cmd/internal/obj: simplify Plists

Keep Plists in a slice instead of a linked list.
Eliminate unnecessary fields.
Also, while here remove gc's unused breakpc and continpc vars.

Change-Id: Ia04264036c0442843869965d247ccf68a5295115
Reviewed-on: https://go-review.googlesource.com/29367
Run-TryBot: Matthew Dempsky <mdempsky@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Dave Cheney <dave@cheney.net>

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

@@ -1260,8 +1260,6 @@ func funccompile(n *Node) {
 	compile(n)
 	Curfn = nil
 	Pc = nil
-	continpc = nil
-	breakpc = nil
 	funcdepth = 0
 	dclcontext = PEXTERN
 	if nerrors != 0 {

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

@@ -274,10 +274,6 @@ var writearchive bool
 
 var Nacl bool
 
-var continpc *obj.Prog
-
-var breakpc *obj.Prog
-
 var Pc *obj.Prog
 
 var nodfp *Node

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

@@ -372,11 +372,7 @@ func compile(fn *Node) {
 		return
 	}
 
-	continpc = nil
-	breakpc = nil
-
-	pl := newplist()
-	pl.Name = Linksym(Curfn.Func.Nname.Sym)
+	newplist()
 
 	setlineno(Curfn)
 

src/cmd/internal/obj/link.go

@@ -679,8 +679,7 @@ type Link struct {
 	Hash          map[SymVer]*LSym
 	LineHist      LineHist
 	Imports       []string
-	Plist         *Plist
-	Plast         *Plist
+	Plists        []*Plist
 	Sym_div       *LSym
 	Sym_divu      *LSym
 	Sym_mod       *LSym

src/cmd/internal/obj/plist.go

@@ -11,10 +11,7 @@ import (
 )
 
 type Plist struct {
-	Name    *LSym
 	Firstpc *Prog
-	Recur   int
-	Link    *Plist
 }
 
 /*
@@ -22,12 +19,7 @@ type Plist struct {
  */
 func Linknewplist(ctxt *Link) *Plist {
 	pl := new(Plist)
-	if ctxt.Plist == nil {
-		ctxt.Plist = pl
-	} else {
-		ctxt.Plast.Link = pl
-	}
-	ctxt.Plast = pl
+	ctxt.Plists = append(ctxt.Plists, pl)
 	return pl
 }
 
@@ -45,7 +37,7 @@ func flushplist(ctxt *Link, freeProgs bool) {
 	var etext *Prog
 	var text []*LSym
 
-	for pl := ctxt.Plist; pl != nil; pl = pl.Link {
+	for _, pl := range ctxt.Plists {
 		var plink *Prog
 		for p := pl.Firstpc; p != nil; p = plink {
 			if ctxt.Debugasm != 0 && ctxt.Debugvlog != 0 {
@@ -182,8 +174,7 @@ func flushplist(ctxt *Link, freeProgs bool) {
 	// Add to running list in ctxt.
 	ctxt.Text = append(ctxt.Text, text...)
 	ctxt.Data = append(ctxt.Data, gendwarf(ctxt, text)...)
-	ctxt.Plist = nil
-	ctxt.Plast = nil
+	ctxt.Plists = nil
 	ctxt.Curp = nil
 	if freeProgs {
 		ctxt.freeProgs()