[dev.link] cmd/link: remove AddExtSym

They used to be different at some point, but now AddExtSym and
LookupOrCreateSym are identical. Remove one.

Change-Id: I299444d987e32a7f43915b3c1bbcc5ae906e9b6a
Reviewed-on: https://go-review.googlesource.com/c/go/+/223977
Run-TryBot: Cherry Zhang <cherryyz@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Than McIntosh <thanm@google.com>

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

@@ -186,7 +186,7 @@ var gdbscript string
 var dwarfp2 []loader.Sym
 
 func (d *dwctxt2) writeabbrev() loader.Sym {
-	abrvs := d.ldr.AddExtSym(".debug_abbrev", 0)
+	abrvs := d.ldr.LookupOrCreateSym(".debug_abbrev", 0)
 	u := d.ldr.MakeSymbolUpdater(abrvs)
 	u.SetType(sym.SDWARFSECT)
 	u.AddBytes(dwarf.GetAbbrev())
@@ -1372,7 +1372,7 @@ func appendPCDeltaCFA(arch *sys.Arch, b []byte, deltapc, cfa int64) []byte {
 }
 
 func (d *dwctxt2) writeframes(syms []loader.Sym) []loader.Sym {
-	fs := d.ldr.AddExtSym(".debug_frame", 0)
+	fs := d.ldr.LookupOrCreateSym(".debug_frame", 0)
 	fsd := dwSym(fs)
 	fsu := d.ldr.MakeSymbolUpdater(fs)
 	fsu.SetType(sym.SDWARFSECT)
@@ -1540,7 +1540,7 @@ func appendSyms(syms []loader.Sym, src []sym.LoaderSym) []loader.Sym {
 
 func (d *dwctxt2) writeinfo(syms []loader.Sym, units []*sym.CompilationUnit, abbrevsym loader.Sym, pubNames, pubTypes *pubWriter2) []loader.Sym {
 
-	infosec := d.ldr.AddExtSym(".debug_info", 0)
+	infosec := d.ldr.LookupOrCreateSym(".debug_info", 0)
 	disu := d.ldr.MakeSymbolUpdater(infosec)
 	disu.SetType(sym.SDWARFINFO)
 	d.ldr.SetAttrReachable(infosec, true)
@@ -1641,7 +1641,7 @@ type pubWriter2 struct {
 }
 
 func newPubWriter2(d *dwctxt2, sname string) *pubWriter2 {
-	s := d.ldr.AddExtSym(sname, 0)
+	s := d.ldr.LookupOrCreateSym(sname, 0)
 	u := d.ldr.MakeSymbolUpdater(s)
 	u.SetType(sym.SDWARFSECT)
 	return &pubWriter2{d: d, s: s, su: u, sname: sname}
@@ -1714,7 +1714,7 @@ func (d *dwctxt2) writegdbscript(syms []loader.Sym) []loader.Sym {
 	}
 
 	if gdbscript != "" {
-		gs := d.ldr.AddExtSym(".debug_gdb_scripts", 0)
+		gs := d.ldr.LookupOrCreateSym(".debug_gdb_scripts", 0)
 		u := d.ldr.MakeSymbolUpdater(gs)
 		u.SetType(sym.SDWARFSECT)
 
@@ -2065,13 +2065,13 @@ func (d *dwctxt2) dwarfGenerateDebugSyms() {
 	sort.Sort(compilationUnitByStartPC(d.linkctxt.compUnits))
 
 	// Create .debug_line and .debug_ranges section symbols
-	debugLine := d.ldr.AddExtSym(".debug_line", 0)
+	debugLine := d.ldr.LookupOrCreateSym(".debug_line", 0)
 	dlu := d.ldr.MakeSymbolUpdater(debugLine)
 	dlu.SetType(sym.SDWARFSECT)
 	d.ldr.SetAttrReachable(debugLine, true)
 	syms = append(syms, debugLine)
 
-	debugRanges := d.ldr.AddExtSym(".debug_ranges", 0)
+	debugRanges := d.ldr.LookupOrCreateSym(".debug_ranges", 0)
 	dru := d.ldr.MakeSymbolUpdater(debugRanges)
 	dru.SetType(sym.SDWARFRANGE)
 	d.ldr.SetAttrReachable(debugRanges, true)
@@ -2141,7 +2141,7 @@ func (d *dwctxt2) collectlocs(syms []loader.Sym, units []*sym.CompilationUnit) [
 
 	// Don't emit .debug_loc if it's empty -- it makes the ARM linker mad.
 	if !empty {
-		locsym := d.ldr.AddExtSym(".debug_loc", 0)
+		locsym := d.ldr.LookupOrCreateSym(".debug_loc", 0)
 		u := d.ldr.MakeSymbolUpdater(locsym)
 		u.SetType(sym.SDWARFLOC)
 		d.ldr.SetAttrReachable(locsym, true)

src/cmd/link/internal/loader/loader.go

@@ -333,7 +333,7 @@ func (l *Loader) addObj(pkg string, r *oReader) Sym {
 // If the symbol already exist, it returns the index of that symbol.
 func (l *Loader) AddSym(name string, ver int, r *oReader, li int, kind int, dupok bool, typ sym.SymKind) (Sym, bool) {
 	if l.extStart != 0 {
-		panic("AddSym called after AddExtSym is called")
+		panic("AddSym called after external symbol is created")
 	}
 	i := Sym(len(l.objSyms))
 	addToGlobal := func() {
@@ -412,23 +412,6 @@ func (l *Loader) newExtSym(name string, ver int) Sym {
 	return i
 }
 
-// Add an external symbol (without index). Return the index of newly added
-// symbol, or 0 if not added.
-func (l *Loader) AddExtSym(name string, ver int) Sym {
-	i := l.Lookup(name, ver)
-	if i != 0 {
-		return i
-	}
-	i = l.newExtSym(name, ver)
-	static := ver >= sym.SymVerStatic || ver < 0
-	if static {
-		l.extStaticSyms[nameVer{name, ver}] = i
-	} else {
-		l.symsByName[ver][name] = i
-	}
-	return i
-}
-
 // LookupOrCreateSym looks up the symbol with the specified name/version,
 // returning its Sym index if found. If the lookup fails, a new external
 // Sym will be created, entered into the lookup tables, and returned.
@@ -1726,7 +1709,7 @@ func loadObjRefs(l *Loader, r *oReader, syms *sym.Symbols) {
 		osym.Read(r.Reader, r.SymOff(ndef+i))
 		name := strings.Replace(osym.Name, "\"\".", r.pkgprefix, -1)
 		v := abiToVer(osym.ABI, r.version)
-		r.syms[ndef+i] = l.AddExtSym(name, v)
+		r.syms[ndef+i] = l.LookupOrCreateSym(name, v)
 	}
 }
 

src/cmd/link/internal/loader/loader_test.go

@@ -39,17 +39,17 @@ func TestAddMaterializedSymbol(t *testing.T) {
 	ts3 := addDummyObjSym(t, ldr, or, "type.string")
 
 	// Create some external symbols.
-	es1 := ldr.AddExtSym("extnew1", 0)
+	es1 := ldr.LookupOrCreateSym("extnew1", 0)
 	if es1 == 0 {
-		t.Fatalf("AddExtSym failed for extnew1")
+		t.Fatalf("LookupOrCreateSym failed for extnew1")
 	}
-	es1x := ldr.AddExtSym("extnew1", 0)
+	es1x := ldr.LookupOrCreateSym("extnew1", 0)
 	if es1x != es1 {
-		t.Fatalf("AddExtSym lookup: expected %d got %d for second lookup", es1, es1x)
+		t.Fatalf("LookupOrCreateSym lookup: expected %d got %d for second lookup", es1, es1x)
 	}
-	es2 := ldr.AddExtSym("go.info.type.uint8", 0)
+	es2 := ldr.LookupOrCreateSym("go.info.type.uint8", 0)
 	if es2 == 0 {
-		t.Fatalf("AddExtSym failed for go.info.type.uint8")
+		t.Fatalf("LookupOrCreateSym failed for go.info.type.uint8")
 	}
 	// Create a nameless symbol
 	es3 := ldr.CreateExtSym("")
@@ -99,7 +99,7 @@ func TestAddMaterializedSymbol(t *testing.T) {
 
 	// Test expansion of attr bitmaps
 	for idx := 0; idx < 36; idx++ {
-		es := ldr.AddExtSym(fmt.Sprintf("zext%d", idx), 0)
+		es := ldr.LookupOrCreateSym(fmt.Sprintf("zext%d", idx), 0)
 		if ldr.AttrOnList(es) {
 			t.Errorf("expected OnList after creation")
 		}
@@ -235,7 +235,7 @@ func TestAddDataMethods(t *testing.T) {
 
 	// Populate loader with some symbols.
 	addDummyObjSym(t, ldr, or, "type.uint8")
-	ldr.AddExtSym("hello", 0)
+	ldr.LookupOrCreateSym("hello", 0)
 
 	arch := sys.ArchAMD64
 	var testpoints = []struct {
@@ -325,9 +325,9 @@ func TestAddDataMethods(t *testing.T) {
 	var pmi Sym
 	for k, tp := range testpoints {
 		name := fmt.Sprintf("new%d", k+1)
-		mi := ldr.AddExtSym(name, 0)
+		mi := ldr.LookupOrCreateSym(name, 0)
 		if mi == 0 {
-			t.Fatalf("AddExtSym failed for '" + name + "'")
+			t.Fatalf("LookupOrCreateSym failed for '" + name + "'")
 		}
 		mi = tp.addDataFunc(ldr, mi, pmi)
 		if ldr.SymType(mi) != tp.expKind {
@@ -359,12 +359,12 @@ func TestOuterSub(t *testing.T) {
 
 	// Populate loader with some symbols.
 	addDummyObjSym(t, ldr, or, "type.uint8")
-	es1 := ldr.AddExtSym("outer", 0)
+	es1 := ldr.LookupOrCreateSym("outer", 0)
-	es2 := ldr.AddExtSym("sub1", 0)
+	es2 := ldr.LookupOrCreateSym("sub1", 0)
-	es3 := ldr.AddExtSym("sub2", 0)
+	es3 := ldr.LookupOrCreateSym("sub2", 0)
-	es4 := ldr.AddExtSym("sub3", 0)
+	es4 := ldr.LookupOrCreateSym("sub3", 0)
-	es5 := ldr.AddExtSym("sub4", 0)
+	es5 := ldr.LookupOrCreateSym("sub4", 0)
-	es6 := ldr.AddExtSym("sub5", 0)
+	es6 := ldr.LookupOrCreateSym("sub5", 0)
 
 	// Should not have an outer sym initially
 	if ldr.OuterSym(es1) != 0 {