cmd/compile/internal/types: remove Type.sym and rename Type.nod to Type.obj

Now that Ntype is gone, we no longer require separate sym and nod
fields for Type. It's now always the case that t.sym == t.nod.Sym(),
or that t.sym and t.nod are both nil.

While here, rename nod to obj, to better reflect that in fact it's
always an object (i.e., *ir.Name), not merely a type literal (which no
longer exists in package ir).

Change-Id: Iba4c1590ca585b816ff6b70947ad2a1109918955
Reviewed-on: https://go-review.googlesource.com/c/go/+/405656
Run-TryBot: Matthew Dempsky <mdempsky@google.com>
Reviewed-by: Cuong Manh Le <cuong.manhle.vn@gmail.com>
Reviewed-by: David Chase <drchase@google.com>
TryBot-Result: Gopher Robot <gobot@golang.org>

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

@@ -42,7 +42,7 @@ func identical(t1, t2 *Type, flags int, assumedEqual map[typePair]struct{}) bool
 	if t1 == nil || t2 == nil || t1.kind != t2.kind {
 		return false
 	}
-	if t1.sym != nil || t2.sym != nil {
+	if t1.obj != nil || t2.obj != nil {
 		if flags&identStrict == 0 && (t1.HasShape() || t2.HasShape()) {
 			switch t1.kind {
 			case TINT8, TUINT8, TINT16, TUINT16, TINT32, TUINT32, TINT64, TUINT64, TINT, TUINT, TUINTPTR, TCOMPLEX64, TCOMPLEX128, TFLOAT32, TFLOAT64, TBOOL, TSTRING, TPTR, TUNSAFEPTR:

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

@@ -21,7 +21,7 @@ func TestSizeof(t *testing.T) {
 		_64bit uintptr     // size on 64bit platforms
 	}{
 		{Sym{}, 32, 64},
-		{Type{}, 64, 112},
+		{Type{}, 60, 104},
 		{Map{}, 20, 40},
 		{Forward{}, 20, 32},
 		{Func{}, 28, 48},

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

@@ -168,7 +168,7 @@ type Type struct {
 	allMethods Fields
 
 	// canonical OTYPE node for a named type (should be an ir.Name node with same sym)
-	nod Object
+	obj Object
 	// the underlying type (type literal or predeclared type) for a defined type
 	underlying *Type
 
@@ -178,7 +178,6 @@ type Type struct {
 		slice *Type // []T, or nil
 	}
 
-	sym    *Sym  // symbol containing name, for named types
 	vargen int32 // unique name for OTYPE/ONAME
 
 	kind  Kind  // kind of type
@@ -238,7 +237,12 @@ func (t *Type) SetHasShape(b bool) { t.flags.set(typeHasShape, b) }
 func (t *Type) Kind() Kind { return t.kind }
 
 // Sym returns the name of type t.
-func (t *Type) Sym() *Sym { return t.sym }
+func (t *Type) Sym() *Sym {
+	if t.obj != nil {
+		return t.obj.Sym()
+	}
+	return nil
+}
 
 // OrigType returns the original generic type that t is an
 // instantiation of, if any.
@@ -251,8 +255,8 @@ func (t *Type) Underlying() *Type { return t.underlying }
 // Pos returns a position associated with t, if any.
 // This should only be used for diagnostics.
 func (t *Type) Pos() src.XPos {
-	if t.nod != nil {
-		return t.nod.Pos()
+	if t.obj != nil {
+		return t.obj.Pos()
 	}
 	return src.NoXPos
 }
@@ -1190,7 +1194,7 @@ func (t *Type) cmp(x *Type) Cmp {
 		return cmpForNe(t.kind < x.kind)
 	}
 
-	if t.sym != nil || x.sym != nil {
+	if t.obj != nil || x.obj != nil {
 		// Special case: we keep byte and uint8 separate
 		// for error messages. Treat them as equal.
 		switch t.kind {
@@ -1212,11 +1216,11 @@ func (t *Type) cmp(x *Type) Cmp {
 		}
 	}
 
-	if c := t.sym.cmpsym(x.sym); c != CMPeq {
+	if c := t.Sym().cmpsym(x.Sym()); c != CMPeq {
 		return c
 	}
 
-	if x.sym != nil {
+	if x.obj != nil {
 		// Syms non-nil, if vargens match then equal.
 		if t.vargen != x.vargen {
 			return cmpForNe(t.vargen < x.vargen)
@@ -1708,9 +1712,8 @@ var (
 // the type is complete.
 func NewNamed(obj Object) *Type {
 	t := newType(TFORW)
-	t.sym = obj.Sym()
-	t.nod = obj
-	if t.sym.Pkg == ShapePkg {
+	t.obj = obj
+	if obj.Sym().Pkg == ShapePkg {
 		t.SetIsShape(true)
 		t.SetHasShape(true)
 	}
@@ -1719,10 +1722,7 @@ func NewNamed(obj Object) *Type {
 
 // Obj returns the canonical type name node for a named type t, nil for an unnamed type.
 func (t *Type) Obj() Object {
-	if t.sym != nil {
-		return t.nod
-	}
-	return nil
+	return t.obj
 }
 
 // typeGen tracks the number of function-scoped defined types that
@@ -1815,8 +1815,7 @@ func fieldsHasShape(fields []*Field) bool {
 // NewBasic returns a new basic type of the given kind.
 func newBasic(kind Kind, obj Object) *Type {
 	t := newType(kind)
-	t.sym = obj.Sym()
-	t.nod = obj
+	t.obj = obj
 	return t
 }
 
@@ -1845,8 +1844,7 @@ func NewInterface(pkg *Pkg, methods []*Field, implicit bool) *Type {
 // and specified index within the typeparam list.
 func NewTypeParam(obj Object, index int) *Type {
 	t := newType(TTYPEPARAM)
-	t.sym = obj.Sym()
-	t.nod = obj
+	t.obj = obj
 	t.extra.(*Typeparam).index = index
 	t.SetHasTParam(true)
 	return t

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

@@ -64,8 +64,7 @@ func InitTypes(defTypeName func(sym *Sym, typ *Type) Object) {
 	defBasic := func(kind Kind, pkg *Pkg, name string) *Type {
 		typ := newType(kind)
 		obj := defTypeName(pkg.Lookup(name), typ)
-		typ.sym = obj.Sym()
-		typ.nod = obj
+		typ.obj = obj
 		if kind != TANY {
 			CheckSize(typ)
 		}