[dev.unified] cmd/compile: write RTTI into unified IR export data

This CL adds `rtype` methods for unified IR for writing/reading types
that need to have their *runtime._type value available.

For now, this just builds on the existing type writing/reading
mechanics and calling reflectdata.TypePtrAt; but longer term, reading
of derived types can be changed to use dictionary lookups instead.

Change-Id: I6f803b84546fa7df2877a8a3bcbf2623e4b03449
Reviewed-on: https://go-review.googlesource.com/c/go/+/419456
Run-TryBot: Matthew Dempsky <mdempsky@google.com>
TryBot-Result: Gopher Robot <gobot@golang.org>
Reviewed-by: Keith Randall <khr@golang.org>
Reviewed-by: David Chase <drchase@google.com>

3 files changed, 91 insertions, 32 deletions

diff --git a/src/cmd/compile/internal/noder/reader.go b/src/cmd/compile/internal/noder/reader.go
index 6b7ac5494f..6692446792 100644
--- a/src/cmd/compile/internal/noder/reader.go
+++ b/src/cmd/compile/internal/noder/reader.go
@@ -1390,17 +1390,10 @@ func (r *reader) forStmt(label *types.Sym) ir.Node {
 
 	if r.Bool() {
 		pos := r.pos()
+		rang := ir.NewRangeStmt(pos, nil, nil, nil, nil)
+		rang.Label = label
 
 		names, lhs := r.assignList()
-		x := r.expr()
-
-		body := r.blockStmt()
-		r.closeAnotherScope()
-
-		rang := ir.NewRangeStmt(pos, nil, nil, x, body)
-		if x.Type().IsMap() {
-			rang.RType = reflectdata.TypePtrAt(pos, x.Type())
-		}
 		if len(lhs) >= 1 {
 			rang.Key = lhs[0]
 			if len(lhs) >= 2 {
@@ -1408,10 +1401,13 @@ func (r *reader) forStmt(label *types.Sym) ir.Node {
 			}
 		}
 		rang.Def = r.initDefn(rang, names)
-		rang.Label = label
 
+		rang.X = r.expr()
+		if rang.X.Type().IsMap() {
+			rang.RType = r.rtype(pos)
+		}
 		{
-			keyType, valueType := rangeTypes(pos, x.Type())
+			keyType, valueType := rangeTypes(pos, rang.X.Type())
 
 			if rang.Key != nil {
 				rang.KeyTypeWord, rang.KeySrcRType = convRTTI(pos, rang.Key.Type(), keyType)
@@ -1421,6 +1417,9 @@ func (r *reader) forStmt(label *types.Sym) ir.Node {
 			}
 		}
 
+		rang.Body = r.blockStmt()
+		r.closeAnotherScope()
+
 		return rang
 	}
 
@@ -1741,7 +1740,7 @@ func (r *reader) expr() (res ir.Node) {
 		switch n.Op() {
 		case ir.OINDEXMAP:
 			n := n.(*ir.IndexExpr)
-			n.RType = reflectdata.TypePtrAt(pos, x.Type())
+			n.RType = r.rtype(pos)
 		}
 		return n
 
@@ -1762,10 +1761,12 @@ func (r *reader) expr() (res ir.Node) {
 		x := r.expr()
 		pos := r.pos()
 		typ := r.exprType(false)
+		srcRType := r.rtype(pos)
 
+		// TODO(mdempsky): Always emit ODYNAMICDOTTYPE for uniformity?
 		if typ, ok := typ.(*ir.DynamicType); ok && typ.Op() == ir.ODYNAMICTYPE {
 			assert := ir.NewDynamicTypeAssertExpr(pos, ir.ODYNAMICDOTTYPE, x, typ.RType)
-			assert.SrcRType = reflectdata.TypePtrAt(pos, x.Type())
+			assert.SrcRType = srcRType
 			assert.ITab = typ.ITab
 			return typed(typ.Type(), assert)
 		}
@@ -1810,16 +1811,16 @@ func (r *reader) expr() (res ir.Node) {
 		switch n.Op() {
 		case ir.OAPPEND:
 			n := n.(*ir.CallExpr)
-			n.RType = reflectdata.TypePtrAt(pos, n.Type().Elem())
+			n.RType = r.rtype(pos)
 		case ir.OCOPY:
 			n := n.(*ir.BinaryExpr)
-			n.RType = reflectdata.TypePtrAt(pos, n.X.Type().Elem())
+			n.RType = r.rtype(pos)
 		case ir.ODELETE:
 			n := n.(*ir.CallExpr)
-			n.RType = reflectdata.TypePtrAt(pos, n.Args[0].Type())
+			n.RType = r.rtype(pos)
 		case ir.OUNSAFESLICE:
 			n := n.(*ir.BinaryExpr)
-			n.RType = reflectdata.TypePtrAt(pos, n.Type().Elem())
+			n.RType = r.rtype(pos)
 		}
 		return n
 
@@ -1828,14 +1829,7 @@ func (r *reader) expr() (res ir.Node) {
 		typ := r.exprType(false)
 		extra := r.exprs()
 		n := typecheck.Expr(ir.NewCallExpr(pos, ir.OMAKE, nil, append([]ir.Node{typ}, extra...))).(*ir.MakeExpr)
-		switch n.Op() {
-		case ir.OMAKECHAN:
-			n.RType = reflectdata.TypePtrAt(pos, typ.Type())
-		case ir.OMAKEMAP:
-			n.RType = reflectdata.TypePtrAt(pos, typ.Type())
-		case ir.OMAKESLICE:
-			n.RType = reflectdata.TypePtrAt(pos, typ.Type().Elem())
-		}
+		n.RType = r.rtype(pos)
 		return n
 
 	case exprNew:
@@ -1969,6 +1963,10 @@ func (r *reader) compLit() ir.Node {
 	if typ.Kind() == types.TFORW {
 		base.FatalfAt(pos, "unresolved composite literal type: %v", typ)
 	}
+	var rtype ir.Node
+	if typ.IsMap() {
+		rtype = r.rtype(pos)
+	}
 	isStruct := typ.Kind() == types.TSTRUCT
 
 	elems := make([]ir.Node, r.Len())
@@ -1987,10 +1985,9 @@ func (r *reader) compLit() ir.Node {
 	}
 
 	lit := typecheck.Expr(ir.NewCompLitExpr(pos, ir.OCOMPLIT, typ, elems))
-	switch lit.Op() {
-	case ir.OMAPLIT:
+	if rtype != nil {
 		lit := lit.(*ir.CompLitExpr)
-		lit.RType = reflectdata.TypePtrAt(pos, typ)
+		lit.RType = rtype
 	}
 	if typ0.IsPtr() {
 		lit = typecheck.Expr(typecheck.NodAddrAt(pos, lit))
@@ -2060,6 +2057,12 @@ func (r *reader) exprs() []ir.Node {
 	return nodes
 }
 
+func (r *reader) rtype(pos src.XPos) ir.Node {
+	r.Sync(pkgbits.SyncRType)
+	// TODO(mdempsky): For derived types, use dictionary instead.
+	return reflectdata.TypePtrAt(pos, r.typ())
+}
+
 func (r *reader) exprType(nilOK bool) ir.Node {
 	r.Sync(pkgbits.SyncExprType)
 
diff --git a/src/cmd/compile/internal/noder/writer.go b/src/cmd/compile/internal/noder/writer.go
index 93e81bdc82..5dd252a2a5 100644
--- a/src/cmd/compile/internal/noder/writer.go
+++ b/src/cmd/compile/internal/noder/writer.go
@@ -1299,6 +1299,11 @@ func (w *writer) forStmt(stmt *syntax.ForStmt) {
 		w.pos(rang)
 		w.assignList(rang.Lhs)
 		w.expr(rang.X)
+
+		xtyp := w.p.typeOf(rang.X)
+		if _, isMap := types2.CoreType(xtyp).(*types2.Map); isMap {
+			w.rtype(xtyp)
+		}
 	} else {
 		w.pos(stmt)
 		w.stmt(stmt.Init)
@@ -1549,8 +1554,10 @@ func (w *writer) expr(expr syntax.Expr) {
 	case *syntax.IndexExpr:
 		_ = w.p.typeOf(expr.Index) // ensure this is an index expression, not an instantiation
 
+		xtyp := w.p.typeOf(expr.X)
+
 		var keyType types2.Type
-		if mapType, ok := types2.CoreType(w.p.typeOf(expr.X)).(*types2.Map); ok {
+		if mapType, ok := types2.CoreType(xtyp).(*types2.Map); ok {
 			keyType = mapType.Key()
 		}
 
@@ -1558,6 +1565,9 @@ func (w *writer) expr(expr syntax.Expr) {
 		w.expr(expr.X)
 		w.pos(expr)
 		w.implicitConvExpr(expr, keyType, expr.Index)
+		if keyType != nil {
+			w.rtype(xtyp)
+		}
 
 	case *syntax.SliceExpr:
 		w.Code(exprSlice)
@@ -1574,6 +1584,7 @@ func (w *writer) expr(expr syntax.Expr) {
 		w.expr(expr.X)
 		w.pos(expr)
 		w.exprType(iface, expr.Type, false)
+		w.rtype(iface)
 
 	case *syntax.Operation:
 		if expr.Y == nil {
@@ -1622,8 +1633,9 @@ func (w *writer) expr(expr syntax.Expr) {
 			break
 		}
 
-		if name, ok := unparen(expr.Fun).(*syntax.Name); ok && tv.IsBuiltin() {
-			switch name.Value {
+		var rtype types2.Type
+		if tv.IsBuiltin() {
+			switch obj, _ := lookupObj(w.p.info, expr.Fun); obj.Name() {
 			case "make":
 				assert(len(expr.ArgList) >= 1)
 				assert(!expr.HasDots)
@@ -1632,6 +1644,19 @@ func (w *writer) expr(expr syntax.Expr) {
 				w.pos(expr)
 				w.exprType(nil, expr.ArgList[0], false)
 				w.exprs(expr.ArgList[1:])
+
+				typ := w.p.typeOf(expr)
+				switch coreType := types2.CoreType(typ).(type) {
+				default:
+					w.p.fatalf(expr, "unexpected core type: %v", coreType)
+				case *types2.Chan:
+					w.rtype(typ)
+				case *types2.Map:
+					w.rtype(typ)
+				case *types2.Slice:
+					w.rtype(sliceElem(typ))
+				}
+
 				return
 
 			case "new":
@@ -1642,6 +1667,23 @@ func (w *writer) expr(expr syntax.Expr) {
 				w.pos(expr)
 				w.exprType(nil, expr.ArgList[0], false)
 				return
+
+			case "append":
+				rtype = sliceElem(w.p.typeOf(expr))
+			case "copy":
+				typ := w.p.typeOf(expr.ArgList[0])
+				if tuple, ok := typ.(*types2.Tuple); ok { // "copy(g())"
+					typ = tuple.At(0).Type()
+				}
+				rtype = sliceElem(typ)
+			case "delete":
+				typ := w.p.typeOf(expr.ArgList[0])
+				if tuple, ok := typ.(*types2.Tuple); ok { // "delete(g())"
+					typ = tuple.At(0).Type()
+				}
+				rtype = typ
+			case "Slice":
+				rtype = sliceElem(w.p.typeOf(expr))
 			}
 		}
 
@@ -1676,9 +1718,16 @@ func (w *writer) expr(expr syntax.Expr) {
 
 		w.multiExpr(expr, paramType, expr.ArgList)
 		w.Bool(expr.HasDots)
+		if rtype != nil {
+			w.rtype(rtype)
+		}
 	}
 }
 
+func sliceElem(typ types2.Type) types2.Type {
+	return types2.CoreType(typ).(*types2.Slice).Elem()
+}
+
 func (w *writer) optExpr(expr syntax.Expr) {
 	if w.Bool(expr != nil) {
 		w.expr(expr)
@@ -1757,12 +1806,13 @@ func (w *writer) compLit(lit *syntax.CompositeLit) {
 	}
 	var keyType, elemType types2.Type
 	var structType *types2.Struct
-	switch typ := types2.CoreType(typ).(type) {
+	switch typ0 := typ; typ := types2.CoreType(typ).(type) {
 	default:
 		w.p.fatalf(lit, "unexpected composite literal type: %v", typ)
 	case *types2.Array:
 		elemType = typ.Elem()
 	case *types2.Map:
+		w.rtype(typ0)
 		keyType, elemType = typ.Key(), typ.Elem()
 	case *types2.Slice:
 		elemType = typ.Elem()
@@ -1833,6 +1883,11 @@ func (w *writer) exprs(exprs []syntax.Expr) {
 	}
 }
 
+func (w *writer) rtype(typ types2.Type) {
+	w.Sync(pkgbits.SyncRType)
+	w.typ(typ)
+}
+
 func (w *writer) exprType(iface types2.Type, typ syntax.Expr, nilOK bool) {
 	base.Assertf(iface == nil || isInterface(iface), "%v must be nil or an interface type", iface)
 
diff --git a/src/internal/pkgbits/sync.go b/src/internal/pkgbits/sync.go
index 6a5999eb6b..54e478d932 100644
--- a/src/internal/pkgbits/sync.go
+++ b/src/internal/pkgbits/sync.go
@@ -112,4 +112,5 @@ const (
 	SyncOptLabel
 
 	SyncMultiExpr
+	SyncRType
 )