[dev.link] cmd/link, cmd/compile: create content addressable pcdata syms

Switch pcdata over to content addressable symbols. This is the last
step before removing these from pclntab_old.

No meaningful benchmarks changes come from this work.

Change-Id: I3f74f3d6026a278babe437c8010e22992c92bd89
Reviewed-on: https://go-review.googlesource.com/c/go/+/247399
Reviewed-by: Austin Clements <austin@google.com>
Reviewed-by: Than McIntosh <thanm@google.com>

src/cmd/internal/goobj/funcinfo.go

@@ -23,12 +23,11 @@ type FuncInfo struct {
 	Locals uint32
 	FuncID objabi.FuncID
 
-	Pcsp        uint32
+	Pcsp        SymRef
-	Pcfile      uint32
+	Pcfile      SymRef
-	Pcline      uint32
+	Pcline      SymRef
-	Pcinline    uint32
+	Pcinline    SymRef
-	Pcdata      []uint32
+	Pcdata      []SymRef
-	PcdataEnd   uint32
 	Funcdataoff []uint32
 	File        []CUFileIndex
 
@@ -41,20 +40,24 @@ func (a *FuncInfo) Write(w *bytes.Buffer) {
 		binary.LittleEndian.PutUint32(b[:], x)
 		w.Write(b[:])
 	}
+	writeSymRef := func(s SymRef) {
+		writeUint32(s.PkgIdx)
+		writeUint32(s.SymIdx)
+	}
 
 	writeUint32(a.Args)
 	writeUint32(a.Locals)
 	writeUint32(uint32(a.FuncID))
 
-	writeUint32(a.Pcsp)
+	writeSymRef(a.Pcsp)
-	writeUint32(a.Pcfile)
+	writeSymRef(a.Pcfile)
-	writeUint32(a.Pcline)
+	writeSymRef(a.Pcline)
-	writeUint32(a.Pcinline)
+	writeSymRef(a.Pcinline)
 	writeUint32(uint32(len(a.Pcdata)))
-	for _, x := range a.Pcdata {
+	for _, sym := range a.Pcdata {
-		writeUint32(x)
+		writeSymRef(sym)
 	}
-	writeUint32(a.PcdataEnd)
+
 	writeUint32(uint32(len(a.Funcdataoff)))
 	for _, x := range a.Funcdataoff {
 		writeUint32(x)
@@ -75,21 +78,23 @@ func (a *FuncInfo) Read(b []byte) {
 		b = b[4:]
 		return x
 	}
+	readSymIdx := func() SymRef {
+		return SymRef{readUint32(), readUint32()}
+	}
 
 	a.Args = readUint32()
 	a.Locals = readUint32()
 	a.FuncID = objabi.FuncID(readUint32())
 
-	a.Pcsp = readUint32()
+	a.Pcsp = readSymIdx()
-	a.Pcfile = readUint32()
+	a.Pcfile = readSymIdx()
-	a.Pcline = readUint32()
+	a.Pcline = readSymIdx()
-	a.Pcinline = readUint32()
+	a.Pcinline = readSymIdx()
-	pcdatalen := readUint32()
+	a.Pcdata = make([]SymRef, readUint32())
-	a.Pcdata = make([]uint32, pcdatalen)
 	for i := range a.Pcdata {
-		a.Pcdata[i] = readUint32()
+		a.Pcdata[i] = readSymIdx()
 	}
-	a.PcdataEnd = readUint32()
+
 	funcdataofflen := readUint32()
 	a.Funcdataoff = make([]uint32, funcdataofflen)
 	for i := range a.Funcdataoff {
@@ -127,11 +132,13 @@ type FuncInfoLengths struct {
 func (*FuncInfo) ReadFuncInfoLengths(b []byte) FuncInfoLengths {
 	var result FuncInfoLengths
 
-	const numpcdataOff = 28
+	// Offset to the number of pcdata values. This value is determined by counting
+	// the number of bytes until we write pcdata to the file.
+	const numpcdataOff = 44
 	result.NumPcdata = binary.LittleEndian.Uint32(b[numpcdataOff:])
 	result.PcdataOff = numpcdataOff + 4
 
-	numfuncdataoffOff := result.PcdataOff + 4*(result.NumPcdata+1)
+	numfuncdataoffOff := result.PcdataOff + 8*result.NumPcdata
 	result.NumFuncdataoff = binary.LittleEndian.Uint32(b[numfuncdataoffOff:])
 	result.FuncdataoffOff = numfuncdataoffOff + 4
 
@@ -154,29 +161,28 @@ func (*FuncInfo) ReadLocals(b []byte) uint32 { return binary.LittleEndian.Uint32
 
 func (*FuncInfo) ReadFuncID(b []byte) uint32 { return binary.LittleEndian.Uint32(b[8:]) }
 
-// return start and end offsets.
+func (*FuncInfo) ReadPcsp(b []byte) SymRef {
-func (*FuncInfo) ReadPcsp(b []byte) (uint32, uint32) {
+	return SymRef{binary.LittleEndian.Uint32(b[12:]), binary.LittleEndian.Uint32(b[16:])}
-	return binary.LittleEndian.Uint32(b[12:]), binary.LittleEndian.Uint32(b[16:])
 }
 
-// return start and end offsets.
+func (*FuncInfo) ReadPcfile(b []byte) SymRef {
-func (*FuncInfo) ReadPcfile(b []byte) (uint32, uint32) {
+	return SymRef{binary.LittleEndian.Uint32(b[20:]), binary.LittleEndian.Uint32(b[24:])}
-	return binary.LittleEndian.Uint32(b[16:]), binary.LittleEndian.Uint32(b[20:])
 }
 
-// return start and end offsets.
+func (*FuncInfo) ReadPcline(b []byte) SymRef {
-func (*FuncInfo) ReadPcline(b []byte) (uint32, uint32) {
+	return SymRef{binary.LittleEndian.Uint32(b[28:]), binary.LittleEndian.Uint32(b[32:])}
-	return binary.LittleEndian.Uint32(b[20:]), binary.LittleEndian.Uint32(b[24:])
 }
 
-// return start and end offsets.
+func (*FuncInfo) ReadPcinline(b []byte) SymRef {
-func (*FuncInfo) ReadPcinline(b []byte, pcdataoffset uint32) (uint32, uint32) {
+	return SymRef{binary.LittleEndian.Uint32(b[36:]), binary.LittleEndian.Uint32(b[40:])}
-	return binary.LittleEndian.Uint32(b[24:]), binary.LittleEndian.Uint32(b[pcdataoffset:])
 }
 
-// return start and end offsets.
+func (*FuncInfo) ReadPcdata(b []byte) []SymRef {
-func (*FuncInfo) ReadPcdata(b []byte, pcdataoffset uint32, k uint32) (uint32, uint32) {
+	syms := make([]SymRef, binary.LittleEndian.Uint32(b[44:]))
-	return binary.LittleEndian.Uint32(b[pcdataoffset+4*k:]), binary.LittleEndian.Uint32(b[pcdataoffset+4+4*k:])
+	for i := range syms {
+		syms[i] = SymRef{binary.LittleEndian.Uint32(b[48+i*8:]), binary.LittleEndian.Uint32(b[52+i*8:])}
+	}
+	return syms
 }
 
 func (*FuncInfo) ReadFuncdataoff(b []byte, funcdataofffoff uint32, k uint32) int64 {

src/cmd/internal/goobj/objfile.go

@@ -421,8 +421,11 @@ const (
 	AuxDwarfLoc
 	AuxDwarfRanges
 	AuxDwarfLines
-
+	AuxPcsp
-	// TODO: more. Pcdata?
+	AuxPcfile
+	AuxPcline
+	AuxPcinline
+	AuxPcdata
 )
 
 func (a *Aux) Type() uint8 { return a[0] }
@@ -827,11 +830,6 @@ func (r *Reader) Data(i uint32) []byte {
 	return r.BytesAt(base+off, int(end-off))
 }
 
-// AuxDataBase returns the base offset of the aux data block.
-func (r *Reader) PcdataBase() uint32 {
-	return r.h.Offsets[BlkPcdata]
-}
-
 // NRefName returns the number of referenced symbol names.
 func (r *Reader) NRefName() int {
 	return int(r.h.Offsets[BlkRefName+1]-r.h.Offsets[BlkRefName]) / RefNameSize

src/cmd/internal/obj/link.go

@@ -624,11 +624,12 @@ func (s *LSym) CanBeAnSSASym() {
 }
 
 type Pcln struct {
-	Pcsp        Pcdata
+	// Aux symbols for pcln
-	Pcfile      Pcdata
+	Pcsp        *LSym
-	Pcline      Pcdata
+	Pcfile      *LSym
-	Pcinline    Pcdata
+	Pcline      *LSym
-	Pcdata      []Pcdata
+	Pcinline    *LSym
+	Pcdata      []*LSym
 	Funcdata    []*LSym
 	Funcdataoff []int64
 	UsedFiles   map[goobj.CUFileIndex]struct{} // file indices used while generating pcfile
@@ -650,10 +651,6 @@ type Auto struct {
 	Gotype  *LSym
 }
 
-type Pcdata struct {
-	P []byte
-}
-
 // Link holds the context for writing object code from a compiler
 // to be linker input or for reading that input into the linker.
 type Link struct {

src/cmd/internal/obj/objfile.go

@@ -185,7 +185,11 @@ func WriteObjFile(ctxt *Link, b *bio.Writer) {
 	// Pcdata
 	h.Offsets[goobj.BlkPcdata] = w.Offset()
 	for _, s := range ctxt.Text { // iteration order must match genFuncInfoSyms
-		if s.Func != nil {
+		// Because of the phase order, it's possible that we try to write an invalid
+		// object file, and the Pcln variables haven't been filled in. As such, we
+		// need to check that Pcsp exists, and assume the other pcln variables exist
+		// as well. Tests like test/fixedbugs/issue22200.go demonstrate this issue.
+		if s.Func != nil && s.Func.Pcln.Pcsp != nil {
 			pc := &s.Func.Pcln
 			w.Bytes(pc.Pcsp.P)
 			w.Bytes(pc.Pcfile.P)
@@ -478,6 +482,22 @@ func (w *writer) Aux(s *LSym) {
 		if s.Func.dwarfDebugLinesSym != nil && s.Func.dwarfDebugLinesSym.Size != 0 {
 			w.aux1(goobj.AuxDwarfLines, s.Func.dwarfDebugLinesSym)
 		}
+		if s.Func.Pcln.Pcsp != nil && s.Func.Pcln.Pcsp.Size != 0 {
+			w.aux1(goobj.AuxPcsp, s.Func.Pcln.Pcsp)
+		}
+		if s.Func.Pcln.Pcfile != nil && s.Func.Pcln.Pcfile.Size != 0 {
+			w.aux1(goobj.AuxPcfile, s.Func.Pcln.Pcfile)
+		}
+		if s.Func.Pcln.Pcline != nil && s.Func.Pcln.Pcline.Size != 0 {
+			w.aux1(goobj.AuxPcline, s.Func.Pcln.Pcline)
+		}
+		if s.Func.Pcln.Pcinline != nil && s.Func.Pcln.Pcinline.Size != 0 {
+			w.aux1(goobj.AuxPcinline, s.Func.Pcln.Pcinline)
+		}
+		for _, pcSym := range s.Func.Pcln.Pcdata {
+			w.aux1(goobj.AuxPcdata, pcSym)
+		}
+
 	}
 }
 
@@ -559,6 +579,19 @@ func nAuxSym(s *LSym) int {
 		if s.Func.dwarfDebugLinesSym != nil && s.Func.dwarfDebugLinesSym.Size != 0 {
 			n++
 		}
+		if s.Func.Pcln.Pcsp != nil && s.Func.Pcln.Pcsp.Size != 0 {
+			n++
+		}
+		if s.Func.Pcln.Pcfile != nil && s.Func.Pcln.Pcfile.Size != 0 {
+			n++
+		}
+		if s.Func.Pcln.Pcline != nil && s.Func.Pcln.Pcline.Size != 0 {
+			n++
+		}
+		if s.Func.Pcln.Pcinline != nil && s.Func.Pcln.Pcinline.Size != 0 {
+			n++
+		}
+		n += len(s.Func.Pcln.Pcdata)
 	}
 	return n
 }
@@ -566,7 +599,17 @@ func nAuxSym(s *LSym) int {
 // generate symbols for FuncInfo.
 func genFuncInfoSyms(ctxt *Link) {
 	infosyms := make([]*LSym, 0, len(ctxt.Text))
-	var pcdataoff uint32
+	hashedsyms := make([]*LSym, 0, 4*len(ctxt.Text))
+	preparePcSym := func(s *LSym) *LSym {
+		if s == nil {
+			return s
+		}
+		s.PkgIdx = goobj.PkgIdxHashed
+		s.SymIdx = int32(len(hashedsyms) + len(ctxt.hasheddefs))
+		s.Set(AttrIndexed, true)
+		hashedsyms = append(hashedsyms, s)
+		return s
+	}
 	var b bytes.Buffer
 	symidx := int32(len(ctxt.defs))
 	for _, s := range ctxt.Text {
@@ -579,20 +622,14 @@ func genFuncInfoSyms(ctxt *Link) {
 			FuncID: objabi.FuncID(s.Func.FuncID),
 		}
 		pc := &s.Func.Pcln
-		o.Pcsp = pcdataoff
+		o.Pcsp = makeSymRef(preparePcSym(pc.Pcsp))
-		pcdataoff += uint32(len(pc.Pcsp.P))
+		o.Pcfile = makeSymRef(preparePcSym(pc.Pcfile))
-		o.Pcfile = pcdataoff
+		o.Pcline = makeSymRef(preparePcSym(pc.Pcline))
-		pcdataoff += uint32(len(pc.Pcfile.P))
+		o.Pcinline = makeSymRef(preparePcSym(pc.Pcinline))
-		o.Pcline = pcdataoff
+		o.Pcdata = make([]goobj.SymRef, len(pc.Pcdata))
-		pcdataoff += uint32(len(pc.Pcline.P))
+		for i, pcSym := range pc.Pcdata {
-		o.Pcinline = pcdataoff
+			o.Pcdata[i] = makeSymRef(preparePcSym(pcSym))
-		pcdataoff += uint32(len(pc.Pcinline.P))
-		o.Pcdata = make([]uint32, len(pc.Pcdata))
-		for i, pcd := range pc.Pcdata {
-			o.Pcdata[i] = pcdataoff
-			pcdataoff += uint32(len(pcd.P))
 		}
-		o.PcdataEnd = pcdataoff
 		o.Funcdataoff = make([]uint32, len(pc.Funcdataoff))
 		for i, x := range pc.Funcdataoff {
 			o.Funcdataoff[i] = uint32(x)
@@ -642,9 +679,9 @@ func genFuncInfoSyms(ctxt *Link) {
 		}
 	}
 	ctxt.defs = append(ctxt.defs, infosyms...)
+	ctxt.hasheddefs = append(ctxt.hasheddefs, hashedsyms...)
 }
 
-// debugDumpAux is a dumper for selected aux symbols.
 func writeAuxSymDebug(ctxt *Link, par *LSym, aux *LSym) {
 	// Most aux symbols (ex: funcdata) are not interesting--
 	// pick out just the DWARF ones for now.

src/cmd/internal/obj/pcln.go

@@ -6,6 +6,7 @@ package obj
 
 import (
 	"cmd/internal/goobj"
+	"cmd/internal/objabi"
 	"encoding/binary"
 	"log"
 )
@@ -14,16 +15,19 @@ import (
 // returned by valfunc parameterized by arg. The invocation of valfunc to update the
 // current value is, for each p,
 //
-//	val = valfunc(func, val, p, 0, arg);
+//	sym = valfunc(func, p, 0, arg);
-//	record val as value at p->pc;
+//	record sym.P as value at p->pc;
-//	val = valfunc(func, val, p, 1, arg);
+//	sym = valfunc(func, p, 1, arg);
 //
 // where func is the function, val is the current value, p is the instruction being
 // considered, and arg can be used to further parameterize valfunc.
-func funcpctab(ctxt *Link, dst *Pcdata, func_ *LSym, desc string, valfunc func(*Link, *LSym, int32, *Prog, int32, interface{}) int32, arg interface{}) {
+func funcpctab(ctxt *Link, func_ *LSym, desc string, valfunc func(*Link, *LSym, int32, *Prog, int32, interface{}) int32, arg interface{}) *LSym {
 	dbg := desc == ctxt.Debugpcln
-
+	dst := []byte{}
-	dst.P = dst.P[:0]
+	sym := &LSym{
+		Type:      objabi.SRODATA,
+		Attribute: AttrContentAddressable,
+	}
 
 	if dbg {
 		ctxt.Logf("funcpctab %s [valfunc=%s]\n", func_.Name, desc)
@@ -32,7 +36,8 @@ func funcpctab(ctxt *Link, dst *Pcdata, func_ *LSym, desc string, valfunc func(*
 	val := int32(-1)
 	oldval := val
 	if func_.Func.Text == nil {
-		return
+		// Return the emtpy symbol we've built so far.
+		return sym
 	}
 
 	pc := func_.Func.Text.Pc
@@ -88,13 +93,13 @@ func funcpctab(ctxt *Link, dst *Pcdata, func_ *LSym, desc string, valfunc func(*
 		if started {
 			pcdelta := (p.Pc - pc) / int64(ctxt.Arch.MinLC)
 			n := binary.PutUvarint(buf, uint64(pcdelta))
-			dst.P = append(dst.P, buf[:n]...)
+			dst = append(dst, buf[:n]...)
 			pc = p.Pc
 		}
 
 		delta := val - oldval
 		n := binary.PutVarint(buf, int64(delta))
-		dst.P = append(dst.P, buf[:n]...)
+		dst = append(dst, buf[:n]...)
 		oldval = val
 		started = true
 		val = valfunc(ctxt, func_, val, p, 1, arg)
@@ -109,18 +114,22 @@ func funcpctab(ctxt *Link, dst *Pcdata, func_ *LSym, desc string, valfunc func(*
 			ctxt.Diag("negative pc offset: %v", v)
 		}
 		n := binary.PutUvarint(buf, uint64(v))
-		dst.P = append(dst.P, buf[:n]...)
+		dst = append(dst, buf[:n]...)
 		// add terminating varint-encoded 0, which is just 0
-		dst.P = append(dst.P, 0)
+		dst = append(dst, 0)
 	}
 
 	if dbg {
-		ctxt.Logf("wrote %d bytes to %p\n", len(dst.P), dst)
+		ctxt.Logf("wrote %d bytes to %p\n", len(dst), dst)
-		for _, p := range dst.P {
+		for _, p := range dst {
 			ctxt.Logf(" %02x", p)
 		}
 		ctxt.Logf("\n")
 	}
+
+	sym.Size = int64(len(dst))
+	sym.P = dst
+	return sym
 }
 
 // pctofileline computes either the file number (arg == 0)
@@ -268,18 +277,17 @@ func linkpcln(ctxt *Link, cursym *LSym) {
 		}
 	}
 
-	pcln.Pcdata = make([]Pcdata, npcdata)
+	pcln.Pcdata = make([]*LSym, npcdata)
-	pcln.Pcdata = pcln.Pcdata[:npcdata]
 	pcln.Funcdata = make([]*LSym, nfuncdata)
 	pcln.Funcdataoff = make([]int64, nfuncdata)
 	pcln.Funcdataoff = pcln.Funcdataoff[:nfuncdata]
 
-	funcpctab(ctxt, &pcln.Pcsp, cursym, "pctospadj", pctospadj, nil)
+	pcln.Pcsp = funcpctab(ctxt, cursym, "pctospadj", pctospadj, nil)
-	funcpctab(ctxt, &pcln.Pcfile, cursym, "pctofile", pctofileline, pcln)
+	pcln.Pcfile = funcpctab(ctxt, cursym, "pctofile", pctofileline, pcln)
-	funcpctab(ctxt, &pcln.Pcline, cursym, "pctoline", pctofileline, nil)
+	pcln.Pcline = funcpctab(ctxt, cursym, "pctoline", pctofileline, nil)
 
 	pcinlineState := new(pcinlineState)
-	funcpctab(ctxt, &pcln.Pcinline, cursym, "pctoinline", pcinlineState.pctoinline, nil)
+	pcln.Pcinline = funcpctab(ctxt, cursym, "pctoinline", pcinlineState.pctoinline, nil)
 	for _, inlMark := range cursym.Func.InlMarks {
 		pcinlineState.setParentPC(ctxt, int(inlMark.id), int32(inlMark.p.Pc))
 	}
@@ -309,9 +317,14 @@ func linkpcln(ctxt *Link, cursym *LSym) {
 	// pcdata.
 	for i := 0; i < npcdata; i++ {
 		if (havepc[i/32]>>uint(i%32))&1 == 0 {
-			continue
+			// use an empty symbol.
+			pcln.Pcdata[i] = &LSym{
+				Type:      objabi.SRODATA,
+				Attribute: AttrContentAddressable,
+			}
+		} else {
+			pcln.Pcdata[i] = funcpctab(ctxt, cursym, "pctopcdata", pctopcdata, interface{}(uint32(i)))
 		}
-		funcpctab(ctxt, &pcln.Pcdata[i], cursym, "pctopcdata", pctopcdata, interface{}(uint32(i)))
 	}
 
 	// funcdata

src/cmd/internal/objfile/goobj.go

@@ -236,7 +236,15 @@ func (f *goobjFile) PCToLine(pc uint64) (string, int, *gosym.Func) {
 	if arch == nil {
 		return "", 0, nil
 	}
-	pcdataBase := r.PcdataBase()
+	getSymData := func(s goobj.SymRef) []byte {
+		if s.PkgIdx != goobj.PkgIdxHashed {
+			// We don't need the data for non-hashed symbols, yet.
+			panic("not supported")
+		}
+		i := uint32(s.SymIdx + uint32(r.NSym()+r.NHashed64def()))
+		return r.BytesAt(r.DataOff(i), r.DataSize(i))
+	}
+
 	ndef := uint32(r.NSym() + r.NHashed64def() + r.NHasheddef() + r.NNonpkgdef())
 	for i := uint32(0); i < ndef; i++ {
 		osym := r.Sym(i)
@@ -262,11 +270,9 @@ func (f *goobjFile) PCToLine(pc uint64) (string, int, *gosym.Func) {
 		b := r.BytesAt(r.DataOff(isym), r.DataSize(isym))
 		var info *goobj.FuncInfo
 		lengths := info.ReadFuncInfoLengths(b)
-		off, end := info.ReadPcline(b)
+		pcline := getSymData(info.ReadPcline(b))
-		pcline := r.BytesAt(pcdataBase+off, int(end-off))
 		line := int(pcValue(pcline, pc-addr, arch))
-		off, end = info.ReadPcfile(b)
+		pcfile := getSymData(info.ReadPcfile(b))
-		pcfile := r.BytesAt(pcdataBase+off, int(end-off))
 		fileID := pcValue(pcfile, pc-addr, arch)
 		globalFileID := info.ReadFile(b, lengths.FileOff, uint32(fileID))
 		fileName := r.File(int(globalFileID))

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

@@ -1421,7 +1421,7 @@ func (d *dwctxt) writeframes(fs loader.Sym) dwarfSecInfo {
 			deltaBuf = dwarf.AppendUleb128(deltaBuf, uint64(thearch.Dwarfreglr))
 		}
 
-		for pcsp.Init(fpcsp); !pcsp.Done; pcsp.Next() {
+		for pcsp.Init(d.linkctxt.loader.Data(fpcsp)); !pcsp.Done; pcsp.Next() {
 			nextpc := pcsp.NextPC
 
 			// pciterinit goes up to the end of the function,

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

@@ -2252,7 +2252,7 @@ func (sc *stkChk) check(up *chain, depth int) int {
 	var ch1 chain
 	pcsp := obj.NewPCIter(uint32(ctxt.Arch.MinLC))
 	ri := 0
-	for pcsp.Init(info.Pcsp()); !pcsp.Done; pcsp.Next() {
+	for pcsp.Init(ldr.Data(info.Pcsp())); !pcsp.Done; pcsp.Next() {
 		// pcsp.value is in effect for [pcsp.pc, pcsp.nextpc).
 
 		// Check stack size in effect for this span.

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

@@ -592,9 +592,8 @@ func (ctxt *Link) pclntab(container loader.Bitmap) *pclntab {
 		fi := ldr.FuncInfo(s)
 		if fi.Valid() {
 			fi.Preload()
-			npc := fi.NumPcdata()
+			for _, dataSym := range fi.Pcdata() {
-			for i := uint32(0); i < npc; i++ {
+				pcdata = append(pcdata, sym.Pcdata{P: ldr.Data(dataSym)})
-				pcdata = append(pcdata, sym.Pcdata{P: fi.Pcdata(int(i))})
 			}
 			nfd := fi.NumFuncdataoff()
 			for i := uint32(0); i < nfd; i++ {
@@ -666,15 +665,15 @@ func (ctxt *Link) pclntab(container loader.Bitmap) *pclntab {
 
 		cu := ldr.SymUnit(s)
 		if fi.Valid() {
-			pcsp = sym.Pcdata{P: fi.Pcsp()}
+			pcsp = sym.Pcdata{P: ldr.Data(fi.Pcsp())}
-			pcfile = sym.Pcdata{P: fi.Pcfile()}
+			pcfile = sym.Pcdata{P: ldr.Data(fi.Pcfile())}
-			pcline = sym.Pcdata{P: fi.Pcline()}
+			pcline = sym.Pcdata{P: ldr.Data(fi.Pcline())}
 		}
 
 		if fi.Valid() && fi.NumInlTree() > 0 {
 			its := oldState.genInlTreeSym(cu, fi, ctxt.Arch, state)
 			funcdata[objabi.FUNCDATA_InlTree] = its
-			pcdata[objabi.PCDATA_InlTreeIndex] = sym.Pcdata{P: fi.Pcinline()}
+			pcdata[objabi.PCDATA_InlTreeIndex] = sym.Pcdata{P: ldr.Data(fi.Pcinline())}
 		}
 
 		// pcdata

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

@@ -1878,19 +1878,24 @@ func (fi *FuncInfo) FuncID() objabi.FuncID {
 	return objabi.FuncID((*goobj.FuncInfo)(nil).ReadFuncID(fi.data))
 }
 
-func (fi *FuncInfo) Pcsp() []byte {
+func (fi *FuncInfo) Pcsp() Sym {
-	pcsp, end := (*goobj.FuncInfo)(nil).ReadPcsp(fi.data)
+	sym := (*goobj.FuncInfo)(nil).ReadPcsp(fi.data)
-	return fi.r.BytesAt(fi.r.PcdataBase()+pcsp, int(end-pcsp))
+	return fi.l.resolve(fi.r, sym)
 }
 
-func (fi *FuncInfo) Pcfile() []byte {
+func (fi *FuncInfo) Pcfile() Sym {
-	pcf, end := (*goobj.FuncInfo)(nil).ReadPcfile(fi.data)
+	sym := (*goobj.FuncInfo)(nil).ReadPcfile(fi.data)
-	return fi.r.BytesAt(fi.r.PcdataBase()+pcf, int(end-pcf))
+	return fi.l.resolve(fi.r, sym)
 }
 
-func (fi *FuncInfo) Pcline() []byte {
+func (fi *FuncInfo) Pcline() Sym {
-	pcln, end := (*goobj.FuncInfo)(nil).ReadPcline(fi.data)
+	sym := (*goobj.FuncInfo)(nil).ReadPcline(fi.data)
-	return fi.r.BytesAt(fi.r.PcdataBase()+pcln, int(end-pcln))
+	return fi.l.resolve(fi.r, sym)
+}
+
+func (fi *FuncInfo) Pcinline() Sym {
+	sym := (*goobj.FuncInfo)(nil).ReadPcinline(fi.data)
+	return fi.l.resolve(fi.r, sym)
 }
 
 // Preload has to be called prior to invoking the various methods
@@ -1899,27 +1904,16 @@ func (fi *FuncInfo) Preload() {
 	fi.lengths = (*goobj.FuncInfo)(nil).ReadFuncInfoLengths(fi.data)
 }
 
-func (fi *FuncInfo) Pcinline() []byte {
+func (fi *FuncInfo) Pcdata() []Sym {
 	if !fi.lengths.Initialized {
 		panic("need to call Preload first")
 	}
-	pcinl, end := (*goobj.FuncInfo)(nil).ReadPcinline(fi.data, fi.lengths.PcdataOff)
+	syms := (*goobj.FuncInfo)(nil).ReadPcdata(fi.data)
-	return fi.r.BytesAt(fi.r.PcdataBase()+pcinl, int(end-pcinl))
+	ret := make([]Sym, len(syms))
-}
+	for i := range ret {
-
+		ret[i] = fi.l.resolve(fi.r, syms[i])
-func (fi *FuncInfo) NumPcdata() uint32 {
-	if !fi.lengths.Initialized {
-		panic("need to call Preload first")
 	}
-	return fi.lengths.NumPcdata
+	return ret
-}
-
-func (fi *FuncInfo) Pcdata(k int) []byte {
-	if !fi.lengths.Initialized {
-		panic("need to call Preload first")
-	}
-	pcdat, end := (*goobj.FuncInfo)(nil).ReadPcdata(fi.data, fi.lengths.PcdataOff, uint32(k))
-	return fi.r.BytesAt(fi.r.PcdataBase()+pcdat, int(end-pcdat))
 }
 
 func (fi *FuncInfo) NumFuncdataoff() uint32 {