cmd/compile: don't set Ntype in noder2 anymore

Now that we are no longer calling the old typechecker at all during the
noder2 pass, we don't need to create and set an Ntype node ((which is
just a node representation of the type which we already know) for the
Name and Closure nodes. This should reduce memory usage a bit for -G=3.

Change-Id: I6b1345007ce067a89ee64955a53f25645c303f4d
Reviewed-on: https://go-review.googlesource.com/c/go/+/308909
Trust: Dan Scales <danscales@google.com>
Run-TryBot: Dan Scales <danscales@google.com>
TryBot-Result: Go Bot <gobot@golang.org>
Reviewed-by: Robert Griesemer <gri@golang.org>

src/cmd/compile/internal/inline/inl.go

@@ -506,7 +506,10 @@ func inlcopy(n ir.Node) ir.Node {
 			newfn.Nname = ir.NewNameAt(oldfn.Nname.Pos(), oldfn.Nname.Sym())
 			// XXX OK to share fn.Type() ??
 			newfn.Nname.SetType(oldfn.Nname.Type())
-			newfn.Nname.Ntype = inlcopy(oldfn.Nname.Ntype).(ir.Ntype)
+			// Ntype can be nil for -G=3 mode.
+			if oldfn.Nname.Ntype != nil {
+				newfn.Nname.Ntype = inlcopy(oldfn.Nname.Ntype).(ir.Ntype)
+			}
 			newfn.Body = inlcopylist(oldfn.Body)
 			// Make shallow copy of the Dcl and ClosureVar slices
 			newfn.Dcl = append([]*ir.Name(nil), oldfn.Dcl...)
@@ -1213,7 +1216,10 @@ func (subst *inlsubst) closure(n *ir.ClosureExpr) ir.Node {
 	newfn.SetIsHiddenClosure(true)
 	newfn.Nname = ir.NewNameAt(n.Pos(), ir.BlankNode.Sym())
 	newfn.Nname.Func = newfn
-	newfn.Nname.Ntype = subst.node(oldfn.Nname.Ntype).(ir.Ntype)
+	// Ntype can be nil for -G=3 mode.
+	if oldfn.Nname.Ntype != nil {
+		newfn.Nname.Ntype = subst.node(oldfn.Nname.Ntype).(ir.Ntype)
+	}
 	newfn.Nname.Defn = newfn
 
 	m.(*ir.ClosureExpr).Func = newfn

src/cmd/compile/internal/noder/expr.go

@@ -360,8 +360,6 @@ func (g *irgen) funcLit(typ2 types2.Type, expr *syntax.FuncLit) ir.Node {
 	typ := g.typ(typ2)
 	fn.Nname.Func = fn
 	fn.Nname.Defn = fn
-	// Set Ntype for now to be compatible with later parts of compile, remove later.
-	fn.Nname.Ntype = ir.TypeNode(typ)
 	typed(typ, fn.Nname)
 	fn.SetTypecheck(1)
 

src/cmd/compile/internal/noder/object.go

@@ -147,9 +147,6 @@ func (g *irgen) objFinish(name *ir.Name, class ir.Class, typ *types.Type) {
 		sym.SetFunc(true)
 	}
 
-	// We already know name's type, but typecheck is really eager to try
-	// recomputing it later. This appears to prevent that at least.
-	name.Ntype = ir.TypeNode(typ)
 	name.SetTypecheck(1)
 	name.SetWalkdef(1)
 

src/cmd/compile/internal/noder/stencil.go

@@ -298,7 +298,6 @@ func (g *irgen) genericSubst(newsym *types.Sym, nameNode *ir.Name, targs []ir.No
 		subst.fields(ir.PPARAM, append(oldt.Recvs().FieldSlice(), oldt.Params().FieldSlice()...), newf.Dcl),
 		subst.fields(ir.PPARAMOUT, oldt.Results().FieldSlice(), newf.Dcl))
 
-	newf.Nname.Ntype = ir.TypeNode(newt)
 	newf.Nname.SetType(newt)
 	ir.MarkFunc(newf.Nname)
 	newf.SetTypecheck(1)
@@ -497,8 +496,7 @@ func (subst *subster) node(n ir.Node) ir.Node {
 
 		case ir.OCLOSURE:
 			x := x.(*ir.ClosureExpr)
-			// Need to save/duplicate x.Func.Nname,
+			// Need to duplicate x.Func.Nname, x.Func.Dcl, x.Func.ClosureVars, and
-			// x.Func.Nname.Ntype, x.Func.Dcl, x.Func.ClosureVars, and
 			// x.Func.Body.
 			oldfn := x.Func
 			newfn := ir.NewFunc(oldfn.Pos())
@@ -522,8 +520,6 @@ func (subst *subster) node(n ir.Node) ir.Node {
 			newfn.Dcl = subst.namelist(oldfn.Dcl)
 			newfn.ClosureVars = subst.namelist(oldfn.ClosureVars)
 
-			// Set Ntype for now to be compatible with later parts of compiler
-			newfn.Nname.Ntype = subst.node(oldfn.Nname.Ntype).(ir.Ntype)
 			typed(subst.typ(oldfn.Nname.Type()), newfn.Nname)
 			typed(newfn.Nname.Type(), m)
 			newfn.SetTypecheck(1)