cmd/compile: cleanups for Node trimming sequence

Suggested during code reviews of last 15 CLs (or so).

Change-Id: If780f6eb47a7a31df133c64d5dcf0eaf04d8447b
Reviewed-on: https://go-review.googlesource.com/10675
Reviewed-by: Ian Lance Taylor <iant@golang.org>
Reviewed-by: Josh Bleecher Snyder <josharian@gmail.com>

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

@@ -72,7 +72,7 @@ func closurebody(body *NodeList) *Node {
 	var v *Node
 	for l := func_.Func.Cvars; l != nil; l = l.Next {
 		v = l.N
-		v.Name.Param.Closure.Name.Closure = v.Name.Outer
+		v.Name.Param.Closure.Name.Param.Closure = v.Name.Param.Outer
 		v.Name.Param.Outerexpr = oldname(v.Sym)
 	}
 

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

@@ -411,7 +411,7 @@ type EscState struct {
 	walkgen   uint32
 }
 
-// funcSym returns n.Nname.Sym if no nils are encountered along the way.
+// funcSym returns fn.Func.Nname.Sym if no nils are encountered along the way.
 func funcSym(fn *Node) *Sym {
 	if fn == nil || fn.Func.Nname == nil {
 		return nil
@@ -1238,7 +1238,14 @@ func escassignfromtag(e *EscState, note *string, dsts *NodeList, src *Node) uint
 	return em0
 }
 
-// e.addDereference constructs a suitable OIND note applied to src.
+func escassignDereference(e *EscState, dst *Node, src *Node) {
+	if src.Op == OLITERAL {
+		return
+	}
+	escassign(e, dst, e.addDereference(src))
+}
+
+// addDereference constructs a suitable OIND note applied to src.
 // Because this is for purposes of escape accounting, not execution,
 // some semantically dubious node combinations are (currently) possible.
 func (e *EscState) addDereference(n *Node) *Node {

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

@@ -236,6 +236,9 @@ func Jconv(n *Node, flag int) string {
 	if n.Name != nil && n.Name.Funcdepth != 0 {
 		fmt.Fprintf(&buf, " f(%d)", n.Name.Funcdepth)
 	}
+	if n.Func != nil && n.Func.Depth != 0 {
+		fmt.Fprintf(&buf, " ff(%d)", n.Func.Depth)
+	}
 
 	switch n.Esc {
 	case EscUnknown:

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

@@ -98,6 +98,9 @@ type NilVal struct{}
 func (v Val) Ctype() int {
 	switch x := v.U.(type) {
 	default:
+		Fatal("unexpected Ctype for %T", v.U)
+		panic("not reached")
+	case nil:
 		return 0
 	case *NilVal:
 		return CTNIL

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

@@ -18,9 +18,11 @@ const (
 	InitPending    = 2
 )
 
-var initlist *NodeList
-var initplans = make(map[*Node]*InitPlan)
-var inittemps = make(map[*Node]*Node)
+var (
+	initlist  *NodeList
+	initplans map[*Node]*InitPlan
+	inittemps = make(map[*Node]*Node)
+)
 
 // init1 walks the AST starting at n, and accumulates in out
 // the list of definitions needing init code in dependency order.
@@ -255,9 +257,11 @@ func initreorder(l *NodeList, out **NodeList) {
 // to include in the init() function body.
 func initfix(l *NodeList) *NodeList {
 	var lout *NodeList
+	initplans = make(map[*Node]*InitPlan)
 	lno := int(lineno)
 	initreorder(l, &lout)
 	lineno = int32(lno)
+	initplans = nil
 	return lout
 }
 

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

@@ -333,6 +333,7 @@ func importdot(opkg *Pkg, pack *Node) {
 		s1.Block = s.Block
 		if s1.Def.Name == nil {
 			Dump("s1def", s1.Def)
+			Fatal("missing Name")
 		}
 		s1.Def.Name.Pack = pack
 		s1.Origpkg = opkg

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

@@ -280,7 +280,6 @@ func (s *exprSwitch) walk(sw *Node) {
 		sw.Nbody = concat(cas, sw.Nbody)
 		walkstmtlist(sw.Nbody)
 	}
-
 }
 
 // walkCases generates an AST implementing the cases in cc.

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

@@ -73,15 +73,15 @@ type Node struct {
 
 // Name holds Node fields used only by named nodes (ONAME, OPACK, some OLITERAL).
 type Name struct {
-	Pack     *Node // real package for import . names
-	Pkg      *Pkg  // pkg for OPACK nodes
-	Heapaddr *Node // temp holding heap address of param
-	Inlvar   *Node // ONAME substitute while inlining
-	Defn     *Node // initializing assignment
-	Curfn    *Node // function for local variables
-	*Param
+	Pack      *Node // real package for import . names
+	Pkg       *Pkg  // pkg for OPACK nodes
+	Heapaddr  *Node // temp holding heap address of param
+	Inlvar    *Node // ONAME substitute while inlining
+	Defn      *Node // initializing assignment
+	Curfn     *Node // function for local variables
+	Param     *Param
 	Decldepth int32 // declaration loop depth, increased for every loop or label
-	Vargen    int32 // unique name for OTYPE/ONAME within a function.  Function outputs are numbered starting at one.
+	Vargen    int32 // unique name for ONAME within a function.  Function outputs are numbered starting at one.
 	Iota      int32 // value if this name is iota
 	Funcdepth int32
 	Method    bool // OCALLMETH name

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

@@ -823,7 +823,7 @@ OpSwitch:
 		}
 		l.Addrtaken = true
 		if l.Name != nil && l.Name.Param != nil && l.Name.Param.Closure != nil {
-			l.Name.Closure.Addrtaken = true
+			l.Name.Param.Closure.Addrtaken = true
 		}
 		defaultlit(&n.Left, nil)
 		l = n.Left
@@ -2832,36 +2832,36 @@ func keydup(n *Node, hash map[uint32][]*Node) {
 		return // we dont check variables
 	}
 
-	var b uint32
+	var h uint32
 	switch n.Val.Ctype() {
 	default: // unknown, bool, nil
-		b = 23
+		h = 23
 
 	case CTINT, CTRUNE:
-		b = uint32(Mpgetfix(n.Val.U.(*Mpint)))
+		h = uint32(Mpgetfix(n.Val.U.(*Mpint)))
 
 	case CTFLT:
 		d := mpgetflt(n.Val.U.(*Mpflt))
 		x := math.Float64bits(d)
 		for i := 0; i < 8; i++ {
-			b = b*PRIME1 + uint32(x&0xFF)
+			h = h*PRIME1 + uint32(x&0xFF)
 			x >>= 8
 		}
 
 	case CTSTR:
-		b = 0
+		h = 0
 		s := n.Val.U.(string)
 		for i := len(n.Val.U.(string)); i > 0; i-- {
-			b = b*PRIME1 + uint32(s[0])
+			h = h*PRIME1 + uint32(s[0])
 			s = s[1:]
 		}
 	}
 
 	var cmp Node
-	for _, a := range hash[b] {
+	for _, a := range hash[h] {
 		cmp.Op = OEQ
 		cmp.Left = n
-		b = 0
+		b := uint32(0)
 		if a.Op == OCONVIFACE && orign.Op == OCONVIFACE {
 			if Eqtype(a.Left.Type, n.Type) {
 				cmp.Right = a.Left
@@ -2880,7 +2880,7 @@ func keydup(n *Node, hash map[uint32][]*Node) {
 		}
 	}
 
-	hash[b] = append(hash[b], orign)
+	hash[h] = append(hash[h], orign)
 }
 
 func indexdup(n *Node, hash map[int64]*Node) {
@@ -3936,7 +3936,7 @@ func markbreaklist(l *NodeList, implicit *Node) {
 				lab = new(Label)
 				lab.Def = n.Name.Defn
 				n.Left.Sym.Label = lab
-				markbreak(n.Name.Defn, n.Name.Defn) // XXX
+				markbreak(n.Name.Defn, n.Name.Defn)
 				n.Left.Sym.Label = nil
 				l = l.Next
 				continue