[dev.link] cmd/link: use new dodata on darwin/amd64

This probably breaks darwin/arm64. Will fix.

Change-Id: I8be168985124f971e9d8ab5bc95c303336dd705b
Reviewed-on: https://go-review.googlesource.com/c/go/+/230019
Reviewed-by: Than McIntosh <thanm@google.com>

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

@@ -1355,8 +1355,7 @@ func (ctxt *Link) dodata2(symGroupType []sym.SymKind) {
 	//
 	// On darwin, we need the symbol table numbers for dynreloc.
 	if ctxt.HeadType == objabi.Hdarwin {
-		panic("not yet implemented for darwin")
-		//	machosymorder(ctxt)
+		machosymorder(ctxt)
 	}
 	state.dynreloc2(ctxt)
 

src/cmd/link/internal/ld/data2.go

@@ -45,7 +45,8 @@ func (ctxt *Link) dodata() {
 	//
 	// On darwin, we need the symbol table numbers for dynreloc.
 	if ctxt.HeadType == objabi.Hdarwin {
-		machosymorder(ctxt)
+		panic("not supported")
+		//machosymorder(ctxt)
 	}
 	state.dynreloc(ctxt)
 

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

@@ -8,6 +8,7 @@ import (
 	"bytes"
 	"cmd/internal/objabi"
 	"cmd/internal/sys"
+	"cmd/link/internal/loader"
 	"cmd/link/internal/sym"
 	"debug/macho"
 	"encoding/binary"
@@ -216,7 +217,7 @@ const (
 
 var nkind [NumSymKind]int
 
-var sortsym []*sym.Symbol
+var sortsym []loader.Sym
 
 var nsortsym int
 
@@ -743,106 +744,125 @@ func Asmbmacho(ctxt *Link) {
 	}
 }
 
-func symkind(s *sym.Symbol) int {
-	if s.Type == sym.SDYNIMPORT {
+func symkind(ldr *loader.Loader, s loader.Sym) int {
+	if ldr.SymType(s) == sym.SDYNIMPORT {
 		return SymKindUndef
 	}
-	if s.Attr.CgoExport() {
+	if ldr.AttrCgoExport(s) {
 		return SymKindExtdef
 	}
 	return SymKindLocal
 }
 
-func addsym(ctxt *Link, s *sym.Symbol, name string, type_ SymbolType, addr int64, gotype *sym.Symbol) {
-	if s == nil {
-		return
+func collectmachosyms(ctxt *Link) {
+	ldr := ctxt.loader
+
+	addsym := func(s loader.Sym) {
+		sortsym = append(sortsym, s)
+		nkind[symkind(ldr, s)]++
 	}
 
-	switch type_ {
-	default:
-		return
-
-	case DataSym, BSSSym, TextSym:
-		break
+	// Add special runtime.text and runtime.etext symbols.
+	// We've already included this symbol in Textp on darwin if ctxt.DynlinkingGo().
+	// See data.go:/textaddress
+	if !ctxt.DynlinkingGo() {
+		s := ldr.Lookup("runtime.text", 0)
+		if ldr.SymType(s) == sym.STEXT {
+			addsym(s)
+		}
+		s = ldr.Lookup("runtime.etext", 0)
+		if ldr.SymType(s) == sym.STEXT {
+			addsym(s)
+		}
 	}
 
-	if sortsym != nil {
-		sortsym[nsortsym] = s
-		nkind[symkind(s)]++
+	// Add text symbols.
+	for _, s := range ctxt.Textp2 {
+		addsym(s)
 	}
 
-	nsortsym++
+	shouldBeInSymbolTable := func(s loader.Sym) bool {
+		if ldr.AttrNotInSymbolTable(s) {
+			return false
+		}
+		name := ldr.RawSymName(s) // TODO: try not to read the name
+		if name == "" || name[0] == '.' {
+			return false
+		}
+		return true
 	}
 
-type machoscmp []*sym.Symbol
-
-func (x machoscmp) Len() int {
-	return len(x)
+	// Add data symbols and external references.
+	for s := loader.Sym(1); s < loader.Sym(ldr.NSym()); s++ {
+		if !ldr.AttrReachable(s) {
+			continue
+		}
+		t := ldr.SymType(s)
+		if t >= sym.SELFRXSECT && t < sym.SXREF { // data sections handled in dodata
+			if t == sym.STLSBSS {
+				// TLSBSS is not used on darwin. See data.go:allocateDataSections
+				continue
+			}
+			if !shouldBeInSymbolTable(s) {
+				continue
+			}
+			addsym(s)
 		}
 
-func (x machoscmp) Swap(i, j int) {
-	x[i], x[j] = x[j], x[i]
+		switch t {
+		case sym.SDYNIMPORT, sym.SHOSTOBJ, sym.SUNDEFEXT, sym.SCONST:
+			addsym(s)
 		}
 
-func (x machoscmp) Less(i, j int) bool {
-	s1 := x[i]
-	s2 := x[j]
-
-	k1 := symkind(s1)
-	k2 := symkind(s2)
-	if k1 != k2 {
-		return k1 < k2
-	}
-
-	return s1.Extname() < s2.Extname()
-}
-
-func machogenasmsym(ctxt *Link) {
-	genasmsym(ctxt, addsym)
-	for _, s := range ctxt.Syms.Allsym {
 		// Some 64-bit functions have a "$INODE64" or "$INODE64$UNIX2003" suffix.
-		if s.Type == sym.SDYNIMPORT && s.Dynimplib() == "/usr/lib/libSystem.B.dylib" {
+		if t == sym.SDYNIMPORT && ldr.SymDynimplib(s) == "/usr/lib/libSystem.B.dylib" {
 			// But only on macOS.
 			if machoPlatform == PLATFORM_MACOS {
-				switch n := s.Extname(); n {
+				switch n := ldr.SymExtname(s); n {
 				case "fdopendir":
 					switch objabi.GOARCH {
 					case "amd64":
-						s.SetExtname(n + "$INODE64")
+						ldr.SetSymExtname(s, n+"$INODE64")
 					case "386":
-						s.SetExtname(n + "$INODE64$UNIX2003")
+						ldr.SetSymExtname(s, n+"$INODE64$UNIX2003")
 					}
 				case "readdir_r", "getfsstat":
 					switch objabi.GOARCH {
 					case "amd64", "386":
-						s.SetExtname(n + "$INODE64")
+						ldr.SetSymExtname(s, n+"$INODE64")
+					}
 				}
 			}
 		}
 	}
 
-		if s.Type == sym.SDYNIMPORT || s.Type == sym.SHOSTOBJ || s.Type == sym.SUNDEFEXT {
-			if s.Attr.Reachable() {
-				addsym(ctxt, s, "", DataSym, 0, nil)
-			}
-		}
-	}
+	nsortsym = len(sortsym)
 }
 
 func machosymorder(ctxt *Link) {
+	ldr := ctxt.loader
+
 	// 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 := range dynexp {
-		dynexp[i].Attr |= sym.AttrReachable
+	for _, s := range ctxt.dynexp2 {
+		if !ldr.AttrReachable(s) {
+			panic("dynexp symbol is not reachable")
 		}
-	machogenasmsym(ctxt)
-	sortsym = make([]*sym.Symbol, nsortsym)
-	nsortsym = 0
-	machogenasmsym(ctxt)
-	sort.Sort(machoscmp(sortsym[:nsortsym]))
-	for i := 0; i < nsortsym; i++ {
-		sortsym[i].Dynid = int32(i)
+	}
+	collectmachosyms(ctxt)
+	sort.Slice(sortsym[:nsortsym], func(i, j int) bool {
+		s1 := sortsym[i]
+		s2 := sortsym[j]
+		k1 := symkind(ldr, s1)
+		k2 := symkind(ldr, s2)
+		if k1 != k2 {
+			return k1 < k2
+		}
+		return ldr.SymExtname(s1) < ldr.SymExtname(s2) // Note: unnamed symbols are not added in collectmachosyms
+	})
+	for i, s := range sortsym {
+		ldr.SetSymDynid(s, int32(i))
 	}
 }
 
@@ -877,7 +897,7 @@ func machosymtab(ctxt *Link) {
 	symstr := ctxt.Syms.Lookup(".machosymstr", 0)
 
 	for i := 0; i < nsortsym; i++ {
-		s := sortsym[i]
+		s := ctxt.loader.Syms[sortsym[i]]
 		symtab.AddUint32(ctxt.Arch, uint32(symstr.Size))
 
 		export := machoShouldExport(ctxt, s)

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

@@ -202,8 +202,16 @@ func Main(arch *sys.Arch, theArch Arch) {
 
 	if *flagnewDoData {
 		// New dodata() is currently only implemented for selected targets.
-		if !(ctxt.IsElf() &&
-			(ctxt.IsAMD64() || ctxt.Is386())) {
+		switch {
+		case ctxt.IsElf():
+			if !(ctxt.IsAMD64() || ctxt.Is386()) {
+				*flagnewDoData = false
+			}
+		case ctxt.IsDarwin():
+			if !ctxt.IsAMD64() {
+				*flagnewDoData = false
+			}
+		default:
 			*flagnewDoData = false
 		}
 	}