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[dev.link] cmd/link: store external relocations in Reloc2 format
Store external relocations in (almost) the same format as the Go objects, so we can handle them more uniformly. There is a small speedup: (linking cmd/compile) Deadcode 67.8ms ± 3% 61.1ms ± 3% -9.94% (p=0.008 n=5+5) Dostkcheck 41.2ms ± 2% 38.8ms ± 3% -5.99% (p=0.008 n=5+5) Change-Id: I8616e10b26235904201d6c9465f5ae32a49c9949 Reviewed-on: https://go-review.googlesource.com/c/go/+/226365 Run-TryBot: Cherry Zhang <cherryyz@google.com> Reviewed-by: Than McIntosh <thanm@google.com> TryBot-Result: Gobot Gobot <gobot@golang.org>
This commit is contained in:
Cherry Zhang
parent
aef23f5be9
commit
6e3bde5f30
6 changed files with 103 additions and 160 deletions
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@ -68,6 +68,14 @@ type Reloc2 struct {
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func (rel Reloc2) Type() objabi.RelocType { return objabi.RelocType(rel.Reloc2.Type()) + rel.typ }
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func (rel Reloc2) Sym() Sym { return rel.l.resolve(rel.r, rel.Reloc2.Sym()) }
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func (rel Reloc2) SetSym(s Sym) { rel.Reloc2.SetSym(goobj2.SymRef{PkgIdx: 0, SymIdx: uint32(s)}) }
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func (rel Reloc2) SetType(t objabi.RelocType) {
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if t != objabi.RelocType(uint8(t)) {
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panic("SetType: type doesn't fit into Reloc2")
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}
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rel.Reloc2.SetType(uint8(t))
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}
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// Aux2 holds a "handle" to access an aux symbol record from an
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// object file.
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@ -269,14 +277,15 @@ type elfsetstringFunc func(s *sym.Symbol, str string, off int)
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// extSymPayload holds the payload (data + relocations) for linker-synthesized
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// external symbols (note that symbol value is stored in a separate slice).
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type extSymPayload struct {
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name string // TODO: would this be better as offset into str table?
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size int64
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ver int
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kind sym.SymKind
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objidx uint32 // index of original object if sym made by cloneToExternal
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gotype Sym // Gotype (0 if not present)
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relocs []Reloc
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data []byte
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name string // TODO: would this be better as offset into str table?
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size int64
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ver int
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kind sym.SymKind
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objidx uint32 // index of original object if sym made by cloneToExternal
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gotype Sym // Gotype (0 if not present)
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relocs []goobj2.Reloc2
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reltypes []objabi.RelocType // relocation types
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data []byte
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}
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const (
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@ -1468,91 +1477,15 @@ func (l *Loader) growExtAttrBitmaps() {
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}
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}
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// At method returns the j-th reloc for a global symbol.
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func (relocs *Relocs) At(j int) Reloc {
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if relocs.l.isExtReader(relocs.r) {
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pp := relocs.l.payloads[relocs.li]
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return pp.relocs[j]
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}
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rel := goobj2.Reloc{}
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rel.Read(relocs.r.Reader, relocs.r.RelocOff(relocs.li, j))
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target := relocs.l.resolve(relocs.r, rel.Sym)
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return Reloc{
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Off: rel.Off,
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Size: rel.Siz,
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Type: objabi.RelocType(rel.Type),
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Add: rel.Add,
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Sym: target,
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}
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}
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// At2 returns the j-th reloc for a global symbol.
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func (relocs *Relocs) At2(j int) Reloc2 {
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if relocs.l.isExtReader(relocs.r) {
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pp := relocs.l.payloads[relocs.li]
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r := pp.relocs[j]
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// XXX populate a goobj2.Reloc from external reloc record.
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// Ugly. Maybe we just want to use this format to store the
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// reloc record in the first place?
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// Also there is more speedup if we could remove the
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// conditional here.
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var b goobj2.Reloc2
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b.Set(r.Off, r.Size, 0, r.Add, goobj2.SymRef{PkgIdx: 0, SymIdx: uint32(r.Sym)})
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return Reloc2{&b, relocs.r, relocs.l, r.Type}
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return Reloc2{&relocs.rs[j], relocs.r, relocs.l, pp.reltypes[j]}
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}
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return Reloc2{&relocs.rs[j], relocs.r, relocs.l, 0}
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}
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// ReadAll method reads all relocations for a symbol into the
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// specified slice. If the slice capacity is not large enough, a new
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// larger slice will be allocated. Final slice is returned.
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func (relocs *Relocs) ReadAll(dst []Reloc) []Reloc {
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return relocs.readAll(dst, false)
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}
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// ReadSyms method reads all relocation target symbols and reloc types
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// for a symbol into the specified slice. It is like ReadAll but only
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// fill in the Sym and Type fields.
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func (relocs *Relocs) ReadSyms(dst []Reloc) []Reloc {
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return relocs.readAll(dst, true)
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}
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func (relocs *Relocs) readAll(dst []Reloc, onlySymType bool) []Reloc {
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if relocs.Count == 0 {
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return dst[:0]
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}
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if cap(dst) < relocs.Count {
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dst = make([]Reloc, relocs.Count)
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}
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dst = dst[:0]
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if relocs.l.isExtReader(relocs.r) {
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pp := relocs.l.payloads[relocs.li]
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dst = append(dst, pp.relocs...)
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return dst
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}
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off := relocs.r.RelocOff(relocs.li, 0)
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rel := goobj2.Reloc{}
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for i := 0; i < relocs.Count; i++ {
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if onlySymType {
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rel.ReadSymType(relocs.r.Reader, off)
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} else {
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rel.Read(relocs.r.Reader, off)
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}
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off += uint32(rel.Size())
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target := relocs.l.resolve(relocs.r, rel.Sym)
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dst = append(dst, Reloc{
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Off: rel.Off,
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Size: rel.Siz,
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Type: objabi.RelocType(rel.Type),
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Add: rel.Add,
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Sym: target,
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})
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}
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return dst
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}
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// Relocs returns a Relocs object for the given global sym.
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func (l *Loader) Relocs(i Sym) Relocs {
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r, li := l.toLocal(i)
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@ -1569,6 +1502,7 @@ func (l *Loader) relocs(r *oReader, li int) Relocs {
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if l.isExtReader(r) {
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pp := l.payloads[li]
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n = len(pp.relocs)
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rs = pp.relocs
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} else {
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rs = r.Relocs2(li)
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n = len(rs)
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@ -2237,7 +2171,15 @@ func (l *Loader) cloneToExternal(symIdx Sym) {
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// Copy relocations
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relocs := l.Relocs(symIdx)
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pp.relocs = relocs.ReadAll(nil)
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pp.relocs = make([]goobj2.Reloc2, relocs.Count)
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pp.reltypes = make([]objabi.RelocType, relocs.Count)
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for i := range pp.relocs {
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// Copy the relocs slice.
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// Convert local reference to global reference.
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rel := relocs.At2(i)
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pp.relocs[i].Set(rel.Off(), rel.Siz(), 0, rel.Add(), goobj2.SymRef{PkgIdx: 0, SymIdx: uint32(rel.Sym())})
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pp.reltypes[i] = rel.Type()
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}
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// Copy data
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pp.data = r.Data(li)
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@ -2634,7 +2576,7 @@ func (l *Loader) convertRelocations(src *Relocs, dst *sym.Symbol, strict bool) {
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}
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if rs != 0 && l.Syms[rs] != nil && l.Syms[rs].Type == sym.SABIALIAS {
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rsrelocs := l.Relocs(rs)
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rs = rsrelocs.At(0).Sym
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rs = rsrelocs.At2(0).Sym()
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}
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if strict && rs != 0 && l.Syms[rs] == nil && rt != objabi.R_USETYPE {
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panic("nil reloc target in convertRelocations")
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@ -2659,14 +2601,13 @@ func (l *Loader) convertRelocations(src *Relocs, dst *sym.Symbol, strict bool) {
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// results returned; if "limit" is -1, then all undefs are returned.
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func (l *Loader) UndefinedRelocTargets(limit int) []Sym {
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result := []Sym{}
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rslice := []Reloc{}
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for si := Sym(1); si < Sym(len(l.objSyms)); si++ {
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relocs := l.Relocs(si)
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rslice = relocs.ReadSyms(rslice)
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for ri := 0; ri < relocs.Count; ri++ {
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r := &rslice[ri]
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if r.Sym != 0 && l.SymType(r.Sym) == sym.SXREF && l.RawSymName(r.Sym) != ".got" {
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result = append(result, r.Sym)
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r := relocs.At2(ri)
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rs := r.Sym()
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if rs != 0 && l.SymType(rs) == sym.SXREF && l.RawSymName(rs) != ".got" {
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result = append(result, rs)
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if limit != -1 && len(result) >= limit {
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break
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}
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