n.Type // may or may not be specified
 	dumpexporttype(t)
 
-	if t != nil && !isideal(t) {
+	if t != nil && !t.IsUntyped() {
 		exportf("\tconst %v %v = %v\n", Sconv(s, FmtSharp), Tconv(t, FmtSharp), Vconv(n.Val(), FmtSharp))
 	} else {
 		exportf("\tconst %v = %v\n", Sconv(s, FmtSharp), Vconv(n.Val(), FmtSharp))
diff --git a/src/cmd/compile/internal/gc/fmt.go b/src/cmd/compile/internal/gc/fmt.go
index b9a0a61638c..7ed08516a0f 100644
--- a/src/cmd/compile/internal/gc/fmt.go
+++ b/src/cmd/compile/internal/gc/fmt.go
@@ -1366,7 +1366,7 @@ func exprfmt(n *Node, prec int) string {
 		if n.Right != nil {
 			return fmt.Sprintf("make(%v, %v, %v)", n.Type, n.Left, n.Right)
 		}
-		if n.Left != nil && (n.Op == OMAKESLICE || !isideal(n.Left.Type)) {
+		if n.Left != nil && (n.Op == OMAKESLICE || !n.Left.Type.IsUntyped()) {
 			return fmt.Sprintf("make(%v, %v)", n.Type, n.Left)
 		}
 		return fmt.Sprintf("make(%v)", n.Type)
diff --git a/src/cmd/compile/internal/gc/gen.go b/src/cmd/compile/internal/gc/gen.go
index f99e8d4a098..4a98f41bcb8 100644
--- a/src/cmd/compile/internal/gc/gen.go
+++ b/src/cmd/compile/internal/gc/gen.go
@@ -403,7 +403,7 @@ func cgen_dottype(n *Node, res, resok *Node, wb bool) {
 	Regalloc(&r1, byteptr, nil)
 	iface.Type = byteptr
 	Cgen(&iface, &r1)
-	if !isnilinter(n.Left.Type) {
+	if !n.Left.Type.IsEmptyInterface() {
 		// Holding itab, want concrete type in second word.
 		p := Thearch.Ginscmp(OEQ, byteptr, &r1, Nodintconst(0), -1)
 		r2 = r1
@@ -492,7 +492,7 @@ func Cgen_As2dottype(n, res, resok *Node) {
 	Regalloc(&r1, byteptr, res)
 	iface.Type = byteptr
 	Cgen(&iface, &r1)
-	if !isnilinter(n.Left.Type) {
+	if !n.Left.Type.IsEmptyInterface() {
 		// Holding itab, want concrete type in second word.
 		p := Thearch.Ginscmp(OEQ, byteptr, &r1, Nodintconst(0), -1)
 		r2 = r1
diff --git a/src/cmd/compile/internal/gc/racewalk.go b/src/cmd/compile/internal/gc/racewalk.go
index 6ef6d47b8f6..09889a40f3a 100644
--- a/src/cmd/compile/internal/gc/racewalk.go
+++ b/src/cmd/compile/internal/gc/racewalk.go
@@ -222,7 +222,7 @@ func instrumentnode(np **Node, init *Nodes, wr int, skip int) {
 
 	case OSPTR, OLEN, OCAP:
 		instrumentnode(&n.Left, init, 0, 0)
-		if Istype(n.Left.Type, TMAP) {
+		if n.Left.Type.IsMap() {
 			n1 := Nod(OCONVNOP, n.Left, nil)
 			n1.Type = Ptrto(Types[TUINT8])
 			n1 = Nod(OIND, n1, nil)
diff --git a/src/cmd/compile/internal/gc/reflect.go b/src/cmd/compile/internal/gc/reflect.go
index 7d07b4b0642..95e5214a430 100644
--- a/src/cmd/compile/internal/gc/reflect.go
+++ b/src/cmd/compile/internal/gc/reflect.go
@@ -918,7 +918,7 @@ func typesymprefix(prefix string, t *Type) *Sym {
 }
 
 func typenamesym(t *Type) *Sym {
-	if t == nil || (t.IsPtr() && t.Elem() == nil) || isideal(t) {
+	if t == nil || (t.IsPtr() && t.Elem() == nil) || t.IsUntyped() {
 		Fatalf("typename %v", t)
 	}
 	s := typesym(t)
@@ -946,7 +946,7 @@ func typename(t *Type) *Node {
 }
 
 func itabname(t, itype *Type) *Node {
-	if t == nil || (t.IsPtr() && t.Elem() == nil) || isideal(t) {
+	if t == nil || (t.IsPtr() && t.Elem() == nil) || t.IsUntyped() {
 		Fatalf("itabname %v", t)
 	}
 	s := Pkglookup(Tconv(t, FmtLeft)+","+Tconv(itype, FmtLeft), itabpkg)
@@ -1076,7 +1076,7 @@ func dtypesym(t *Type) *Sym {
 		t = Types[t.Etype]
 	}
 
-	if isideal(t) {
+	if t.IsUntyped() {
 		Fatalf("dtypesym %v", t)
 	}
 
diff --git a/src/cmd/compile/internal/gc/ssa.go b/src/cmd/compile/internal/gc/ssa.go
index 193ee07903e..0f696c2f9a7 100644
--- a/src/cmd/compile/internal/gc/ssa.go
+++ b/src/cmd/compile/internal/gc/ssa.go
@@ -3475,7 +3475,7 @@ func (s *state) floatToUint(cvttab *f2uCvtTab, n *Node, x *ssa.Value, ft, tt *Ty
 func (s *state) ifaceType(n *Node, v *ssa.Value) *ssa.Value {
 	byteptr := Ptrto(Types[TUINT8]) // type used in runtime prototypes for runtime type (*byte)
 
-	if isnilinter(n.Type) {
+	if n.Type.IsEmptyInterface() {
 		// Have *eface. The type is the first word in the struct.
 		return s.newValue1(ssa.OpITab, byteptr, v)
 	}
@@ -4189,7 +4189,7 @@ func (e *ssaExport) SplitInterface(name ssa.LocalSlot) (ssa.LocalSlot, ssa.Local
 	if n.Class == PAUTO && !n.Addrtaken {
 		// Split this interface up into two separate variables.
 		f := ".itab"
-		if isnilinter(n.Type) {
+		if n.Type.IsEmptyInterface() {
 			f = ".type"
 		}
 		c := e.namedAuto(n.Sym.Name+f, t)
diff --git a/src/cmd/compile/internal/gc/subr.go b/src/cmd/compile/internal/gc/subr.go
index 3e224c483a3..f1f6c98cebf 100644
--- a/src/cmd/compile/internal/gc/subr.go
+++ b/src/cmd/compile/internal/gc/subr.go
@@ -569,10 +569,6 @@ func isptrto(t *Type, et EType) bool {
 	return true
 }
 
-func Istype(t *Type, et EType) bool {
-	return t != nil && t.Etype == et
-}
-
 func isblank(n *Node) bool {
 	if n == nil {
 		return false
@@ -584,25 +580,6 @@ func isblanksym(s *Sym) bool {
 	return s != nil && s.Name == "_"
 }
 
-func isnilinter(t *Type) bool {
-	return t.IsInterface() && t.NumFields() == 0
-}
-
-func isideal(t *Type) bool {
-	if t == nil {
-		return false
-	}
-	if t == idealstring || t == idealbool {
-		return true
-	}
-	switch t.Etype {
-	case TNIL, TIDEAL:
-		return true
-	}
-
-	return false
-}
-
 // given receiver of type t (t == r or t == *r)
 // return type to hang methods off (r).
 func methtype(t *Type, mustname int) *Type {
@@ -812,7 +789,7 @@ func assignop(src *Type, dst *Type, why *string) Op {
 	// both are empty interface types.
 	// For assignable but different non-empty interface types,
 	// we want to recompute the itab.
-	if Eqtype(src.Orig, dst.Orig) && (src.Sym == nil || dst.Sym == nil || isnilinter(src)) {
+	if Eqtype(src.Orig, dst.Orig) && (src.Sym == nil || dst.Sym == nil || src.IsEmptyInterface()) {
 		return OCONVNOP
 	}
 
@@ -2269,7 +2246,7 @@ func isdirectiface(t *Type) bool {
 // 'I' if t is an interface type, and 'E' if t is an empty interface type.
 // It is used to build calls to the conv* and assert* runtime routines.
 func (t *Type) iet() byte {
-	if isnilinter(t) {
+	if t.IsEmptyInterface() {
 		return 'E'
 	}
 	if t.IsInterface() {
diff --git a/src/cmd/compile/internal/gc/swt.go b/src/cmd/compile/internal/gc/swt.go
index 996bd69113c..cbf284c8f19 100644
--- a/src/cmd/compile/internal/gc/swt.go
+++ b/src/cmd/compile/internal/gc/swt.go
@@ -149,7 +149,7 @@ func typecheckswitch(n *Node) {
 					var missing, have *Field
 					var ptr int
 					switch {
-					case n1.Op == OLITERAL && Istype(n1.Type, TNIL):
+					case n1.Op == OLITERAL && n1.Type.IsKind(TNIL):
 					case n1.Op != OTYPE && n1.Type != nil: // should this be ||?
 						Yyerror("%v is not a type", Nconv(n1, FmtLong))
 						// reset to original type
@@ -170,7 +170,7 @@ func typecheckswitch(n *Node) {
 			ll := ncase.List
 			if ncase.Rlist.Len() != 0 {
 				nvar := ncase.Rlist.First()
-				if ll.Len() == 1 && ll.First().Type != nil && !Istype(ll.First().Type, TNIL) {
+				if ll.Len() == 1 && ll.First().Type != nil && !ll.First().Type.IsKind(TNIL) {
 					// single entry type switch
 					nvar.Name.Param.Ntype = typenod(ll.First().Type)
 				} else {
@@ -449,7 +449,7 @@ func caseClauses(sw *Node, kind int) []*caseClause {
 			switch {
 			case n.Left.Op == OLITERAL:
 				c.typ = caseKindTypeNil
-			case Istype(n.Left.Type, TINTER):
+			case n.Left.Type.IsInterface():
 				c.typ = caseKindTypeVar
 			default:
 				c.typ = caseKindTypeConst
@@ -528,7 +528,7 @@ func (s *typeSwitch) walk(sw *Node) {
 	}
 
 	cond.Right = walkexpr(cond.Right, &sw.Ninit)
-	if !Istype(cond.Right.Type, TINTER) {
+	if !cond.Right.Type.IsInterface() {
 		Yyerror("type switch must be on an interface")
 		return
 	}
@@ -594,7 +594,7 @@ func (s *typeSwitch) walk(sw *Node) {
 	i.Left = typecheck(i.Left, Erv)
 	cas = append(cas, i)
 
-	if !isnilinter(cond.Right.Type) {
+	if !cond.Right.Type.IsEmptyInterface() {
 		// Load type from itab.
 		typ = NodSym(ODOTPTR, typ, nil)
 		typ.Type = Ptrto(Types[TUINT8])
diff --git a/src/cmd/compile/internal/gc/type.go b/src/cmd/compile/internal/gc/type.go
index 9d2da7f14bf..1aefc9cf245 100644
--- a/src/cmd/compile/internal/gc/type.go
+++ b/src/cmd/compile/internal/gc/type.go
@@ -830,6 +830,11 @@ func (t *Type) cmp(x *Type) ssa.Cmp {
 	return t.Elem().cmp(x.Elem())
 }
 
+// IsKind reports whether t is a Type of the specified kind.
+func (t *Type) IsKind(et EType) bool {
+	return t != nil && t.Etype == et
+}
+
 func (t *Type) IsBoolean() bool {
 	return t.Etype == TBOOL
 }
@@ -911,6 +916,11 @@ func (t *Type) IsInterface() bool {
 	return t.Etype == TINTER
 }
 
+// IsEmptyInterface reports whether t is an empty interface type.
+func (t *Type) IsEmptyInterface() bool {
+	return t.IsInterface() && t.NumFields() == 0
+}
+
 func (t *Type) ElemType() ssa.Type {
 	// TODO(josharian): If Type ever moves to a shared
 	// internal package, remove this silly wrapper.
@@ -948,3 +958,18 @@ func (t *Type) SetNumElem(n int64) {
 func (t *Type) IsMemory() bool { return false }
 func (t *Type) IsFlags() bool  { return false }
 func (t *Type) IsVoid() bool   { return false }
+
+// IsUntyped reports whether t is an untyped type.
+func (t *Type) IsUntyped() bool {
+	if t == nil {
+		return false
+	}
+	if t == idealstring || t == idealbool {
+		return true
+	}
+	switch t.Etype {
+	case TNIL, TIDEAL:
+		return true
+	}
+	return false
+}
diff --git a/src/cmd/compile/internal/gc/typecheck.go b/src/cmd/compile/internal/gc/typecheck.go
index 47c79b81d11..636691ebbb1 100644
--- a/src/cmd/compile/internal/gc/typecheck.go
+++ b/src/cmd/compile/internal/gc/typecheck.go
@@ -226,7 +226,7 @@ func callrecvlist(l Nodes) bool {
 // The result of indexlit MUST be assigned back to n, e.g.
 // 	n.Left = indexlit(n.Left)
 func indexlit(n *Node) *Node {
-	if n == nil || !isideal(n.Type) {
+	if n == nil || !n.Type.IsUntyped() {
 		return n
 	}
 	switch consttype(n) {
@@ -885,7 +885,7 @@ OpSwitch:
 		if lookdot(n, t, 0) == nil {
 			// Legitimate field or method lookup failed, try to explain the error
 			switch {
-			case isnilinter(t):
+			case t.IsEmptyInterface():
 				Yyerror("%v undefined (type %v is interface with no methods)", n, n.Left.Type)
 
 			case t.IsPtr() && t.Elem().IsInterface():
@@ -1123,7 +1123,7 @@ OpSwitch:
 			return n
 		}
 		var tp *Type
-		if Istype(t, TSTRING) {
+		if t.IsString() {
 			n.Type = t
 			n.Op = OSLICESTR
 		} else if t.IsPtr() && t.Elem().IsArray() {
@@ -1184,7 +1184,7 @@ OpSwitch:
 			n.Type = nil
 			return n
 		}
-		if Istype(t, TSTRING) {
+		if t.IsString() {
 			Yyerror("invalid operation %v (3-index slice of string)", n)
 			n.Type = nil
 			return n
@@ -1593,7 +1593,7 @@ OpSwitch:
 
 		// Unpack multiple-return result before type-checking.
 		var funarg *Type
-		if Istype(t, TSTRUCT) && t.Funarg {
+		if t.IsStruct() && t.Funarg {
 			funarg = t
 			t = t.Field(0).Type
 		}
@@ -1624,7 +1624,7 @@ OpSwitch:
 				return n
 			}
 
-			if Istype(t.Elem(), TUINT8) && Istype(args.Second().Type, TSTRING) {
+			if t.Elem().IsKind(TUINT8) && args.Second().Type.IsString() {
 				args.SetIndex(1, defaultlit(args.Index(1), Types[TSTRING]))
 				break OpSwitch
 			}
@@ -3704,7 +3704,7 @@ func typecheckdef(n *Node) *Node {
 				goto ret
 			}
 
-			if !isideal(e.Type) && !Eqtype(t, e.Type) {
+			if !e.Type.IsUntyped() && !Eqtype(t, e.Type) {
 				Yyerror("cannot use %v as type %v in const initializer", Nconv(e, FmtLong), t)
 				goto ret
 			}
@@ -3776,7 +3776,7 @@ func typecheckdef(n *Node) *Node {
 	}
 
 ret:
-	if n.Op != OLITERAL && n.Type != nil && isideal(n.Type) {
+	if n.Op != OLITERAL && n.Type != nil && n.Type.IsUntyped() {
 		Fatalf("got %v for %v", n.Type, n)
 	}
 	last := len(typecheckdefstack) - 1
diff --git a/src/cmd/compile/internal/gc/walk.go b/src/cmd/compile/internal/gc/walk.go
index 9f241ff10c6..2715dc03c8e 100644
--- a/src/cmd/compile/internal/gc/walk.go
+++ b/src/cmd/compile/internal/gc/walk.go
@@ -990,7 +990,7 @@ opswitch:
 		// Optimize convT2E or convT2I as a two-word copy when T is pointer-shaped.
 		if isdirectiface(n.Left.Type) {
 			var t *Node
-			if isnilinter(n.Type) {
+			if n.Type.IsEmptyInterface() {
 				t = typename(n.Left.Type)
 			} else {
 				t = itabname(n.Left.Type, n.Type)
@@ -1003,7 +1003,7 @@ opswitch:
 		}
 
 		var ll []*Node
-		if isnilinter(n.Type) {
+		if n.Type.IsEmptyInterface() {
 			if !n.Left.Type.IsInterface() {
 				ll = append(ll, typename(n.Left.Type))
 			}
@@ -1504,7 +1504,7 @@ opswitch:
 			Fatalf("ifaceeq %v %v %v", Oconv(n.Op, 0), n.Left.Type, n.Right.Type)
 		}
 		var fn *Node
-		if isnilinter(n.Left.Type) {
+		if n.Left.Type.IsEmptyInterface() {
 			fn = syslook("efaceeq")
 		} else {
 			fn = syslook("ifaceeq")
@@ -1924,7 +1924,7 @@ func walkprint(nn *Node, init *Nodes) *Node {
 		t = n.Type
 		et = n.Type.Etype
 		if n.Type.IsInterface() {
-			if isnilinter(n.Type) {
+			if n.Type.IsEmptyInterface() {
 				on = syslook("printeface")
 			} else {
 				on = syslook("printiface")
@@ -2894,7 +2894,7 @@ func walkappend(n *Node, init *Nodes, dst *Node) *Node {
 	nsrc := n.List.First()
 
 	// Resolve slice type of multi-valued return.
-	if Istype(nsrc.Type, TSTRUCT) {
+	if nsrc.Type.IsStruct() {
 		nsrc.Type = nsrc.Type.Elem().Elem()
 	}
 	argc := n.List.Len() - 1