cmd/link: replace Autom linked list with slice

Change-Id: I939129da0e71a7ccc61bec79515a34f0b1e59502
Reviewed-on: https://go-review.googlesource.com/20162
Reviewed-by: Dave Cheney <dave@cheney.net>
Reviewed-by: Ian Lance Taylor <iant@golang.org>
Run-TryBot: David Crawshaw <crawshaw@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>

src/cmd/link/internal/ld/dwarf.go

@@ -1589,7 +1589,7 @@ func writelines() {
 			dt, da int
 			offs   int64
 		)
-		for a := s.Autom; a != nil; a = a.Link {
+		for _, a := range s.Autom {
 			switch a.Name {
 			case obj.A_AUTO:
 				dt = DW_ABRV_AUTO

src/cmd/link/internal/ld/go.go

@@ -394,7 +394,7 @@ func markflood() {
 			if Debug['v'] > 1 {
 				fmt.Fprintf(&Bso, "marktext %s\n", s.Name)
 			}
-			for a := s.Autom; a != nil; a = a.Link {
+			for _, a := range s.Autom {
 				mark1(a.Gotype, s)
 			}
 		}

src/cmd/link/internal/ld/lib.go

@@ -1964,7 +1964,6 @@ func genasmsym(put func(*LSym, string, int, int64, int64, int, *LSym)) {
 		}
 	}
 
-	var a *Auto
 	var off int32
 	for s := Ctxt.Textp; s != nil; s = s.Next {
 		put(s, s.Name, 'T', s.Value, s.Size, int(s.Version), s.Gotype)
@@ -1972,7 +1971,7 @@ func genasmsym(put func(*LSym, string, int, int64, int64, int, *LSym)) {
 		// NOTE(ality): acid can't produce a stack trace without .frame symbols
 		put(nil, ".frame", 'm', int64(s.Locals)+int64(Thearch.Ptrsize), 0, 0, nil)
 
-		for a = s.Autom; a != nil; a = a.Link {
+		for _, a := range s.Autom {
 			// Emit a or p according to actual offset, even if label is wrong.
 			// This avoids negative offsets, which cannot be encoded.
 			if a.Name != obj.A_AUTO && a.Name != obj.A_PARAM {

src/cmd/link/internal/ld/link.go

@@ -67,7 +67,7 @@ type LSym struct {
 	Dynimplib   string
 	Dynimpvers  string
 	Sect        *Section
-	Autom       *Auto
+	Autom       []Auto
 	Pcln        *Pcln
 	P           []byte
 	R           []Reloc
@@ -145,10 +145,9 @@ type Reloc struct {
 
 type Auto struct {
 	Asym    *LSym
-	Link    *Auto
+	Gotype  *LSym
 	Aoffset int32
 	Name    int16
-	Gotype  *LSym
 }
 
 type Shlib struct {

src/cmd/link/internal/ld/objfile.go

@@ -266,15 +266,14 @@ overwrite:
 		}
 		rdint(f) // v&1 is Leaf, currently unused
 		n := rdint(f)
-		var a *Auto
+		s.Autom = make([]Auto, n)
 		for i := 0; i < n; i++ {
-			a = new(Auto)
-			a.Asym = rdsym(ctxt, f, pkg)
-			a.Aoffset = rdint32(f)
-			a.Name = rdint16(f)
-			a.Gotype = rdsym(ctxt, f, pkg)
-			a.Link = s.Autom
-			s.Autom = a
+			s.Autom[i] = Auto{
+				Asym:    rdsym(ctxt, f, pkg),
+				Aoffset: rdint32(f),
+				Name:    rdint16(f),
+				Gotype:  rdsym(ctxt, f, pkg),
+			}
 		}
 
 		s.Pcln = new(Pcln)