cmd/compile/internal/types: replace Type.Val with Type.Elem

This reduces the API surface of Type slightly (for #25056), but also
makes it more consistent with the reflect and go/types APIs.

Passes toolstash-check.

Change-Id: Ief9a8eb461ae6e88895f347e2a1b7b8a62423222
Reviewed-on: https://go-review.googlesource.com/109138
Run-TryBot: Matthew Dempsky <mdempsky@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>

src/cmd/compile/internal/gc/align.go

@@ -286,7 +286,7 @@ func dowidth(t *types.Type) {
 
 	case TMAP: // implemented as pointer
 		w = int64(Widthptr)
-		checkwidth(t.Val())
+		checkwidth(t.Elem())
 		checkwidth(t.Key())
 
 	case TFORW: // should have been filled in

src/cmd/compile/internal/gc/bexport.go

@@ -476,12 +476,9 @@ func (p *exporter) markType(t *types.Type) {
 	// perfect. Worst case, we might miss opportunities to inline
 	// some function calls in downstream packages.
 	switch t.Etype {
-	case TPTR32, TPTR64, TARRAY, TSLICE, TCHAN:
+	case TPTR32, TPTR64, TARRAY, TSLICE, TCHAN, TMAP:
 		p.markType(t.Elem())
 
-	case TMAP:
-		p.markType(t.Val())
-
 	case TSTRUCT:
 		for _, f := range t.FieldSlice() {
 			if types.IsExported(f.Sym.Name) || f.Embedded != 0 {
@@ -798,7 +795,7 @@ func (p *exporter) typ(t *types.Type) {
 	case TMAP:
 		p.tag(mapTag)
 		p.typ(t.Key())
-		p.typ(t.Val())
+		p.typ(t.Elem())
 
 	case TCHAN:
 		p.tag(chanTag)

src/cmd/compile/internal/gc/bimport.go

@@ -587,7 +587,7 @@ func (p *importer) typ() *types.Type {
 		t = p.newtyp(TMAP)
 		mt := t.MapType()
 		mt.Key = p.typ()
-		mt.Val = p.typ()
+		mt.Elem = p.typ()
 
 	case chanTag:
 		t = p.newtyp(TCHAN)

src/cmd/compile/internal/gc/fmt.go

@@ -739,7 +739,7 @@ func typefmt(t *types.Type, flag FmtFlag, mode fmtMode, depth int) string {
 		return "chan " + tmodeString(t.Elem(), mode, depth)
 
 	case TMAP:
-		return "map[" + tmodeString(t.Key(), mode, depth) + "]" + tmodeString(t.Val(), mode, depth)
+		return "map[" + tmodeString(t.Key(), mode, depth) + "]" + tmodeString(t.Elem(), mode, depth)
 
 	case TINTER:
 		if t.IsEmptyInterface() {
@@ -803,20 +803,19 @@ func typefmt(t *types.Type, flag FmtFlag, mode fmtMode, depth int) string {
 			mt := m.MapType()
 			// Format the bucket struct for map[x]y as map.bucket[x]y.
 			// This avoids a recursive print that generates very long names.
-			if mt.Bucket == t {
-				return "map.bucket[" + tmodeString(m.Key(), mode, depth) + "]" + tmodeString(m.Val(), mode, depth)
-			}
-
-			if mt.Hmap == t {
-				return "map.hdr[" + tmodeString(m.Key(), mode, depth) + "]" + tmodeString(m.Val(), mode, depth)
-			}
-
-			if mt.Hiter == t {
-				return "map.iter[" + tmodeString(m.Key(), mode, depth) + "]" + tmodeString(m.Val(), mode, depth)
-			}
-
+			var subtype string
+			switch t {
+			case mt.Bucket:
+				subtype = "bucket"
+			case mt.Hmap:
+				subtype = "hdr"
+			case mt.Hiter:
+				subtype = "iter"
+			default:
 				Fatalf("unknown internal map type")
 			}
+			return fmt.Sprintf("map.%s[%s]%s", subtype, tmodeString(m.Key(), mode, depth), tmodeString(m.Elem(), mode, depth))
+		}
 
 		buf := make([]byte, 0, 64)
 		if t.IsFuncArgStruct() {

src/cmd/compile/internal/gc/iexport.go

@@ -638,7 +638,7 @@ func (w *exportWriter) doTyp(t *types.Type) {
 	case TMAP:
 		w.startType(mapType)
 		w.typ(t.Key())
-		w.typ(t.Val())
+		w.typ(t.Elem())
 
 	case TFUNC:
 		w.startType(signatureType)

src/cmd/compile/internal/gc/range.go

@@ -71,7 +71,7 @@ func typecheckrangeExpr(n *Node) {
 
 	case TMAP:
 		t1 = t.Key()
-		t2 = t.Val()
+		t2 = t.Elem()
 
 	case TCHAN:
 		if !t.ChanDir().CanRecv() {
@@ -297,7 +297,7 @@ func walkrange(n *Node) *Node {
 
 		fn := syslook("mapiterinit")
 
-		fn = substArgTypes(fn, t.Key(), t.Val(), th)
+		fn = substArgTypes(fn, t.Key(), t.Elem(), th)
 		init = append(init, mkcall1(fn, nil, nil, typename(t), ha, nod(OADDR, hit, nil)))
 		n.Left = nod(ONE, nodSym(ODOT, hit, keysym), nodnil())
 

src/cmd/compile/internal/gc/reflect.go

@@ -85,7 +85,7 @@ func bmap(t *types.Type) *types.Type {
 
 	bucket := types.New(TSTRUCT)
 	keytype := t.Key()
-	valtype := t.Val()
+	valtype := t.Elem()
 	dowidth(keytype)
 	dowidth(valtype)
 	if keytype.Width > MAXKEYSIZE {
@@ -172,7 +172,7 @@ func bmap(t *types.Type) *types.Type {
 	if t.Key().Width > MAXKEYSIZE && !keytype.IsPtr() {
 		Fatalf("key indirect incorrect for %v", t)
 	}
-	if t.Val().Width > MAXVALSIZE && !valtype.IsPtr() {
+	if t.Elem().Width > MAXVALSIZE && !valtype.IsPtr() {
 		Fatalf("value indirect incorrect for %v", t)
 	}
 	if keytype.Width%int64(keytype.Align) != 0 {
@@ -287,7 +287,7 @@ func hiter(t *types.Type) *types.Type {
 	// must match ../../../../runtime/map.go:hiter.
 	fields := []*types.Field{
 		makefield("key", types.NewPtr(t.Key())),  // Used in range.go for TMAP.
-		makefield("val", types.NewPtr(t.Val())), // Used in range.go for TMAP.
+		makefield("val", types.NewPtr(t.Elem())), // Used in range.go for TMAP.
 		makefield("t", types.Types[TUNSAFEPTR]),
 		makefield("h", types.NewPtr(hmap)),
 		makefield("buckets", types.NewPtr(bmap)),
@@ -1245,7 +1245,7 @@ func dtypesym(t *types.Type) *obj.LSym {
 	// ../../../../runtime/type.go:/mapType
 	case TMAP:
 		s1 := dtypesym(t.Key())
-		s2 := dtypesym(t.Val())
+		s2 := dtypesym(t.Elem())
 		s3 := dtypesym(bmap(t))
 		s4 := dtypesym(hmap(t))
 		ot = dcommontype(lsym, t)
@@ -1261,11 +1261,11 @@ func dtypesym(t *types.Type) *obj.LSym {
 			ot = duint8(lsym, ot, 0) // not indirect
 		}
 
-		if t.Val().Width > MAXVALSIZE {
+		if t.Elem().Width > MAXVALSIZE {
 			ot = duint8(lsym, ot, uint8(Widthptr))
 			ot = duint8(lsym, ot, 1) // indirect
 		} else {
-			ot = duint8(lsym, ot, uint8(t.Val().Width))
+			ot = duint8(lsym, ot, uint8(t.Elem().Width))
 			ot = duint8(lsym, ot, 0) // not indirect
 		}
 

src/cmd/compile/internal/gc/sinit.go

@@ -947,7 +947,7 @@ func maplit(n *Node, m *Node, init *Nodes) {
 
 		// build types [count]Tindex and [count]Tvalue
 		tk := types.NewArray(n.Type.Key(), int64(len(stat)))
-		tv := types.NewArray(n.Type.Val(), int64(len(stat)))
+		tv := types.NewArray(n.Type.Elem(), int64(len(stat)))
 
 		// TODO(josharian): suppress alg generation for these types?
 		dowidth(tk)
@@ -1012,7 +1012,7 @@ func addMapEntries(m *Node, dyn []*Node, init *Nodes) {
 	// Use temporaries so that mapassign1 can have addressable key, val.
 	// TODO(josharian): avoid map key temporaries for mapfast_* assignments with literal keys.
 	key := temp(m.Type.Key())
-	val := temp(m.Type.Val())
+	val := temp(m.Type.Elem())
 
 	for _, r := range dyn {
 		index, value := r.Left, r.Right

src/cmd/compile/internal/gc/subr.go

@@ -612,7 +612,6 @@ func eqtype1(t1, t2 *types.Type, cmpTags bool, assumedEqual map[typePair]struct{
 		if !eqtype1(t1.Key(), t2.Key(), cmpTags, assumedEqual) {
 			return false
 		}
-		return eqtype1(t1.Val(), t2.Val(), cmpTags, assumedEqual)
 	}
 
 	return eqtype1(t1.Elem(), t2.Elem(), cmpTags, assumedEqual)

src/cmd/compile/internal/gc/typecheck.go

@@ -1019,7 +1019,7 @@ func typecheck1(n *Node, top int) *Node {
 			if n.Right.Type != nil {
 				n.Right = assignconv(n.Right, t.Key(), "map index")
 			}
-			n.Type = t.Val()
+			n.Type = t.Elem()
 			n.Op = OINDEXMAP
 			n.ResetAux()
 		}
@@ -3012,10 +3012,10 @@ func typecheckcomplit(n *Node) *Node {
 			}
 
 			r = l.Right
-			pushtype(r, t.Val())
+			pushtype(r, t.Elem())
 			r = typecheck(r, Erv)
-			r = defaultlit(r, t.Val())
-			l.Right = assignconv(r, t.Val(), "map value")
+			r = defaultlit(r, t.Elem())
+			l.Right = assignconv(r, t.Elem(), "map value")
 		}
 
 		n.Op = OMAPLIT

src/cmd/compile/internal/gc/walk.go

@@ -822,7 +822,7 @@ opswitch:
 		//   a = *var
 		a := n.List.First()
 
-		if w := t.Val().Width; w <= 1024 { // 1024 must match ../../../../runtime/map.go:maxZero
+		if w := t.Elem().Width; w <= 1024 { // 1024 must match ../../../../runtime/map.go:maxZero
 			fn := mapfn(mapaccess2[fast], t)
 			r = mkcall1(fn, fn.Type.Results(), init, typename(t), r.Left, key)
 		} else {
@@ -842,7 +842,7 @@ opswitch:
 
 		// don't generate a = *var if a is _
 		if !a.isBlank() {
-			var_ := temp(types.NewPtr(t.Val()))
+			var_ := temp(types.NewPtr(t.Elem()))
 			var_.SetTypecheck(1)
 			var_.SetNonNil(true) // mapaccess always returns a non-nil pointer
 			n.List.SetFirst(var_)
@@ -1196,17 +1196,17 @@ opswitch:
 				key = nod(OADDR, key, nil)
 			}
 
-			if w := t.Val().Width; w <= 1024 { // 1024 must match ../../../../runtime/map.go:maxZero
-				n = mkcall1(mapfn(mapaccess1[fast], t), types.NewPtr(t.Val()), init, typename(t), map_, key)
+			if w := t.Elem().Width; w <= 1024 { // 1024 must match ../../../../runtime/map.go:maxZero
+				n = mkcall1(mapfn(mapaccess1[fast], t), types.NewPtr(t.Elem()), init, typename(t), map_, key)
 			} else {
 				z := zeroaddr(w)
-				n = mkcall1(mapfn("mapaccess1_fat", t), types.NewPtr(t.Val()), init, typename(t), map_, key, z)
+				n = mkcall1(mapfn("mapaccess1_fat", t), types.NewPtr(t.Elem()), init, typename(t), map_, key, z)
 			}
 		}
-		n.Type = types.NewPtr(t.Val())
+		n.Type = types.NewPtr(t.Elem())
 		n.SetNonNil(true) // mapaccess1* and mapassign always return non-nil pointers.
 		n = nod(OIND, n, nil)
-		n.Type = t.Val()
+		n.Type = t.Elem()
 		n.SetTypecheck(1)
 
 	case ORECV:
@@ -1498,7 +1498,7 @@ opswitch:
 				// Call runtime.makehmap to allocate an
 				// hmap on the heap and initialize hmap's hash0 field.
 				fn := syslook("makemap_small")
-				fn = substArgTypes(fn, t.Key(), t.Val())
+				fn = substArgTypes(fn, t.Key(), t.Elem())
 				n = mkcall1(fn, n.Type, init)
 			}
 		} else {
@@ -1525,7 +1525,7 @@ opswitch:
 			}
 
 			fn := syslook(fnname)
-			fn = substArgTypes(fn, hmapType, t.Key(), t.Val())
+			fn = substArgTypes(fn, hmapType, t.Key(), t.Elem())
 			n = mkcall1(fn, n.Type, init, typename(n.Type), conv(hint, argtype), h)
 		}
 
@@ -2792,7 +2792,7 @@ func mapfn(name string, t *types.Type) *Node {
 		Fatalf("mapfn %v", t)
 	}
 	fn := syslook(name)
-	fn = substArgTypes(fn, t.Key(), t.Val(), t.Key(), t.Val())
+	fn = substArgTypes(fn, t.Key(), t.Elem(), t.Key(), t.Elem())
 	return fn
 }
 
@@ -2801,7 +2801,7 @@ func mapfndel(name string, t *types.Type) *Node {
 		Fatalf("mapfn %v", t)
 	}
 	fn := syslook(name)
-	fn = substArgTypes(fn, t.Key(), t.Val(), t.Key())
+	fn = substArgTypes(fn, t.Key(), t.Elem(), t.Key())
 	return fn
 }
 
@@ -2828,7 +2828,7 @@ var mapdelete = mkmapnames("mapdelete", "")
 
 func mapfast(t *types.Type) int {
 	// Check ../../runtime/map.go:maxValueSize before changing.
-	if t.Val().Width > 128 {
+	if t.Elem().Width > 128 {
 		return mapslow
 	}
 	switch algtype(t.Key()) {

src/cmd/compile/internal/types/type.go

@@ -220,7 +220,7 @@ func (t *Type) SetPkg(pkg *Pkg) {
 // Map contains Type fields specific to maps.
 type Map struct {
 	Key  *Type // Key type
-	Val *Type // Val (elem) type
+	Elem *Type // Val (elem) type
 
 	Bucket *Type // internal struct type representing a hash bucket
 	Hmap   *Type // internal struct type representing the Hmap (map header object)
@@ -539,7 +539,7 @@ func NewMap(k, v *Type) *Type {
 	t := New(TMAP)
 	mt := t.MapType()
 	mt.Key = k
-	mt.Val = v
+	mt.Elem = v
 	return t
 }
 
@@ -650,11 +650,11 @@ func SubstAny(t *Type, types *[]*Type) *Type {
 
 	case TMAP:
 		key := SubstAny(t.Key(), types)
-		val := SubstAny(t.Val(), types)
-		if key != t.Key() || val != t.Val() {
+		elem := SubstAny(t.Elem(), types)
+		if key != t.Key() || elem != t.Elem() {
 			t = t.copy()
 			t.Extra.(*Map).Key = key
-			t.Extra.(*Map).Val = val
+			t.Extra.(*Map).Elem = elem
 		}
 
 	case TFUNC:
@@ -787,14 +787,8 @@ func (t *Type) Key() *Type {
 	return t.Extra.(*Map).Key
 }
 
-// Val returns the value type of map type t.
-func (t *Type) Val() *Type {
-	t.wantEtype(TMAP)
-	return t.Extra.(*Map).Val
-}
-
 // Elem returns the type of elements of t.
-// Usable with pointers, channels, arrays, and slices.
+// Usable with pointers, channels, arrays, slices, and maps.
 func (t *Type) Elem() *Type {
 	switch t.Etype {
 	case TPTR32, TPTR64:
@@ -805,6 +799,8 @@ func (t *Type) Elem() *Type {
 		return t.Extra.(Slice).Elem
 	case TCHAN:
 		return t.Extra.(*Chan).Elem
+	case TMAP:
+		return t.Extra.(*Map).Elem
 	}
 	Fatalf("Type.Elem %s", t.Etype)
 	return nil
@@ -1104,7 +1100,7 @@ func (t *Type) cmp(x *Type) Cmp {
 		if c := t.Key().cmp(x.Key()); c != CMPeq {
 			return c
 		}
-		return t.Val().cmp(x.Val())
+		return t.Elem().cmp(x.Elem())
 
 	case TPTR32, TPTR64, TSLICE:
 		// No special cases for these, they are handled