diff --git a/src/cmd/compile/internal/escape/escape.go b/src/cmd/compile/internal/escape/escape.go
index 213ef7832d..6bebe5422f 100644
--- a/src/cmd/compile/internal/escape/escape.go
+++ b/src/cmd/compile/internal/escape/escape.go
@@ -587,7 +587,7 @@ func (e *escape) exprSkipInit(k hole, n ir.Node) {
 
 	switch n.Op() {
 	default:
-		base.Fatalf("unexpected expr: %v", n)
+		base.Fatalf("unexpected expr: %s %v", n.Op().String(), n)
 
 	case ir.OLITERAL, ir.ONIL, ir.OGETG, ir.OTYPE, ir.OMETHEXPR, ir.OLINKSYMOFFSET:
 		// nop
diff --git a/src/cmd/compile/internal/inline/inl.go b/src/cmd/compile/internal/inline/inl.go
index 1941dc44bc..4470df1d2a 100644
--- a/src/cmd/compile/internal/inline/inl.go
+++ b/src/cmd/compile/internal/inline/inl.go
@@ -354,7 +354,7 @@ func (v *hairyVisitor) doNode(n ir.Node) bool {
 		return true
 
 	case ir.OCLOSURE:
-		if base.Debug.InlFuncsWithClosures == 0 {
+		if base.Debug.InlFuncsWithClosures == 0 || typecheck.Go117ExportTypes { // TODO: remove latter condition
 			v.reason = "not inlining functions with closures"
 			return true
 		}
@@ -1013,7 +1013,9 @@ func mkinlcall(n *ir.CallExpr, fn *ir.Func, maxCost int32, inlMap map[*ir.Func]b
 	lab := ir.NewLabelStmt(base.Pos, retlabel)
 	body = append(body, lab)
 
-	typecheck.Stmts(body)
+	if !typecheck.Go117ExportTypes {
+		typecheck.Stmts(body)
+	}
 
 	if base.Flag.GenDwarfInl > 0 {
 		for _, v := range inlfvars {
diff --git a/src/cmd/compile/internal/typecheck/func.go b/src/cmd/compile/internal/typecheck/func.go
index bc31284a85..eaae2a81fa 100644
--- a/src/cmd/compile/internal/typecheck/func.go
+++ b/src/cmd/compile/internal/typecheck/func.go
@@ -144,15 +144,18 @@ func ImportedBody(fn *ir.Func) {
 		fmt.Printf("typecheck import [%v] %L { %v }\n", fn.Sym(), fn, ir.Nodes(fn.Inl.Body))
 	}
 
-	savefn := ir.CurFunc
-	ir.CurFunc = fn
-	if inTypeCheckInl {
-		base.Fatalf("inTypeCheckInl should not be set recursively")
+	if !go117ExportTypes {
+		// If we didn't export & import types, typecheck the code here.
+		savefn := ir.CurFunc
+		ir.CurFunc = fn
+		if inTypeCheckInl {
+			base.Fatalf("inTypeCheckInl should not be set recursively")
+		}
+		inTypeCheckInl = true
+		Stmts(fn.Inl.Body)
+		inTypeCheckInl = false
+		ir.CurFunc = savefn
 	}
-	inTypeCheckInl = true
-	Stmts(fn.Inl.Body)
-	inTypeCheckInl = false
-	ir.CurFunc = savefn
 
 	base.Pos = lno
 }
diff --git a/src/cmd/compile/internal/typecheck/iexport.go b/src/cmd/compile/internal/typecheck/iexport.go
index 43cc4e4a25..8f8931e495 100644
--- a/src/cmd/compile/internal/typecheck/iexport.go
+++ b/src/cmd/compile/internal/typecheck/iexport.go
@@ -633,6 +633,79 @@ func (w *exportWriter) selector(s *types.Sym) {
 	w.string(s.Name)
 }
 
+func (w *exportWriter) typ(t *types.Type) {
+	w.data.uint64(w.p.typOff(t))
+}
+
+// The "exotic" functions in this section encode a wider range of
+// items than the standard encoding functions above. These include
+// types that do not appear in declarations, only in code, such as
+// method types. These methods need to be separate from the standard
+// encoding functions because we don't want to modify the encoding
+// generated by the standard functions (because that exported
+// information is read by tools besides the compiler).
+
+// exoticType exports a type to the writer.
+func (w *exportWriter) exoticType(t *types.Type) {
+	switch {
+	case t == nil:
+		// Calls-as-statements have no type.
+		w.data.uint64(exoticTypeNil)
+	case t.IsStruct() && t.StructType().Funarg != types.FunargNone:
+		// These are weird structs for representing tuples of types returned
+		// by multi-return functions.
+		// They don't fit the standard struct type mold. For instance,
+		// they don't have any package info.
+		w.data.uint64(exoticTypeTuple)
+		w.uint64(uint64(t.StructType().Funarg))
+		w.uint64(uint64(t.NumFields()))
+		for _, f := range t.FieldSlice() {
+			w.pos(f.Pos)
+			s := f.Sym
+			if s == nil {
+				w.uint64(0)
+			} else if s.Pkg == nil {
+				w.uint64(exoticTypeSymNoPkg)
+				w.string(s.Name)
+			} else {
+				w.uint64(exoticTypeSymWithPkg)
+				w.pkg(s.Pkg)
+				w.string(s.Name)
+			}
+			w.typ(f.Type)
+			if f.Embedded != 0 || f.Note != "" {
+				panic("extra info in funarg struct field")
+			}
+		}
+	case t.Kind() == types.TFUNC && t.Recv() != nil:
+		w.data.uint64(exoticTypeRecv)
+		// interface method types have a fake receiver type.
+		isFakeRecv := t.Recv().Type == types.FakeRecvType()
+		w.bool(isFakeRecv)
+		if !isFakeRecv {
+			w.exoticParam(t.Recv())
+		}
+		w.exoticSignature(t)
+
+	default:
+		// A regular type.
+		w.data.uint64(exoticTypeRegular)
+		w.typ(t)
+	}
+}
+
+const (
+	exoticTypeNil = iota
+	exoticTypeTuple
+	exoticTypeRecv
+	exoticTypeRegular
+)
+const (
+	exoticTypeSymNil = iota
+	exoticTypeSymNoPkg
+	exoticTypeSymWithPkg
+)
+
 // Export a selector, but one whose package may not match
 // the package being compiled. This is a separate function
 // because the standard selector() serialization format is fixed
@@ -653,8 +726,42 @@ func (w *exportWriter) exoticSelector(s *types.Sym) {
 	}
 }
 
-func (w *exportWriter) typ(t *types.Type) {
-	w.data.uint64(w.p.typOff(t))
+func (w *exportWriter) exoticSignature(t *types.Type) {
+	hasPkg := t.Pkg() != nil
+	w.bool(hasPkg)
+	if hasPkg {
+		w.pkg(t.Pkg())
+	}
+	w.exoticParamList(t.Params().FieldSlice())
+	w.exoticParamList(t.Results().FieldSlice())
+}
+
+func (w *exportWriter) exoticParamList(fs []*types.Field) {
+	w.uint64(uint64(len(fs)))
+	for _, f := range fs {
+		w.exoticParam(f)
+	}
+
+}
+func (w *exportWriter) exoticParam(f *types.Field) {
+	w.pos(f.Pos)
+	w.exoticSym(f.Sym)
+	w.uint64(uint64(f.Offset))
+	w.exoticType(f.Type)
+	w.bool(f.IsDDD())
+}
+func (w *exportWriter) exoticSym(s *types.Sym) {
+	if s == nil {
+		w.string("")
+		return
+	}
+	if s.Name == "" {
+		base.Fatalf("empty symbol name")
+	}
+	w.string(s.Name)
+	if !types.IsExported(s.Name) {
+		w.pkg(s.Pkg)
+	}
 }
 
 func (p *iexporter) newWriter() *exportWriter {
@@ -1133,6 +1240,7 @@ func (w *exportWriter) writeNames(dcl []*ir.Name) {
 }
 
 func (w *exportWriter) funcBody(fn *ir.Func) {
+	//fmt.Printf("Exporting %s\n", fn.Nname.Sym().Name)
 	w.writeNames(fn.Inl.Dcl)
 
 	w.stmtList(fn.Inl.Body)
@@ -1208,7 +1316,11 @@ func (w *exportWriter) stmt(n ir.Node) {
 
 	case ir.OAS2, ir.OAS2DOTTYPE, ir.OAS2FUNC, ir.OAS2MAPR, ir.OAS2RECV:
 		n := n.(*ir.AssignListStmt)
-		w.op(ir.OAS2)
+		if go117ExportTypes {
+			w.op(n.Op())
+		} else {
+			w.op(ir.OAS2)
+		}
 		w.pos(n.Pos())
 		w.exprList(n.Lhs)
 		w.exprList(n.Rhs)
@@ -1220,7 +1332,7 @@ func (w *exportWriter) stmt(n ir.Node) {
 		w.exprList(n.Results)
 
 	// case ORETJMP:
-	// 	unreachable - generated by compiler for trampolin routines
+	// 	unreachable - generated by compiler for trampoline routines
 
 	case ir.OGO, ir.ODEFER:
 		n := n.(*ir.GoDeferStmt)
@@ -1357,10 +1469,15 @@ func (w *exportWriter) expr(n ir.Node) {
 		if (n.Class == ir.PEXTERN || n.Class == ir.PFUNC) && !ir.IsBlank(n) {
 			w.op(ir.ONONAME)
 			w.qualifiedIdent(n)
+			if go117ExportTypes {
+				w.typ(n.Type())
+			}
 			break
 		}
 
 		// Function scope name.
+		// We don't need a type here, as the type will be provided at the
+		// declaration of n.
 		w.op(ir.ONAME)
 		w.localName(n)
 
@@ -1418,9 +1535,16 @@ func (w *exportWriter) expr(n ir.Node) {
 
 	case ir.OPTRLIT:
 		n := n.(*ir.AddrExpr)
-		w.op(ir.OADDR)
+		if go117ExportTypes {
+			w.op(ir.OPTRLIT)
+		} else {
+			w.op(ir.OADDR)
+		}
 		w.pos(n.Pos())
 		w.expr(n.X)
+		if go117ExportTypes {
+			w.typ(n.Type())
+		}
 
 	case ir.OSTRUCTLIT:
 		n := n.(*ir.CompLitExpr)
@@ -1431,11 +1555,17 @@ func (w *exportWriter) expr(n ir.Node) {
 
 	case ir.OARRAYLIT, ir.OSLICELIT, ir.OMAPLIT:
 		n := n.(*ir.CompLitExpr)
-		w.op(ir.OCOMPLIT)
+		if go117ExportTypes {
+			w.op(n.Op())
+		} else {
+			w.op(ir.OCOMPLIT)
+		}
 		w.pos(n.Pos())
 		w.typ(n.Type())
 		w.exprList(n.List)
-
+		if go117ExportTypes && n.Op() == ir.OSLICELIT {
+			w.uint64(uint64(n.Len))
+		}
 	case ir.OKEY:
 		n := n.(*ir.KeyExpr)
 		w.op(ir.OKEY)
@@ -1448,39 +1578,89 @@ func (w *exportWriter) expr(n ir.Node) {
 
 	case ir.OXDOT, ir.ODOT, ir.ODOTPTR, ir.ODOTINTER, ir.ODOTMETH, ir.OCALLPART, ir.OMETHEXPR:
 		n := n.(*ir.SelectorExpr)
-		w.op(ir.OXDOT)
+		if go117ExportTypes {
+			if n.Op() == ir.OXDOT {
+				base.Fatalf("shouldn't encounter XDOT  in new exporter")
+			}
+			w.op(n.Op())
+		} else {
+			w.op(ir.OXDOT)
+		}
 		w.pos(n.Pos())
 		w.expr(n.X)
 		w.exoticSelector(n.Sel)
+		if go117ExportTypes {
+			w.exoticType(n.Type())
+			if n.Op() == ir.ODOT || n.Op() == ir.ODOTPTR || n.Op() == ir.ODOTINTER || n.Op() == ir.OMETHEXPR {
+				w.exoticParam(n.Selection)
+				if n.Op() == ir.OMETHEXPR {
+					name := ir.MethodExprName(n)
+					w.bool(name != nil)
+					if name != nil {
+						w.exoticType(name.Type())
+					}
+				}
+			}
+			// n.Selection is not required for ODOTMETH and OCALLPART. It will
+			// be reconstructed during import.
+		}
 
 	case ir.ODOTTYPE, ir.ODOTTYPE2:
 		n := n.(*ir.TypeAssertExpr)
-		w.op(ir.ODOTTYPE)
+		if go117ExportTypes {
+			w.op(n.Op())
+		} else {
+			w.op(ir.ODOTTYPE)
+		}
 		w.pos(n.Pos())
 		w.expr(n.X)
 		w.typ(n.Type())
 
 	case ir.OINDEX, ir.OINDEXMAP:
 		n := n.(*ir.IndexExpr)
-		w.op(ir.OINDEX)
+		if go117ExportTypes {
+			w.op(n.Op())
+		} else {
+			w.op(ir.OINDEX)
+		}
 		w.pos(n.Pos())
 		w.expr(n.X)
 		w.expr(n.Index)
+		if go117ExportTypes {
+			w.typ(n.Type())
+			if n.Op() == ir.OINDEXMAP {
+				w.bool(n.Assigned)
+			}
+		}
 
 	case ir.OSLICE, ir.OSLICESTR, ir.OSLICEARR:
 		n := n.(*ir.SliceExpr)
-		w.op(ir.OSLICE)
+		if go117ExportTypes {
+			w.op(n.Op())
+		} else {
+			w.op(ir.OSLICE)
+		}
 		w.pos(n.Pos())
 		w.expr(n.X)
 		w.exprsOrNil(n.Low, n.High)
+		if go117ExportTypes {
+			w.typ(n.Type())
+		}
 
 	case ir.OSLICE3, ir.OSLICE3ARR:
 		n := n.(*ir.SliceExpr)
-		w.op(ir.OSLICE3)
+		if go117ExportTypes {
+			w.op(n.Op())
+		} else {
+			w.op(ir.OSLICE3)
+		}
 		w.pos(n.Pos())
 		w.expr(n.X)
 		w.exprsOrNil(n.Low, n.High)
 		w.expr(n.Max)
+		if go117ExportTypes {
+			w.typ(n.Type())
+		}
 
 	case ir.OCOPY, ir.OCOMPLEX:
 		// treated like other builtin calls (see e.g., OREAL)
@@ -1489,11 +1669,19 @@ func (w *exportWriter) expr(n ir.Node) {
 		w.pos(n.Pos())
 		w.expr(n.X)
 		w.expr(n.Y)
-		w.op(ir.OEND)
+		if go117ExportTypes {
+			w.typ(n.Type())
+		} else {
+			w.op(ir.OEND)
+		}
 
 	case ir.OCONV, ir.OCONVIFACE, ir.OCONVNOP, ir.OBYTES2STR, ir.ORUNES2STR, ir.OSTR2BYTES, ir.OSTR2RUNES, ir.ORUNESTR:
 		n := n.(*ir.ConvExpr)
-		w.op(ir.OCONV)
+		if go117ExportTypes {
+			w.op(n.Op())
+		} else {
+			w.op(ir.OCONV)
+		}
 		w.pos(n.Pos())
 		w.typ(n.Type())
 		w.expr(n.X)
@@ -1503,7 +1691,13 @@ func (w *exportWriter) expr(n ir.Node) {
 		w.op(n.Op())
 		w.pos(n.Pos())
 		w.expr(n.X)
-		w.op(ir.OEND)
+		if go117ExportTypes {
+			if n.Op() != ir.OPANIC {
+				w.typ(n.Type())
+			}
+		} else {
+			w.op(ir.OEND)
+		}
 
 	case ir.OAPPEND, ir.ODELETE, ir.ORECOVER, ir.OPRINT, ir.OPRINTN:
 		n := n.(*ir.CallExpr)
@@ -1516,15 +1710,28 @@ func (w *exportWriter) expr(n ir.Node) {
 		} else if n.IsDDD {
 			base.Fatalf("exporter: unexpected '...' with %v call", n.Op())
 		}
+		if go117ExportTypes {
+			if n.Op() != ir.ODELETE && n.Op() != ir.OPRINT && n.Op() != ir.OPRINTN {
+				w.typ(n.Type())
+			}
+		}
 
 	case ir.OCALL, ir.OCALLFUNC, ir.OCALLMETH, ir.OCALLINTER, ir.OGETG:
 		n := n.(*ir.CallExpr)
-		w.op(ir.OCALL)
+		if go117ExportTypes {
+			w.op(n.Op())
+		} else {
+			w.op(ir.OCALL)
+		}
 		w.pos(n.Pos())
 		w.stmtList(n.Init())
 		w.expr(n.X)
 		w.exprList(n.Args)
 		w.bool(n.IsDDD)
+		if go117ExportTypes {
+			w.exoticType(n.Type())
+			w.uint64(uint64(n.Use))
+		}
 
 	case ir.OMAKEMAP, ir.OMAKECHAN, ir.OMAKESLICE:
 		n := n.(*ir.MakeExpr)
@@ -1540,6 +1747,12 @@ func (w *exportWriter) expr(n ir.Node) {
 			w.expr(n.Cap)
 			w.op(ir.OEND)
 		case n.Len != nil && (n.Op() == ir.OMAKESLICE || !n.Len.Type().IsUntyped()):
+			// Note: the extra conditional exists because make(T) for
+			// T a map or chan type, gets an untyped zero added as
+			// an argument. Don't serialize that argument here.
+			w.expr(n.Len)
+			w.op(ir.OEND)
+		case n.Len != nil && go117ExportTypes:
 			w.expr(n.Len)
 			w.op(ir.OEND)
 		}
@@ -1550,18 +1763,27 @@ func (w *exportWriter) expr(n ir.Node) {
 		w.op(n.Op())
 		w.pos(n.Pos())
 		w.expr(n.X)
+		if go117ExportTypes {
+			w.typ(n.Type())
+		}
 
 	case ir.OADDR:
 		n := n.(*ir.AddrExpr)
 		w.op(n.Op())
 		w.pos(n.Pos())
 		w.expr(n.X)
+		if go117ExportTypes {
+			w.typ(n.Type())
+		}
 
 	case ir.ODEREF:
 		n := n.(*ir.StarExpr)
 		w.op(n.Op())
 		w.pos(n.Pos())
 		w.expr(n.X)
+		if go117ExportTypes {
+			w.typ(n.Type())
+		}
 
 	case ir.OSEND:
 		n := n.(*ir.SendStmt)
@@ -1578,6 +1800,9 @@ func (w *exportWriter) expr(n ir.Node) {
 		w.pos(n.Pos())
 		w.expr(n.X)
 		w.expr(n.Y)
+		if go117ExportTypes {
+			w.typ(n.Type())
+		}
 
 	case ir.OANDAND, ir.OOROR:
 		n := n.(*ir.LogicalExpr)
@@ -1585,12 +1810,18 @@ func (w *exportWriter) expr(n ir.Node) {
 		w.pos(n.Pos())
 		w.expr(n.X)
 		w.expr(n.Y)
+		if go117ExportTypes {
+			w.typ(n.Type())
+		}
 
 	case ir.OADDSTR:
 		n := n.(*ir.AddStringExpr)
 		w.op(ir.OADDSTR)
 		w.pos(n.Pos())
 		w.exprList(n.List)
+		if go117ExportTypes {
+			w.typ(n.Type())
+		}
 
 	case ir.ODCLCONST:
 		// if exporting, DCLCONST should just be removed as its usage
@@ -1633,6 +1864,9 @@ func (w *exportWriter) fieldList(list ir.Nodes) {
 		w.pos(n.Pos())
 		w.selector(n.Field)
 		w.expr(n.Value)
+		if go117ExportTypes {
+			w.uint64(uint64(n.Offset))
+		}
 	}
 }
 
@@ -1693,3 +1927,13 @@ func (w *intWriter) uint64(x uint64) {
 	n := binary.PutUvarint(buf[:], x)
 	w.Write(buf[:n])
 }
+
+// If go117ExportTypes is true, then we write type information when
+// exporting function bodies, so those function bodies don't need to
+// be re-typechecked on import.
+// This flag adds some other info to the serialized stream as well
+// which was previously recomputed during typechecking, like
+// specializing opcodes (e.g. OXDOT to ODOTPTR) and ancillary
+// information (e.g. length field for OSLICELIT).
+const go117ExportTypes = true
+const Go117ExportTypes = go117ExportTypes
diff --git a/src/cmd/compile/internal/typecheck/iimport.go b/src/cmd/compile/internal/typecheck/iimport.go
index 35a1a0083a..0d5d892ef5 100644
--- a/src/cmd/compile/internal/typecheck/iimport.go
+++ b/src/cmd/compile/internal/typecheck/iimport.go
@@ -466,21 +466,6 @@ func (r *importReader) ident(selector bool) *types.Sym {
 func (r *importReader) localIdent() *types.Sym { return r.ident(false) }
 func (r *importReader) selector() *types.Sym   { return r.ident(true) }
 
-func (r *importReader) exoticSelector() *types.Sym {
-	name := r.string()
-	if name == "" {
-		return nil
-	}
-	pkg := r.currPkg
-	if types.IsExported(name) {
-		pkg = types.LocalPkg
-	}
-	if r.uint64() != 0 {
-		pkg = r.pkg()
-	}
-	return pkg.Lookup(name)
-}
-
 func (r *importReader) qualifiedIdent() *ir.Ident {
 	name := r.string()
 	pkg := r.pkg()
@@ -516,6 +501,114 @@ func (r *importReader) typ() *types.Type {
 	return r.p.typAt(r.uint64())
 }
 
+func (r *importReader) exoticType() *types.Type {
+	switch r.uint64() {
+	case exoticTypeNil:
+		return nil
+	case exoticTypeTuple:
+		funarg := types.Funarg(r.uint64())
+		n := r.uint64()
+		fs := make([]*types.Field, n)
+		for i := range fs {
+			pos := r.pos()
+			var sym *types.Sym
+			switch r.uint64() {
+			case exoticTypeSymNil:
+				sym = nil
+			case exoticTypeSymNoPkg:
+				sym = types.NoPkg.Lookup(r.string())
+			case exoticTypeSymWithPkg:
+				pkg := r.pkg()
+				sym = pkg.Lookup(r.string())
+			default:
+				base.Fatalf("unknown symbol kind")
+			}
+			typ := r.typ()
+			f := types.NewField(pos, sym, typ)
+			fs[i] = f
+		}
+		t := types.NewStruct(types.NoPkg, fs)
+		t.StructType().Funarg = funarg
+		return t
+	case exoticTypeRecv:
+		var rcvr *types.Field
+		if r.bool() { // isFakeRecv
+			rcvr = fakeRecvField()
+		} else {
+			rcvr = r.exoticParam()
+		}
+		return r.exoticSignature(rcvr)
+	case exoticTypeRegular:
+		return r.typ()
+	default:
+		base.Fatalf("bad kind of call type")
+		return nil
+	}
+}
+
+func (r *importReader) exoticSelector() *types.Sym {
+	name := r.string()
+	if name == "" {
+		return nil
+	}
+	pkg := r.currPkg
+	if types.IsExported(name) {
+		pkg = types.LocalPkg
+	}
+	if r.uint64() != 0 {
+		pkg = r.pkg()
+	}
+	return pkg.Lookup(name)
+}
+
+func (r *importReader) exoticSignature(recv *types.Field) *types.Type {
+	var pkg *types.Pkg
+	if r.bool() { // hasPkg
+		pkg = r.pkg()
+	}
+	params := r.exoticParamList()
+	results := r.exoticParamList()
+	return types.NewSignature(pkg, recv, nil, params, results)
+}
+
+func (r *importReader) exoticParamList() []*types.Field {
+	n := r.uint64()
+	fs := make([]*types.Field, n)
+	for i := range fs {
+		fs[i] = r.exoticParam()
+	}
+	return fs
+}
+
+func (r *importReader) exoticParam() *types.Field {
+	pos := r.pos()
+	sym := r.exoticSym()
+	off := r.uint64()
+	typ := r.exoticType()
+	ddd := r.bool()
+	f := types.NewField(pos, sym, typ)
+	f.Offset = int64(off)
+	if sym != nil {
+		f.Nname = ir.NewNameAt(pos, sym)
+	}
+	f.SetIsDDD(ddd)
+	return f
+}
+
+func (r *importReader) exoticSym() *types.Sym {
+	name := r.string()
+	if name == "" {
+		return nil
+	}
+	var pkg *types.Pkg
+	if types.IsExported(name) {
+		pkg = types.LocalPkg
+	} else {
+		pkg = r.pkg()
+	}
+	return pkg.Lookup(name)
+}
+
 func (p *iimporter) typAt(off uint64) *types.Type {
 	t, ok := p.typCache[off]
 	if !ok {
@@ -815,6 +908,11 @@ func (r *importReader) funcBody(fn *ir.Func) {
 		// functions).
 		body = []ir.Node{}
 	}
+	if go117ExportTypes {
+		ir.VisitList(body, func(n ir.Node) {
+			n.SetTypecheck(1)
+		})
+	}
 	fn.Inl.Body = body
 
 	r.curfn = outerfn
@@ -942,7 +1040,8 @@ func (r *importReader) expr() ir.Node {
 
 // TODO(gri) split into expr and stmt
 func (r *importReader) node() ir.Node {
-	switch op := r.op(); op {
+	op := r.op()
+	switch op {
 	// expressions
 	// case OPAREN:
 	// 	unreachable - unpacked by exporter
@@ -964,7 +1063,16 @@ func (r *importReader) node() ir.Node {
 		return n
 
 	case ir.ONONAME:
-		return r.qualifiedIdent()
+		n := r.qualifiedIdent()
+		if go117ExportTypes {
+			n2 := Resolve(n)
+			typ := r.typ()
+			if n2.Type() == nil {
+				n2.SetType(typ)
+			}
+			return n2
+		}
+		return n
 
 	case ir.ONAME:
 		return r.localName()
@@ -1028,64 +1136,145 @@ func (r *importReader) node() ir.Node {
 
 		return clo
 
-	// case OPTRLIT:
-	//	unreachable - mapped to case OADDR below by exporter
-
 	case ir.OSTRUCTLIT:
+		if go117ExportTypes {
+			pos := r.pos()
+			typ := r.typ()
+			list := r.fieldList()
+			n := ir.NewCompLitExpr(pos, ir.OSTRUCTLIT, nil, list)
+			n.SetType(typ)
+			return n
+		}
 		return ir.NewCompLitExpr(r.pos(), ir.OCOMPLIT, ir.TypeNode(r.typ()), r.fieldList())
 
-	// case OARRAYLIT, OSLICELIT, OMAPLIT:
-	// 	unreachable - mapped to case OCOMPLIT below by exporter
-
 	case ir.OCOMPLIT:
 		return ir.NewCompLitExpr(r.pos(), ir.OCOMPLIT, ir.TypeNode(r.typ()), r.exprList())
 
+	case ir.OARRAYLIT, ir.OSLICELIT, ir.OMAPLIT:
+		if !go117ExportTypes {
+			// unreachable - mapped to OCOMPLIT by exporter
+			goto error
+		}
+		pos := r.pos()
+		typ := r.typ()
+		list := r.exprList()
+		n := ir.NewCompLitExpr(pos, op, ir.TypeNode(typ), list)
+		n.SetType(typ)
+		if op == ir.OSLICELIT {
+			n.Len = int64(r.uint64())
+		}
+		return n
+
 	case ir.OKEY:
 		return ir.NewKeyExpr(r.pos(), r.expr(), r.expr())
 
 	// case OSTRUCTKEY:
 	//	unreachable - handled in case OSTRUCTLIT by elemList
 
-	// case OCALLPART:
-	//	unreachable - mapped to case OXDOT below by exporter
-
-	// case OXDOT, ODOT, ODOTPTR, ODOTINTER, ODOTMETH:
-	// 	unreachable - mapped to case OXDOT below by exporter
-
 	case ir.OXDOT:
 		// see parser.new_dotname
+		if go117ExportTypes {
+			base.Fatalf("shouldn't encounter XDOT in new importer")
+		}
 		return ir.NewSelectorExpr(r.pos(), ir.OXDOT, r.expr(), r.exoticSelector())
 
-	// case ODOTTYPE, ODOTTYPE2:
-	// 	unreachable - mapped to case ODOTTYPE below by exporter
-
-	case ir.ODOTTYPE:
-		n := ir.NewTypeAssertExpr(r.pos(), r.expr(), nil)
-		n.SetType(r.typ())
+	case ir.ODOT, ir.ODOTPTR, ir.ODOTINTER, ir.ODOTMETH, ir.OCALLPART, ir.OMETHEXPR:
+		if !go117ExportTypes {
+			// unreachable - mapped to case OXDOT by exporter
+			goto error
+		}
+		pos := r.pos()
+		expr := r.expr()
+		sel := r.exoticSelector()
+		n := ir.NewSelectorExpr(pos, ir.OXDOT, expr, sel)
+		n.SetOp(op)
+		n.SetType(r.exoticType())
+		switch op {
+		case ir.ODOT, ir.ODOTPTR, ir.ODOTINTER, ir.OMETHEXPR:
+			n.Selection = r.exoticParam()
+			if op == ir.OMETHEXPR {
+				if r.bool() { // has name
+					ir.MethodExprName(n).SetType(r.exoticType())
+				}
+			}
+		case ir.ODOTMETH, ir.OCALLPART:
+			// These require a Lookup to link to the correct declaration.
+			rcvrType := expr.Type()
+			typ := n.Type()
+			n.Selection = Lookdot(n, rcvrType, 1)
+			if op == ir.OCALLPART {
+				// Lookdot clobbers the opcode and type, undo that.
+				n.SetOp(op)
+				n.SetType(typ)
+			}
+		}
 		return n
 
-	// case OINDEX, OINDEXMAP, OSLICE, OSLICESTR, OSLICEARR, OSLICE3, OSLICE3ARR:
-	// 	unreachable - mapped to cases below by exporter
+	case ir.ODOTTYPE, ir.ODOTTYPE2:
+		n := ir.NewTypeAssertExpr(r.pos(), r.expr(), nil)
+		n.SetType(r.typ())
+		if go117ExportTypes {
+			n.SetOp(op)
+		}
+		return n
 
-	case ir.OINDEX:
-		return ir.NewIndexExpr(r.pos(), r.expr(), r.expr())
+	case ir.OINDEX, ir.OINDEXMAP:
+		n := ir.NewIndexExpr(r.pos(), r.expr(), r.expr())
+		if go117ExportTypes {
+			n.SetOp(op)
+			n.SetType(r.typ())
+			if op == ir.OINDEXMAP {
+				n.Assigned = r.bool()
+			}
+		}
+		return n
 
-	case ir.OSLICE, ir.OSLICE3:
+	case ir.OSLICE, ir.OSLICESTR, ir.OSLICEARR, ir.OSLICE3, ir.OSLICE3ARR:
 		pos, x := r.pos(), r.expr()
 		low, high := r.exprsOrNil()
 		var max ir.Node
 		if op.IsSlice3() {
 			max = r.expr()
 		}
-		return ir.NewSliceExpr(pos, op, x, low, high, max)
+		n := ir.NewSliceExpr(pos, op, x, low, high, max)
+		if go117ExportTypes {
+			n.SetType(r.typ())
+		}
+		return n
 
-	// case OCONV, OCONVIFACE, OCONVNOP, OBYTES2STR, ORUNES2STR, OSTR2BYTES, OSTR2RUNES, ORUNESTR:
-	// 	unreachable - mapped to OCONV case below by exporter
-
-	case ir.OCONV:
-		return ir.NewConvExpr(r.pos(), ir.OCONV, r.typ(), r.expr())
+	case ir.OCONV, ir.OCONVIFACE, ir.OCONVNOP, ir.OBYTES2STR, ir.ORUNES2STR, ir.OSTR2BYTES, ir.OSTR2RUNES, ir.ORUNESTR:
+		if !go117ExportTypes && op != ir.OCONV {
+			// 	unreachable - mapped to OCONV case by exporter
+			goto error
+		}
+		return ir.NewConvExpr(r.pos(), op, r.typ(), r.expr())
 
 	case ir.OCOPY, ir.OCOMPLEX, ir.OREAL, ir.OIMAG, ir.OAPPEND, ir.OCAP, ir.OCLOSE, ir.ODELETE, ir.OLEN, ir.OMAKE, ir.ONEW, ir.OPANIC, ir.ORECOVER, ir.OPRINT, ir.OPRINTN:
+		if go117ExportTypes {
+			switch op {
+			case ir.OCOPY, ir.OCOMPLEX:
+				n := ir.NewBinaryExpr(r.pos(), op, r.expr(), r.expr())
+				n.SetType(r.typ())
+				return n
+			case ir.OREAL, ir.OIMAG, ir.OCAP, ir.OCLOSE, ir.OLEN, ir.ONEW, ir.OPANIC:
+				n := ir.NewUnaryExpr(r.pos(), op, r.expr())
+				if op != ir.OPANIC {
+					n.SetType(r.typ())
+				}
+				return n
+			case ir.OAPPEND, ir.ODELETE, ir.ORECOVER, ir.OPRINT, ir.OPRINTN:
+				n := ir.NewCallExpr(r.pos(), op, nil, r.exprList())
+				if op == ir.OAPPEND {
+					n.IsDDD = r.bool()
+				}
+				if op == ir.OAPPEND || op == ir.ORECOVER {
+					n.SetType(r.typ())
+				}
+				return n
+			}
+			// ir.OMAKE
+			goto error
+		}
 		n := builtinCall(r.pos(), op)
 		n.Args = r.exprList()
 		if op == ir.OAPPEND {
@@ -1093,18 +1282,37 @@ func (r *importReader) node() ir.Node {
 		}
 		return n
 
-	// case OCALLFUNC, OCALLMETH, OCALLINTER, OGETG:
-	// 	unreachable - mapped to OCALL case below by exporter
-
-	case ir.OCALL:
+	case ir.OCALL, ir.OCALLFUNC, ir.OCALLMETH, ir.OCALLINTER, ir.OGETG:
 		pos := r.pos()
 		init := r.stmtList()
 		n := ir.NewCallExpr(pos, ir.OCALL, r.expr(), r.exprList())
+		if go117ExportTypes {
+			n.SetOp(op)
+		}
 		*n.PtrInit() = init
 		n.IsDDD = r.bool()
+		if go117ExportTypes {
+			n.SetType(r.exoticType())
+			n.Use = ir.CallUse(r.uint64())
+		}
 		return n
 
 	case ir.OMAKEMAP, ir.OMAKECHAN, ir.OMAKESLICE:
+		if go117ExportTypes {
+			pos := r.pos()
+			typ := r.typ()
+			list := r.exprList()
+			var len_, cap_ ir.Node
+			if len(list) > 0 {
+				len_ = list[0]
+			}
+			if len(list) > 1 {
+				cap_ = list[1]
+			}
+			n := ir.NewMakeExpr(pos, op, len_, cap_)
+			n.SetType(typ)
+			return n
+		}
 		n := builtinCall(r.pos(), ir.OMAKE)
 		n.Args.Append(ir.TypeNode(r.typ()))
 		n.Args.Append(r.exprList()...)
@@ -1112,21 +1320,42 @@ func (r *importReader) node() ir.Node {
 
 	// unary expressions
 	case ir.OPLUS, ir.ONEG, ir.OBITNOT, ir.ONOT, ir.ORECV:
-		return ir.NewUnaryExpr(r.pos(), op, r.expr())
+		n := ir.NewUnaryExpr(r.pos(), op, r.expr())
+		if go117ExportTypes {
+			n.SetType(r.typ())
+		}
+		return n
 
-	case ir.OADDR:
-		return NodAddrAt(r.pos(), r.expr())
+	case ir.OADDR, ir.OPTRLIT:
+		n := NodAddrAt(r.pos(), r.expr())
+		if go117ExportTypes {
+			n.SetOp(op)
+			n.SetType(r.typ())
+		}
+		return n
 
 	case ir.ODEREF:
-		return ir.NewStarExpr(r.pos(), r.expr())
+		n := ir.NewStarExpr(r.pos(), r.expr())
+		if go117ExportTypes {
+			n.SetType(r.typ())
+		}
+		return n
 
 	// binary expressions
 	case ir.OADD, ir.OAND, ir.OANDNOT, ir.ODIV, ir.OEQ, ir.OGE, ir.OGT, ir.OLE, ir.OLT,
 		ir.OLSH, ir.OMOD, ir.OMUL, ir.ONE, ir.OOR, ir.ORSH, ir.OSUB, ir.OXOR:
-		return ir.NewBinaryExpr(r.pos(), op, r.expr(), r.expr())
+		n := ir.NewBinaryExpr(r.pos(), op, r.expr(), r.expr())
+		if go117ExportTypes {
+			n.SetType(r.typ())
+		}
+		return n
 
 	case ir.OANDAND, ir.OOROR:
-		return ir.NewLogicalExpr(r.pos(), op, r.expr(), r.expr())
+		n := ir.NewLogicalExpr(r.pos(), op, r.expr(), r.expr())
+		if go117ExportTypes {
+			n.SetType(r.typ())
+		}
+		return n
 
 	case ir.OSEND:
 		return ir.NewSendStmt(r.pos(), r.expr(), r.expr())
@@ -1134,6 +1363,11 @@ func (r *importReader) node() ir.Node {
 	case ir.OADDSTR:
 		pos := r.pos()
 		list := r.exprList()
+		if go117ExportTypes {
+			n := ir.NewAddStringExpr(pos, list)
+			n.SetType(r.typ())
+			return n
+		}
 		x := list[0]
 		for _, y := range list[1:] {
 			x = ir.NewBinaryExpr(pos, ir.OADD, x, y)
@@ -1149,8 +1383,8 @@ func (r *importReader) node() ir.Node {
 		stmts.Append(ir.NewAssignStmt(n.Pos(), n, nil))
 		return ir.NewBlockStmt(n.Pos(), stmts)
 
-	// case OAS, OASWB:
-	// 	unreachable - mapped to OAS case below by exporter
+	// case OASWB:
+	// 	unreachable - never exported
 
 	case ir.OAS:
 		return ir.NewAssignStmt(r.pos(), r.expr(), r.expr())
@@ -1165,11 +1399,12 @@ func (r *importReader) node() ir.Node {
 		}
 		return n
 
-	// case OAS2DOTTYPE, OAS2FUNC, OAS2MAPR, OAS2RECV:
-	// 	unreachable - mapped to OAS2 case below by exporter
-
-	case ir.OAS2:
-		return ir.NewAssignListStmt(r.pos(), ir.OAS2, r.exprList(), r.exprList())
+	case ir.OAS2, ir.OAS2DOTTYPE, ir.OAS2FUNC, ir.OAS2MAPR, ir.OAS2RECV:
+		if !go117ExportTypes && op != ir.OAS2 {
+			// unreachable - mapped to case OAS2 by exporter
+			goto error
+		}
+		return ir.NewAssignListStmt(r.pos(), op, r.exprList(), r.exprList())
 
 	case ir.ORETURN:
 		return ir.NewReturnStmt(r.pos(), r.exprList())
@@ -1241,6 +1476,10 @@ func (r *importReader) node() ir.Node {
 			"\t==> please file an issue and assign to gri@", op, int(op))
 		panic("unreachable") // satisfy compiler
 	}
+error:
+	base.Fatalf("cannot import %v (%d) node\n"+
+		"\t==> please file an issue and assign to khr@", op, int(op))
+	panic("unreachable") // satisfy compiler
 }
 
 func (r *importReader) op() ir.Op {
@@ -1253,7 +1492,11 @@ func (r *importReader) op() ir.Op {
 func (r *importReader) fieldList() []ir.Node {
 	list := make([]ir.Node, r.uint64())
 	for i := range list {
-		list[i] = ir.NewStructKeyExpr(r.pos(), r.selector(), r.expr())
+		x := ir.NewStructKeyExpr(r.pos(), r.selector(), r.expr())
+		if go117ExportTypes {
+			x.Offset = int64(r.uint64())
+		}
+		list[i] = x
 	}
 	return list
 }
@@ -1270,5 +1513,9 @@ func (r *importReader) exprsOrNil() (a, b ir.Node) {
 }
 
 func builtinCall(pos src.XPos, op ir.Op) *ir.CallExpr {
+	if go117ExportTypes {
+		// These should all be encoded as direct ops, not OCALL.
+		base.Fatalf("builtinCall should not be invoked when types are included in inport/export")
+	}
 	return ir.NewCallExpr(pos, ir.OCALL, ir.NewIdent(base.Pos, types.BuiltinPkg.Lookup(ir.OpNames[op])), nil)
 }
diff --git a/test/closure3.dir/main.go b/test/closure3.dir/main.go
index 2fc33753ed..e8e1e99860 100644
--- a/test/closure3.dir/main.go
+++ b/test/closure3.dir/main.go
@@ -93,11 +93,11 @@ func main() {
 		y := func(x int) int { // ERROR "can inline main.func11" "func literal does not escape"
 			return x + 2
 		}
-		y, sink = func() (func(int) int, int) { // ERROR "can inline main.func12"
-			return func(x int) int { // ERROR "can inline main.func12"
+		y, sink = func() (func(int) int, int) { // ERROR "func literal does not escape"
+			return func(x int) int { // ERROR "can inline main.func12" "func literal escapes"
 				return x + 1
 			}, 42
-		}() // ERROR "func literal does not escape" "inlining call to main.func12"
+		}()
 		if y(40) != 41 {
 			ppanic("y(40) != 41")
 		}
@@ -105,14 +105,14 @@ func main() {
 
 	{
 		func() { // ERROR "func literal does not escape"
-			y := func(x int) int { // ERROR "func literal does not escape" "can inline main.func13.1"
+			y := func(x int) int { // ERROR "can inline main.func13.1" "func literal does not escape"
 				return x + 2
 			}
-			y, sink = func() (func(int) int, int) { // ERROR "can inline main.func13.2"
-				return func(x int) int { // ERROR "can inline main.func13.2"
+			y, sink = func() (func(int) int, int) { // ERROR "func literal does not escape"
+				return func(x int) int { // ERROR "can inline main.func13.2" "func literal escapes"
 					return x + 1
 				}, 42
-			}() // ERROR "inlining call to main.func13.2" "func literal does not escape"
+			}()
 			if y(40) != 41 {
 				ppanic("y(40) != 41")
 			}
@@ -187,29 +187,29 @@ func main() {
 
 	{
 		x := 42
-		if z := func(y int) int { // ERROR "can inline main.func22"
-			return func() int { // ERROR "can inline main.func22.1" "can inline main.func30"
+		if z := func(y int) int { // ERROR "func literal does not escape"
+			return func() int { // ERROR "can inline main.func22.1"
 				return x + y
 			}() // ERROR "inlining call to main.func22.1"
-		}(1); z != 43 { // ERROR "inlining call to main.func22" "inlining call to main.func30"
+		}(1); z != 43 {
 			ppanic("z != 43")
 		}
-		if z := func(y int) int { // ERROR "func literal does not escape" "can inline main.func23"
-			return func() int { // ERROR "can inline main.func23.1" "can inline main.func31"
+		if z := func(y int) int { // ERROR "func literal does not escape"
+			return func() int { // ERROR "can inline main.func23.1"
 				return x + y
 			}() // ERROR "inlining call to main.func23.1"
-		}; z(1) != 43 { // ERROR "inlining call to main.func23" "inlining call to main.func31"
+		}; z(1) != 43 {
 			ppanic("z(1) != 43")
 		}
 	}
 
 	{
 		a := 1
-		func() { // ERROR "can inline main.func24"
-			func() { // ERROR "can inline main.func24" "can inline main.func32"
+		func() { // ERROR "func literal does not escape"
+			func() { // ERROR "can inline main.func24"
 				a = 2
 			}() // ERROR "inlining call to main.func24"
-		}() // ERROR "inlining call to main.func24" "inlining call to main.func32"
+		}()
 		if a != 2 {
 			ppanic("a != 2")
 		}
@@ -250,12 +250,12 @@ func main() {
 		a := 2
 		if r := func(x int) int { // ERROR "func literal does not escape"
 			b := 3
-			return func(y int) int { // ERROR "can inline main.func27.1"
+			return func(y int) int { // ERROR "func literal does not escape"
 				c := 5
-				return func(z int) int { // ERROR "can inline main.func27.1.1" "can inline main.func27.2"
+				return func(z int) int { // ERROR "can inline main.func27.1.1"
 					return a*x + b*y + c*z
 				}(10) // ERROR "inlining call to main.func27.1.1"
-			}(100) // ERROR "inlining call to main.func27.1" "inlining call to main.func27.2"
+			}(100)
 		}(1000); r != 2350 {
 			ppanic("r != 2350")
 		}
@@ -265,15 +265,15 @@ func main() {
 		a := 2
 		if r := func(x int) int { // ERROR "func literal does not escape"
 			b := 3
-			return func(y int) int { // ERROR "can inline main.func28.1"
+			return func(y int) int { // ERROR "func literal does not escape"
 				c := 5
-				func(z int) { // ERROR "can inline main.func28.1.1" "can inline main.func28.2"
+				func(z int) { // ERROR "can inline main.func28.1.1"
 					a = a * x
 					b = b * y
 					c = c * z
 				}(10) // ERROR "inlining call to main.func28.1.1"
 				return a + c
-			}(100) + b // ERROR "inlining call to main.func28.1" "inlining call to main.func28.2"
+			}(100) + b
 		}(1000); r != 2350 {
 			ppanic("r != 2350")
 		}
diff --git a/test/inline.go b/test/inline.go
index bc23768d01..b0911056ca 100644
--- a/test/inline.go
+++ b/test/inline.go
@@ -58,7 +58,7 @@ func _() int { // ERROR "can inline _"
 var somethingWrong error
 
 // local closures can be inlined
-func l(x, y int) (int, int, error) { // ERROR "can inline l"
+func l(x, y int) (int, int, error) {
 	e := func(err error) (int, int, error) { // ERROR "can inline l.func1" "func literal does not escape" "leaking param: err to result"
 		return 0, 0, err
 	}
@@ -90,19 +90,19 @@ func n() int {
 // make sure assignment inside closure is detected
 func o() int {
 	foo := func() int { return 1 } // ERROR "can inline o.func1" "func literal does not escape"
-	func(x int) {                  // ERROR "can inline o.func2"
+	func(x int) {                  // ERROR "func literal does not escape"
 		if x > 10 {
-			foo = func() int { return 2 } // ERROR "can inline o.func2"
+			foo = func() int { return 2 } // ERROR "can inline o.func2" "func literal escapes"
 		}
-	}(11) // ERROR "func literal does not escape" "inlining call to o.func2"
+	}(11)
 	return foo()
 }
 
-func p() int { // ERROR "can inline p"
+func p() int {
 	return func() int { return 42 }() // ERROR "can inline p.func1" "inlining call to p.func1"
 }
 
-func q(x int) int { // ERROR "can inline q"
+func q(x int) int {
 	foo := func() int { return x * 2 } // ERROR "can inline q.func1" "func literal does not escape"
 	return foo()                       // ERROR "inlining call to q.func1"
 }
@@ -111,15 +111,15 @@ func r(z int) int {
 	foo := func(x int) int { // ERROR "can inline r.func1" "func literal does not escape"
 		return x + z
 	}
-	bar := func(x int) int { // ERROR "func literal does not escape" "can inline r.func2"
-		return x + func(y int) int { // ERROR "can inline r.func2.1" "can inline r.func3"
+	bar := func(x int) int { // ERROR "func literal does not escape"
+		return x + func(y int) int { // ERROR "can inline r.func2.1"
 			return 2*y + x*z
 		}(x) // ERROR "inlining call to r.func2.1"
 	}
-	return foo(42) + bar(42) // ERROR "inlining call to r.func1" "inlining call to r.func2" "inlining call to r.func3"
+	return foo(42) + bar(42) // ERROR "inlining call to r.func1"
 }
 
-func s0(x int) int { // ERROR "can inline s0"
+func s0(x int) int {
 	foo := func() { // ERROR "can inline s0.func1" "func literal does not escape"
 		x = x + 1
 	}
@@ -127,7 +127,7 @@ func s0(x int) int { // ERROR "can inline s0"
 	return x
 }
 
-func s1(x int) int { // ERROR "can inline s1"
+func s1(x int) int {
 	foo := func() int { // ERROR "can inline s1.func1" "func literal does not escape"
 		return x
 	}