cmd/internal/obj: various code cleanups

Mostly replacing C-Style loops with range expressions, but also other
simplifications like the introduction of writeBool and unindenting some
code.

Passes toolstash -cmp on std cmd.

Change-Id: I799bccd4e5d411428dcf122b8588a564a9217e7c
Reviewed-on: https://go-review.googlesource.com/104936
Run-TryBot: Daniel Martí <mvdan@mvdan.cc>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Marvin Stenger <marvin.stenger94@gmail.com>
Reviewed-by: Ilya Tocar <ilya.tocar@intel.com>

src/cmd/internal/obj/objfile.go

@@ -56,8 +56,8 @@ func (w *objWriter) addLengths(s *LSym) {
 	data += len(pc.Pcfile.P)
 	data += len(pc.Pcline.P)
 	data += len(pc.Pcinline.P)
-	for i := 0; i < len(pc.Pcdata); i++ {
-		data += len(pc.Pcdata[i].P)
+	for _, pcd := range pc.Pcdata {
+		data += len(pcd.P)
 	}
 
 	w.nData += data
@@ -124,8 +124,8 @@ func WriteObjFile(ctxt *Link, b *bufio.Writer) {
 		w.wr.Write(pc.Pcfile.P)
 		w.wr.Write(pc.Pcline.P)
 		w.wr.Write(pc.Pcinline.P)
-		for i := 0; i < len(pc.Pcdata); i++ {
-			w.wr.Write(pc.Pcdata[i].P)
+		for _, pcd := range pc.Pcdata {
+			w.wr.Write(pcd.P)
 		}
 	}
 	for _, s := range ctxt.Data {
@@ -175,11 +175,7 @@ func (w *objWriter) writeRef(s *LSym, isPath bool) {
 		w.writeString(s.Name)
 	}
 	// Write "version".
-	if s.Static() {
-		w.writeInt(1)
-	} else {
-		w.writeInt(0)
-	}
+	w.writeBool(s.Static())
 	w.nRefs++
 	s.RefIdx = w.nRefs
 	m[s.Name] = w.nRefs
@@ -188,8 +184,8 @@ func (w *objWriter) writeRef(s *LSym, isPath bool) {
 func (w *objWriter) writeRefs(s *LSym) {
 	w.writeRef(s, false)
 	w.writeRef(s.Gotype, false)
-	for i := range s.R {
-		w.writeRef(s.R[i].Sym, false)
+	for _, r := range s.R {
+		w.writeRef(r.Sym, false)
 	}
 
 	if s.Type == objabi.STEXT {
@@ -309,7 +305,7 @@ func (w *objWriter) writeSym(s *LSym) {
 
 	w.writeInt(int64(len(s.R)))
 	var r *Reloc
-	for i := 0; i < len(s.R); i++ {
+	for i := range s.R {
 		r = &s.R[i]
 		w.writeInt(int64(r.Off))
 		w.writeInt(int64(r.Siz))
@@ -324,11 +320,7 @@ func (w *objWriter) writeSym(s *LSym) {
 
 	w.writeInt(int64(s.Func.Args))
 	w.writeInt(int64(s.Func.Locals))
-	if s.NoSplit() {
-		w.writeInt(1)
-	} else {
-		w.writeInt(0)
-	}
+	w.writeBool(s.NoSplit())
 	flags = int64(0)
 	if s.Leaf() {
 		flags |= 1
@@ -365,14 +357,14 @@ func (w *objWriter) writeSym(s *LSym) {
 	w.writeInt(int64(len(pc.Pcline.P)))
 	w.writeInt(int64(len(pc.Pcinline.P)))
 	w.writeInt(int64(len(pc.Pcdata)))
-	for i := 0; i < len(pc.Pcdata); i++ {
-		w.writeInt(int64(len(pc.Pcdata[i].P)))
+	for _, pcd := range pc.Pcdata {
+		w.writeInt(int64(len(pcd.P)))
 	}
 	w.writeInt(int64(len(pc.Funcdataoff)))
-	for i := 0; i < len(pc.Funcdataoff); i++ {
+	for i := range pc.Funcdataoff {
 		w.writeRefIndex(pc.Funcdata[i])
 	}
-	for i := 0; i < len(pc.Funcdataoff); i++ {
+	for i := range pc.Funcdataoff {
 		w.writeInt(pc.Funcdataoff[i])
 	}
 	w.writeInt(int64(len(pc.File)))
@@ -391,6 +383,14 @@ func (w *objWriter) writeSym(s *LSym) {
 	}
 }
 
+func (w *objWriter) writeBool(b bool) {
+	if b {
+		w.writeInt(1)
+	} else {
+		w.writeInt(0)
+	}
+}
+
 func (w *objWriter) writeInt(sval int64) {
 	var v uint64
 	uv := (uint64(sval) << 1) ^ uint64(sval>>63)
@@ -766,7 +766,7 @@ func (ft *DwarfFixupTable) RegisterChildDIEOffsets(s *LSym, vars []*dwarf.Var, c
 
 	// Generate the slice of declOffset's based in vars/coffsets
 	doffsets := make([]declOffset, len(coffsets))
-	for i := 0; i < len(coffsets); i++ {
+	for i := range coffsets {
 		doffsets[i].dclIdx = vars[i].ChildIndex
 		doffsets[i].offset = coffsets[i]
 	}
@@ -791,9 +791,9 @@ func (ft *DwarfFixupTable) processFixups(slot int, s *LSym) {
 	sf := &ft.svec[slot]
 	for _, f := range sf.fixups {
 		dfound := false
-		for i := 0; i < len(sf.doffsets); i++ {
-			if sf.doffsets[i].dclIdx == f.dclidx {
-				f.refsym.R[f.relidx].Add += int64(sf.doffsets[i].offset)
+		for _, doffset := range sf.doffsets {
+			if doffset.dclIdx == f.dclidx {
+				f.refsym.R[f.relidx].Add += int64(doffset.offset)
 				dfound = true
 				break
 			}
@@ -833,7 +833,7 @@ func (ft *DwarfFixupTable) Finalize(myimportpath string, trace bool) {
 	// resulting list (don't want to rely on map ordering here).
 	fns := make([]*LSym, len(ft.precursor))
 	idx := 0
-	for fn, _ := range ft.precursor {
+	for fn := range ft.precursor {
 		fns[idx] = fn
 		idx++
 	}
@@ -845,8 +845,7 @@ func (ft *DwarfFixupTable) Finalize(myimportpath string, trace bool) {
 	}
 
 	// Generate any missing abstract functions.
-	for i := 0; i < len(fns); i++ {
-		s := fns[i]
+	for _, s := range fns {
 		absfn := ft.AbsFuncDwarfSym(s)
 		slot, found := ft.symtab[absfn]
 		if !found || !ft.svec[slot].defseen {
@@ -855,8 +854,7 @@ func (ft *DwarfFixupTable) Finalize(myimportpath string, trace bool) {
 	}
 
 	// Apply fixups.
-	for i := 0; i < len(fns); i++ {
-		s := fns[i]
+	for _, s := range fns {
 		absfn := ft.AbsFuncDwarfSym(s)
 		slot, found := ft.symtab[absfn]
 		if !found {

src/cmd/internal/obj/pass.go

@@ -118,10 +118,6 @@ func checkaddr(ctxt *Link, p *Prog, a *Addr) {
 }
 
 func linkpatch(ctxt *Link, sym *LSym, newprog ProgAlloc) {
-	var c int32
-	var name string
-	var q *Prog
-
 	for p := sym.Func.Text; p != nil; p = p.Link {
 		checkaddr(ctxt, p, &p.From)
 		if p.GetFrom3() != nil {
@@ -144,12 +140,12 @@ func linkpatch(ctxt *Link, sym *LSym, newprog ProgAlloc) {
 		if p.To.Sym != nil {
 			continue
 		}
-		c = int32(p.To.Offset)
-		for q = sym.Func.Text; q != nil; {
-			if int64(c) == q.Pc {
+		q := sym.Func.Text
+		for q != nil {
+			if p.To.Offset == q.Pc {
 				break
 			}
-			if q.Forwd != nil && int64(c) >= q.Forwd.Pc {
+			if q.Forwd != nil && p.To.Offset >= q.Forwd.Pc {
 				q = q.Forwd
 			} else {
 				q = q.Link
@@ -157,11 +153,11 @@ func linkpatch(ctxt *Link, sym *LSym, newprog ProgAlloc) {
 		}
 
 		if q == nil {
-			name = "<nil>"
+			name := "<nil>"
 			if p.To.Sym != nil {
 				name = p.To.Sym.Name
 			}
-			ctxt.Diag("branch out of range (%#x)\n%v [%s]", uint32(c), p, name)
+			ctxt.Diag("branch out of range (%#x)\n%v [%s]", uint32(p.To.Offset), p, name)
 			p.To.Type = TYPE_NONE
 		}
 

src/cmd/internal/obj/pcln.go

@@ -118,8 +118,8 @@ func funcpctab(ctxt *Link, dst *Pcdata, func_ *LSym, desc string, valfunc func(*
 
 	if dbg {
 		ctxt.Logf("wrote %d bytes to %p\n", len(dst.P), dst)
-		for i := 0; i < len(dst.P); i++ {
-			ctxt.Logf(" %02x", dst.P[i])
+		for _, p := range dst.P {
+			ctxt.Logf(" %02x", p)
 		}
 		ctxt.Logf("\n")
 	}
@@ -342,10 +342,11 @@ func linkpcln(ctxt *Link, cursym *LSym) {
 
 	// funcdata
 	if nfuncdata > 0 {
-		var i int
 		for p := cursym.Func.Text; p != nil; p = p.Link {
-			if p.As == AFUNCDATA {
-				i = int(p.From.Offset)
+			if p.As != AFUNCDATA {
+				continue
+			}
+			i := int(p.From.Offset)
 			pcln.Funcdataoff[i] = p.To.Offset
 			if p.To.Type != TYPE_CONST {
 				// TODO: Dedup.
@@ -354,5 +355,4 @@ func linkpcln(ctxt *Link, cursym *LSym) {
 			}
 		}
 	}
-	}
 }

src/cmd/internal/obj/util.go

@@ -165,10 +165,6 @@ func (ctxt *Link) CanReuseProgs() bool {
 	return !ctxt.Debugasm
 }
 
-func (ctxt *Link) Dconv(a *Addr) string {
-	return Dconv(nil, a)
-}
-
 func Dconv(p *Prog, a *Addr) string {
 	var str string