cmd/link, cmd/internal/obj: give Headtype a type

Separate out windows/windowsgui properly so we are not encoding some
of the Headtype value in a separate headstring global.

Remove one of the two copies of the variable from cmd/link.

Remove duplicate string to headtype list.

Change-Id: Ifa20fb9652a1dc95161e154aac11f15ad0f709d0
Reviewed-on: https://go-review.googlesource.com/28853
Run-TryBot: David Crawshaw <crawshaw@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Ian Lance Taylor <iant@golang.org>

src/cmd/internal/obj/link.go

@@ -626,7 +626,7 @@ const (
 // to be linker input or for reading that input into the linker.
 type Link struct {
 	Goarm         int32
-	Headtype      int
+	Headtype      HeadType
 	Arch          *LinkArch
 	Debugasm      int32
 	Debugvlog     int32
@@ -725,9 +725,11 @@ type LinkArch struct {
 	UnaryDst   map[As]bool // Instruction takes one operand, a destination.
 }
 
-/* executable header types */
+// HeadType is the executable header type.
+type HeadType uint8
+
 const (
-	Hunknown = 0 + iota
+	Hunknown HeadType = iota
 	Hdarwin
 	Hdragonfly
 	Hfreebsd
@@ -738,8 +740,67 @@ const (
 	Hplan9
 	Hsolaris
 	Hwindows
+	Hwindowsgui
 )
 
+func (h *HeadType) Set(s string) error {
+	switch s {
+	case "darwin":
+		*h = Hdarwin
+	case "dragonfly":
+		*h = Hdragonfly
+	case "freebsd":
+		*h = Hfreebsd
+	case "linux", "android":
+		*h = Hlinux
+	case "nacl":
+		*h = Hnacl
+	case "netbsd":
+		*h = Hnetbsd
+	case "openbsd":
+		*h = Hopenbsd
+	case "plan9":
+		*h = Hplan9
+	case "solaris":
+		*h = Hsolaris
+	case "windows":
+		*h = Hwindows
+	case "windowsgui":
+		*h = Hwindowsgui
+	default:
+		return fmt.Errorf("invalid headtype: %q", s)
+	}
+	return nil
+}
+
+func (h *HeadType) String() string {
+	switch *h {
+	case Hdarwin:
+		return "darwin"
+	case Hdragonfly:
+		return "dragonfly"
+	case Hfreebsd:
+		return "freebsd"
+	case Hlinux:
+		return "linux"
+	case Hnacl:
+		return "nacl"
+	case Hnetbsd:
+		return "netbsd"
+	case Hopenbsd:
+		return "openbsd"
+	case Hplan9:
+		return "plan9"
+	case Hsolaris:
+		return "solaris"
+	case Hwindows:
+		return "windows"
+	case Hwindowsgui:
+		return "windowsgui"
+	}
+	return fmt.Sprintf("HeadType(%d)", *h)
+}
+
 // AsmBuf is a simple buffer to assemble variable-length x86 instructions into.
 type AsmBuf struct {
 	buf [100]byte

src/cmd/internal/obj/sym.go

@@ -36,45 +36,8 @@ import (
 	"log"
 	"os"
 	"path/filepath"
-	"strconv"
 )
 
-var headers = []struct {
-	name string
-	val  int
-}{
-	{"darwin", Hdarwin},
-	{"dragonfly", Hdragonfly},
-	{"freebsd", Hfreebsd},
-	{"linux", Hlinux},
-	{"android", Hlinux}, // must be after "linux" entry or else headstr(Hlinux) == "android"
-	{"nacl", Hnacl},
-	{"netbsd", Hnetbsd},
-	{"openbsd", Hopenbsd},
-	{"plan9", Hplan9},
-	{"solaris", Hsolaris},
-	{"windows", Hwindows},
-	{"windowsgui", Hwindows},
-}
-
-func headtype(name string) int {
-	for i := 0; i < len(headers); i++ {
-		if name == headers[i].name {
-			return headers[i].val
-		}
-	}
-	return -1
-}
-
-func Headstr(v int) string {
-	for i := 0; i < len(headers); i++ {
-		if v == headers[i].val {
-			return headers[i].name
-		}
-	}
-	return strconv.Itoa(v)
-}
-
 func Linknew(arch *LinkArch) *Link {
 	ctxt := new(Link)
 	ctxt.Hash = make(map[SymVer]*LSym)
@@ -95,7 +58,7 @@ func Linknew(arch *LinkArch) *Link {
 	ctxt.LineHist.GOROOT_FINAL = ctxt.Goroot_final
 	ctxt.LineHist.Dir = ctxt.Pathname
 
-	ctxt.Headtype = headtype(Getgoos())
+	ctxt.Headtype.Set(Getgoos())
 	if ctxt.Headtype < 0 {
 		log.Fatalf("unknown goos %s", Getgoos())
 	}

src/cmd/internal/obj/x86/asm6.go

@@ -2188,7 +2188,7 @@ func prefixof(ctxt *obj.Link, p *obj.Prog, a *obj.Addr) int {
 					if isAndroid {
 						return 0x65 // GS
 					}
-					log.Fatalf("unknown TLS base register for %s", obj.Headstr(ctxt.Headtype))
+					log.Fatalf("unknown TLS base register for %s", ctxt.Headtype)
 
 				case obj.Hdarwin,
 					obj.Hdragonfly,
@@ -2201,7 +2201,7 @@ func prefixof(ctxt *obj.Link, p *obj.Prog, a *obj.Addr) int {
 
 			switch ctxt.Headtype {
 			default:
-				log.Fatalf("unknown TLS base register for %s", obj.Headstr(ctxt.Headtype))
+				log.Fatalf("unknown TLS base register for %s", ctxt.Headtype)
 
 			case obj.Hlinux:
 				if isAndroid {
@@ -4016,7 +4016,7 @@ func doasm(ctxt *obj.Link, p *obj.Prog) {
 						// are handled in prefixof above and should not be listed here.
 						switch ctxt.Headtype {
 						default:
-							log.Fatalf("unknown TLS base location for %s", obj.Headstr(ctxt.Headtype))
+							log.Fatalf("unknown TLS base location for %s", ctxt.Headtype)
 
 						case obj.Hlinux,
 							obj.Hnacl:
@@ -4074,7 +4074,7 @@ func doasm(ctxt *obj.Link, p *obj.Prog) {
 							ctxt.AsmBuf.Put1(0x8B)
 							asmand(ctxt, p, &pp.From, &p.To)
 
-						case obj.Hwindows:
+						case obj.Hwindows, obj.Hwindowsgui:
 							// Windows TLS base is always 0x14(FS).
 							pp.From = p.From
 
@@ -4092,7 +4092,7 @@ func doasm(ctxt *obj.Link, p *obj.Prog) {
 
 					switch ctxt.Headtype {
 					default:
-						log.Fatalf("unknown TLS base location for %s", obj.Headstr(ctxt.Headtype))
+						log.Fatalf("unknown TLS base location for %s", ctxt.Headtype)
 
 					case obj.Hlinux:
 						if !ctxt.Flag_shared {
@@ -4146,7 +4146,7 @@ func doasm(ctxt *obj.Link, p *obj.Prog) {
 							0x8B)
 						asmand(ctxt, p, &pp.From, &p.To)
 
-					case obj.Hwindows:
+					case obj.Hwindows, obj.Hwindowsgui:
 						// Windows TLS base is always 0x28(GS).
 						pp.From = p.From
 

src/cmd/internal/obj/x86/obj6.go

@@ -55,7 +55,8 @@ func CanUse1InsnTLS(ctxt *obj.Link) bool {
 		case obj.Hlinux,
 			obj.Hnacl,
 			obj.Hplan9,
-			obj.Hwindows:
+			obj.Hwindows,
+			obj.Hwindowsgui:
 			return false
 		}
 
@@ -63,8 +64,7 @@ func CanUse1InsnTLS(ctxt *obj.Link) bool {
 	}
 
 	switch ctxt.Headtype {
-	case obj.Hplan9,
-		obj.Hwindows:
+	case obj.Hplan9, obj.Hwindows, obj.Hwindowsgui:
 		return false
 	case obj.Hlinux:
 		return !ctxt.Flag_shared
@@ -181,7 +181,7 @@ func progedit(ctxt *obj.Link, p *obj.Prog) {
 	}
 
 	// TODO: Remove.
-	if ctxt.Headtype == obj.Hwindows && p.Mode == 64 || ctxt.Headtype == obj.Hplan9 {
+	if (ctxt.Headtype == obj.Hwindows || ctxt.Headtype == obj.Hwindowsgui) && p.Mode == 64 || ctxt.Headtype == obj.Hplan9 {
 		if p.From.Scale == 1 && p.From.Index == REG_TLS {
 			p.From.Scale = 2
 		}

src/cmd/link/internal/amd64/asm.go

@@ -227,7 +227,7 @@ func adddynrel(ctxt *ld.Link, s *ld.Symbol, r *ld.Reloc) {
 	switch r.Type {
 	case obj.R_CALL,
 		obj.R_PCREL:
-		if ld.HEADTYPE == obj.Hwindows {
+		if ld.Headtype == obj.Hwindows || ld.Headtype == obj.Hwindowsgui {
 			// nothing to do, the relocation will be laid out in pereloc1
 			return
 		} else {
@@ -240,7 +240,7 @@ func adddynrel(ctxt *ld.Link, s *ld.Symbol, r *ld.Reloc) {
 
 	case obj.R_ADDR:
 		if s.Type == obj.STEXT && ld.Iself {
-			if ld.HEADTYPE == obj.Hsolaris {
+			if ld.Headtype == obj.Hsolaris {
 				addpltsym(ctxt, targ)
 				r.Sym = ld.Linklookup(ctxt, ".plt", 0)
 				r.Add += int64(targ.Plt)
@@ -273,7 +273,7 @@ func adddynrel(ctxt *ld.Link, s *ld.Symbol, r *ld.Reloc) {
 			return
 		}
 
-		if ld.HEADTYPE == obj.Hdarwin && s.Size == int64(ld.SysArch.PtrSize) && r.Off == 0 {
+		if ld.Headtype == obj.Hdarwin && s.Size == int64(ld.SysArch.PtrSize) && r.Off == 0 {
 			// Mach-O relocations are a royal pain to lay out.
 			// They use a compact stateful bytecode representation
 			// that is too much bother to deal with.
@@ -298,7 +298,7 @@ func adddynrel(ctxt *ld.Link, s *ld.Symbol, r *ld.Reloc) {
 			return
 		}
 
-		if ld.HEADTYPE == obj.Hwindows {
+		if ld.Headtype == obj.Hwindows || ld.Headtype == obj.Hwindowsgui {
 			// nothing to do, the relocation will be laid out in pereloc1
 			return
 		}
@@ -548,7 +548,7 @@ func addpltsym(ctxt *ld.Link, s *ld.Symbol) {
 		ld.Adduint64(ctxt, rela, 0)
 
 		s.Plt = int32(plt.Size - 16)
-	} else if ld.HEADTYPE == obj.Hdarwin {
+	} else if ld.Headtype == obj.Hdarwin {
 		// To do lazy symbol lookup right, we're supposed
 		// to tell the dynamic loader which library each
 		// symbol comes from and format the link info
@@ -590,7 +590,7 @@ func addgotsym(ctxt *ld.Link, s *ld.Symbol) {
 		ld.Addaddrplus(ctxt, rela, got, int64(s.Got))
 		ld.Adduint64(ctxt, rela, ld.ELF64_R_INFO(uint32(s.Dynid), ld.R_X86_64_GLOB_DAT))
 		ld.Adduint64(ctxt, rela, 0)
-	} else if ld.HEADTYPE == obj.Hdarwin {
+	} else if ld.Headtype == obj.Hdarwin {
 		ld.Adduint32(ctxt, ld.Linklookup(ctxt, ".linkedit.got", 0), uint32(s.Dynid))
 	} else {
 		ctxt.Diag("addgotsym: unsupported binary format")
@@ -639,13 +639,13 @@ func asmb(ctxt *ld.Link) {
 	ld.Dwarfblk(ctxt, int64(ld.Segdwarf.Vaddr), int64(ld.Segdwarf.Filelen))
 
 	machlink := int64(0)
-	if ld.HEADTYPE == obj.Hdarwin {
+	if ld.Headtype == obj.Hdarwin {
 		machlink = ld.Domacholink(ctxt)
 	}
 
-	switch ld.HEADTYPE {
+	switch ld.Headtype {
 	default:
-		ctxt.Diag("unknown header type %d", ld.HEADTYPE)
+		ctxt.Diag("unknown header type %d", ld.Headtype)
 		fallthrough
 
 	case obj.Hplan9:
@@ -663,7 +663,8 @@ func asmb(ctxt *ld.Link) {
 		ld.Flag8 = true /* 64-bit addresses */
 
 	case obj.Hnacl,
-		obj.Hwindows:
+		obj.Hwindows,
+		obj.Hwindowsgui:
 		break
 	}
 
@@ -675,7 +676,7 @@ func asmb(ctxt *ld.Link) {
 		if ctxt.Debugvlog != 0 {
 			ctxt.Logf("%5.2f sym\n", obj.Cputime())
 		}
-		switch ld.HEADTYPE {
+		switch ld.Headtype {
 		default:
 		case obj.Hplan9:
 			*ld.FlagS = true
@@ -694,13 +695,14 @@ func asmb(ctxt *ld.Link) {
 			symo = int64(ld.Segdwarf.Fileoff + ld.Segdwarf.Filelen)
 			symo = ld.Rnd(symo, int64(*ld.FlagRound))
 
-		case obj.Hwindows:
+		case obj.Hwindows,
+			obj.Hwindowsgui:
 			symo = int64(ld.Segdwarf.Fileoff + ld.Segdwarf.Filelen)
 			symo = ld.Rnd(symo, ld.PEFILEALIGN)
 		}
 
 		ld.Cseek(symo)
-		switch ld.HEADTYPE {
+		switch ld.Headtype {
 		default:
 			if ld.Iself {
 				ld.Cseek(symo)
@@ -731,7 +733,7 @@ func asmb(ctxt *ld.Link) {
 				ld.Cflush()
 			}
 
-		case obj.Hwindows:
+		case obj.Hwindows, obj.Hwindowsgui:
 			if ctxt.Debugvlog != 0 {
 				ctxt.Logf("%5.2f dwarf\n", obj.Cputime())
 			}
@@ -747,7 +749,7 @@ func asmb(ctxt *ld.Link) {
 		ctxt.Logf("%5.2f headr\n", obj.Cputime())
 	}
 	ld.Cseek(0)
-	switch ld.HEADTYPE {
+	switch ld.Headtype {
 	default:
 	case obj.Hplan9: /* plan9 */
 		magic := int32(4*26*26 + 7)
@@ -776,7 +778,8 @@ func asmb(ctxt *ld.Link) {
 		obj.Hnacl:
 		ld.Asmbelf(ctxt, symo)
 
-	case obj.Hwindows:
+	case obj.Hwindows,
+		obj.Hwindowsgui:
 		ld.Asmbpe(ctxt)
 	}
 

src/cmd/link/internal/amd64/obj.go

@@ -93,13 +93,13 @@ func archinit(ctxt *ld.Link) {
 		ld.Linkmode = ld.LinkExternal
 	}
 
-	switch ld.HEADTYPE {
+	switch ld.Headtype {
 	default:
 		if ld.Linkmode == ld.LinkAuto {
 			ld.Linkmode = ld.LinkInternal
 		}
 		if ld.Linkmode == ld.LinkExternal && obj.Getgoextlinkenabled() != "1" {
-			log.Fatalf("cannot use -linkmode=external with -H %s", ld.Headstr(int(ld.HEADTYPE)))
+			log.Fatalf("cannot use -linkmode=external with -H %s", ld.Headtype)
 		}
 
 	case obj.Hdarwin,
@@ -110,13 +110,14 @@ func archinit(ctxt *ld.Link) {
 		obj.Hnetbsd,
 		obj.Hopenbsd,
 		obj.Hsolaris,
-		obj.Hwindows:
+		obj.Hwindows,
+		obj.Hwindowsgui:
 		break
 	}
 
-	switch ld.HEADTYPE {
+	switch ld.Headtype {
 	default:
-		ld.Exitf("unknown -H option: %v", ld.HEADTYPE)
+		ld.Exitf("unknown -H option: %v", ld.Headtype)
 
 	case obj.Hplan9: /* plan 9 */
 		ld.HEADR = 32 + 8
@@ -179,7 +180,7 @@ func archinit(ctxt *ld.Link) {
 			*ld.FlagRound = 0x10000
 		}
 
-	case obj.Hwindows: /* PE executable */
+	case obj.Hwindows, obj.Hwindowsgui: /* PE executable */
 		ld.Peinit(ctxt)
 
 		ld.HEADR = ld.PEFILEHEADR

src/cmd/link/internal/arm/asm.go

@@ -439,7 +439,7 @@ func archreloc(ctxt *ld.Link, r *ld.Reloc, s *ld.Symbol, val *int64) int {
 			// the section load address.
 			// we need to compensate that by removing the instruction's address
 			// from addend.
-			if ld.HEADTYPE == obj.Hdarwin {
+			if ld.Headtype == obj.Hdarwin {
 				r.Xadd -= ld.Symaddr(ctxt, s) + int64(r.Off)
 			}
 
@@ -618,7 +618,7 @@ func asmb(ctxt *ld.Link) {
 	ld.Dwarfblk(ctxt, int64(ld.Segdwarf.Vaddr), int64(ld.Segdwarf.Filelen))
 
 	machlink := uint32(0)
-	if ld.HEADTYPE == obj.Hdarwin {
+	if ld.Headtype == obj.Hdarwin {
 		machlink = uint32(ld.Domacholink(ctxt))
 	}
 
@@ -632,7 +632,7 @@ func asmb(ctxt *ld.Link) {
 		if ctxt.Debugvlog != 0 {
 			ctxt.Logf("%5.2f sym\n", obj.Cputime())
 		}
-		switch ld.HEADTYPE {
+		switch ld.Headtype {
 		default:
 			if ld.Iself {
 				symo = uint32(ld.Segdwarf.Fileoff + ld.Segdwarf.Filelen)
@@ -647,7 +647,7 @@ func asmb(ctxt *ld.Link) {
 		}
 
 		ld.Cseek(int64(symo))
-		switch ld.HEADTYPE {
+		switch ld.Headtype {
 		default:
 			if ld.Iself {
 				if ctxt.Debugvlog != 0 {
@@ -688,7 +688,7 @@ func asmb(ctxt *ld.Link) {
 		ctxt.Logf("%5.2f header\n", obj.Cputime())
 	}
 	ld.Cseek(0)
-	switch ld.HEADTYPE {
+	switch ld.Headtype {
 	default:
 	case obj.Hplan9: /* plan 9 */
 		ld.Lputb(0x647)                      /* magic */

src/cmd/link/internal/arm/obj.go

@@ -89,13 +89,13 @@ func archinit(ctxt *ld.Link) {
 		ld.Linkmode = ld.LinkExternal
 	}
 
-	switch ld.HEADTYPE {
+	switch ld.Headtype {
 	default:
 		if ld.Linkmode == ld.LinkAuto {
 			ld.Linkmode = ld.LinkInternal
 		}
 		if ld.Linkmode == ld.LinkExternal && obj.Getgoextlinkenabled() != "1" {
-			log.Fatalf("cannot use -linkmode=external with -H %s", ld.Headstr(int(ld.HEADTYPE)))
+			log.Fatalf("cannot use -linkmode=external with -H %s", ld.Headtype)
 		}
 
 	case obj.Hlinux,
@@ -105,9 +105,9 @@ func archinit(ctxt *ld.Link) {
 		break
 	}
 
-	switch ld.HEADTYPE {
+	switch ld.Headtype {
 	default:
-		ld.Exitf("unknown -H option: %v", ld.HEADTYPE)
+		ld.Exitf("unknown -H option: %v", ld.Headtype)
 
 	case obj.Hplan9: /* plan 9 */
 		ld.HEADR = 32

src/cmd/link/internal/arm64/asm.go

@@ -284,7 +284,7 @@ func archreloc(ctxt *ld.Link, r *ld.Reloc, s *ld.Symbol, val *int64) int {
 			// the BR26 relocation should be fully resolved at link time.
 			// That is the reason why the next if block is disabled. When the bug in ld64
 			// is fixed, we can enable this block and also enable duff's device in cmd/7g.
-			if false && ld.HEADTYPE == obj.Hdarwin {
+			if false && ld.Headtype == obj.Hdarwin {
 				var o0, o1 uint32
 
 				if ctxt.Arch.ByteOrder == binary.BigEndian {
@@ -361,8 +361,8 @@ func archreloc(ctxt *ld.Link, r *ld.Reloc, s *ld.Symbol, val *int64) int {
 
 	case obj.R_ARM64_TLS_LE:
 		r.Done = 0
-		if ld.HEADTYPE != obj.Hlinux {
-			ctxt.Diag("TLS reloc on unsupported OS %s", ld.Headstr(int(ld.HEADTYPE)))
+		if ld.Headtype != obj.Hlinux {
+			ctxt.Diag("TLS reloc on unsupported OS %s", ld.Headtype)
 		}
 		// The TCB is two pointers. This is not documented anywhere, but is
 		// de facto part of the ABI.
@@ -427,7 +427,7 @@ func asmb(ctxt *ld.Link) {
 	ld.Dwarfblk(ctxt, int64(ld.Segdwarf.Vaddr), int64(ld.Segdwarf.Filelen))
 
 	machlink := uint32(0)
-	if ld.HEADTYPE == obj.Hdarwin {
+	if ld.Headtype == obj.Hdarwin {
 		machlink = uint32(ld.Domacholink(ctxt))
 	}
 
@@ -441,7 +441,7 @@ func asmb(ctxt *ld.Link) {
 		if ctxt.Debugvlog != 0 {
 			ctxt.Logf("%5.2f sym\n", obj.Cputime())
 		}
-		switch ld.HEADTYPE {
+		switch ld.Headtype {
 		default:
 			if ld.Iself {
 				symo = uint32(ld.Segdwarf.Fileoff + ld.Segdwarf.Filelen)
@@ -456,7 +456,7 @@ func asmb(ctxt *ld.Link) {
 		}
 
 		ld.Cseek(int64(symo))
-		switch ld.HEADTYPE {
+		switch ld.Headtype {
 		default:
 			if ld.Iself {
 				if ctxt.Debugvlog != 0 {
@@ -497,7 +497,7 @@ func asmb(ctxt *ld.Link) {
 		ctxt.Logf("%5.2f header\n", obj.Cputime())
 	}
 	ld.Cseek(0)
-	switch ld.HEADTYPE {
+	switch ld.Headtype {
 	default:
 	case obj.Hplan9: /* plan 9 */
 		ld.Thearch.Lput(0x647)                      /* magic */

src/cmd/link/internal/arm64/obj.go

@@ -87,17 +87,17 @@ func archinit(ctxt *ld.Link) {
 	}
 
 	// Darwin/arm64 only supports external linking
-	if ld.HEADTYPE == obj.Hdarwin {
+	if ld.Headtype == obj.Hdarwin {
 		ld.Linkmode = ld.LinkExternal
 	}
 
-	switch ld.HEADTYPE {
+	switch ld.Headtype {
 	default:
 		if ld.Linkmode == ld.LinkAuto {
 			ld.Linkmode = ld.LinkInternal
 		}
 		if ld.Linkmode == ld.LinkExternal && obj.Getgoextlinkenabled() != "1" {
-			log.Fatalf("cannot use -linkmode=external with -H %s", ld.Headstr(int(ld.HEADTYPE)))
+			log.Fatalf("cannot use -linkmode=external with -H %s", ld.Headtype)
 		}
 	case obj.Hlinux, obj.Hdarwin:
 		break
@@ -107,9 +107,9 @@ func archinit(ctxt *ld.Link) {
 		ld.Linkmode = ld.LinkExternal
 	}
 
-	switch ld.HEADTYPE {
+	switch ld.Headtype {
 	default:
-		ld.Exitf("unknown -H option: %v", ld.HEADTYPE)
+		ld.Exitf("unknown -H option: %v", ld.Headtype)
 
 	case obj.Hplan9: /* plan 9 */
 		ld.HEADR = 32

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

@@ -360,7 +360,7 @@ func relocsym(ctxt *Link, s *Symbol) {
 
 		// We need to be able to reference dynimport symbols when linking against
 		// shared libraries, and Solaris needs it always
-		if HEADTYPE != obj.Hsolaris && r.Sym != nil && r.Sym.Type == obj.SDYNIMPORT && !ctxt.DynlinkingGo() {
+		if Headtype != obj.Hsolaris && r.Sym != nil && r.Sym.Type == obj.SDYNIMPORT && !ctxt.DynlinkingGo() {
 			if !(SysArch.Family == sys.PPC64 && Linkmode == LinkExternal && r.Sym.Name == ".TOC.") {
 				ctxt.Diag("unhandled relocation for %s (type %d rtype %d)", r.Sym.Name, r.Sym.Type, r.Type)
 			}
@@ -401,7 +401,7 @@ func relocsym(ctxt *Link, s *Symbol) {
 		case obj.R_TLS_LE:
 			isAndroidX86 := goos == "android" && (SysArch.InFamily(sys.AMD64, sys.I386))
 
-			if Linkmode == LinkExternal && Iself && HEADTYPE != obj.Hopenbsd && !isAndroidX86 {
+			if Linkmode == LinkExternal && Iself && Headtype != obj.Hopenbsd && !isAndroidX86 {
 				r.Done = 0
 				if r.Sym == nil {
 					r.Sym = ctxt.Tlsg
@@ -424,18 +424,18 @@ func relocsym(ctxt *Link, s *Symbol) {
 				// related to the fact that our own TLS storage happens
 				// to take up 8 bytes.
 				o = 8 + r.Sym.Value
-			} else if Iself || ctxt.Headtype == obj.Hplan9 || ctxt.Headtype == obj.Hdarwin || isAndroidX86 {
+			} else if Iself || Headtype == obj.Hplan9 || Headtype == obj.Hdarwin || isAndroidX86 {
 				o = int64(ctxt.Tlsoffset) + r.Add
-			} else if ctxt.Headtype == obj.Hwindows {
+			} else if Headtype == obj.Hwindows || Headtype == obj.Hwindowsgui {
 				o = r.Add
 			} else {
-				log.Fatalf("unexpected R_TLS_LE relocation for %s", Headstr(ctxt.Headtype))
+				log.Fatalf("unexpected R_TLS_LE relocation for %s", Headtype)
 			}
 
 		case obj.R_TLS_IE:
 			isAndroidX86 := goos == "android" && (SysArch.InFamily(sys.AMD64, sys.I386))
 
-			if Linkmode == LinkExternal && Iself && HEADTYPE != obj.Hopenbsd && !isAndroidX86 {
+			if Linkmode == LinkExternal && Iself && Headtype != obj.Hopenbsd && !isAndroidX86 {
 				r.Done = 0
 				if r.Sym == nil {
 					r.Sym = ctxt.Tlsg
@@ -473,7 +473,7 @@ func relocsym(ctxt *Link, s *Symbol) {
 					if SysArch.Family == sys.AMD64 {
 						o = 0
 					}
-				} else if HEADTYPE == obj.Hdarwin {
+				} else if Headtype == obj.Hdarwin {
 					// ld64 for arm64 has a bug where if the address pointed to by o exists in the
 					// symbol table (dynid >= 0), or is inside a symbol that exists in the symbol
 					// table, then it will add o twice into the relocated value.
@@ -487,10 +487,10 @@ func relocsym(ctxt *Link, s *Symbol) {
 							o += Symaddr(ctxt, rs)
 						}
 					}
-				} else if HEADTYPE == obj.Hwindows {
+				} else if Headtype == obj.Hwindows || Headtype == obj.Hwindowsgui {
 					// nothing to do
 				} else {
-					ctxt.Diag("unhandled pcrel relocation for %s", headstring)
+					ctxt.Diag("unhandled pcrel relocation for %s", Headtype)
 				}
 
 				break
@@ -555,7 +555,7 @@ func relocsym(ctxt *Link, s *Symbol) {
 					if SysArch.Family == sys.AMD64 {
 						o = 0
 					}
-				} else if HEADTYPE == obj.Hdarwin {
+				} else if Headtype == obj.Hdarwin {
 					if r.Type == obj.R_CALL {
 						if rs.Type != obj.SHOSTOBJ {
 							o += int64(uint64(Symaddr(ctxt, rs)) - rs.Sect.Vaddr)
@@ -567,7 +567,7 @@ func relocsym(ctxt *Link, s *Symbol) {
 					} else {
 						o += int64(r.Siz)
 					}
-				} else if HEADTYPE == obj.Hwindows && SysArch.Family == sys.AMD64 { // only amd64 needs PCREL
+				} else if (Headtype == obj.Hwindows || Headtype == obj.Hwindowsgui) && SysArch.Family == sys.AMD64 { // only amd64 needs PCREL
 					// PE/COFF's PC32 relocation uses the address after the relocated
 					// bytes as the base. Compensate by skewing the addend.
 					o += int64(r.Siz)
@@ -575,7 +575,7 @@ func relocsym(ctxt *Link, s *Symbol) {
 					// relocated address, compensate that.
 					o -= int64(s.Sect.Vaddr - PEBASE)
 				} else {
-					ctxt.Diag("unhandled pcrel relocation for %s", headstring)
+					ctxt.Diag("unhandled pcrel relocation for %s", Headtype)
 				}
 
 				break
@@ -657,7 +657,7 @@ func (ctxt *Link) reloc() {
 }
 
 func dynrelocsym(ctxt *Link, s *Symbol) {
-	if HEADTYPE == obj.Hwindows && Linkmode != LinkExternal {
+	if (Headtype == obj.Hwindows || Headtype == obj.Hwindowsgui) && Linkmode != LinkExternal {
 		rel := Linklookup(ctxt, ".rel", 0)
 		if s == rel {
 			return
@@ -713,7 +713,7 @@ func dynrelocsym(ctxt *Link, s *Symbol) {
 func dynreloc(ctxt *Link, data *[obj.SXREF][]*Symbol) {
 	// -d suppresses dynamic loader format, so we may as well not
 	// compute these sections or mark their symbols as reachable.
-	if *FlagD && HEADTYPE != obj.Hwindows {
+	if *FlagD && Headtype != obj.Hwindows && Headtype != obj.Hwindowsgui {
 		return
 	}
 	if ctxt.Debugvlog != 0 {
@@ -1201,7 +1201,7 @@ func (ctxt *Link) dodata() {
 	// symbol, which is itself data.
 	//
 	// On darwin, we need the symbol table numbers for dynreloc.
-	if HEADTYPE == obj.Hdarwin {
+	if Headtype == obj.Hdarwin {
 		machosymorder(ctxt)
 	}
 	dynreloc(ctxt, &data)
@@ -1423,7 +1423,7 @@ func (ctxt *Link) dodata() {
 
 	if len(data[obj.STLSBSS]) > 0 {
 		var sect *Section
-		if Iself && (Linkmode == LinkExternal || !*FlagD) && HEADTYPE != obj.Hopenbsd {
+		if Iself && (Linkmode == LinkExternal || !*FlagD) && Headtype != obj.Hopenbsd {
 			sect = addsection(&Segdata, ".tbss", 06)
 			sect.Align = int32(SysArch.PtrSize)
 			sect.Vaddr = 0
@@ -1740,7 +1740,7 @@ func (ctxt *Link) dodata() {
 }
 
 func dodataSect(ctxt *Link, symn int, syms []*Symbol) (result []*Symbol, maxAlign int32) {
-	if HEADTYPE == obj.Hdarwin {
+	if Headtype == obj.Hdarwin {
 		// Some symbols may no longer belong in syms
 		// due to movement in machosymorder.
 		newSyms := make([]*Symbol, 0, len(syms))
@@ -1862,7 +1862,7 @@ func (ctxt *Link) textaddress() {
 	sect.Align = int32(Funcalign)
 	Linklookup(ctxt, "runtime.text", 0).Sect = sect
 	Linklookup(ctxt, "runtime.etext", 0).Sect = sect
-	if HEADTYPE == obj.Hwindows {
+	if Headtype == obj.Hwindows || Headtype == obj.Hwindowsgui {
 		Linklookup(ctxt, ".text", 0).Sect = sect
 	}
 	va := uint64(*FlagTextAddr)
@@ -1908,7 +1908,7 @@ func (ctxt *Link) address() {
 
 	Segtext.Length = va - uint64(*FlagTextAddr)
 	Segtext.Filelen = Segtext.Length
-	if HEADTYPE == obj.Hnacl {
+	if Headtype == obj.Hnacl {
 		va += 32 // room for the "halt sled"
 	}
 
@@ -1936,10 +1936,10 @@ func (ctxt *Link) address() {
 	Segdata.Vaddr = va
 	Segdata.Fileoff = va - Segtext.Vaddr + Segtext.Fileoff
 	Segdata.Filelen = 0
-	if HEADTYPE == obj.Hwindows {
+	if Headtype == obj.Hwindows || Headtype == obj.Hwindowsgui {
 		Segdata.Fileoff = Segtext.Fileoff + uint64(Rnd(int64(Segtext.Length), PEFILEALIGN))
 	}
-	if HEADTYPE == obj.Hplan9 {
+	if Headtype == obj.Hplan9 {
 		Segdata.Fileoff = Segtext.Fileoff + Segtext.Filelen
 	}
 	var data *Section
@@ -1979,7 +1979,7 @@ func (ctxt *Link) address() {
 	Segdwarf.Vaddr = va
 	Segdwarf.Fileoff = Segdata.Fileoff + uint64(Rnd(int64(Segdata.Filelen), int64(*FlagRound)))
 	Segdwarf.Filelen = 0
-	if HEADTYPE == obj.Hwindows {
+	if Headtype == obj.Hwindows || Headtype == obj.Hwindowsgui {
 		Segdwarf.Fileoff = Segdata.Fileoff + uint64(Rnd(int64(Segdata.Filelen), int64(PEFILEALIGN)))
 	}
 	for s := Segdwarf.Sect; s != nil; s = s.Next {
@@ -1989,7 +1989,7 @@ func (ctxt *Link) address() {
 		}
 		s.Vaddr = va
 		va += uint64(vlen)
-		if HEADTYPE == obj.Hwindows {
+		if Headtype == obj.Hwindows || Headtype == obj.Hwindowsgui {
 			va = uint64(Rnd(int64(va), PEFILEALIGN))
 		}
 		Segdwarf.Length = va - Segdwarf.Vaddr
@@ -2050,7 +2050,7 @@ func (ctxt *Link) address() {
 
 	ctxt.xdefine("runtime.text", obj.STEXT, int64(text.Vaddr))
 	ctxt.xdefine("runtime.etext", obj.STEXT, int64(text.Vaddr+text.Length))
-	if HEADTYPE == obj.Hwindows {
+	if Headtype == obj.Hwindows || Headtype == obj.Hwindowsgui {
 		ctxt.xdefine(".text", obj.STEXT, int64(text.Vaddr))
 	}
 	ctxt.xdefine("runtime.rodata", obj.SRODATA, int64(rodata.Vaddr))

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

@@ -1401,15 +1401,15 @@ func dwarfgeneratedebugsyms(ctxt *Link) {
 	if *FlagW { // disable dwarf
 		return
 	}
-	if *FlagS && HEADTYPE != obj.Hdarwin {
+	if *FlagS && Headtype != obj.Hdarwin {
 		return
 	}
-	if HEADTYPE == obj.Hplan9 {
+	if Headtype == obj.Hplan9 {
 		return
 	}
 
 	if Linkmode == LinkExternal {
-		if !Iself && HEADTYPE != obj.Hdarwin {
+		if !Iself && Headtype != obj.Hdarwin {
 			return
 		}
 	}

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

@@ -947,7 +947,7 @@ func Elfinit(ctxt *Link) {
 	// 32-bit architectures
 	case sys.ARM:
 		// we use EABI on both linux/arm and freebsd/arm.
-		if HEADTYPE == obj.Hlinux || HEADTYPE == obj.Hfreebsd {
+		if Headtype == obj.Hlinux || Headtype == obj.Hfreebsd {
 			// We set a value here that makes no indication of which
 			// float ABI the object uses, because this is information
 			// used by the dynamic linker to compare executables and
@@ -1836,15 +1836,15 @@ func (ctxt *Link) doelf() {
 	// for dynamic internal linker or external linking, so that various
 	// binutils could correctly calculate PT_TLS size.
 	// see https://golang.org/issue/5200.
-	if HEADTYPE != obj.Hopenbsd {
+	if Headtype != obj.Hopenbsd {
 		if !*FlagD || Linkmode == LinkExternal {
 			Addstring(ctxt, shstrtab, ".tbss")
 		}
 	}
-	if HEADTYPE == obj.Hnetbsd {
+	if Headtype == obj.Hnetbsd {
 		Addstring(ctxt, shstrtab, ".note.netbsd.ident")
 	}
-	if HEADTYPE == obj.Hopenbsd {
+	if Headtype == obj.Hopenbsd {
 		Addstring(ctxt, shstrtab, ".note.openbsd.ident")
 	}
 	if len(buildinfo) > 0 {
@@ -2189,7 +2189,7 @@ func Asmbelf(ctxt *Link, symo int64) {
 	 * segment boundaries downwards to include it.
 	 * Except on NaCl where it must not be loaded.
 	 */
-	if HEADTYPE != obj.Hnacl {
+	if Headtype != obj.Hnacl {
 		o := int64(Segtext.Vaddr - pph.vaddr)
 		Segtext.Vaddr -= uint64(o)
 		Segtext.Length += uint64(o)
@@ -2206,7 +2206,7 @@ func Asmbelf(ctxt *Link, symo int64) {
 		sh.flags = SHF_ALLOC
 		sh.addralign = 1
 		if interpreter == "" {
-			switch HEADTYPE {
+			switch Headtype {
 			case obj.Hlinux:
 				interpreter = Thearch.Linuxdynld
 
@@ -2236,9 +2236,9 @@ func Asmbelf(ctxt *Link, symo int64) {
 	}
 
 	pnote = nil
-	if HEADTYPE == obj.Hnetbsd || HEADTYPE == obj.Hopenbsd {
+	if Headtype == obj.Hnetbsd || Headtype == obj.Hopenbsd {
 		var sh *ElfShdr
-		switch HEADTYPE {
+		switch Headtype {
 		case obj.Hnetbsd:
 			sh = elfshname(ctxt, ".note.netbsd.ident")
 			resoff -= int64(elfnetbsdsig(sh, uint64(startva), uint64(resoff)))
@@ -2434,7 +2434,7 @@ func Asmbelf(ctxt *Link, symo int64) {
 		// Do not emit PT_TLS for OpenBSD since ld.so(1) does
 		// not currently support it. This is handled
 		// appropriately in runtime/cgo.
-		if HEADTYPE != obj.Hopenbsd {
+		if Headtype != obj.Hopenbsd {
 			tlssize := uint64(0)
 			for sect := Segdata.Sect; sect != nil; sect = sect.Next {
 				if sect.Name == ".tbss" {
@@ -2451,7 +2451,7 @@ func Asmbelf(ctxt *Link, symo int64) {
 		}
 	}
 
-	if HEADTYPE == obj.Hlinux {
+	if Headtype == obj.Hlinux {
 		ph := newElfPhdr(ctxt)
 		ph.type_ = PT_GNU_STACK
 		ph.flags = PF_W + PF_R
@@ -2538,13 +2538,13 @@ elfobj:
 	eh.ident[EI_MAG1] = 'E'
 	eh.ident[EI_MAG2] = 'L'
 	eh.ident[EI_MAG3] = 'F'
-	if HEADTYPE == obj.Hfreebsd {
+	if Headtype == obj.Hfreebsd {
 		eh.ident[EI_OSABI] = ELFOSABI_FREEBSD
-	} else if HEADTYPE == obj.Hnetbsd {
+	} else if Headtype == obj.Hnetbsd {
 		eh.ident[EI_OSABI] = ELFOSABI_NETBSD
-	} else if HEADTYPE == obj.Hopenbsd {
+	} else if Headtype == obj.Hopenbsd {
 		eh.ident[EI_OSABI] = ELFOSABI_OPENBSD
-	} else if HEADTYPE == obj.Hdragonfly {
+	} else if Headtype == obj.Hdragonfly {
 		eh.ident[EI_OSABI] = ELFOSABI_NONE
 	}
 	if elf64 {
@@ -2585,10 +2585,10 @@ elfobj:
 		a += int64(elfwriteinterp(ctxt))
 	}
 	if Linkmode != LinkExternal {
-		if HEADTYPE == obj.Hnetbsd {
+		if Headtype == obj.Hnetbsd {
 			a += int64(elfwritenetbsdsig(ctxt))
 		}
-		if HEADTYPE == obj.Hopenbsd {
+		if Headtype == obj.Hopenbsd {
 			a += int64(elfwriteopenbsdsig(ctxt))
 		}
 		if len(buildinfo) > 0 {

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

@@ -174,7 +174,7 @@ func loadcgo(ctxt *Link, file string, pkg string, p string) {
 				// to force a link of foo.so.
 				havedynamic = 1
 
-				if HEADTYPE == obj.Hdarwin {
+				if Headtype == obj.Hdarwin {
 					Machoadddynlib(lib)
 				} else {
 					dynlib = append(dynlib, lib)
@@ -322,9 +322,9 @@ func Adddynsym(ctxt *Link, s *Symbol) {
 
 	if Iself {
 		Elfadddynsym(ctxt, s)
-	} else if HEADTYPE == obj.Hdarwin {
+	} else if Headtype == obj.Hdarwin {
 		ctxt.Diag("adddynsym: missed symbol %s (%s)", s.Name, s.Extname)
-	} else if HEADTYPE == obj.Hwindows {
+	} else if Headtype == obj.Hwindows {
 		// already taken care of
 	} else {
 		ctxt.Diag("adddynsym: unsupported binary format")
@@ -363,7 +363,7 @@ func fieldtrack(ctxt *Link) {
 }
 
 func (ctxt *Link) addexport() {
-	if HEADTYPE == obj.Hdarwin {
+	if Headtype == obj.Hdarwin {
 		return
 	}
 

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

@@ -183,7 +183,7 @@ var (
 
 	debug_s  bool // backup old value of debug['s']
 	HEADR    int32
-	HEADTYPE int32
+	Headtype obj.HeadType
 
 	nerrors  int
 	Linkmode int
@@ -206,10 +206,6 @@ const (
 	Pkgdef
 )
 
-var (
-	headstring string
-)
-
 // TODO(dfc) outBuf duplicates bio.Writer
 type outBuf struct {
 	w   *bufio.Writer
@@ -465,7 +461,7 @@ func (ctxt *Link) loadlib() {
 		// dependency problems when compiling natively (external linking requires
 		// runtime/cgo, runtime/cgo requires cmd/cgo, but cmd/cgo needs to be
 		// compiled using external linking.)
-		if SysArch.InFamily(sys.ARM, sys.ARM64) && HEADTYPE == obj.Hdarwin && iscgo {
+		if SysArch.InFamily(sys.ARM, sys.ARM64) && Headtype == obj.Hdarwin && iscgo {
 			Linkmode = LinkExternal
 		}
 
@@ -605,7 +601,7 @@ func (ctxt *Link) loadlib() {
 			if *flagLibGCC != "none" {
 				hostArchive(ctxt, *flagLibGCC)
 			}
-			if HEADTYPE == obj.Hwindows {
+			if Headtype == obj.Hwindows || Headtype == obj.Hwindowsgui {
 				if p := ctxt.findLibPath("libmingwex.a"); p != "none" {
 					hostArchive(ctxt, p)
 				}
@@ -639,7 +635,7 @@ func (ctxt *Link) loadlib() {
 	// statically linked binaries.
 	switch Buildmode {
 	case BuildmodeExe, BuildmodePIE:
-		if havedynamic == 0 && HEADTYPE != obj.Hdarwin && HEADTYPE != obj.Hsolaris {
+		if havedynamic == 0 && Headtype != obj.Hdarwin && Headtype != obj.Hsolaris {
 			*FlagD = true
 		}
 	}
@@ -805,7 +801,7 @@ func ldhostobj(ld func(*Link, *bio.Reader, string, int64, string), f *bio.Reader
 	// force external linking for any libraries that link in code that
 	// uses errno. This can be removed if the Go linker ever supports
 	// these relocation types.
-	if HEADTYPE == obj.Hdragonfly {
+	if Headtype == obj.Hdragonfly {
 		if pkg == "net" || pkg == "os/user" {
 			isinternal = false
 		}
@@ -980,23 +976,20 @@ func (l *Link) hostlink() {
 		argv = append(argv, "-s")
 	}
 
-	if HEADTYPE == obj.Hdarwin {
+	switch Headtype {
+	case obj.Hdarwin:
 		argv = append(argv, "-Wl,-no_pie,-headerpad,1144")
-	}
-	if HEADTYPE == obj.Hopenbsd {
+	case obj.Hopenbsd:
 		argv = append(argv, "-Wl,-nopie")
-	}
-	if HEADTYPE == obj.Hwindows {
-		if headstring == "windowsgui" {
-			argv = append(argv, "-mwindows")
-		} else {
-			argv = append(argv, "-mconsole")
-		}
+	case obj.Hwindows:
+		argv = append(argv, "-mconsole")
+	case obj.Hwindowsgui:
+		argv = append(argv, "-mwindows")
 	}
 
 	switch Buildmode {
 	case BuildmodeExe:
-		if HEADTYPE == obj.Hdarwin {
+		if Headtype == obj.Hdarwin {
 			argv = append(argv, "-Wl,-pagezero_size,4000000")
 		}
 	case BuildmodePIE:
@@ -1005,7 +998,7 @@ func (l *Link) hostlink() {
 		}
 		argv = append(argv, "-pie")
 	case BuildmodeCShared:
-		if HEADTYPE == obj.Hdarwin {
+		if Headtype == obj.Hdarwin {
 			argv = append(argv, "-dynamiclib", "-Wl,-read_only_relocs,suppress")
 		} else {
 			// ELF.
@@ -1170,7 +1163,7 @@ func (l *Link) hostlink() {
 			}
 		}
 	}
-	if HEADTYPE == obj.Hwindows {
+	if Headtype == obj.Hwindows || Headtype == obj.Hwindowsgui {
 		// libmingw32 and libmingwex have some inter-dependencies,
 		// so must use linker groups.
 		argv = append(argv, "-Wl,--start-group", "-lmingwex", "-lmingw32", "-Wl,--end-group")
@@ -1191,7 +1184,7 @@ func (l *Link) hostlink() {
 		l.Logf("%s", out)
 	}
 
-	if !*FlagS && !debug_s && HEADTYPE == obj.Hdarwin {
+	if !*FlagS && !debug_s && Headtype == obj.Hdarwin {
 		// Skip combining dwarf on arm.
 		if !SysArch.InFamily(sys.ARM, sys.ARM64) {
 			dsym := filepath.Join(*flagTmpdir, "go.dwarf")
@@ -1828,16 +1821,6 @@ func usage() {
 	Exit(2)
 }
 
-func setheadtype(s string) {
-	h := headtype(s)
-	if h < 0 {
-		Exitf("unknown header type -H %s", s)
-	}
-
-	headstring = s
-	HEADTYPE = int32(headtype(s))
-}
-
 func doversion() {
 	Exitf("version %s", obj.Getgoversion())
 }
@@ -1905,7 +1888,7 @@ func genasmsym(ctxt *Link, put func(*Link, *Symbol, string, int, int64, int64, i
 			put(ctxt, nil, s.Name, 'f', s.Value, 0, int(s.Version), nil)
 
 		case obj.SHOSTOBJ:
-			if HEADTYPE == obj.Hwindows || Iself {
+			if Headtype == obj.Hwindows || Headtype == obj.Hwindowsgui || Iself {
 				put(ctxt, s, s.Name, 'U', s.Value, 0, int(s.Version), nil)
 			}
 
@@ -1916,7 +1899,7 @@ func genasmsym(ctxt *Link, put func(*Link, *Symbol, string, int, int64, int64, i
 			put(ctxt, s, s.Extname, 'U', 0, 0, int(s.Version), nil)
 
 		case obj.STLSBSS:
-			if Linkmode == LinkExternal && HEADTYPE != obj.Hopenbsd {
+			if Linkmode == LinkExternal && Headtype != obj.Hopenbsd {
 				put(ctxt, s, s.Name, 't', Symaddr(ctxt, s), s.Size, int(s.Version), s.Gotype)
 			}
 		}

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

@@ -161,7 +161,6 @@ type Shlib struct {
 
 type Link struct {
 	Goarm     int32
-	Headtype  int
 	Arch      *sys.Arch
 	Debugvlog int
 	Bso       *bufio.Writer

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

@@ -35,7 +35,6 @@ import (
 	"cmd/internal/obj"
 	"cmd/internal/sys"
 	"flag"
-	"fmt"
 	"log"
 	"os"
 	"runtime"
@@ -49,6 +48,7 @@ var (
 
 func init() {
 	flag.Var(&Buildmode, "buildmode", "set build `mode`")
+	flag.Var(&Headtype, "H", "set header `type`")
 	flag.Var(&rpath, "r", "set the ELF dynamic linker search `path` to dir1:dir2:...")
 }
 
@@ -101,10 +101,6 @@ func Main() {
 	ctxt := linknew(SysArch)
 	ctxt.Bso = bufio.NewWriter(os.Stdout)
 
-	nerrors = 0
-	HEADTYPE = -1
-	Linkmode = LinkAuto
-
 	// For testing behavior of go command when tools crash silently.
 	// Undocumented, not in standard flag parser to avoid
 	// exposing in usage message.
@@ -120,7 +116,6 @@ func Main() {
 	}
 	obj.Flagfn1("B", "add an ELF NT_GNU_BUILD_ID `note` when using ELF", addbuildinfo)
 	obj.Flagfn1("L", "add specified `directory` to library path", func(a string) { Lflag(ctxt, a) })
-	obj.Flagfn1("H", "set header `type`", setheadtype)
 	obj.Flagfn0("V", "print version and exit", doversion)
 	obj.Flagfn1("X", "add string value `definition` of the form importpath.name=value", func(s string) { addstrdata1(ctxt, s) })
 	obj.Flagcount("v", "print link trace", &ctxt.Debugvlog)
@@ -139,7 +134,7 @@ func Main() {
 
 	if *flagOutfile == "" {
 		*flagOutfile = "a.out"
-		if HEADTYPE == obj.Hwindows {
+		if Headtype == obj.Hwindows || Headtype == obj.Hwindowsgui {
 			*flagOutfile += ".exe"
 		}
 	}
@@ -148,14 +143,11 @@ func Main() {
 
 	libinit(ctxt) // creates outfile
 
-	if HEADTYPE == -1 {
-		HEADTYPE = int32(headtype(goos))
-	}
-	ctxt.Headtype = int(HEADTYPE)
-	if headstring == "" {
-		headstring = Headstr(int(HEADTYPE))
+	if Headtype == obj.Hunknown {
+		Headtype.Set(obj.Getgoos())
 	}
 
+	ctxt.computeTLSOffset()
 	Thearch.Archinit(ctxt)
 
 	if *FlagLinkshared && !Iself {
@@ -163,7 +155,7 @@ func Main() {
 	}
 
 	if ctxt.Debugvlog != 0 {
-		ctxt.Logf("HEADER = -H%d -T0x%x -D0x%x -R0x%x\n", HEADTYPE, uint64(*FlagTextAddr), uint64(*FlagDataAddr), uint32(*FlagRound))
+		ctxt.Logf("HEADER = -H%d -T0x%x -D0x%x -R0x%x\n", Headtype, uint64(*FlagTextAddr), uint64(*FlagDataAddr), uint32(*FlagRound))
 	}
 
 	if Buildmode == BuildmodeShared {
@@ -191,11 +183,11 @@ func Main() {
 	ctxt.callgraph()
 
 	ctxt.doelf()
-	if HEADTYPE == obj.Hdarwin {
+	if Headtype == obj.Hdarwin {
 		ctxt.domacho()
 	}
 	ctxt.dostkcheck()
-	if HEADTYPE == obj.Hwindows {
+	if Headtype == obj.Hwindows || Headtype == obj.Hwindowsgui {
 		ctxt.dope()
 	}
 	ctxt.addexport()
@@ -223,97 +215,6 @@ func Main() {
 	errorexit()
 }
 
-// A BuildMode indicates the sort of object we are building:
-//   "exe": build a main package and everything it imports into an executable.
-//   "c-shared": build a main package, plus all packages that it imports, into a
-//     single C shared library. The only callable symbols will be those functions
-//     marked as exported.
-//   "shared": combine all packages passed on the command line, and their
-//     dependencies, into a single shared library that will be used when
-//     building with the -linkshared option.
-type BuildMode uint8
-
-const (
-	BuildmodeUnset BuildMode = iota
-	BuildmodeExe
-	BuildmodePIE
-	BuildmodeCArchive
-	BuildmodeCShared
-	BuildmodeShared
-)
-
-func (mode *BuildMode) Set(s string) error {
-	goos := obj.Getgoos()
-	goarch := obj.Getgoarch()
-	badmode := func() error {
-		return fmt.Errorf("buildmode %s not supported on %s/%s", s, goos, goarch)
-	}
-	switch s {
-	default:
-		return fmt.Errorf("invalid buildmode: %q", s)
-	case "exe":
-		*mode = BuildmodeExe
-	case "pie":
-		switch goos {
-		case "android", "linux":
-		default:
-			return badmode()
-		}
-		*mode = BuildmodePIE
-	case "c-archive":
-		switch goos {
-		case "darwin", "linux":
-		case "windows":
-			switch goarch {
-			case "amd64", "386":
-			default:
-				return badmode()
-			}
-		default:
-			return badmode()
-		}
-		*mode = BuildmodeCArchive
-	case "c-shared":
-		switch goarch {
-		case "386", "amd64", "arm", "arm64":
-		default:
-			return badmode()
-		}
-		*mode = BuildmodeCShared
-	case "shared":
-		switch goos {
-		case "linux":
-			switch goarch {
-			case "386", "amd64", "arm", "arm64", "ppc64le", "s390x":
-			default:
-				return badmode()
-			}
-		default:
-			return badmode()
-		}
-		*mode = BuildmodeShared
-	}
-	return nil
-}
-
-func (mode *BuildMode) String() string {
-	switch *mode {
-	case BuildmodeUnset:
-		return "" // avoid showing a default in usage message
-	case BuildmodeExe:
-		return "exe"
-	case BuildmodePIE:
-		return "pie"
-	case BuildmodeCArchive:
-		return "c-archive"
-	case BuildmodeCShared:
-		return "c-shared"
-	case BuildmodeShared:
-		return "shared"
-	}
-	return fmt.Sprintf("BuildMode(%d)", uint8(*mode))
-}
-
 type Rpath struct {
 	set bool
 	val string

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

@@ -1244,7 +1244,7 @@ func Asmbpe(ctxt *Link) {
 	oh.SizeOfImage = uint32(nextsectoff)
 	oh64.SizeOfHeaders = uint32(PEFILEHEADR)
 	oh.SizeOfHeaders = uint32(PEFILEHEADR)
-	if headstring == "windowsgui" {
+	if Headtype == obj.Hwindowsgui {
 		oh64.Subsystem = IMAGE_SUBSYSTEM_WINDOWS_GUI
 		oh.Subsystem = IMAGE_SUBSYSTEM_WINDOWS_GUI
 	} else {

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

@@ -34,28 +34,10 @@ package ld
 import (
 	"cmd/internal/obj"
 	"cmd/internal/sys"
+	"fmt"
 	"log"
-	"strconv"
 )
 
-var headers = []struct {
-	name string
-	val  int
-}{
-	{"darwin", obj.Hdarwin},
-	{"dragonfly", obj.Hdragonfly},
-	{"freebsd", obj.Hfreebsd},
-	{"linux", obj.Hlinux},
-	{"android", obj.Hlinux}, // must be after "linux" entry or else headstr(Hlinux) == "android"
-	{"nacl", obj.Hnacl},
-	{"netbsd", obj.Hnetbsd},
-	{"openbsd", obj.Hopenbsd},
-	{"plan9", obj.Hplan9},
-	{"solaris", obj.Hsolaris},
-	{"windows", obj.Hwindows},
-	{"windowsgui", obj.Hwindows},
-}
-
 func linknew(arch *sys.Arch) *Link {
 	ctxt := &Link{
 		Hash: []map[string]*Symbol{
@@ -73,18 +55,21 @@ func linknew(arch *sys.Arch) *Link {
 		log.Fatalf("invalid goarch %s (want %s)", p, arch.Name)
 	}
 
-	ctxt.Headtype = headtype(obj.Getgoos())
-	if ctxt.Headtype < 0 {
-		log.Fatalf("unknown goos %s", obj.Getgoos())
+	// On arm, record goarm.
+	if ctxt.Arch.Family == sys.ARM {
+		ctxt.Goarm = obj.Getgoarm()
 	}
 
-	// Record thread-local storage offset.
-	// TODO(rsc): Move tlsoffset back into the linker.
-	switch ctxt.Headtype {
+	return ctxt
+}
+
+// computeTLSOffset records the thread-local storage offset.
+func (ctxt *Link) computeTLSOffset() {
+	switch Headtype {
 	default:
-		log.Fatalf("unknown thread-local storage offset for %s", Headstr(ctxt.Headtype))
+		log.Fatalf("unknown thread-local storage offset for %s", Headtype)
 
-	case obj.Hplan9, obj.Hwindows:
+	case obj.Hplan9, obj.Hwindows, obj.Hwindowsgui:
 		break
 
 		/*
@@ -152,12 +137,6 @@ func linknew(arch *sys.Arch) *Link {
 		}
 	}
 
-	// On arm, record goarm.
-	if ctxt.Arch.Family == sys.ARM {
-		ctxt.Goarm = obj.Getgoarm()
-	}
-
-	return ctxt
 }
 
 func linknewsym(ctxt *Link, name string, v int) *Symbol {
@@ -195,20 +174,93 @@ func Linkrlookup(ctxt *Link, name string, v int) *Symbol {
 	return ctxt.Hash[v][name]
 }
 
-func Headstr(v int) string {
-	for i := 0; i < len(headers); i++ {
-		if v == headers[i].val {
-			return headers[i].name
+// A BuildMode indicates the sort of object we are building:
+//   "exe": build a main package and everything it imports into an executable.
+//   "c-shared": build a main package, plus all packages that it imports, into a
+//     single C shared library. The only callable symbols will be those functions
+//     marked as exported.
+//   "shared": combine all packages passed on the command line, and their
+//     dependencies, into a single shared library that will be used when
+//     building with the -linkshared option.
+type BuildMode uint8
+
+const (
+	BuildmodeUnset BuildMode = iota
+	BuildmodeExe
+	BuildmodePIE
+	BuildmodeCArchive
+	BuildmodeCShared
+	BuildmodeShared
+)
+
+func (mode *BuildMode) Set(s string) error {
+	goos := obj.Getgoos()
+	goarch := obj.Getgoarch()
+	badmode := func() error {
+		return fmt.Errorf("buildmode %s not supported on %s/%s", s, goos, goarch)
+	}
+	switch s {
+	default:
+		return fmt.Errorf("invalid buildmode: %q", s)
+	case "exe":
+		*mode = BuildmodeExe
+	case "pie":
+		switch goos {
+		case "android", "linux":
+		default:
+			return badmode()
+		}
+		*mode = BuildmodePIE
+	case "c-archive":
+		switch goos {
+		case "darwin", "linux":
+		case "windows":
+			switch goarch {
+			case "amd64", "386":
+			default:
+				return badmode()
+			}
+		default:
+			return badmode()
 		}
+		*mode = BuildmodeCArchive
+	case "c-shared":
+		switch goarch {
+		case "386", "amd64", "arm", "arm64":
+		default:
+			return badmode()
+		}
+		*mode = BuildmodeCShared
+	case "shared":
+		switch goos {
+		case "linux":
+			switch goarch {
+			case "386", "amd64", "arm", "arm64", "ppc64le", "s390x":
+			default:
+				return badmode()
+			}
+		default:
+			return badmode()
+		}
+		*mode = BuildmodeShared
 	}
-	return strconv.Itoa(v)
+	return nil
 }
 
-func headtype(name string) int {
-	for i := 0; i < len(headers); i++ {
-		if name == headers[i].name {
-			return headers[i].val
-		}
+func (mode *BuildMode) String() string {
+	switch *mode {
+	case BuildmodeUnset:
+		return "" // avoid showing a default in usage message
+	case BuildmodeExe:
+		return "exe"
+	case BuildmodePIE:
+		return "pie"
+	case BuildmodeCArchive:
+		return "c-archive"
+	case BuildmodeCShared:
+		return "c-shared"
+	case BuildmodeShared:
+		return "shared"
 	}
-	return -1
+	return fmt.Sprintf("BuildMode(%d)", uint8(*mode))
 }

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

@@ -226,7 +226,7 @@ func putplan9sym(ctxt *Link, x *Symbol, s string, t int, addr int64, size int64,
 		'Z',
 		'm':
 		l := 4
-		if HEADTYPE == obj.Hplan9 && SysArch.Family == sys.AMD64 && !Flag8 {
+		if Headtype == obj.Hplan9 && SysArch.Family == sys.AMD64 && !Flag8 {
 			Lputb(uint32(addr >> 32))
 			l = 8
 		}

src/cmd/link/internal/mips64/asm.go

@@ -228,7 +228,7 @@ func asmb(ctxt *ld.Link) {
 		if ctxt.Debugvlog != 0 {
 			ctxt.Logf("%5.2f sym\n", obj.Cputime())
 		}
-		switch ld.HEADTYPE {
+		switch ld.Headtype {
 		default:
 			if ld.Iself {
 				symo = uint32(ld.Segdwarf.Fileoff + ld.Segdwarf.Filelen)
@@ -240,7 +240,7 @@ func asmb(ctxt *ld.Link) {
 		}
 
 		ld.Cseek(int64(symo))
-		switch ld.HEADTYPE {
+		switch ld.Headtype {
 		default:
 			if ld.Iself {
 				if ctxt.Debugvlog != 0 {
@@ -276,7 +276,7 @@ func asmb(ctxt *ld.Link) {
 		ctxt.Logf("%5.2f header\n", obj.Cputime())
 	}
 	ld.Cseek(0)
-	switch ld.HEADTYPE {
+	switch ld.Headtype {
 	default:
 	case obj.Hplan9: /* plan 9 */
 		magic := uint32(4*18*18 + 7)

src/cmd/link/internal/mips64/obj.go

@@ -99,22 +99,22 @@ func archinit(ctxt *ld.Link) {
 		ld.Linkmode = ld.LinkInternal
 	}
 
-	switch ld.HEADTYPE {
+	switch ld.Headtype {
 	default:
 		if ld.Linkmode == ld.LinkAuto {
 			ld.Linkmode = ld.LinkInternal
 		}
 		if ld.Linkmode == ld.LinkExternal && obj.Getgoextlinkenabled() != "1" {
-			log.Fatalf("cannot use -linkmode=external with -H %s", ld.Headstr(int(ld.HEADTYPE)))
+			log.Fatalf("cannot use -linkmode=external with -H %s", ld.Headtype)
 		}
 
 	case obj.Hlinux:
 		break
 	}
 
-	switch ld.HEADTYPE {
+	switch ld.Headtype {
 	default:
-		ld.Exitf("unknown -H option: %v", ld.HEADTYPE)
+		ld.Exitf("unknown -H option: %v", ld.Headtype)
 
 	case obj.Hplan9: /* plan 9 */
 		ld.HEADR = 32

src/cmd/link/internal/ppc64/asm.go

@@ -849,7 +849,7 @@ func asmb(ctxt *ld.Link) {
 		if ctxt.Debugvlog != 0 {
 			ctxt.Logf("%5.2f sym\n", obj.Cputime())
 		}
-		switch ld.HEADTYPE {
+		switch ld.Headtype {
 		default:
 			if ld.Iself {
 				symo = uint32(ld.Segdwarf.Fileoff + ld.Segdwarf.Filelen)
@@ -861,7 +861,7 @@ func asmb(ctxt *ld.Link) {
 		}
 
 		ld.Cseek(int64(symo))
-		switch ld.HEADTYPE {
+		switch ld.Headtype {
 		default:
 			if ld.Iself {
 				if ctxt.Debugvlog != 0 {
@@ -897,7 +897,7 @@ func asmb(ctxt *ld.Link) {
 		ctxt.Logf("%5.2f header\n", obj.Cputime())
 	}
 	ld.Cseek(0)
-	switch ld.HEADTYPE {
+	switch ld.Headtype {
 	default:
 	case obj.Hplan9: /* plan 9 */
 		ld.Thearch.Lput(0x647)                      /* magic */

src/cmd/link/internal/ppc64/obj.go

@@ -114,22 +114,22 @@ func archinit(ctxt *ld.Link) {
 		toc.Type = obj.SDYNIMPORT
 	}
 
-	switch ld.HEADTYPE {
+	switch ld.Headtype {
 	default:
 		if ld.Linkmode == ld.LinkAuto {
 			ld.Linkmode = ld.LinkInternal
 		}
 		if ld.Linkmode == ld.LinkExternal && obj.Getgoextlinkenabled() != "1" {
-			log.Fatalf("cannot use -linkmode=external with -H %s", ld.Headstr(int(ld.HEADTYPE)))
+			log.Fatalf("cannot use -linkmode=external with -H %s", ld.Headtype)
 		}
 
 	case obj.Hlinux:
 		break
 	}
 
-	switch ld.HEADTYPE {
+	switch ld.Headtype {
 	default:
-		ld.Exitf("unknown -H option: %v", ld.HEADTYPE)
+		ld.Exitf("unknown -H option: %v", ld.Headtype)
 
 	case obj.Hplan9: /* plan 9 */
 		ld.HEADR = 32

src/cmd/link/internal/s390x/asm.go

@@ -571,7 +571,7 @@ func asmb(ctxt *ld.Link) {
 		ctxt.Logf("%5.2f header\n", obj.Cputime())
 	}
 	ld.Cseek(0)
-	switch ld.HEADTYPE {
+	switch ld.Headtype {
 	default:
 		ctxt.Diag("unsupported operating system")
 	case obj.Hlinux:

src/cmd/link/internal/s390x/obj.go

@@ -90,9 +90,9 @@ func archinit(ctxt *ld.Link) {
 		ld.Linkmode = ld.LinkExternal
 	}
 
-	switch ld.HEADTYPE {
+	switch ld.Headtype {
 	default:
-		ld.Exitf("unknown -H option: %v", ld.HEADTYPE)
+		ld.Exitf("unknown -H option: %v", ld.Headtype)
 
 	case obj.Hlinux: // s390x ELF
 		ld.Elfinit(ctxt)

src/cmd/link/internal/x86/asm.go

@@ -308,7 +308,7 @@ func adddynrel(ctxt *ld.Link, s *ld.Symbol, r *ld.Reloc) {
 			return
 		}
 
-		if ld.HEADTYPE == obj.Hdarwin && s.Size == int64(ld.SysArch.PtrSize) && r.Off == 0 {
+		if ld.Headtype == obj.Hdarwin && s.Size == int64(ld.SysArch.PtrSize) && r.Off == 0 {
 			// Mach-O relocations are a royal pain to lay out.
 			// They use a compact stateful bytecode representation
 			// that is too much bother to deal with.
@@ -333,7 +333,7 @@ func adddynrel(ctxt *ld.Link, s *ld.Symbol, r *ld.Reloc) {
 			return
 		}
 
-		if ld.HEADTYPE == obj.Hwindows && s.Size == int64(ld.SysArch.PtrSize) {
+		if (ld.Headtype == obj.Hwindows || ld.Headtype == obj.Hwindowsgui) && s.Size == int64(ld.SysArch.PtrSize) {
 			// nothing to do, the relocation will be laid out in pereloc1
 			return
 		}
@@ -582,7 +582,7 @@ func addpltsym(ctxt *ld.Link, s *ld.Symbol) {
 		ld.Adduint32(ctxt, rel, ld.ELF32_R_INFO(uint32(s.Dynid), ld.R_386_JMP_SLOT))
 
 		s.Plt = int32(plt.Size - 16)
-	} else if ld.HEADTYPE == obj.Hdarwin {
+	} else if ld.Headtype == obj.Hdarwin {
 		// Same laziness as in 6l.
 
 		plt := ld.Linklookup(ctxt, ".plt", 0)
@@ -616,7 +616,7 @@ func addgotsym(ctxt *ld.Link, s *ld.Symbol) {
 		rel := ld.Linklookup(ctxt, ".rel", 0)
 		ld.Addaddrplus(ctxt, rel, got, int64(s.Got))
 		ld.Adduint32(ctxt, rel, ld.ELF32_R_INFO(uint32(s.Dynid), ld.R_386_GLOB_DAT))
-	} else if ld.HEADTYPE == obj.Hdarwin {
+	} else if ld.Headtype == obj.Hdarwin {
 		ld.Adduint32(ctxt, ld.Linklookup(ctxt, ".linkedit.got", 0), uint32(s.Dynid))
 	} else {
 		ctxt.Diag("addgotsym: unsupported binary format")
@@ -661,7 +661,7 @@ func asmb(ctxt *ld.Link) {
 	ld.Dwarfblk(ctxt, int64(ld.Segdwarf.Vaddr), int64(ld.Segdwarf.Filelen))
 
 	machlink := uint32(0)
-	if ld.HEADTYPE == obj.Hdarwin {
+	if ld.Headtype == obj.Hdarwin {
 		machlink = uint32(ld.Domacholink(ctxt))
 	}
 
@@ -674,7 +674,7 @@ func asmb(ctxt *ld.Link) {
 		if ctxt.Debugvlog != 0 {
 			ctxt.Logf("%5.2f sym\n", obj.Cputime())
 		}
-		switch ld.HEADTYPE {
+		switch ld.Headtype {
 		default:
 			if ld.Iself {
 				symo = uint32(ld.Segdwarf.Fileoff + ld.Segdwarf.Filelen)
@@ -687,13 +687,13 @@ func asmb(ctxt *ld.Link) {
 		case obj.Hdarwin:
 			symo = uint32(ld.Segdwarf.Fileoff + uint64(ld.Rnd(int64(ld.Segdwarf.Filelen), int64(*ld.FlagRound))) + uint64(machlink))
 
-		case obj.Hwindows:
+		case obj.Hwindows, obj.Hwindowsgui:
 			symo = uint32(ld.Segdwarf.Fileoff + ld.Segdwarf.Filelen)
 			symo = uint32(ld.Rnd(int64(symo), ld.PEFILEALIGN))
 		}
 
 		ld.Cseek(int64(symo))
-		switch ld.HEADTYPE {
+		switch ld.Headtype {
 		default:
 			if ld.Iself {
 				if ctxt.Debugvlog != 0 {
@@ -722,7 +722,7 @@ func asmb(ctxt *ld.Link) {
 				ld.Cflush()
 			}
 
-		case obj.Hwindows:
+		case obj.Hwindows, obj.Hwindowsgui:
 			if ctxt.Debugvlog != 0 {
 				ctxt.Logf("%5.2f dwarf\n", obj.Cputime())
 			}
@@ -738,7 +738,7 @@ func asmb(ctxt *ld.Link) {
 		ctxt.Logf("%5.2f headr\n", obj.Cputime())
 	}
 	ld.Cseek(0)
-	switch ld.HEADTYPE {
+	switch ld.Headtype {
 	default:
 	case obj.Hplan9: /* plan9 */
 		magic := int32(4*11*11 + 7)
@@ -762,7 +762,7 @@ func asmb(ctxt *ld.Link) {
 		obj.Hnacl:
 		ld.Asmbelf(ctxt, int64(symo))
 
-	case obj.Hwindows:
+	case obj.Hwindows, obj.Hwindowsgui:
 		ld.Asmbpe(ctxt)
 	}
 

src/cmd/link/internal/x86/obj.go

@@ -92,13 +92,13 @@ func archinit(ctxt *ld.Link) {
 		got.Attr |= ld.AttrReachable
 	}
 
-	switch ld.HEADTYPE {
+	switch ld.Headtype {
 	default:
 		if ld.Linkmode == ld.LinkAuto {
 			ld.Linkmode = ld.LinkInternal
 		}
 		if ld.Linkmode == ld.LinkExternal && obj.Getgoextlinkenabled() != "1" {
-			log.Fatalf("cannot use -linkmode=external with -H %s", ld.Headstr(int(ld.HEADTYPE)))
+			log.Fatalf("cannot use -linkmode=external with -H %s", ld.Headtype)
 		}
 
 	case obj.Hdarwin,
@@ -106,13 +106,14 @@ func archinit(ctxt *ld.Link) {
 		obj.Hlinux,
 		obj.Hnetbsd,
 		obj.Hopenbsd,
-		obj.Hwindows:
+		obj.Hwindows,
+		obj.Hwindowsgui:
 		break
 	}
 
-	switch ld.HEADTYPE {
+	switch ld.Headtype {
 	default:
-		ld.Exitf("unknown -H option: %v", ld.HEADTYPE)
+		ld.Exitf("unknown -H option: %v", ld.Headtype)
 
 	case obj.Hplan9: /* plan 9 */
 		ld.HEADR = 32
@@ -172,7 +173,7 @@ func archinit(ctxt *ld.Link) {
 			*ld.FlagRound = 0x10000
 		}
 
-	case obj.Hwindows: /* PE executable */
+	case obj.Hwindows, obj.Hwindowsgui: /* PE executable */
 		ld.Peinit(ctxt)
 
 		ld.HEADR = ld.PEFILEHEADR