cmd/link/internal/ld: simple cleanups

Simplify some C-style loops with range statements, and move some
declarations closer to their uses.

While at it, ensure that all the SymbolType consts are typed.

Change-Id: I04b06afb2c1fb249ef8093a0c5cca0a597d1e05c
Reviewed-on: https://go-review.googlesource.com/105217
Run-TryBot: Daniel Martí <mvdan@mvdan.cc>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Ian Lance Taylor <iant@golang.org>

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

@@ -504,7 +504,7 @@ func windynrelocsym(ctxt *Link, s *sym.Symbol) {
 	if s == rel {
 		return
 	}
-	for ri := 0; ri < len(s.R); ri++ {
+	for ri := range s.R {
 		r := &s.R[ri]
 		targ := r.Sym
 		if targ == nil {
@@ -550,7 +550,7 @@ func dynrelocsym(ctxt *Link, s *sym.Symbol) {
 		return
 	}
 
-	for ri := 0; ri < len(s.R); ri++ {
+	for ri := range s.R {
 		r := &s.R[ri]
 		if ctxt.BuildMode == BuildModePIE && ctxt.LinkMode == LinkInternal {
 			// It's expected that some relocations will be done
@@ -620,7 +620,6 @@ func CodeblkPad(ctxt *Link, addr int64, size int64, pad []byte) {
 	}
 
 	eaddr := addr + size
-	var q []byte
 	for _, s := range syms {
 		if !s.Attr.Reachable() {
 			continue
@@ -638,7 +637,7 @@ func CodeblkPad(ctxt *Link, addr int64, size int64, pad []byte) {
 		}
 
 		ctxt.Logf("%.6x\t%-20s\n", uint64(addr), s.Name)
-		q = s.P
+		q := s.P
 
 		for len(q) >= 16 {
 			ctxt.Logf("%.6x\t% x\n", uint64(addr), q[:16])
@@ -1195,7 +1194,6 @@ func (ctxt *Link) dodata() {
 		sect.Align = dataMaxAlign[sym.SELFGOT]
 		datsize = Rnd(datsize, int64(sect.Align))
 		sect.Vaddr = uint64(datsize)
-		var toc *sym.Symbol
 		for _, s := range data[sym.SELFGOT] {
 			datsize = aligndatsize(datsize, s)
 			s.Sect = sect
@@ -1203,7 +1201,7 @@ func (ctxt *Link) dodata() {
 			s.Value = int64(uint64(datsize) - sect.Vaddr)
 
 			// Resolve .TOC. symbol for this object file (ppc64)
-			toc = ctxt.Syms.ROLookup(".TOC.", int(s.Version))
+			toc := ctxt.Syms.ROLookup(".TOC.", int(s.Version))
 			if toc != nil {
 				toc.Sect = sect
 				toc.Outer = s

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

@@ -295,7 +295,7 @@ func (d *deadcodepass) flood() {
 
 		mpos := 0 // 0-3, the R_METHODOFF relocs of runtime.uncommontype
 		var methods []methodref
-		for i := 0; i < len(s.R); i++ {
+		for i := range s.R {
 			r := &s.R[i]
 			if r.Sym == nil {
 				continue

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

@@ -463,11 +463,9 @@ func newtype(ctxt *Link, gotype *sym.Symbol) *dwarf.DWDie {
 		dotypedef(ctxt, &dwtypes, name, die)
 		newrefattr(die, dwarf.DW_AT_type, mustFind(ctxt, "void"))
 		nfields := decodetypeFuncInCount(ctxt.Arch, gotype)
-		var fld *dwarf.DWDie
-		var s *sym.Symbol
 		for i := 0; i < nfields; i++ {
-			s = decodetypeFuncInType(ctxt.Arch, gotype, i)
-			fld = newdie(ctxt, die, dwarf.DW_ABRV_FUNCTYPEPARAM, s.Name[5:], 0)
+			s := decodetypeFuncInType(ctxt.Arch, gotype, i)
+			fld := newdie(ctxt, die, dwarf.DW_ABRV_FUNCTYPEPARAM, s.Name[5:], 0)
 			newrefattr(fld, dwarf.DW_AT_type, defgotype(ctxt, s))
 		}
 
@@ -476,8 +474,8 @@ func newtype(ctxt *Link, gotype *sym.Symbol) *dwarf.DWDie {
 		}
 		nfields = decodetypeFuncOutCount(ctxt.Arch, gotype)
 		for i := 0; i < nfields; i++ {
-			s = decodetypeFuncOutType(ctxt.Arch, gotype, i)
-			fld = newdie(ctxt, die, dwarf.DW_ABRV_FUNCTYPEPARAM, s.Name[5:], 0)
+			s := decodetypeFuncOutType(ctxt.Arch, gotype, i)
+			fld := newdie(ctxt, die, dwarf.DW_ABRV_FUNCTYPEPARAM, s.Name[5:], 0)
 			newrefattr(fld, dwarf.DW_AT_type, defptrto(ctxt, defgotype(ctxt, s)))
 		}
 
@@ -667,15 +665,10 @@ func synthesizeslicetypes(ctxt *Link, die *dwarf.DWDie) {
 }
 
 func mkinternaltypename(base string, arg1 string, arg2 string) string {
-	var buf string
-
 	if arg2 == "" {
-		buf = fmt.Sprintf("%s<%s>", base, arg1)
-	} else {
-		buf = fmt.Sprintf("%s<%s,%s>", base, arg1, arg2)
+		return fmt.Sprintf("%s<%s>", base, arg1)
 	}
-	n := buf
-	return n
+	return fmt.Sprintf("%s<%s,%s>", base, arg1, arg2)
 }
 
 // synthesizemaptypes is way too closely married to runtime/hashmap.c
@@ -1208,7 +1201,7 @@ func writelines(ctxt *Link, lib *sym.Library, textp []*sym.Symbol, ls *sym.Symbo
 		// example, files mentioned only in an inlined subroutine).
 		dsym := ctxt.Syms.Lookup(dwarf.InfoPrefix+s.Name, int(s.Version))
 		importInfoSymbol(ctxt, dsym)
-		for ri := 0; ri < len(dsym.R); ri++ {
+		for ri := range dsym.R {
 			r := &dsym.R[ri]
 			if r.Type != objabi.R_DWARFFILEREF {
 				continue
@@ -1321,9 +1314,8 @@ func writelines(ctxt *Link, lib *sym.Library, textp []*sym.Symbol, ls *sym.Symbo
 	// DIE flavors (ex: variables) then those DIEs would need to
 	// be included below.
 	missing := make(map[int]interface{})
-	for fidx := 0; fidx < len(funcs); fidx++ {
-		f := funcs[fidx]
-		for ri := 0; ri < len(f.R); ri++ {
+	for _, f := range funcs {
+		for ri := range f.R {
 			r := &f.R[ri]
 			if r.Type != objabi.R_DWARFFILEREF {
 				continue

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

@@ -1349,7 +1349,7 @@ func elfrelocsect(ctxt *Link, sect *sym.Section, syms []*sym.Symbol) {
 		if s.Value >= int64(eaddr) {
 			break
 		}
-		for ri := 0; ri < len(s.R); ri++ {
+		for ri := range s.R {
 			r := &s.R[ri]
 			if r.Done {
 				continue

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

@@ -275,9 +275,9 @@ func loadinternal(ctxt *Link, name string) *sym.Library {
 		return nil
 	}
 
-	for i := 0; i < len(ctxt.Libdir); i++ {
+	for _, libdir := range ctxt.Libdir {
 		if ctxt.linkShared {
-			shlibname := filepath.Join(ctxt.Libdir[i], name+".shlibname")
+			shlibname := filepath.Join(libdir, name+".shlibname")
 			if ctxt.Debugvlog != 0 {
 				ctxt.Logf("searching for %s.a in %s\n", name, shlibname)
 			}
@@ -285,7 +285,7 @@ func loadinternal(ctxt *Link, name string) *sym.Library {
 				return addlibpath(ctxt, "internal", "internal", "", name, shlibname)
 			}
 		}
-		pname := filepath.Join(ctxt.Libdir[i], name+".a")
+		pname := filepath.Join(libdir, name+".a")
 		if ctxt.Debugvlog != 0 {
 			ctxt.Logf("searching for %s.a in %s\n", name, pname)
 		}
@@ -484,7 +484,7 @@ func (ctxt *Link) loadlib() {
 		x = sym.AttrCgoExportStatic
 	}
 	w := 0
-	for i := 0; i < len(dynexp); i++ {
+	for i := range dynexp {
 		if dynexp[i].Attr&x != 0 {
 			dynexp[w] = dynexp[i]
 			w++
@@ -868,8 +868,8 @@ var internalpkg = []string{
 
 func ldhostobj(ld func(*Link, *bio.Reader, string, int64, string), headType objabi.HeadType, f *bio.Reader, pkg string, length int64, pn string, file string) *Hostobj {
 	isinternal := false
-	for i := 0; i < len(internalpkg); i++ {
-		if pkg == internalpkg[i] {
+	for _, intpkg := range internalpkg {
+		if pkg == intpkg {
 			isinternal = true
 			break
 		}
@@ -1955,22 +1955,18 @@ func usage() {
 	Exit(2)
 }
 
-func doversion() {
-	Exitf("version %s", objabi.Version)
-}
-
 type SymbolType int8
 
 const (
 	// see also http://9p.io/magic/man2html/1/nm
 	TextSym      SymbolType = 'T'
-	DataSym                 = 'D'
-	BSSSym                  = 'B'
-	UndefinedSym            = 'U'
-	TLSSym                  = 't'
-	FrameSym                = 'm'
-	ParamSym                = 'p'
-	AutoSym                 = 'a'
+	DataSym      SymbolType = 'D'
+	BSSSym       SymbolType = 'B'
+	UndefinedSym SymbolType = 'U'
+	TLSSym       SymbolType = 't'
+	FrameSym     SymbolType = 'm'
+	ParamSym     SymbolType = 'p'
+	AutoSym      SymbolType = 'a'
 
 	// Deleted auto (not a real sym, just placeholder for type)
 	DeletedAutoSym = 'x'
@@ -2256,7 +2252,7 @@ func bgetc(r *bio.Reader) int {
 
 type markKind uint8 // for postorder traversal
 const (
-	unvisited markKind = iota
+	_ markKind = iota
 	visiting
 	visited
 )

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

@@ -234,7 +234,7 @@ func machowrite(arch *sys.Arch, out *OutBuf, linkmode LinkMode) int {
 	o1 := out.Offset()
 
 	loadsize := 4 * 4 * ndebug
-	for i := 0; i < len(load); i++ {
+	for i := range load {
 		loadsize += 4 * (len(load[i].data) + 2)
 	}
 	if arch.PtrSize == 8 {
@@ -327,7 +327,7 @@ func machowrite(arch *sys.Arch, out *OutBuf, linkmode LinkMode) int {
 		}
 	}
 
-	for i := 0; i < len(load); i++ {
+	for i := range load {
 		l := &load[i]
 		out.Write32(l.type_)
 		out.Write32(4 * (uint32(len(l.data)) + 2))
@@ -621,13 +621,13 @@ func Asmbmacho(ctxt *Link) {
 			ml.data[0] = 12 /* offset to string */
 			stringtouint32(ml.data[1:], "/usr/lib/dyld")
 
-			for i := 0; i < len(dylib); i++ {
-				ml = newMachoLoad(ctxt.Arch, LC_LOAD_DYLIB, 4+(uint32(len(dylib[i]))+1+7)/8*2)
+			for _, lib := range dylib {
+				ml = newMachoLoad(ctxt.Arch, LC_LOAD_DYLIB, 4+(uint32(len(lib))+1+7)/8*2)
 				ml.data[0] = 24 /* offset of string from beginning of load */
 				ml.data[1] = 0  /* time stamp */
 				ml.data[2] = 0  /* version */
 				ml.data[3] = 0  /* compatibility version */
-				stringtouint32(ml.data[4:], dylib[i])
+				stringtouint32(ml.data[4:], lib)
 			}
 		}
 	}
@@ -721,7 +721,7 @@ func machosymorder(ctxt *Link) {
 	// On Mac OS X Mountain Lion, we must sort exported symbols
 	// So we sort them here and pre-allocate dynid for them
 	// See https://golang.org/issue/4029
-	for i := 0; i < len(dynexp); i++ {
+	for i := range dynexp {
 		dynexp[i].Attr |= sym.AttrReachable
 	}
 	machogenasmsym(ctxt)
@@ -919,7 +919,7 @@ func machorelocsect(ctxt *Link, sect *sym.Section, syms []*sym.Symbol) {
 		if s.Value >= int64(eaddr) {
 			break
 		}
-		for ri := 0; ri < len(s.R); ri++ {
+		for ri := range s.R {
 			r := &s.R[ri]
 			if r.Done {
 				continue

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

@@ -122,11 +122,8 @@ func numberfile(ctxt *Link, file *sym.Symbol) {
 }
 
 func renumberfiles(ctxt *Link, files []*sym.Symbol, d *sym.Pcdata) {
-	var f *sym.Symbol
-
 	// Give files numbers.
-	for i := 0; i < len(files); i++ {
-		f = files[i]
+	for _, f := range files {
 		numberfile(ctxt, f)
 	}
 
@@ -399,7 +396,7 @@ func (ctxt *Link) pclntab() {
 		off = addpctab(ctxt, ftab, off, &pcln.Pcline)
 		off = int32(ftab.SetUint32(ctxt.Arch, int64(off), uint32(len(pcln.Pcdata))))
 		off = int32(ftab.SetUint32(ctxt.Arch, int64(off), uint32(len(pcln.Funcdata))))
-		for i := 0; i < len(pcln.Pcdata); i++ {
+		for i := range pcln.Pcdata {
 			off = addpctab(ctxt, ftab, off, &pcln.Pcdata[i])
 		}
 
@@ -409,7 +406,7 @@ func (ctxt *Link) pclntab() {
 			if off&int32(ctxt.Arch.PtrSize-1) != 0 {
 				off += 4
 			}
-			for i := 0; i < len(pcln.Funcdata); i++ {
+			for i := range pcln.Funcdata {
 				if pcln.Funcdata[i] == nil {
 					ftab.SetUint(ctxt.Arch, int64(off)+int64(ctxt.Arch.PtrSize)*int64(i), uint64(pcln.Funcdataoff[i]))
 				} else {

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

@@ -526,7 +526,7 @@ func (f *peFile) emitRelocations(ctxt *Link) {
 			if sym.Value >= int64(eaddr) {
 				break
 			}
-			for ri := 0; ri < len(sym.R); ri++ {
+			for ri := range sym.R {
 				r := &sym.R[ri]
 				if r.Done {
 					continue
@@ -1082,9 +1082,8 @@ func addimports(ctxt *Link, datsect *peSection) {
 	}
 
 	// write function names
-	var m *Imp
 	for d := dr; d != nil; d = d.next {
-		for m = d.ms; m != nil; m = m.next {
+		for m := d.ms; m != nil; m = m.next {
 			m.off = uint64(pefile.nextSectOffset) + uint64(ctxt.Out.Offset()) - uint64(startoff)
 			ctxt.Out.Write16(0) // hint
 			strput(ctxt.Out, m.s.Extname)
@@ -1097,7 +1096,7 @@ func addimports(ctxt *Link, datsect *peSection) {
 	n = uint64(ctxt.Out.Offset())
 	for d := dr; d != nil; d = d.next {
 		d.thunkoff = uint64(ctxt.Out.Offset()) - n
-		for m = d.ms; m != nil; m = m.next {
+		for m := d.ms; m != nil; m = m.next {
 			if pe64 != 0 {
 				ctxt.Out.Write64(m.off)
 			} else {
@@ -1126,7 +1125,7 @@ func addimports(ctxt *Link, datsect *peSection) {
 
 	ctxt.Out.SeekSet(int64(uint64(datsect.pointerToRawData) + ftbase))
 	for d := dr; d != nil; d = d.next {
-		for m = d.ms; m != nil; m = m.next {
+		for m := d.ms; m != nil; m = m.next {
 			if pe64 != 0 {
 				ctxt.Out.Write64(m.off)
 			} else {
@@ -1287,13 +1286,10 @@ func addpersrc(ctxt *Link) {
 	h.checkOffset(ctxt.Out.Offset())
 
 	// relocation
-	var p []byte
-	var r *sym.Reloc
-	var val uint32
-	for ri := 0; ri < len(rsrcsym.R); ri++ {
-		r = &rsrcsym.R[ri]
-		p = rsrcsym.P[r.Off:]
-		val = uint32(int64(h.virtualAddress) + r.Add)
+	for ri := range rsrcsym.R {
+		r := &rsrcsym.R[ri]
+		p := rsrcsym.P[r.Off:]
+		val := uint32(int64(h.virtualAddress) + r.Add)
 
 		// 32-bit little-endian
 		p[0] = byte(val)