cmd/compile: convert inl.go to use nodeSeq

Passes toolstash -cmp.

Update #14473.

Change-Id: I60ef7cac553b346ca6b8cc7152cd184e59994b66
Reviewed-on: https://go-review.googlesource.com/20216
Run-TryBot: Ian Lance Taylor <iant@golang.org>
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>

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

@@ -292,7 +292,7 @@ func orderexprinplace(np **Node, outer *Order) {
 	n := *np
 	var order Order
 	orderexpr(&n, &order, nil)
-	addinitslice(&n, order.out)
+	addinit(&n, order.out)
 
 	// insert new temporaries from order
 	// at head of outer list.

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

@@ -2708,8 +2708,8 @@ func mkpkg(path string) *Pkg {
 	return p
 }
 
-func addinit(np **Node, init *NodeList) {
-	if init == nil {
+func addinit(np **Node, init nodesOrNodeList) {
+	if nodeSeqLen(init) == 0 {
 		return
 	}
 
@@ -2725,18 +2725,10 @@ func addinit(np **Node, init *NodeList) {
 		*np = n
 	}
 
-	n.Ninit = concat(init, n.Ninit)
+	setNodeSeq(&n.Ninit, append(nodeSeqSlice(init), nodeSeqSlice(n.Ninit)...))
 	n.Ullman = UINF
 }
 
-func addinitslice(np **Node, init []*Node) {
-	var l *NodeList
-	for _, n := range init {
-		l = list(l, n)
-	}
-	addinit(np, l)
-}
-
 var reservedimports = []string{
 	"go",
 	"type",

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

@@ -603,13 +603,15 @@ func nodeSeqIterate(ns nodesOrNodeList) nodeSeqIterator {
 	}
 }
 
-// nodeSeqLen returns the length of either a *NodeList or a Nodes.
+// nodeSeqLen returns the length of a *NodeList, a Nodes, or a []*Node.
 func nodeSeqLen(ns nodesOrNodeList) int {
 	switch ns := ns.(type) {
 	case *NodeList:
 		return count(ns)
 	case Nodes:
 		return len(ns.Slice())
+	case []*Node:
+		return len(ns)
 	default:
 		panic("can't happen")
 	}
@@ -641,6 +643,27 @@ func nodeSeqSecond(ns nodesOrNodeList) *Node {
 	}
 }
 
+// nodeSeqSlice returns a []*Node containing the contents of a
+// *NodeList, a Nodes, or a []*Node.
+// This is an interim function during the transition from NodeList to Nodes.
+// TODO(iant): Remove when transition is complete.
+func nodeSeqSlice(ns nodesOrNodeList) []*Node {
+	switch ns := ns.(type) {
+	case *NodeList:
+		var s []*Node
+		for l := ns; l != nil; l = l.Next {
+			s = append(s, l.N)
+		}
+		return s
+	case Nodes:
+		return ns.Slice()
+	case []*Node:
+		return ns
+	default:
+		panic("can't happen")
+	}
+}
+
 // setNodeSeq implements *a = b.
 // a must have type **NodeList, *Nodes, or *[]*Node.
 // b must have type *NodeList, Nodes, []*Node, or nil.