[dev.link] cmd/link/internal/objfile: relocate loader to new package

Third change of several to update the loader API to reflect the final
consensus version of the loader API as described in Cherry's doc.
This piece:

   - move objfile.Loader into its own separate package, and update
     clients accordingly.

This includes a few minor cleanups, including converting a couple
of loader-related functions to methods, and privatizing some of the
loader methods such as ToGlobal/ToLocal.

Change-Id: Iae20585751a45491d8b19dcffc096aadae6bbfc6
Reviewed-on: https://go-review.googlesource.com/c/go/+/200998
Run-TryBot: Than McIntosh <thanm@google.com>
Reviewed-by: Jeremy Faller <jeremy@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>

src/cmd/dist/buildtool.go

@@ -73,6 +73,7 @@ var bootstrapDirs = []string{
 	"cmd/link/internal/arm64",
 	"cmd/link/internal/ld",
 	"cmd/link/internal/loadelf",
+	"cmd/link/internal/loader",
 	"cmd/link/internal/loadmacho",
 	"cmd/link/internal/loadpe",
 	"cmd/link/internal/loadxcoff",

src/cmd/link/internal/ld/deadcode2.go

@@ -8,7 +8,7 @@ import (
 	"bytes"
 	"cmd/internal/objabi"
 	"cmd/internal/sys"
-	"cmd/link/internal/objfile"
+	"cmd/link/internal/loader"
 	"cmd/link/internal/sym"
 	"fmt"
 	"strings"
@@ -26,15 +26,15 @@ var _ = fmt.Print
 // - Debug output:
 //   Emit messages about which symbols are kept or deleted.
 
-type workQueue []objfile.Sym
+type workQueue []loader.Sym
 
-func (q *workQueue) push(i objfile.Sym) { *q = append(*q, i) }
+func (q *workQueue) push(i loader.Sym) { *q = append(*q, i) }
-func (q *workQueue) pop() objfile.Sym   { i := (*q)[len(*q)-1]; *q = (*q)[:len(*q)-1]; return i }
+func (q *workQueue) pop() loader.Sym   { i := (*q)[len(*q)-1]; *q = (*q)[:len(*q)-1]; return i }
 func (q *workQueue) empty() bool       { return len(*q) == 0 }
 
 type deadcodePass2 struct {
 	ctxt *Link
-	loader *objfile.Loader
+	ldr  *loader.Loader
 	wq   workQueue
 
 	ifaceMethod     map[methodsig]bool // methods declared in reached interfaces
@@ -43,7 +43,7 @@ type deadcodePass2 struct {
 }
 
 func (d *deadcodePass2) init() {
-	d.loader.InitReachable()
+	d.ldr.InitReachable()
 	d.ifaceMethod = make(map[methodsig]bool)
 
 	var names []string
@@ -67,15 +67,16 @@ func (d *deadcodePass2) init() {
 
 			// We don't keep the go.plugin.exports symbol,
 			// but we do keep the symbols it refers to.
-			exportsIdx := d.loader.Lookup("go.plugin.exports", 0)
+			exportsIdx := d.ldr.Lookup("go.plugin.exports", 0)
 			if exportsIdx != 0 {
-				relocs := d.loader.Relocs(exportsIdx)
+				relocs := d.ldr.Relocs(exportsIdx)
 				for i := 0; i < relocs.Count; i++ {
 					d.mark(relocs.At(i).Sym)
 				}
 			}
 		}
 	}
+
 	dynexpMap := d.ctxt.cgo_export_dynamic
 	if d.ctxt.LinkMode == LinkExternal {
 		dynexpMap = d.ctxt.cgo_export_static
@@ -86,9 +87,9 @@ func (d *deadcodePass2) init() {
 
 	for _, name := range names {
 		// Mark symbol as an data/ABI0 symbol.
-		d.mark(d.loader.Lookup(name, 0))
+		d.mark(d.ldr.Lookup(name, 0))
 		// Also mark any Go functions (internal ABI).
-		d.mark(d.loader.Lookup(name, sym.SymVerABIInternal))
+		d.mark(d.ldr.Lookup(name, sym.SymVerABIInternal))
 	}
 }
 
@@ -96,13 +97,13 @@ func (d *deadcodePass2) flood() {
 	for !d.wq.empty() {
 		symIdx := d.wq.pop()
 
-		d.reflectSeen = d.reflectSeen || d.loader.IsReflectMethod(symIdx)
+		d.reflectSeen = d.reflectSeen || d.ldr.IsReflectMethod(symIdx)
 
-		name := d.loader.RawSymName(symIdx)
+		name := d.ldr.RawSymName(symIdx)
 		if strings.HasPrefix(name, "type.") && name[5] != '.' { // TODO: use an attribute instead of checking name
-			p := d.loader.Data(symIdx)
+			p := d.ldr.Data(symIdx)
 			if len(p) != 0 && decodetypeKind(d.ctxt.Arch, p)&kindMask == kindInterface {
-				for _, sig := range decodeIfaceMethods2(d.loader, d.ctxt.Arch, symIdx) {
+				for _, sig := range decodeIfaceMethods2(d.ldr, d.ctxt.Arch, symIdx) {
 					if d.ctxt.Debugvlog > 1 {
 						d.ctxt.Logf("reached iface method: %s\n", sig)
 					}
@@ -112,7 +113,7 @@ func (d *deadcodePass2) flood() {
 		}
 
 		var methods []methodref2
-		relocs := d.loader.Relocs(symIdx)
+		relocs := d.ldr.Relocs(symIdx)
 		for i := 0; i < relocs.Count; i++ {
 			r := relocs.At(i)
 			if r.Type == objabi.R_WEAKADDROFF {
@@ -134,18 +135,18 @@ func (d *deadcodePass2) flood() {
 			}
 			d.mark(r.Sym)
 		}
-		naux := d.loader.NAux(symIdx)
+		naux := d.ldr.NAux(symIdx)
 		for i := 0; i < naux; i++ {
-			d.mark(d.loader.AuxSym(symIdx, i))
+			d.mark(d.ldr.AuxSym(symIdx, i))
 		}
 
 		if len(methods) != 0 {
 			// Decode runtime type information for type methods
 			// to help work out which methods can be called
 			// dynamically via interfaces.
-			methodsigs := decodetypeMethods2(d.loader, d.ctxt.Arch, symIdx)
+			methodsigs := decodetypeMethods2(d.ldr, d.ctxt.Arch, symIdx)
 			if len(methods) != len(methodsigs) {
-				panic(fmt.Sprintf("%q has %d method relocations for %d methods", d.loader.SymName(symIdx), len(methods), len(methodsigs)))
+				panic(fmt.Sprintf("%q has %d method relocations for %d methods", d.ldr.SymName(symIdx), len(methods), len(methodsigs)))
 			}
 			for i, m := range methodsigs {
 				methods[i].m = m
@@ -155,29 +156,28 @@ func (d *deadcodePass2) flood() {
 	}
 }
 
-func (d *deadcodePass2) mark(symIdx objfile.Sym) {
+func (d *deadcodePass2) mark(symIdx loader.Sym) {
-	if symIdx != 0 && !d.loader.Reachable.Has(symIdx) {
+	if symIdx != 0 && !d.ldr.Reachable.Has(symIdx) {
 		d.wq.push(symIdx)
-		d.loader.Reachable.Set(symIdx)
+		d.ldr.Reachable.Set(symIdx)
 	}
 }
 
 func (d *deadcodePass2) markMethod(m methodref2) {
-	relocs := d.loader.Relocs(m.src)
+	relocs := d.ldr.Relocs(m.src)
 	d.mark(relocs.At(m.r).Sym)
 	d.mark(relocs.At(m.r + 1).Sym)
 	d.mark(relocs.At(m.r + 2).Sym)
 }
 
 func deadcode2(ctxt *Link) {
-	loader := ctxt.loader
+	ldr := ctxt.loader
-	d := deadcodePass2{ctxt: ctxt, loader: loader}
+	d := deadcodePass2{ctxt: ctxt, ldr: ldr}
 	d.init()
 	d.flood()
 
-	callSym := loader.Lookup("reflect.Value.Call", sym.SymVerABIInternal)
+	callSym := ldr.Lookup("reflect.Value.Call", sym.SymVerABIInternal)
-	methSym := loader.Lookup("reflect.Value.Method", sym.SymVerABIInternal)
+	methSym := ldr.Lookup("reflect.Value.Method", sym.SymVerABIInternal)
-
 	if ctxt.DynlinkingGo() {
 		// Exported methods may satisfy interfaces we don't know
 		// about yet when dynamically linking.
@@ -188,7 +188,7 @@ func deadcode2(ctxt *Link) {
 		// Methods might be called via reflection. Give up on
 		// static analysis, mark all exported methods of
 		// all reachable types as reachable.
-		d.reflectSeen = d.reflectSeen || (callSym != 0 && loader.Reachable.Has(callSym)) || (methSym != 0 && loader.Reachable.Has(methSym))
+		d.reflectSeen = d.reflectSeen || (callSym != 0 && ldr.Reachable.Has(callSym)) || (methSym != 0 && ldr.Reachable.Has(methSym))
 
 		// Mark all methods that could satisfy a discovered
 		// interface as reachable. We recheck old marked interfaces
@@ -211,16 +211,17 @@ func deadcode2(ctxt *Link) {
 		d.flood()
 	}
 
-	n := loader.NSym()
+	n := ldr.NSym()
+
 	if ctxt.BuildMode != BuildModeShared {
 		// Keep a itablink if the symbol it points at is being kept.
 		// (When BuildModeShared, always keep itablinks.)
 		for i := 1; i < n; i++ {
-			s := objfile.Sym(i)
+			s := loader.Sym(i)
-			if strings.HasPrefix(loader.RawSymName(s), "go.itablink.") { // TODO: use an attribute instread of checking name
+			if strings.HasPrefix(ldr.RawSymName(s), "go.itablink.") { // TODO: use an attribute instread of checking name
-				relocs := loader.Relocs(s)
+				relocs := ldr.Relocs(s)
-				if relocs.Count > 0 && loader.Reachable.Has(relocs.At(0).Sym) {
+				if relocs.Count > 0 && ldr.Reachable.Has(relocs.At(0).Sym) {
-					loader.Reachable.Set(s)
+					ldr.Reachable.Set(s)
 				}
 			}
 		}
@@ -232,7 +233,7 @@ func deadcode2(ctxt *Link) {
 // the reflect.method struct: mtyp, ifn, and tfn.
 type methodref2 struct {
 	m   methodsig
-	src objfile.Sym // receiver type symbol
+	src loader.Sym // receiver type symbol
 	r   int        // the index of R_METHODOFF relocations
 }
 
@@ -249,13 +250,13 @@ func (m methodref2) isExported() bool {
 // the function type.
 //
 // Conveniently this is the layout of both runtime.method and runtime.imethod.
-func decodeMethodSig2(loader *objfile.Loader, arch *sys.Arch, symIdx objfile.Sym, off, size, count int) []methodsig {
+func decodeMethodSig2(ldr *loader.Loader, arch *sys.Arch, symIdx loader.Sym, off, size, count int) []methodsig {
 	var buf bytes.Buffer
 	var methods []methodsig
 	for i := 0; i < count; i++ {
-		buf.WriteString(decodetypeName2(loader, symIdx, off))
+		buf.WriteString(decodetypeName2(ldr, symIdx, off))
-		mtypSym := decodeRelocSym2(loader, symIdx, int32(off+4))
+		mtypSym := decodeRelocSym2(ldr, symIdx, int32(off+4))
-		mp := loader.Data(mtypSym)
+		mp := ldr.Data(mtypSym)
 
 		buf.WriteRune('(')
 		inCount := decodetypeFuncInCount(arch, mp)
@@ -263,8 +264,8 @@ func decodeMethodSig2(loader *objfile.Loader, arch *sys.Arch, symIdx objfile.Sym
 			if i > 0 {
 				buf.WriteString(", ")
 			}
-			a := decodetypeFuncInType2(loader, arch, mtypSym, i)
+			a := decodetypeFuncInType2(ldr, arch, mtypSym, i)
-			buf.WriteString(loader.SymName(a))
+			buf.WriteString(ldr.SymName(a))
 		}
 		buf.WriteString(") (")
 		outCount := decodetypeFuncOutCount(arch, mp)
@@ -272,8 +273,8 @@ func decodeMethodSig2(loader *objfile.Loader, arch *sys.Arch, symIdx objfile.Sym
 			if i > 0 {
 				buf.WriteString(", ")
 			}
-			a := decodetypeFuncOutType2(loader, arch, mtypSym, i)
+			a := decodetypeFuncOutType2(ldr, arch, mtypSym, i)
-			buf.WriteString(loader.SymName(a))
+			buf.WriteString(ldr.SymName(a))
 		}
 		buf.WriteRune(')')
 
@@ -284,28 +285,28 @@ func decodeMethodSig2(loader *objfile.Loader, arch *sys.Arch, symIdx objfile.Sym
 	return methods
 }
 
-func decodeIfaceMethods2(loader *objfile.Loader, arch *sys.Arch, symIdx objfile.Sym) []methodsig {
+func decodeIfaceMethods2(ldr *loader.Loader, arch *sys.Arch, symIdx loader.Sym) []methodsig {
-	p := loader.Data(symIdx)
+	p := ldr.Data(symIdx)
 	if decodetypeKind(arch, p)&kindMask != kindInterface {
-		panic(fmt.Sprintf("symbol %q is not an interface", loader.SymName(symIdx)))
+		panic(fmt.Sprintf("symbol %q is not an interface", ldr.SymName(symIdx)))
 	}
-	rel := decodeReloc2(loader, symIdx, int32(commonsize(arch)+arch.PtrSize))
+	rel := decodeReloc2(ldr, symIdx, int32(commonsize(arch)+arch.PtrSize))
 	if rel.Sym == 0 {
 		return nil
 	}
 	if rel.Sym != symIdx {
-		panic(fmt.Sprintf("imethod slice pointer in %q leads to a different symbol", loader.SymName(symIdx)))
+		panic(fmt.Sprintf("imethod slice pointer in %q leads to a different symbol", ldr.SymName(symIdx)))
 	}
 	off := int(rel.Add) // array of reflect.imethod values
 	numMethods := int(decodetypeIfaceMethodCount(arch, p))
 	sizeofIMethod := 4 + 4
-	return decodeMethodSig2(loader, arch, symIdx, off, sizeofIMethod, numMethods)
+	return decodeMethodSig2(ldr, arch, symIdx, off, sizeofIMethod, numMethods)
 }
 
-func decodetypeMethods2(loader *objfile.Loader, arch *sys.Arch, symIdx objfile.Sym) []methodsig {
+func decodetypeMethods2(ldr *loader.Loader, arch *sys.Arch, symIdx loader.Sym) []methodsig {
-	p := loader.Data(symIdx)
+	p := ldr.Data(symIdx)
 	if !decodetypeHasUncommon(arch, p) {
-		panic(fmt.Sprintf("no methods on %q", loader.SymName(symIdx)))
+		panic(fmt.Sprintf("no methods on %q", ldr.SymName(symIdx)))
 	}
 	off := commonsize(arch) // reflect.rtype
 	switch decodetypeKind(arch, p) & kindMask {
@@ -333,47 +334,47 @@ func decodetypeMethods2(loader *objfile.Loader, arch *sys.Arch, symIdx objfile.S
 	moff := int(decodeInuxi(arch, p[off+4+2+2:], 4))
 	off += moff                // offset to array of reflect.method values
 	const sizeofMethod = 4 * 4 // sizeof reflect.method in program
-	return decodeMethodSig2(loader, arch, symIdx, off, sizeofMethod, mcount)
+	return decodeMethodSig2(ldr, arch, symIdx, off, sizeofMethod, mcount)
 }
 
-func decodeReloc2(loader *objfile.Loader, symIdx objfile.Sym, off int32) objfile.Reloc {
+func decodeReloc2(ldr *loader.Loader, symIdx loader.Sym, off int32) loader.Reloc {
-	relocs := loader.Relocs(symIdx)
+	relocs := ldr.Relocs(symIdx)
 	for j := 0; j < relocs.Count; j++ {
 		rel := relocs.At(j)
 		if rel.Off == off {
 			return rel
 		}
 	}
-	return objfile.Reloc{}
+	return loader.Reloc{}
 }
 
-func decodeRelocSym2(loader *objfile.Loader, symIdx objfile.Sym, off int32) objfile.Sym {
+func decodeRelocSym2(ldr *loader.Loader, symIdx loader.Sym, off int32) loader.Sym {
-	return decodeReloc2(loader, symIdx, off).Sym
+	return decodeReloc2(ldr, symIdx, off).Sym
 }
 
 // decodetypeName2 decodes the name from a reflect.name.
-func decodetypeName2(loader *objfile.Loader, symIdx objfile.Sym, off int) string {
+func decodetypeName2(ldr *loader.Loader, symIdx loader.Sym, off int) string {
-	r := decodeRelocSym2(loader, symIdx, int32(off))
+	r := decodeRelocSym2(ldr, symIdx, int32(off))
 	if r == 0 {
 		return ""
 	}
 
-	data := loader.Data(r)
+	data := ldr.Data(r)
 	namelen := int(uint16(data[1])<<8 | uint16(data[2]))
 	return string(data[3 : 3+namelen])
 }
 
-func decodetypeFuncInType2(loader *objfile.Loader, arch *sys.Arch, symIdx objfile.Sym, i int) objfile.Sym {
+func decodetypeFuncInType2(ldr *loader.Loader, arch *sys.Arch, symIdx loader.Sym, i int) loader.Sym {
 	uadd := commonsize(arch) + 4
 	if arch.PtrSize == 8 {
 		uadd += 4
 	}
-	if decodetypeHasUncommon(arch, loader.Data(symIdx)) {
+	if decodetypeHasUncommon(arch, ldr.Data(symIdx)) {
 		uadd += uncommonSize()
 	}
-	return decodeRelocSym2(loader, symIdx, int32(uadd+i*arch.PtrSize))
+	return decodeRelocSym2(ldr, symIdx, int32(uadd+i*arch.PtrSize))
 }
 
-func decodetypeFuncOutType2(loader *objfile.Loader, arch *sys.Arch, symIdx objfile.Sym, i int) objfile.Sym {
+func decodetypeFuncOutType2(ldr *loader.Loader, arch *sys.Arch, symIdx loader.Sym, i int) loader.Sym {
-	return decodetypeFuncInType2(loader, arch, symIdx, i+decodetypeFuncInCount(arch, loader.Data(symIdx)))
+	return decodetypeFuncInType2(ldr, arch, symIdx, i+decodetypeFuncInCount(arch, ldr.Data(symIdx)))
 }

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

@@ -38,6 +38,7 @@ import (
 	"cmd/internal/objabi"
 	"cmd/internal/sys"
 	"cmd/link/internal/loadelf"
+	"cmd/link/internal/loader"
 	"cmd/link/internal/loadmacho"
 	"cmd/link/internal/loadpe"
 	"cmd/link/internal/loadxcoff"
@@ -376,7 +377,7 @@ func (ctxt *Link) findLibPath(libname string) string {
 
 func (ctxt *Link) loadlib() {
 	if *flagNewobj {
-		ctxt.loader = objfile.NewLoader()
+		ctxt.loader = loader.NewLoader()
 	}
 
 	ctxt.cgo_export_static = make(map[string]bool)
@@ -434,7 +435,7 @@ func (ctxt *Link) loadlib() {
 
 	if *flagNewobj {
 		// Add references of externally defined symbols.
-		objfile.LoadRefs(ctxt.loader, ctxt.Arch, ctxt.Syms)
+		ctxt.loader.LoadRefs(ctxt.Arch, ctxt.Syms)
 	}
 
 	// Now that we know the link mode, set the dynexp list.
@@ -1772,7 +1773,7 @@ func ldobj(ctxt *Link, f *bio.Reader, lib *sym.Library, length int64, pn string,
 	}
 	var c int
 	if *flagNewobj {
-		objfile.LoadNew(ctxt.loader, ctxt.Arch, ctxt.Syms, f, lib, unit, eof-f.Offset(), pn, flags)
+		ctxt.loader.Preload(ctxt.Arch, ctxt.Syms, f, lib, unit, eof-f.Offset(), pn, flags)
 	} else {
 		c = objfile.Load(ctxt.Arch, ctxt.Syms, f, lib, unit, eof-f.Offset(), pn, flags)
 	}
@@ -2550,7 +2551,7 @@ func dfs(lib *sym.Library, mark map[*sym.Library]markKind, order *[]*sym.Library
 
 func (ctxt *Link) loadlibfull() {
 	// Load full symbol contents, resolve indexed references.
-	objfile.LoadFull(ctxt.loader, ctxt.Arch, ctxt.Syms)
+	ctxt.loader.LoadFull(ctxt.Arch, ctxt.Syms)
 
 	// For now, add all symbols to ctxt.Syms.
 	for _, s := range ctxt.loader.Syms {

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

@@ -35,7 +35,7 @@ import (
 	"cmd/internal/obj"
 	"cmd/internal/objabi"
 	"cmd/internal/sys"
-	"cmd/link/internal/objfile"
+	"cmd/link/internal/loader"
 	"cmd/link/internal/sym"
 	"debug/elf"
 	"fmt"
@@ -98,7 +98,7 @@ type Link struct {
 
 	relocbuf []byte // temporary buffer for applying relocations
 
-	loader  *objfile.Loader
+	loader  *loader.Loader
 	cgodata []cgodata // cgo directives to load, three strings are args for loadcgo
 
 	cgo_export_static  map[string]bool

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

@@ -2,7 +2,7 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
-package objfile
+package loader
 
 import (
 	"bytes"
@@ -87,8 +87,6 @@ func makeBitmap(n int) bitmap {
 }
 
 // A Loader loads new object files and resolves indexed symbol references.
-//
-// TODO: describe local-global index mapping.
 type Loader struct {
 	start    map[*oReader]Sym // map from object file to its start index
 	objs     []objIdx         // sorted by start index (i.e. objIdx.i)
@@ -117,12 +115,12 @@ func NewLoader() *Loader {
 }
 
 // Return the start index in the global index space for a given object file.
-func (l *Loader) StartIndex(r *oReader) Sym {
+func (l *Loader) startIndex(r *oReader) Sym {
 	return l.start[r]
 }
 
 // Add object file r, return the start index.
-func (l *Loader) AddObj(pkg string, r *oReader) Sym {
+func (l *Loader) addObj(pkg string, r *oReader) Sym {
 	if _, ok := l.start[r]; ok {
 		panic("already added")
 	}
@@ -148,10 +146,10 @@ func (l *Loader) AddSym(name string, ver int, i Sym, r *oReader, dupok bool, typ
 		if dupok {
 			return false
 		}
-		overwrite := r.DataSize(int(i-l.StartIndex(r))) != 0
+		overwrite := r.DataSize(int(i-l.startIndex(r))) != 0
 		if overwrite {
 			// new symbol overwrites old symbol.
-			oldr, li := l.ToLocal(oldi)
+			oldr, li := l.toLocal(oldi)
 			oldsym := goobj2.Sym{}
 			oldsym.Read(oldr.Reader, oldr.SymOff(li))
 			oldtyp := sym.AbiSymKindToSymKind[objabi.SymKind(oldsym.Type)]
@@ -190,8 +188,8 @@ func (l *Loader) AddExtSym(name string, ver int) Sym {
 }
 
 // Convert a local index to a global index.
-func (l *Loader) ToGlobal(r *oReader, i int) Sym {
+func (l *Loader) toGlobal(r *oReader, i int) Sym {
-	g := l.StartIndex(r) + Sym(i)
+	g := l.startIndex(r) + Sym(i)
 	if ov, ok := l.overwrite[g]; ok {
 		return ov
 	}
@@ -199,7 +197,7 @@ func (l *Loader) ToGlobal(r *oReader, i int) Sym {
 }
 
 // Convert a global index to a local index.
-func (l *Loader) ToLocal(i Sym) (*oReader, int) {
+func (l *Loader) toLocal(i Sym) (*oReader, int) {
 	if ov, ok := l.overwrite[i]; ok {
 		i = ov
 	}
@@ -216,7 +214,7 @@ func (l *Loader) ToLocal(i Sym) (*oReader, int) {
 }
 
 // Resolve a local symbol reference. Return global index.
-func (l *Loader) Resolve(r *oReader, s goobj2.SymRef) Sym {
+func (l *Loader) resolve(r *oReader, s goobj2.SymRef) Sym {
 	var rr *oReader
 	switch p := s.PkgIdx; p {
 	case goobj2.PkgIdxInvalid:
@@ -245,7 +243,7 @@ func (l *Loader) Resolve(r *oReader, s goobj2.SymRef) Sym {
 			log.Fatalf("reference of nonexisted package %s, from %v", pkg, r.unit.Lib)
 		}
 	}
-	return l.ToGlobal(rr, int(s.SymIdx))
+	return l.toGlobal(rr, int(s.SymIdx))
 }
 
 // Look up a symbol by name, return global index, or 0 if not found.
@@ -266,7 +264,7 @@ func (l *Loader) RawSymName(i Sym) string {
 	if l.extStart != 0 && i >= l.extStart {
 		return ""
 	}
-	r, li := l.ToLocal(i)
+	r, li := l.toLocal(i)
 	osym := goobj2.Sym{}
 	osym.Read(r.Reader, r.SymOff(li))
 	return osym.Name
@@ -277,7 +275,7 @@ func (l *Loader) SymName(i Sym) string {
 	if l.extStart != 0 && i >= l.extStart {
 		return ""
 	}
-	r, li := l.ToLocal(i)
+	r, li := l.toLocal(i)
 	osym := goobj2.Sym{}
 	osym.Read(r.Reader, r.SymOff(li))
 	return strings.Replace(osym.Name, "\"\".", r.pkgprefix, -1)
@@ -288,7 +286,7 @@ func (l *Loader) SymType(i Sym) sym.SymKind {
 	if l.extStart != 0 && i >= l.extStart {
 		return 0
 	}
-	r, li := l.ToLocal(i)
+	r, li := l.toLocal(i)
 	osym := goobj2.Sym{}
 	osym.Read(r.Reader, r.SymOff(li))
 	return sym.AbiSymKindToSymKind[objabi.SymKind(osym.Type)]
@@ -299,7 +297,7 @@ func (l *Loader) SymAttr(i Sym) uint8 {
 	if l.extStart != 0 && i >= l.extStart {
 		return 0
 	}
-	r, li := l.ToLocal(i)
+	r, li := l.toLocal(i)
 	osym := goobj2.Sym{}
 	osym.Read(r.Reader, r.SymOff(li))
 	return osym.Flag
@@ -315,7 +313,7 @@ func (l *Loader) Data(i Sym) []byte {
 	if l.extStart != 0 && i >= l.extStart {
 		return nil
 	}
-	r, li := l.ToLocal(i)
+	r, li := l.toLocal(i)
 	return r.Data(li)
 }
 
@@ -324,7 +322,7 @@ func (l *Loader) NAux(i Sym) int {
 	if l.extStart != 0 && i >= l.extStart {
 		return 0
 	}
-	r, li := l.ToLocal(i)
+	r, li := l.toLocal(i)
 	return r.NAux(li)
 }
 
@@ -334,10 +332,10 @@ func (l *Loader) AuxSym(i Sym, j int) Sym {
 	if l.extStart != 0 && i >= l.extStart {
 		return 0
 	}
-	r, li := l.ToLocal(i)
+	r, li := l.toLocal(i)
 	a := goobj2.Aux{}
 	a.Read(r.Reader, r.AuxOff(li, j))
-	return l.Resolve(r, a.Sym)
+	return l.resolve(r, a.Sym)
 }
 
 // Initialize Reachable bitmap for running deadcode pass.
@@ -349,7 +347,7 @@ func (l *Loader) InitReachable() {
 func (relocs *Relocs) At(j int) Reloc {
 	rel := goobj2.Reloc{}
 	rel.Read(relocs.r.Reader, relocs.r.RelocOff(relocs.li, j))
-	target := relocs.l.Resolve(relocs.r, rel.Sym)
+	target := relocs.l.resolve(relocs.r, rel.Sym)
 	return Reloc{
 		Off:  rel.Off,
 		Size: rel.Siz,
@@ -364,7 +362,7 @@ func (l *Loader) Relocs(i Sym) Relocs {
 	if l.extStart != 0 && i >= l.extStart {
 		return Relocs{}
 	}
-	r, li := l.ToLocal(i)
+	r, li := l.toLocal(i)
 	return l.relocs(r, li)
 }
 
@@ -380,7 +378,7 @@ func (l *Loader) relocs(r *oReader, li int) Relocs {
 
 // Preload a package: add autolibs, add symbols to the symbol table.
 // Does not read symbol data yet.
-func LoadNew(l *Loader, arch *sys.Arch, syms *sym.Symbols, f *bio.Reader, lib *sym.Library, unit *sym.CompilationUnit, length int64, pn string, flags int) {
+func (l *Loader) Preload(arch *sys.Arch, syms *sym.Symbols, f *bio.Reader, lib *sym.Library, unit *sym.CompilationUnit, length int64, pn string, flags int) {
 	roObject, readonly, err := f.Slice(uint64(length))
 	if err != nil {
 		log.Fatal("cannot read object file:", err)
@@ -403,7 +401,7 @@ func LoadNew(l *Loader, arch *sys.Arch, syms *sym.Symbols, f *bio.Reader, lib *s
 		unit.DWARFFileTable[i] = r.DwarfFile(i)
 	}
 
-	istart := l.AddObj(lib.Pkg, or)
+	istart := l.addObj(lib.Pkg, or)
 
 	ndef := r.NSym()
 	nnonpkgdef := r.NNonpkgdef()
@@ -425,7 +423,7 @@ func LoadNew(l *Loader, arch *sys.Arch, syms *sym.Symbols, f *bio.Reader, lib *s
 
 // Make sure referenced symbols are added. Most of them should already be added.
 // This should only be needed for referenced external symbols.
-func LoadRefs(l *Loader, arch *sys.Arch, syms *sym.Symbols) {
+func (l *Loader) LoadRefs(arch *sys.Arch, syms *sym.Symbols) {
 	for _, o := range l.objs[1:] {
 		loadObjRefs(l, o.r, arch, syms)
 	}
@@ -479,7 +477,7 @@ func preprocess(arch *sys.Arch, s *sym.Symbol) {
 }
 
 // Load full contents.
-func LoadFull(l *Loader, arch *sys.Arch, syms *sym.Symbols) {
+func (l *Loader) LoadFull(arch *sys.Arch, syms *sym.Symbols) {
 	// create all Symbols first.
 	l.Syms = make([]*sym.Symbol, l.NSym())
 	for _, o := range l.objs[1:] {
@@ -505,7 +503,7 @@ func LoadFull(l *Loader, arch *sys.Arch, syms *sym.Symbols) {
 
 func loadObjSyms(l *Loader, syms *sym.Symbols, r *oReader) {
 	lib := r.unit.Lib
-	istart := l.StartIndex(r)
+	istart := l.startIndex(r)
 
 	for i, n := 0, r.NSym()+r.NNonpkgdef(); i < n; i++ {
 		osym := goobj2.Sym{}
@@ -550,10 +548,10 @@ func loadObjSyms(l *Loader, syms *sym.Symbols, r *oReader) {
 
 func loadObjFull(l *Loader, r *oReader) {
 	lib := r.unit.Lib
-	istart := l.StartIndex(r)
+	istart := l.startIndex(r)
 
 	resolveSymRef := func(s goobj2.SymRef) *sym.Symbol {
-		i := l.Resolve(r, s)
+		i := l.resolve(r, s)
 		return l.Syms[i]
 	}
 
@@ -735,7 +733,7 @@ func loadObjFull(l *Loader, r *oReader) {
 				Parent:   inl.Parent,
 				File:     resolveSymRef(inl.File),
 				Line:     inl.Line,
-				Func:     l.SymName(l.Resolve(r, inl.Func)),
+				Func:     l.SymName(l.resolve(r, inl.Func)),
 				ParentPC: inl.ParentPC,
 			}
 		}
@@ -754,6 +752,8 @@ func loadObjFull(l *Loader, r *oReader) {
 	}
 }
 
+var emptyPkg = []byte(`"".`)
+
 func patchDWARFName(s *sym.Symbol, r *oReader) {
 	// This is kind of ugly. Really the package name should not
 	// even be included here.

src/cmd/link/internal/loadmacho/ldmacho.go

@@ -10,7 +10,7 @@ import (
 	"cmd/internal/bio"
 	"cmd/internal/objabi"
 	"cmd/internal/sys"
-	"cmd/link/internal/objfile"
+	"cmd/link/internal/loader"
 	"cmd/link/internal/sym"
 	"encoding/binary"
 	"fmt"
@@ -424,7 +424,7 @@ func macholoadsym(m *ldMachoObj, symtab *ldMachoSymtab) int {
 	return 0
 }
 
-func Load(l *objfile.Loader, arch *sys.Arch, syms *sym.Symbols, f *bio.Reader, pkg string, length int64, pn string) error {
+func Load(l *loader.Loader, arch *sys.Arch, syms *sym.Symbols, f *bio.Reader, pkg string, length int64, pn string) error {
 	lookup := func(name string, version int) *sym.Symbol {
 		// Check to see if we've already defined the symbol.
 		if i := l.Lookup(name, version); i != 0 {