[dev.link] cmd/link: remove ctxt.Syms.Allsym

Replace remaining uses with loader.Syms. Reduces some memory
usage.

Change-Id: I6f295b42b8cd734c6c18f08c61a5473506675075
Reviewed-on: https://go-review.googlesource.com/c/go/+/229992
Reviewed-by: Jeremy Faller <jeremy@golang.org>
Reviewed-by: Than McIntosh <thanm@google.com>

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

@@ -28,7 +28,10 @@ func (ctxt *Link) dodata() {
 
 	// Collect data symbols by type into data.
 	state := dodataState{ctxt: ctxt}
-	for _, s := range ctxt.Syms.Allsym {
+	for _, s := range ctxt.loader.Syms {
+		if s == nil {
+			continue
+		}
 		if !s.Attr.Reachable() || s.Attr.Special() || s.Attr.SubSymbol() {
 			continue
 		}

src/cmd/link/internal/ld/elf2.go

@@ -51,7 +51,10 @@ func elfdynhash(ctxt *Link) {
 	chain := make([]uint32, nsym)
 	buckets := make([]uint32, nbucket)
 
-	for _, sy := range ctxt.Syms.Allsym {
+	for _, sy := range ctxt.loader.Syms {
+		if sy == nil {
+			continue
+		}
 		if sy.Dynid <= 0 {
 			continue
 		}

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

@@ -2555,7 +2555,10 @@ func genasmsym(ctxt *Link, put func(*Link, *sym.Symbol, string, SymbolType, int6
 		return true
 	}
 
-	for _, s := range ctxt.Syms.Allsym {
+	for _, s := range ctxt.loader.Syms {
+		if s == nil {
+			continue
+		}
 		if !shouldBeInSymbolTable(s) {
 			continue
 		}
@@ -2909,7 +2912,10 @@ func (ctxt *Link) loadlibfull(symGroupType []sym.SymKind) {
 }
 
 func (ctxt *Link) dumpsyms() {
-	for _, s := range ctxt.Syms.Allsym {
+	for _, s := range ctxt.loader.Syms {
+		if s == nil {
+			continue
+		}
 		fmt.Printf("%s %s reachable=%v onlist=%v outer=%v sub=%v\n", s, s.Type, s.Attr.Reachable(), s.Attr.OnList(), s.Outer, s.Sub)
 		for i := range s.R {
 			fmt.Println("\t", s.R[i].Type, s.R[i].Sym)

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

@@ -364,7 +364,7 @@ func Main(arch *sys.Arch, theArch Arch) {
 	bench.Start("hostlink")
 	ctxt.hostlink()
 	if ctxt.Debugvlog != 0 {
-		ctxt.Logf("%d symbols\n", len(ctxt.Syms.Allsym))
+		ctxt.Logf("%d symbols, %d reachable\n", len(ctxt.loader.Syms), ctxt.loader.NReachableSym())
 		ctxt.Logf("%d liveness data\n", liveness)
 	}
 	bench.Start("Flush")

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

@@ -1646,7 +1646,10 @@ func xcoffCreateExportFile(ctxt *Link) (fname string) {
 	fname = filepath.Join(*flagTmpdir, "export_file.exp")
 	var buf bytes.Buffer
 
-	for _, s := range ctxt.Syms.Allsym {
+	for _, s := range ctxt.loader.Syms {
+		if s == nil {
+			continue
+		}
 		if !s.Attr.CgoExport() {
 			continue
 		}

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

@@ -147,6 +147,16 @@ func (bm Bitmap) Has(i Sym) bool {
 func (bm Bitmap) Len() int {
 	return len(bm) * 32
 }
+
+// return the number of bits set.
+func (bm Bitmap) Count() int {
+	s := 0
+	for _, x := range bm {
+		s += bits.OnesCount32(x)
+	}
+	return s
+}
+
 func MakeBitmap(n int) Bitmap {
 	return make(Bitmap, (n+31)/32)
 }
@@ -625,6 +635,11 @@ func (l *Loader) NDef() int {
 	return int(l.extStart)
 }
 
+// Number of reachable symbols.
+func (l *Loader) NReachableSym() int {
+	return l.attrReachable.Count()
+}
+
 // Returns the raw (unpatched) name of the i-th symbol.
 func (l *Loader) RawSymName(i Sym) string {
 	if l.IsExternal(i) {
@@ -2195,7 +2210,6 @@ func (l *Loader) ExtractSymbols(syms *sym.Symbols) {
 		if s == nil {
 			continue
 		}
-		syms.Allsym = append(syms.Allsym, s) // XXX still add to Allsym for now, as there are code looping through Allsym
 		if s.Version < 0 {
 			s.Version = int16(anonVerReplacement)
 		}
@@ -2209,7 +2223,6 @@ func (l *Loader) ExtractSymbols(syms *sym.Symbols) {
 		}
 		s := l.allocSym(name, ver)
 		l.installSym(i, s)
-		syms.Allsym = append(syms.Allsym, s) // XXX see above
 		return s
 	}
 	syms.Lookup = l.SymLookup
@@ -2221,7 +2234,6 @@ func (l *Loader) ExtractSymbols(syms *sym.Symbols) {
 		i := l.newExtSym(name, ver)
 		s := l.allocSym(name, ver)
 		l.installSym(i, s)
-		syms.Allsym = append(syms.Allsym, s) // XXX see above
 		return s
 	}
 }

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

@@ -34,8 +34,6 @@ type Symbols struct {
 	// Symbol lookup based on name and indexed by version.
 	versions int
 
-	Allsym []*Symbol
-
 	// Provided by the loader
 
 	// Look up the symbol with the given name and version, creating the
@@ -55,7 +53,6 @@ type Symbols struct {
 func NewSymbols() *Symbols {
 	return &Symbols{
 		versions: SymVerStatic,
-		Allsym:   make([]*Symbol, 0, 100000),
 	}
 }