cmd/compile: change Func.Inldcl from []*Node to *[]*Node

Save a few bytes in Func.

Passes toolstash -cmp.

Update #14473.

Change-Id: I824fa7d5cb2d93f6f59938ccd86114abcbea0043
Reviewed-on: https://go-review.googlesource.com/19968Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>

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

@@ -150,7 +150,10 @@ func caninl(fn *Node) {
 
 	fn.Func.Nname.Func.Inl = fn.Nbody
 	fn.Nbody = inlcopylist(fn.Func.Nname.Func.Inl)
-	fn.Func.Nname.Func.Inldcl = inlcopyslice(fn.Func.Nname.Name.Defn.Func.Dcl)
+	inldcl := inlcopyslice(fn.Func.Nname.Name.Defn.Func.Dcl)
+	if len(inldcl) > 0 {
+		fn.Func.Nname.Func.Inldcl = &inldcl
+	}
 	fn.Func.Nname.Func.InlCost = int32(maxBudget - budget)
 
 	// hack, TODO, check for better way to link method nodes back to the thing with the ->inl
@@ -569,9 +572,13 @@ func mkinlcall1(np **Node, fn *Node, isddd bool) {
 	//dumplist("ninit pre", ninit);
 
 	var dcl []*Node
-	if fn.Name.Defn != nil { // local function
-		dcl = fn.Func.Inldcl // imported function
+	if fn.Name.Defn != nil {
+		// local function
+		if fn.Func.Inldcl != nil {
+			dcl = *fn.Func.Inldcl
+		}
 	} else {
+		// imported function
 		dcl = fn.Func.Dcl
 	}
 

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

@@ -153,7 +153,7 @@ type Func struct {
 	Exit       *NodeList
 	cvars      *[]*Node // closure params
 	Dcl        []*Node  // autodcl for this func/closure
-	Inldcl     []*Node  // copy of dcl for use in inlining
+	Inldcl     *[]*Node // copy of dcl for use in inlining
 	Closgen    int
 	Outerfunc  *Node
 	Fieldtrack []*Type