1 // Copyright 2019 The Go Authors. All rights reserved.
2 // Use of this source code is governed by a BSD-style
3 // license that can be found in the LICENSE file.
14 "cmd/link/internal/sym"
26 // Sym encapsulates a global symbol index, used to identify a specific
27 // Go symbol. The 0-valued Sym is corresponds to an invalid symbol.
30 // Relocs encapsulates the set of relocations on a given symbol; an
31 // instance of this type is returned by the Loader Relocs() method.
35 li uint32 // local index of symbol whose relocs we're examining
36 r *oReader // object reader for containing package
40 // ExtReloc contains the payload for an external relocation.
41 type ExtReloc struct {
48 // Reloc holds a "handle" to access a relocation record from an
56 func (rel Reloc) Type() objabi.RelocType { return objabi.RelocType(rel.Reloc.Type()) &^ objabi.R_WEAK }
57 func (rel Reloc) Weak() bool { return objabi.RelocType(rel.Reloc.Type())&objabi.R_WEAK != 0 }
58 func (rel Reloc) SetType(t objabi.RelocType) { rel.Reloc.SetType(uint16(t)) }
59 func (rel Reloc) Sym() Sym { return rel.l.resolve(rel.r, rel.Reloc.Sym()) }
60 func (rel Reloc) SetSym(s Sym) { rel.Reloc.SetSym(goobj.SymRef{PkgIdx: 0, SymIdx: uint32(s)}) }
61 func (rel Reloc) IsMarker() bool { return rel.Siz() == 0 }
63 // Aux holds a "handle" to access an aux symbol record from an
71 func (a Aux) Sym() Sym { return a.l.resolve(a.r, a.Aux.Sym()) }
73 // oReader is a wrapper type of obj.Reader, along with some
77 unit *sym.CompilationUnit
78 version int // version of static symbol
79 flags uint32 // read from object file
81 syms []Sym // Sym's global index, indexed by local index
82 pkg []uint32 // indices of referenced package by PkgIdx (index into loader.objs array)
83 ndef int // cache goobj.Reader.NSym()
84 nhashed64def int // cache goobj.Reader.NHashed64Def()
85 nhasheddef int // cache goobj.Reader.NHashedDef()
86 objidx uint32 // index of this reader in the objs slice
89 // Total number of defined symbols (package symbols, hashed symbols, and
90 // non-package symbols).
91 func (r *oReader) NAlldef() int { return r.ndef + r.nhashed64def + r.nhasheddef + r.NNonpkgdef() }
98 // objSym represents a symbol in an object file. It is a tuple of
99 // the object and the symbol's local index.
100 // For external symbols, objidx is the index of l.extReader (extObj),
101 // s is its index into the payload array.
102 // {0, 0} represents the nil symbol.
104 objidx uint32 // index of the object (in l.objs array)
105 s uint32 // local index
108 type nameVer struct {
116 func (bm Bitmap) Set(i Sym) {
117 n, r := uint(i)/32, uint(i)%32
121 // unset the i-th bit.
122 func (bm Bitmap) Unset(i Sym) {
123 n, r := uint(i)/32, uint(i)%32
127 // whether the i-th bit is set.
128 func (bm Bitmap) Has(i Sym) bool {
129 n, r := uint(i)/32, uint(i)%32
130 return bm[n]&(1<<r) != 0
133 // return current length of bitmap in bits.
134 func (bm Bitmap) Len() int {
138 // return the number of bits set.
139 func (bm Bitmap) Count() int {
141 for _, x := range bm {
142 s += bits.OnesCount32(x)
147 func MakeBitmap(n int) Bitmap {
148 return make(Bitmap, (n+31)/32)
151 // growBitmap insures that the specified bitmap has enough capacity,
152 // reallocating (doubling the size) if needed.
153 func growBitmap(reqLen int, b Bitmap) Bitmap {
156 b = append(b, MakeBitmap(reqLen+1-curLen)...)
161 type symAndSize struct {
166 // A Loader loads new object files and resolves indexed symbol references.
168 // Notes on the layout of global symbol index space:
170 // - Go object files are read before host object files; each Go object
171 // read adds its defined package symbols to the global index space.
172 // Nonpackage symbols are not yet added.
174 // - In loader.LoadNonpkgSyms, add non-package defined symbols and
175 // references in all object files to the global index space.
177 // - Host object file loading happens; the host object loader does a
178 // name/version lookup for each symbol it finds; this can wind up
179 // extending the external symbol index space range. The host object
180 // loader stores symbol payloads in loader.payloads using SymbolBuilder.
182 // - Each symbol gets a unique global index. For duplicated and
183 // overwriting/overwritten symbols, the second (or later) appearance
184 // of the symbol gets the same global index as the first appearance.
186 start map[*oReader]Sym // map from object file to its start index
187 objs []objIdx // sorted by start index (i.e. objIdx.i)
188 extStart Sym // from this index on, the symbols are externally defined
189 builtinSyms []Sym // global index of builtin symbols
191 objSyms []objSym // global index mapping to local index
193 symsByName [2]map[string]Sym // map symbol name to index, two maps are for ABI0 and ABIInternal
194 extStaticSyms map[nameVer]Sym // externally defined static symbols, keyed by name
196 extReader *oReader // a dummy oReader, for external symbols
197 payloadBatch []extSymPayload
198 payloads []*extSymPayload // contents of linker-materialized external syms
199 values []int64 // symbol values, indexed by global sym index
201 sects []*sym.Section // sections
202 symSects []uint16 // symbol's section, index to sects array
204 align []uint8 // symbol 2^N alignment, indexed by global index
206 deferReturnTramp map[Sym]bool // whether the symbol is a trampoline of a deferreturn call
208 objByPkg map[string]uint32 // map package path to the index of its Go object reader
210 anonVersion int // most recently assigned ext static sym pseudo-version
212 // Bitmaps and other side structures used to store data used to store
213 // symbol flags/attributes; these are to be accessed via the
214 // corresponding loader "AttrXXX" and "SetAttrXXX" methods. Please
215 // visit the comments on these methods for more details on the
216 // semantics / interpretation of the specific flags or attribute.
217 attrReachable Bitmap // reachable symbols, indexed by global index
218 attrOnList Bitmap // "on list" symbols, indexed by global index
219 attrLocal Bitmap // "local" symbols, indexed by global index
220 attrNotInSymbolTable Bitmap // "not in symtab" symbols, indexed by global idx
221 attrUsedInIface Bitmap // "used in interface" symbols, indexed by global idx
222 attrVisibilityHidden Bitmap // hidden symbols, indexed by ext sym index
223 attrDuplicateOK Bitmap // dupOK symbols, indexed by ext sym index
224 attrShared Bitmap // shared symbols, indexed by ext sym index
225 attrExternal Bitmap // external symbols, indexed by ext sym index
227 attrReadOnly map[Sym]bool // readonly data for this sym
228 attrSpecial map[Sym]struct{} // "special" frame symbols
229 attrCgoExportDynamic map[Sym]struct{} // "cgo_export_dynamic" symbols
230 attrCgoExportStatic map[Sym]struct{} // "cgo_export_static" symbols
231 generatedSyms map[Sym]struct{} // symbols that generate their content
233 // Outer and Sub relations for symbols.
234 // TODO: figure out whether it's more efficient to just have these
235 // as fields on extSymPayload (note that this won't be a viable
236 // strategy if somewhere in the linker we set sub/outer for a
237 // non-external sym).
241 dynimplib map[Sym]string // stores Dynimplib symbol attribute
242 dynimpvers map[Sym]string // stores Dynimpvers symbol attribute
243 localentry map[Sym]uint8 // stores Localentry symbol attribute
244 extname map[Sym]string // stores Extname symbol attribute
245 elfType map[Sym]elf.SymType // stores elf type symbol property
246 elfSym map[Sym]int32 // stores elf sym symbol property
247 localElfSym map[Sym]int32 // stores "local" elf sym symbol property
248 symPkg map[Sym]string // stores package for symbol, or library for shlib-derived syms
249 plt map[Sym]int32 // stores dynimport for pe objects
250 got map[Sym]int32 // stores got for pe objects
251 dynid map[Sym]int32 // stores Dynid for symbol
253 relocVariant map[relocId]sym.RelocVariant // stores variant relocs
255 // Used to implement field tracking; created during deadcode if
256 // field tracking is enabled. Reachparent[K] contains the index of
257 // the symbol that triggered the marking of symbol K as live.
262 hasUnknownPkgPath bool // if any Go object has unknown package path
264 strictDupMsgs int // number of strict-dup warning/errors, when FlagStrictDups is enabled
266 elfsetstring elfsetstringFunc
268 errorReporter *ErrorReporter
270 npkgsyms int // number of package symbols, for accounting
271 nhashedsyms int // number of hashed symbols, for accounting
289 type elfsetstringFunc func(str string, off int)
291 // extSymPayload holds the payload (data + relocations) for linker-synthesized
292 // external symbols (note that symbol value is stored in a separate slice).
293 type extSymPayload struct {
294 name string // TODO: would this be better as offset into str table?
298 objidx uint32 // index of original object if sym made by cloneToExternal
306 FlagStrictDups = 1 << iota
310 func NewLoader(flags uint32, elfsetstring elfsetstringFunc, reporter *ErrorReporter) *Loader {
311 nbuiltin := goobj.NBuiltin()
312 extReader := &oReader{objidx: extObj}
314 start: make(map[*oReader]Sym),
315 objs: []objIdx{{}, {extReader, 0}}, // reserve index 0 for nil symbol, 1 for external symbols
316 objSyms: make([]objSym, 1, 1), // This will get overwritten later.
317 extReader: extReader,
318 symsByName: [2]map[string]Sym{make(map[string]Sym, 80000), make(map[string]Sym, 50000)}, // preallocate ~2MB for ABI0 and ~1MB for ABI1 symbols
319 objByPkg: make(map[string]uint32),
320 outer: make(map[Sym]Sym),
321 sub: make(map[Sym]Sym),
322 dynimplib: make(map[Sym]string),
323 dynimpvers: make(map[Sym]string),
324 localentry: make(map[Sym]uint8),
325 extname: make(map[Sym]string),
326 attrReadOnly: make(map[Sym]bool),
327 elfType: make(map[Sym]elf.SymType),
328 elfSym: make(map[Sym]int32),
329 localElfSym: make(map[Sym]int32),
330 symPkg: make(map[Sym]string),
331 plt: make(map[Sym]int32),
332 got: make(map[Sym]int32),
333 dynid: make(map[Sym]int32),
334 attrSpecial: make(map[Sym]struct{}),
335 attrCgoExportDynamic: make(map[Sym]struct{}),
336 attrCgoExportStatic: make(map[Sym]struct{}),
337 generatedSyms: make(map[Sym]struct{}),
338 deferReturnTramp: make(map[Sym]bool),
339 extStaticSyms: make(map[nameVer]Sym),
340 builtinSyms: make([]Sym, nbuiltin),
342 elfsetstring: elfsetstring,
343 errorReporter: reporter,
344 sects: []*sym.Section{nil}, // reserve index 0 for nil section
350 // Add object file r, return the start index.
351 func (l *Loader) addObj(pkg string, r *oReader) Sym {
352 if _, ok := l.start[r]; ok {
353 panic("already added")
355 pkg = objabi.PathToPrefix(pkg) // the object file contains escaped package path
356 if _, ok := l.objByPkg[pkg]; !ok {
357 l.objByPkg[pkg] = r.objidx
359 i := Sym(len(l.objSyms))
361 l.objs = append(l.objs, objIdx{r, i})
362 if r.NeedNameExpansion() && !r.FromAssembly() {
363 l.hasUnknownPkgPath = true
368 // Add a symbol from an object file, return the global index.
369 // If the symbol already exist, it returns the index of that symbol.
370 func (st *loadState) addSym(name string, ver int, r *oReader, li uint32, kind int, osym *goobj.Sym) Sym {
373 panic("addSym called after external symbol is created")
375 i := Sym(len(l.objSyms))
376 addToGlobal := func() {
377 l.objSyms = append(l.objSyms, objSym{r.objidx, li})
379 if name == "" && kind != hashed64Def && kind != hashedDef {
381 return i // unnamed aux symbol
383 if ver == r.version {
384 // Static symbol. Add its global index but don't
385 // add to name lookup table, as it cannot be
386 // referenced by name.
392 // Defined package symbols cannot be dup to each other.
393 // We load all the package symbols first, so we don't need
394 // to check dup here.
395 // We still add it to the lookup table, as it may still be
396 // referenced by name (e.g. through linkname).
397 l.symsByName[ver][name] = i
400 case hashed64Def, hashedDef:
401 // Hashed (content-addressable) symbol. Check the hash
402 // but don't add to name lookup table, as they are not
403 // referenced by name. Also no need to do overwriting
404 // check, as same hash indicates same content.
405 var checkHash func() (symAndSize, bool)
406 var addToHashMap func(symAndSize)
407 var h64 uint64 // only used for hashed64Def
408 var h *goobj.HashType // only used for hashedDef
409 if kind == hashed64Def {
410 checkHash = func() (symAndSize, bool) {
411 h64 = r.Hash64(li - uint32(r.ndef))
412 s, existed := st.hashed64Syms[h64]
415 addToHashMap = func(ss symAndSize) { st.hashed64Syms[h64] = ss }
417 checkHash = func() (symAndSize, bool) {
418 h = r.Hash(li - uint32(r.ndef+r.nhashed64def))
419 s, existed := st.hashedSyms[*h]
422 addToHashMap = func(ss symAndSize) { st.hashedSyms[*h] = ss }
425 if s, existed := checkHash(); existed {
426 // The content hash is built from symbol data and relocations. In the
427 // object file, the symbol data may not always contain trailing zeros,
428 // e.g. for [5]int{1,2,3} and [100]int{1,2,3}, the data is same
429 // (although the size is different).
430 // Also, for short symbols, the content hash is the identity function of
431 // the 8 bytes, and trailing zeros doesn't change the hash value, e.g.
432 // hash("A") == hash("A\0\0\0").
433 // So when two symbols have the same hash, we need to use the one with
436 // New symbol has larger size, use the new one. Rewrite the index mapping.
437 l.objSyms[s.sym] = objSym{r.objidx, li}
438 addToHashMap(symAndSize{s.sym, siz})
442 addToHashMap(symAndSize{i, siz})
447 // Non-package (named) symbol. Check if it already exists.
448 oldi, existed := l.symsByName[ver][name]
450 l.symsByName[ver][name] = i
454 // symbol already exists
456 if l.flags&FlagStrictDups != 0 {
457 l.checkdup(name, r, li, oldi)
461 oldr, oldli := l.toLocal(oldi)
462 oldsym := oldr.Sym(oldli)
466 overwrite := r.DataSize(li) != 0
468 // new symbol overwrites old symbol.
469 oldtyp := sym.AbiSymKindToSymKind[objabi.SymKind(oldsym.Type())]
470 if !(oldtyp.IsData() && oldr.DataSize(oldli) == 0) {
471 log.Fatalf("duplicated definition of symbol " + name)
473 l.objSyms[oldi] = objSym{r.objidx, li}
475 // old symbol overwrites new symbol.
476 typ := sym.AbiSymKindToSymKind[objabi.SymKind(oldsym.Type())]
477 if !typ.IsData() { // only allow overwriting data symbol
478 log.Fatalf("duplicated definition of symbol " + name)
484 // newExtSym creates a new external sym with the specified
486 func (l *Loader) newExtSym(name string, ver int) Sym {
487 i := Sym(len(l.objSyms))
491 l.growValues(int(i) + 1)
492 l.growAttrBitmaps(int(i) + 1)
493 pi := l.newPayload(name, ver)
494 l.objSyms = append(l.objSyms, objSym{l.extReader.objidx, uint32(pi)})
495 l.extReader.syms = append(l.extReader.syms, i)
499 // LookupOrCreateSym looks up the symbol with the specified name/version,
500 // returning its Sym index if found. If the lookup fails, a new external
501 // Sym will be created, entered into the lookup tables, and returned.
502 func (l *Loader) LookupOrCreateSym(name string, ver int) Sym {
503 i := l.Lookup(name, ver)
507 i = l.newExtSym(name, ver)
508 static := ver >= sym.SymVerStatic || ver < 0
510 l.extStaticSyms[nameVer{name, ver}] = i
512 l.symsByName[ver][name] = i
517 func (l *Loader) IsExternal(i Sym) bool {
519 return l.isExtReader(r)
522 func (l *Loader) isExtReader(r *oReader) bool {
523 return r == l.extReader
526 // For external symbol, return its index in the payloads array.
527 // XXX result is actually not a global index. We (ab)use the Sym type
528 // so we don't need conversion for accessing bitmaps.
529 func (l *Loader) extIndex(i Sym) Sym {
530 _, li := l.toLocal(i)
534 // Get a new payload for external symbol, return its index in
535 // the payloads array.
536 func (l *Loader) newPayload(name string, ver int) int {
537 pi := len(l.payloads)
538 pp := l.allocPayload()
541 l.payloads = append(l.payloads, pp)
542 l.growExtAttrBitmaps()
546 // getPayload returns a pointer to the extSymPayload struct for an
547 // external symbol if the symbol has a payload. Will panic if the
548 // symbol in question is bogus (zero or not an external sym).
549 func (l *Loader) getPayload(i Sym) *extSymPayload {
550 if !l.IsExternal(i) {
551 panic(fmt.Sprintf("bogus symbol index %d in getPayload", i))
554 return l.payloads[pi]
557 // allocPayload allocates a new payload.
558 func (l *Loader) allocPayload() *extSymPayload {
559 batch := l.payloadBatch
561 batch = make([]extSymPayload, 1000)
564 l.payloadBatch = batch[1:]
568 func (ms *extSymPayload) Grow(siz int64) {
569 if int64(int(siz)) != siz {
570 log.Fatalf("symgrow size %d too long", siz)
572 if int64(len(ms.data)) >= siz {
575 if cap(ms.data) < int(siz) {
577 ms.data = append(ms.data, make([]byte, int(siz)+1-cl)...)
578 ms.data = ms.data[0:cl]
580 ms.data = ms.data[:siz]
583 // Convert a local index to a global index.
584 func (l *Loader) toGlobal(r *oReader, i uint32) Sym {
588 // Convert a global index to a local index.
589 func (l *Loader) toLocal(i Sym) (*oReader, uint32) {
590 return l.objs[l.objSyms[i].objidx].r, l.objSyms[i].s
593 // Resolve a local symbol reference. Return global index.
594 func (l *Loader) resolve(r *oReader, s goobj.SymRef) Sym {
596 switch p := s.PkgIdx; p {
597 case goobj.PkgIdxInvalid:
598 // {0, X} with non-zero X is never a valid sym reference from a Go object.
599 // We steal this space for symbol references from external objects.
600 // In this case, X is just the global index.
601 if l.isExtReader(r) {
608 case goobj.PkgIdxHashed64:
609 i := int(s.SymIdx) + r.ndef
611 case goobj.PkgIdxHashed:
612 i := int(s.SymIdx) + r.ndef + r.nhashed64def
614 case goobj.PkgIdxNone:
615 i := int(s.SymIdx) + r.ndef + r.nhashed64def + r.nhasheddef
617 case goobj.PkgIdxBuiltin:
618 if bi := l.builtinSyms[s.SymIdx]; bi != 0 {
621 l.reportMissingBuiltin(int(s.SymIdx), r.unit.Lib.Pkg)
623 case goobj.PkgIdxSelf:
626 rr = l.objs[r.pkg[p]].r
628 return l.toGlobal(rr, s.SymIdx)
631 // reportMissingBuiltin issues an error in the case where we have a
632 // relocation against a runtime builtin whose definition is not found
633 // when the runtime package is built. The canonical example is
634 // "runtime.racefuncenter" -- currently if you do something like
636 // go build -gcflags=-race myprogram.go
638 // the compiler will insert calls to the builtin runtime.racefuncenter,
639 // but the version of the runtime used for linkage won't actually contain
640 // definitions of that symbol. See issue #42396 for details.
642 // As currently implemented, this is a fatal error. This has drawbacks
643 // in that if there are multiple missing builtins, the error will only
644 // cite the first one. On the plus side, terminating the link here has
645 // advantages in that we won't run the risk of panics or crashes later
646 // on in the linker due to R_CALL relocations with 0-valued target
648 func (l *Loader) reportMissingBuiltin(bsym int, reflib string) {
649 bname, _ := goobj.BuiltinName(bsym)
650 log.Fatalf("reference to undefined builtin %q from package %q",
654 // Look up a symbol by name, return global index, or 0 if not found.
655 // This is more like Syms.ROLookup than Lookup -- it doesn't create
657 func (l *Loader) Lookup(name string, ver int) Sym {
658 if ver >= sym.SymVerStatic || ver < 0 {
659 return l.extStaticSyms[nameVer{name, ver}]
661 return l.symsByName[ver][name]
664 // Check that duplicate symbols have same contents.
665 func (l *Loader) checkdup(name string, r *oReader, li uint32, dup Sym) {
667 rdup, ldup := l.toLocal(dup)
668 pdup := rdup.Data(ldup)
669 if bytes.Equal(p, pdup) {
672 reason := "same length but different contents"
673 if len(p) != len(pdup) {
674 reason = fmt.Sprintf("new length %d != old length %d", len(p), len(pdup))
676 fmt.Fprintf(os.Stderr, "cmd/link: while reading object for '%v': duplicate symbol '%s', previous def at '%v', with mismatched payload: %s\n", r.unit.Lib, name, rdup.unit.Lib, reason)
678 // For the moment, allow DWARF subprogram DIEs for
679 // auto-generated wrapper functions. What seems to happen
680 // here is that we get different line numbers on formal
681 // params; I am guessing that the pos is being inherited
682 // from the spot where the wrapper is needed.
683 allowed := strings.HasPrefix(name, "go.info.go.interface") ||
684 strings.HasPrefix(name, "go.info.go.builtin") ||
685 strings.HasPrefix(name, "go.debuglines")
691 func (l *Loader) NStrictDupMsgs() int { return l.strictDupMsgs }
693 // Number of total symbols.
694 func (l *Loader) NSym() int {
695 return len(l.objSyms)
698 // Number of defined Go symbols.
699 func (l *Loader) NDef() int {
700 return int(l.extStart)
703 // Number of reachable symbols.
704 func (l *Loader) NReachableSym() int {
705 return l.attrReachable.Count()
708 // SymNameLen returns the length of the symbol name, trying hard not to load
710 func (l *Loader) SymNameLen(i Sym) int {
711 // Not much we can do about external symbols.
713 return len(l.SymName(i))
715 r, li := l.toLocal(i)
716 le := r.Sym(li).NameLen(r.Reader)
717 if !r.NeedNameExpansion() {
720 // Just load the symbol name. We don't know how expanded it'll be.
721 return len(l.SymName(i))
724 // Returns the raw (unpatched) name of the i-th symbol.
725 func (l *Loader) RawSymName(i Sym) string {
727 pp := l.getPayload(i)
730 r, li := l.toLocal(i)
731 return r.Sym(li).Name(r.Reader)
734 // Returns the (patched) name of the i-th symbol.
735 func (l *Loader) SymName(i Sym) string {
737 pp := l.getPayload(i)
740 r, li := l.toLocal(i)
741 name := r.Sym(li).Name(r.Reader)
742 if !r.NeedNameExpansion() {
745 return strings.Replace(name, "\"\".", r.pkgprefix, -1)
748 // Returns the version of the i-th symbol.
749 func (l *Loader) SymVersion(i Sym) int {
751 pp := l.getPayload(i)
754 r, li := l.toLocal(i)
755 return int(abiToVer(r.Sym(li).ABI(), r.version))
758 func (l *Loader) IsFileLocal(i Sym) bool {
759 return l.SymVersion(i) >= sym.SymVerStatic
762 // IsFromAssembly returns true if this symbol is derived from an
763 // object file generated by the Go assembler.
764 func (l *Loader) IsFromAssembly(i Sym) bool {
769 return r.FromAssembly()
772 // Returns the type of the i-th symbol.
773 func (l *Loader) SymType(i Sym) sym.SymKind {
775 pp := l.getPayload(i)
781 r, li := l.toLocal(i)
782 return sym.AbiSymKindToSymKind[objabi.SymKind(r.Sym(li).Type())]
785 // Returns the attributes of the i-th symbol.
786 func (l *Loader) SymAttr(i Sym) uint8 {
788 // TODO: do something? External symbols have different representation of attributes.
789 // For now, ReflectMethod, NoSplit, GoType, and Typelink are used and they cannot be
790 // set by external symbol.
793 r, li := l.toLocal(i)
794 return r.Sym(li).Flag()
797 // Returns the size of the i-th symbol.
798 func (l *Loader) SymSize(i Sym) int64 {
800 pp := l.getPayload(i)
803 r, li := l.toLocal(i)
804 return int64(r.Sym(li).Siz())
807 // AttrReachable returns true for symbols that are transitively
808 // referenced from the entry points. Unreachable symbols are not
809 // written to the output.
810 func (l *Loader) AttrReachable(i Sym) bool {
811 return l.attrReachable.Has(i)
814 // SetAttrReachable sets the reachability property for a symbol (see
816 func (l *Loader) SetAttrReachable(i Sym, v bool) {
818 l.attrReachable.Set(i)
820 l.attrReachable.Unset(i)
824 // AttrOnList returns true for symbols that are on some list (such as
825 // the list of all text symbols, or one of the lists of data symbols)
826 // and is consulted to avoid bugs where a symbol is put on a list
828 func (l *Loader) AttrOnList(i Sym) bool {
829 return l.attrOnList.Has(i)
832 // SetAttrOnList sets the "on list" property for a symbol (see
834 func (l *Loader) SetAttrOnList(i Sym, v bool) {
838 l.attrOnList.Unset(i)
842 // AttrLocal returns true for symbols that are only visible within the
843 // module (executable or shared library) being linked. This attribute
844 // is applied to thunks and certain other linker-generated symbols.
845 func (l *Loader) AttrLocal(i Sym) bool {
846 return l.attrLocal.Has(i)
849 // SetAttrLocal the "local" property for a symbol (see AttrLocal above).
850 func (l *Loader) SetAttrLocal(i Sym, v bool) {
858 // AttrUsedInIface returns true for a type symbol that is used in
860 func (l *Loader) AttrUsedInIface(i Sym) bool {
861 return l.attrUsedInIface.Has(i)
864 func (l *Loader) SetAttrUsedInIface(i Sym, v bool) {
866 l.attrUsedInIface.Set(i)
868 l.attrUsedInIface.Unset(i)
872 // SymAddr checks that a symbol is reachable, and returns its value.
873 func (l *Loader) SymAddr(i Sym) int64 {
874 if !l.AttrReachable(i) {
875 panic("unreachable symbol in symaddr")
880 // AttrNotInSymbolTable returns true for symbols that should not be
881 // added to the symbol table of the final generated load module.
882 func (l *Loader) AttrNotInSymbolTable(i Sym) bool {
883 return l.attrNotInSymbolTable.Has(i)
886 // SetAttrNotInSymbolTable the "not in symtab" property for a symbol
887 // (see AttrNotInSymbolTable above).
888 func (l *Loader) SetAttrNotInSymbolTable(i Sym, v bool) {
890 l.attrNotInSymbolTable.Set(i)
892 l.attrNotInSymbolTable.Unset(i)
896 // AttrVisibilityHidden symbols returns true for ELF symbols with
897 // visibility set to STV_HIDDEN. They become local symbols in
898 // the final executable. Only relevant when internally linking
899 // on an ELF platform.
900 func (l *Loader) AttrVisibilityHidden(i Sym) bool {
901 if !l.IsExternal(i) {
904 return l.attrVisibilityHidden.Has(l.extIndex(i))
907 // SetAttrVisibilityHidden sets the "hidden visibility" property for a
908 // symbol (see AttrVisibilityHidden).
909 func (l *Loader) SetAttrVisibilityHidden(i Sym, v bool) {
910 if !l.IsExternal(i) {
911 panic("tried to set visibility attr on non-external symbol")
914 l.attrVisibilityHidden.Set(l.extIndex(i))
916 l.attrVisibilityHidden.Unset(l.extIndex(i))
920 // AttrDuplicateOK returns true for a symbol that can be present in
921 // multiple object files.
922 func (l *Loader) AttrDuplicateOK(i Sym) bool {
923 if !l.IsExternal(i) {
924 // TODO: if this path winds up being taken frequently, it
925 // might make more sense to copy the flag value out of the object
926 // into a larger bitmap during preload.
927 r, li := l.toLocal(i)
928 return r.Sym(li).Dupok()
930 return l.attrDuplicateOK.Has(l.extIndex(i))
933 // SetAttrDuplicateOK sets the "duplicate OK" property for an external
934 // symbol (see AttrDuplicateOK).
935 func (l *Loader) SetAttrDuplicateOK(i Sym, v bool) {
936 if !l.IsExternal(i) {
937 panic("tried to set dupok attr on non-external symbol")
940 l.attrDuplicateOK.Set(l.extIndex(i))
942 l.attrDuplicateOK.Unset(l.extIndex(i))
946 // AttrShared returns true for symbols compiled with the -shared option.
947 func (l *Loader) AttrShared(i Sym) bool {
948 if !l.IsExternal(i) {
949 // TODO: if this path winds up being taken frequently, it
950 // might make more sense to copy the flag value out of the
951 // object into a larger bitmap during preload.
955 return l.attrShared.Has(l.extIndex(i))
958 // SetAttrShared sets the "shared" property for an external
959 // symbol (see AttrShared).
960 func (l *Loader) SetAttrShared(i Sym, v bool) {
961 if !l.IsExternal(i) {
962 panic(fmt.Sprintf("tried to set shared attr on non-external symbol %d %s", i, l.SymName(i)))
965 l.attrShared.Set(l.extIndex(i))
967 l.attrShared.Unset(l.extIndex(i))
971 // AttrExternal returns true for function symbols loaded from host
973 func (l *Loader) AttrExternal(i Sym) bool {
974 if !l.IsExternal(i) {
977 return l.attrExternal.Has(l.extIndex(i))
980 // SetAttrExternal sets the "external" property for an host object
981 // symbol (see AttrExternal).
982 func (l *Loader) SetAttrExternal(i Sym, v bool) {
983 if !l.IsExternal(i) {
984 panic(fmt.Sprintf("tried to set external attr on non-external symbol %q", l.RawSymName(i)))
987 l.attrExternal.Set(l.extIndex(i))
989 l.attrExternal.Unset(l.extIndex(i))
993 // AttrSpecial returns true for a symbols that do not have their
994 // address (i.e. Value) computed by the usual mechanism of
995 // data.go:dodata() & data.go:address().
996 func (l *Loader) AttrSpecial(i Sym) bool {
997 _, ok := l.attrSpecial[i]
1001 // SetAttrSpecial sets the "special" property for a symbol (see
1003 func (l *Loader) SetAttrSpecial(i Sym, v bool) {
1005 l.attrSpecial[i] = struct{}{}
1007 delete(l.attrSpecial, i)
1011 // AttrCgoExportDynamic returns true for a symbol that has been
1012 // specially marked via the "cgo_export_dynamic" compiler directive
1013 // written by cgo (in response to //export directives in the source).
1014 func (l *Loader) AttrCgoExportDynamic(i Sym) bool {
1015 _, ok := l.attrCgoExportDynamic[i]
1019 // SetAttrCgoExportDynamic sets the "cgo_export_dynamic" for a symbol
1020 // (see AttrCgoExportDynamic).
1021 func (l *Loader) SetAttrCgoExportDynamic(i Sym, v bool) {
1023 l.attrCgoExportDynamic[i] = struct{}{}
1025 delete(l.attrCgoExportDynamic, i)
1029 // AttrCgoExportStatic returns true for a symbol that has been
1030 // specially marked via the "cgo_export_static" directive
1032 func (l *Loader) AttrCgoExportStatic(i Sym) bool {
1033 _, ok := l.attrCgoExportStatic[i]
1037 // SetAttrCgoExportStatic sets the "cgo_export_static" for a symbol
1038 // (see AttrCgoExportStatic).
1039 func (l *Loader) SetAttrCgoExportStatic(i Sym, v bool) {
1041 l.attrCgoExportStatic[i] = struct{}{}
1043 delete(l.attrCgoExportStatic, i)
1047 // IsGeneratedSym returns true if a symbol's been previously marked as a
1048 // generator symbol through the SetIsGeneratedSym. The functions for generator
1049 // symbols are kept in the Link context.
1050 func (l *Loader) IsGeneratedSym(i Sym) bool {
1051 _, ok := l.generatedSyms[i]
1055 // SetIsGeneratedSym marks symbols as generated symbols. Data shouldn't be
1056 // stored in generated symbols, and a function is registered and called for
1057 // each of these symbols.
1058 func (l *Loader) SetIsGeneratedSym(i Sym, v bool) {
1059 if !l.IsExternal(i) {
1060 panic("only external symbols can be generated")
1063 l.generatedSyms[i] = struct{}{}
1065 delete(l.generatedSyms, i)
1069 func (l *Loader) AttrCgoExport(i Sym) bool {
1070 return l.AttrCgoExportDynamic(i) || l.AttrCgoExportStatic(i)
1073 // AttrReadOnly returns true for a symbol whose underlying data
1074 // is stored via a read-only mmap.
1075 func (l *Loader) AttrReadOnly(i Sym) bool {
1076 if v, ok := l.attrReadOnly[i]; ok {
1079 if l.IsExternal(i) {
1080 pp := l.getPayload(i)
1082 return l.objs[pp.objidx].r.ReadOnly()
1086 r, _ := l.toLocal(i)
1090 // SetAttrReadOnly sets the "data is read only" property for a symbol
1091 // (see AttrReadOnly).
1092 func (l *Loader) SetAttrReadOnly(i Sym, v bool) {
1093 l.attrReadOnly[i] = v
1096 // AttrSubSymbol returns true for symbols that are listed as a
1097 // sub-symbol of some other outer symbol. The sub/outer mechanism is
1098 // used when loading host objects (sections from the host object
1099 // become regular linker symbols and symbols go on the Sub list of
1100 // their section) and for constructing the global offset table when
1101 // internally linking a dynamic executable.
1103 // Note that in later stages of the linker, we set Outer(S) to some
1104 // container symbol C, but don't set Sub(C). Thus we have two
1105 // distinct scenarios:
1107 // - Outer symbol covers the address ranges of its sub-symbols.
1108 // Outer.Sub is set in this case.
1109 // - Outer symbol doesn't conver the address ranges. It is zero-sized
1110 // and doesn't have sub-symbols. In the case, the inner symbol is
1111 // not actually a "SubSymbol". (Tricky!)
1113 // This method returns TRUE only for sub-symbols in the first scenario.
1115 // FIXME: would be better to do away with this and have a better way
1116 // to represent container symbols.
1118 func (l *Loader) AttrSubSymbol(i Sym) bool {
1119 // we don't explicitly store this attribute any more -- return
1120 // a value based on the sub-symbol setting.
1125 return l.SubSym(o) != 0
1128 // Note that we don't have a 'SetAttrSubSymbol' method in the loader;
1129 // clients should instead use the AddInteriorSym method to establish
1130 // containment relationships for host object symbols.
1132 // Returns whether the i-th symbol has ReflectMethod attribute set.
1133 func (l *Loader) IsReflectMethod(i Sym) bool {
1134 return l.SymAttr(i)&goobj.SymFlagReflectMethod != 0
1137 // Returns whether the i-th symbol is nosplit.
1138 func (l *Loader) IsNoSplit(i Sym) bool {
1139 return l.SymAttr(i)&goobj.SymFlagNoSplit != 0
1142 // Returns whether this is a Go type symbol.
1143 func (l *Loader) IsGoType(i Sym) bool {
1144 return l.SymAttr(i)&goobj.SymFlagGoType != 0
1147 // Returns whether this symbol should be included in typelink.
1148 func (l *Loader) IsTypelink(i Sym) bool {
1149 return l.SymAttr(i)&goobj.SymFlagTypelink != 0
1152 // Returns whether this symbol is an itab symbol.
1153 func (l *Loader) IsItab(i Sym) bool {
1154 if l.IsExternal(i) {
1157 r, li := l.toLocal(i)
1158 return r.Sym(li).IsItab()
1161 // Return whether this is a trampoline of a deferreturn call.
1162 func (l *Loader) IsDeferReturnTramp(i Sym) bool {
1163 return l.deferReturnTramp[i]
1166 // Set that i is a trampoline of a deferreturn call.
1167 func (l *Loader) SetIsDeferReturnTramp(i Sym, v bool) {
1168 l.deferReturnTramp[i] = v
1171 // growValues grows the slice used to store symbol values.
1172 func (l *Loader) growValues(reqLen int) {
1173 curLen := len(l.values)
1174 if reqLen > curLen {
1175 l.values = append(l.values, make([]int64, reqLen+1-curLen)...)
1179 // SymValue returns the value of the i-th symbol. i is global index.
1180 func (l *Loader) SymValue(i Sym) int64 {
1184 // SetSymValue sets the value of the i-th symbol. i is global index.
1185 func (l *Loader) SetSymValue(i Sym, val int64) {
1189 // AddToSymValue adds to the value of the i-th symbol. i is the global index.
1190 func (l *Loader) AddToSymValue(i Sym, val int64) {
1194 // Returns the symbol content of the i-th symbol. i is global index.
1195 func (l *Loader) Data(i Sym) []byte {
1196 if l.IsExternal(i) {
1197 pp := l.getPayload(i)
1203 r, li := l.toLocal(i)
1207 // FreeData clears the symbol data of an external symbol, allowing the memory
1208 // to be freed earlier. No-op for non-external symbols.
1209 // i is global index.
1210 func (l *Loader) FreeData(i Sym) {
1211 if l.IsExternal(i) {
1212 pp := l.getPayload(i)
1219 // SymAlign returns the alignment for a symbol.
1220 func (l *Loader) SymAlign(i Sym) int32 {
1221 if int(i) >= len(l.align) {
1222 // align is extended lazily -- it the sym in question is
1223 // outside the range of the existing slice, then we assume its
1224 // alignment has not yet been set.
1227 // TODO: would it make sense to return an arch-specific
1228 // alignment depending on section type? E.g. STEXT => 32,
1234 return int32(1 << (abits - 1))
1237 // SetSymAlign sets the alignment for a symbol.
1238 func (l *Loader) SetSymAlign(i Sym, align int32) {
1239 // Reject nonsense alignments.
1240 if align < 0 || align&(align-1) != 0 {
1241 panic("bad alignment value")
1243 if int(i) >= len(l.align) {
1244 l.align = append(l.align, make([]uint8, l.NSym()-len(l.align))...)
1249 l.align[i] = uint8(bits.Len32(uint32(align)))
1252 // SymValue returns the section of the i-th symbol. i is global index.
1253 func (l *Loader) SymSect(i Sym) *sym.Section {
1254 if int(i) >= len(l.symSects) {
1255 // symSects is extended lazily -- it the sym in question is
1256 // outside the range of the existing slice, then we assume its
1257 // section has not yet been set.
1260 return l.sects[l.symSects[i]]
1263 // SetSymSect sets the section of the i-th symbol. i is global index.
1264 func (l *Loader) SetSymSect(i Sym, sect *sym.Section) {
1265 if int(i) >= len(l.symSects) {
1266 l.symSects = append(l.symSects, make([]uint16, l.NSym()-len(l.symSects))...)
1268 l.symSects[i] = sect.Index
1271 // growSects grows the slice used to store symbol sections.
1272 func (l *Loader) growSects(reqLen int) {
1273 curLen := len(l.symSects)
1274 if reqLen > curLen {
1275 l.symSects = append(l.symSects, make([]uint16, reqLen+1-curLen)...)
1279 // NewSection creates a new (output) section.
1280 func (l *Loader) NewSection() *sym.Section {
1281 sect := new(sym.Section)
1283 if idx != int(uint16(idx)) {
1284 panic("too many sections created")
1286 sect.Index = uint16(idx)
1287 l.sects = append(l.sects, sect)
1291 // SymDynImplib returns the "dynimplib" attribute for the specified
1292 // symbol, making up a portion of the info for a symbol specified
1293 // on a "cgo_import_dynamic" compiler directive.
1294 func (l *Loader) SymDynimplib(i Sym) string {
1295 return l.dynimplib[i]
1298 // SetSymDynimplib sets the "dynimplib" attribute for a symbol.
1299 func (l *Loader) SetSymDynimplib(i Sym, value string) {
1300 // reject bad symbols
1301 if i >= Sym(len(l.objSyms)) || i == 0 {
1302 panic("bad symbol index in SetDynimplib")
1305 delete(l.dynimplib, i)
1307 l.dynimplib[i] = value
1311 // SymDynimpvers returns the "dynimpvers" attribute for the specified
1312 // symbol, making up a portion of the info for a symbol specified
1313 // on a "cgo_import_dynamic" compiler directive.
1314 func (l *Loader) SymDynimpvers(i Sym) string {
1315 return l.dynimpvers[i]
1318 // SetSymDynimpvers sets the "dynimpvers" attribute for a symbol.
1319 func (l *Loader) SetSymDynimpvers(i Sym, value string) {
1320 // reject bad symbols
1321 if i >= Sym(len(l.objSyms)) || i == 0 {
1322 panic("bad symbol index in SetDynimpvers")
1325 delete(l.dynimpvers, i)
1327 l.dynimpvers[i] = value
1331 // SymExtname returns the "extname" value for the specified
1333 func (l *Loader) SymExtname(i Sym) string {
1334 if s, ok := l.extname[i]; ok {
1340 // SetSymExtname sets the "extname" attribute for a symbol.
1341 func (l *Loader) SetSymExtname(i Sym, value string) {
1342 // reject bad symbols
1343 if i >= Sym(len(l.objSyms)) || i == 0 {
1344 panic("bad symbol index in SetExtname")
1347 delete(l.extname, i)
1349 l.extname[i] = value
1353 // SymElfType returns the previously recorded ELF type for a symbol
1354 // (used only for symbols read from shared libraries by ldshlibsyms).
1355 // It is not set for symbols defined by the packages being linked or
1356 // by symbols read by ldelf (and so is left as elf.STT_NOTYPE).
1357 func (l *Loader) SymElfType(i Sym) elf.SymType {
1358 if et, ok := l.elfType[i]; ok {
1361 return elf.STT_NOTYPE
1364 // SetSymElfType sets the elf type attribute for a symbol.
1365 func (l *Loader) SetSymElfType(i Sym, et elf.SymType) {
1366 // reject bad symbols
1367 if i >= Sym(len(l.objSyms)) || i == 0 {
1368 panic("bad symbol index in SetSymElfType")
1370 if et == elf.STT_NOTYPE {
1371 delete(l.elfType, i)
1377 // SymElfSym returns the ELF symbol index for a given loader
1378 // symbol, assigned during ELF symtab generation.
1379 func (l *Loader) SymElfSym(i Sym) int32 {
1383 // SetSymElfSym sets the elf symbol index for a symbol.
1384 func (l *Loader) SetSymElfSym(i Sym, es int32) {
1386 panic("bad sym index")
1395 // SymLocalElfSym returns the "local" ELF symbol index for a given loader
1396 // symbol, assigned during ELF symtab generation.
1397 func (l *Loader) SymLocalElfSym(i Sym) int32 {
1398 return l.localElfSym[i]
1401 // SetSymLocalElfSym sets the "local" elf symbol index for a symbol.
1402 func (l *Loader) SetSymLocalElfSym(i Sym, es int32) {
1404 panic("bad sym index")
1407 delete(l.localElfSym, i)
1409 l.localElfSym[i] = es
1413 // SymPlt returns the plt value for pe symbols.
1414 func (l *Loader) SymPlt(s Sym) int32 {
1415 if v, ok := l.plt[s]; ok {
1421 // SetPlt sets the plt value for pe symbols.
1422 func (l *Loader) SetPlt(i Sym, v int32) {
1423 if i >= Sym(len(l.objSyms)) || i == 0 {
1424 panic("bad symbol for SetPlt")
1433 // SymGot returns the got value for pe symbols.
1434 func (l *Loader) SymGot(s Sym) int32 {
1435 if v, ok := l.got[s]; ok {
1441 // SetGot sets the got value for pe symbols.
1442 func (l *Loader) SetGot(i Sym, v int32) {
1443 if i >= Sym(len(l.objSyms)) || i == 0 {
1444 panic("bad symbol for SetGot")
1453 // SymDynid returns the "dynid" property for the specified symbol.
1454 func (l *Loader) SymDynid(i Sym) int32 {
1455 if s, ok := l.dynid[i]; ok {
1461 // SetSymDynid sets the "dynid" property for a symbol.
1462 func (l *Loader) SetSymDynid(i Sym, val int32) {
1463 // reject bad symbols
1464 if i >= Sym(len(l.objSyms)) || i == 0 {
1465 panic("bad symbol index in SetSymDynid")
1474 // DynIdSyms returns the set of symbols for which dynID is set to an
1475 // interesting (non-default) value. This is expected to be a fairly
1477 func (l *Loader) DynidSyms() []Sym {
1478 sl := make([]Sym, 0, len(l.dynid))
1479 for s := range l.dynid {
1482 sort.Slice(sl, func(i, j int) bool { return sl[i] < sl[j] })
1486 // SymGoType returns the 'Gotype' property for a given symbol (set by
1487 // the Go compiler for variable symbols). This version relies on
1488 // reading aux symbols for the target sym -- it could be that a faster
1489 // approach would be to check for gotype during preload and copy the
1490 // results in to a map (might want to try this at some point and see
1491 // if it helps speed things up).
1492 func (l *Loader) SymGoType(i Sym) Sym {
1494 var auxs []goobj.Aux
1495 if l.IsExternal(i) {
1496 pp := l.getPayload(i)
1497 r = l.objs[pp.objidx].r
1501 r, li = l.toLocal(i)
1504 for j := range auxs {
1507 case goobj.AuxGotype:
1508 return l.resolve(r, a.Sym())
1514 // SymUnit returns the compilation unit for a given symbol (which will
1515 // typically be nil for external or linker-manufactured symbols).
1516 func (l *Loader) SymUnit(i Sym) *sym.CompilationUnit {
1517 if l.IsExternal(i) {
1518 pp := l.getPayload(i)
1520 r := l.objs[pp.objidx].r
1525 r, _ := l.toLocal(i)
1529 // SymPkg returns the package where the symbol came from (for
1530 // regular compiler-generated Go symbols), but in the case of
1531 // building with "-linkshared" (when a symbol is read from a
1532 // shared library), will hold the library name.
1533 // NOTE: this corresponds to sym.Symbol.File field.
1534 func (l *Loader) SymPkg(i Sym) string {
1535 if f, ok := l.symPkg[i]; ok {
1538 if l.IsExternal(i) {
1539 pp := l.getPayload(i)
1541 r := l.objs[pp.objidx].r
1542 return r.unit.Lib.Pkg
1546 r, _ := l.toLocal(i)
1547 return r.unit.Lib.Pkg
1550 // SetSymPkg sets the package/library for a symbol. This is
1551 // needed mainly for external symbols, specifically those imported
1552 // from shared libraries.
1553 func (l *Loader) SetSymPkg(i Sym, pkg string) {
1554 // reject bad symbols
1555 if i >= Sym(len(l.objSyms)) || i == 0 {
1556 panic("bad symbol index in SetSymPkg")
1561 // SymLocalentry returns the "local entry" value for the specified
1563 func (l *Loader) SymLocalentry(i Sym) uint8 {
1564 return l.localentry[i]
1567 // SetSymLocalentry sets the "local entry" attribute for a symbol.
1568 func (l *Loader) SetSymLocalentry(i Sym, value uint8) {
1569 // reject bad symbols
1570 if i >= Sym(len(l.objSyms)) || i == 0 {
1571 panic("bad symbol index in SetSymLocalentry")
1574 delete(l.localentry, i)
1576 l.localentry[i] = value
1580 // Returns the number of aux symbols given a global index.
1581 func (l *Loader) NAux(i Sym) int {
1582 if l.IsExternal(i) {
1585 r, li := l.toLocal(i)
1589 // Returns the "handle" to the j-th aux symbol of the i-th symbol.
1590 func (l *Loader) Aux(i Sym, j int) Aux {
1591 if l.IsExternal(i) {
1594 r, li := l.toLocal(i)
1595 if j >= r.NAux(li) {
1598 return Aux{r.Aux(li, j), r, l}
1601 // GetFuncDwarfAuxSyms collects and returns the auxiliary DWARF
1602 // symbols associated with a given function symbol. Prior to the
1603 // introduction of the loader, this was done purely using name
1604 // lookups, e.f. for function with name XYZ we would then look up
1605 // go.info.XYZ, etc.
1606 func (l *Loader) GetFuncDwarfAuxSyms(fnSymIdx Sym) (auxDwarfInfo, auxDwarfLoc, auxDwarfRanges, auxDwarfLines Sym) {
1607 if l.SymType(fnSymIdx) != sym.STEXT {
1608 log.Fatalf("error: non-function sym %d/%s t=%s passed to GetFuncDwarfAuxSyms", fnSymIdx, l.SymName(fnSymIdx), l.SymType(fnSymIdx).String())
1610 if l.IsExternal(fnSymIdx) {
1611 // Current expectation is that any external function will
1612 // not have auxsyms.
1615 r, li := l.toLocal(fnSymIdx)
1617 for i := range auxs {
1620 case goobj.AuxDwarfInfo:
1621 auxDwarfInfo = l.resolve(r, a.Sym())
1622 if l.SymType(auxDwarfInfo) != sym.SDWARFFCN {
1623 panic("aux dwarf info sym with wrong type")
1625 case goobj.AuxDwarfLoc:
1626 auxDwarfLoc = l.resolve(r, a.Sym())
1627 if l.SymType(auxDwarfLoc) != sym.SDWARFLOC {
1628 panic("aux dwarf loc sym with wrong type")
1630 case goobj.AuxDwarfRanges:
1631 auxDwarfRanges = l.resolve(r, a.Sym())
1632 if l.SymType(auxDwarfRanges) != sym.SDWARFRANGE {
1633 panic("aux dwarf ranges sym with wrong type")
1635 case goobj.AuxDwarfLines:
1636 auxDwarfLines = l.resolve(r, a.Sym())
1637 if l.SymType(auxDwarfLines) != sym.SDWARFLINES {
1638 panic("aux dwarf lines sym with wrong type")
1645 // AddInteriorSym sets up 'interior' as an interior symbol of
1646 // container/payload symbol 'container'. An interior symbol does not
1647 // itself have data, but gives a name to a subrange of the data in its
1648 // container symbol. The container itself may or may not have a name.
1649 // This method is intended primarily for use in the host object
1650 // loaders, to capture the semantics of symbols and sections in an
1651 // object file. When reading a host object file, we'll typically
1652 // encounter a static section symbol (ex: ".text") containing content
1653 // for a collection of functions, then a series of ELF (or macho, etc)
1654 // symbol table entries each of which points into a sub-section
1655 // (offset and length) of its corresponding container symbol. Within
1656 // the go linker we create a loader.Sym for the container (which is
1657 // expected to have the actual content/payload) and then a set of
1658 // interior loader.Sym's that point into a portion of the container.
1659 func (l *Loader) AddInteriorSym(container Sym, interior Sym) {
1660 // Container symbols are expected to have content/data.
1661 // NB: this restriction may turn out to be too strict (it's possible
1662 // to imagine a zero-sized container with an interior symbol pointing
1663 // into it); it's ok to relax or remove it if we counter an
1664 // oddball host object that triggers this.
1665 if l.SymSize(container) == 0 && len(l.Data(container)) == 0 {
1666 panic("unexpected empty container symbol")
1668 // The interior symbols for a container are not expected to have
1669 // content/data or relocations.
1670 if len(l.Data(interior)) != 0 {
1671 panic("unexpected non-empty interior symbol")
1673 // Interior symbol is expected to be in the symbol table.
1674 if l.AttrNotInSymbolTable(interior) {
1675 panic("interior symbol must be in symtab")
1677 // Only a single level of containment is allowed.
1678 if l.OuterSym(container) != 0 {
1679 panic("outer has outer itself")
1681 // Interior sym should not already have a sibling.
1682 if l.SubSym(interior) != 0 {
1683 panic("sub set for subsym")
1685 // Interior sym should not already point at a container.
1686 if l.OuterSym(interior) != 0 {
1687 panic("outer already set for subsym")
1689 l.sub[interior] = l.sub[container]
1690 l.sub[container] = interior
1691 l.outer[interior] = container
1694 // OuterSym gets the outer symbol for host object loaded symbols.
1695 func (l *Loader) OuterSym(i Sym) Sym {
1696 // FIXME: add check for isExternal?
1700 // SubSym gets the subsymbol for host object loaded symbols.
1701 func (l *Loader) SubSym(i Sym) Sym {
1702 // NB: note -- no check for l.isExternal(), since I am pretty sure
1703 // that later phases in the linker set subsym for "type." syms
1707 // SetCarrierSym declares that 'c' is the carrier or container symbol
1708 // for 's'. Carrier symbols are used in the linker to as a container
1709 // for a collection of sub-symbols where the content of the
1710 // sub-symbols is effectively concatenated to form the content of the
1711 // carrier. The carrier is given a name in the output symbol table
1712 // while the sub-symbol names are not. For example, the Go compiler
1713 // emits named string symbols (type SGOSTRING) when compiling a
1714 // package; after being deduplicated, these symbols are collected into
1715 // a single unit by assigning them a new carrier symbol named
1716 // "go.string.*" (which appears in the final symbol table for the
1717 // output load module).
1718 func (l *Loader) SetCarrierSym(s Sym, c Sym) {
1720 panic("invalid carrier in SetCarrierSym")
1723 panic("invalid sub-symbol in SetCarrierSym")
1725 // Carrier symbols are not expected to have content/data. It is
1726 // ok for them to have non-zero size (to allow for use of generator
1728 if len(l.Data(c)) != 0 {
1729 panic("unexpected non-empty carrier symbol")
1732 // relocsym's foldSubSymbolOffset requires that we only
1733 // have a single level of containment-- enforce here.
1734 if l.outer[c] != 0 {
1735 panic("invalid nested carrier sym")
1739 // Initialize Reachable bitmap and its siblings for running deadcode pass.
1740 func (l *Loader) InitReachable() {
1741 l.growAttrBitmaps(l.NSym() + 1)
1744 type symWithVal struct {
1748 type bySymValue []symWithVal
1750 func (s bySymValue) Len() int { return len(s) }
1751 func (s bySymValue) Swap(i, j int) { s[i], s[j] = s[j], s[i] }
1752 func (s bySymValue) Less(i, j int) bool { return s[i].v < s[j].v }
1754 // SortSub walks through the sub-symbols for 's' and sorts them
1755 // in place by increasing value. Return value is the new
1756 // sub symbol for the specified outer symbol.
1757 func (l *Loader) SortSub(s Sym) Sym {
1759 if s == 0 || l.sub[s] == 0 {
1763 // Sort symbols using a slice first. Use a stable sort on the off
1764 // chance that there's more than once symbol with the same value,
1765 // so as to preserve reproducible builds.
1766 sl := []symWithVal{}
1767 for ss := l.sub[s]; ss != 0; ss = l.sub[ss] {
1768 sl = append(sl, symWithVal{s: ss, v: l.SymValue(ss)})
1770 sort.Stable(bySymValue(sl))
1772 // Then apply any changes needed to the sub map.
1774 for i := len(sl) - 1; i >= 0; i-- {
1780 // Update sub for outer symbol, then return
1785 // SortSyms sorts a list of symbols by their value.
1786 func (l *Loader) SortSyms(ss []Sym) {
1787 sort.SliceStable(ss, func(i, j int) bool { return l.SymValue(ss[i]) < l.SymValue(ss[j]) })
1790 // Insure that reachable bitmap and its siblings have enough size.
1791 func (l *Loader) growAttrBitmaps(reqLen int) {
1792 if reqLen > l.attrReachable.Len() {
1793 // These are indexed by global symbol
1794 l.attrReachable = growBitmap(reqLen, l.attrReachable)
1795 l.attrOnList = growBitmap(reqLen, l.attrOnList)
1796 l.attrLocal = growBitmap(reqLen, l.attrLocal)
1797 l.attrNotInSymbolTable = growBitmap(reqLen, l.attrNotInSymbolTable)
1798 l.attrUsedInIface = growBitmap(reqLen, l.attrUsedInIface)
1800 l.growExtAttrBitmaps()
1803 func (l *Loader) growExtAttrBitmaps() {
1804 // These are indexed by external symbol index (e.g. l.extIndex(i))
1805 extReqLen := len(l.payloads)
1806 if extReqLen > l.attrVisibilityHidden.Len() {
1807 l.attrVisibilityHidden = growBitmap(extReqLen, l.attrVisibilityHidden)
1808 l.attrDuplicateOK = growBitmap(extReqLen, l.attrDuplicateOK)
1809 l.attrShared = growBitmap(extReqLen, l.attrShared)
1810 l.attrExternal = growBitmap(extReqLen, l.attrExternal)
1814 func (relocs *Relocs) Count() int { return len(relocs.rs) }
1816 // At returns the j-th reloc for a global symbol.
1817 func (relocs *Relocs) At(j int) Reloc {
1818 if relocs.l.isExtReader(relocs.r) {
1819 return Reloc{&relocs.rs[j], relocs.r, relocs.l}
1821 return Reloc{&relocs.rs[j], relocs.r, relocs.l}
1824 // Relocs returns a Relocs object for the given global sym.
1825 func (l *Loader) Relocs(i Sym) Relocs {
1826 r, li := l.toLocal(i)
1828 panic(fmt.Sprintf("trying to get oreader for invalid sym %d\n\n", i))
1830 return l.relocs(r, li)
1833 // Relocs returns a Relocs object given a local sym index and reader.
1834 func (l *Loader) relocs(r *oReader, li uint32) Relocs {
1835 var rs []goobj.Reloc
1836 if l.isExtReader(r) {
1837 pp := l.payloads[li]
1850 // FuncInfo provides hooks to access goobj.FuncInfo in the objects.
1851 type FuncInfo struct {
1856 lengths goobj.FuncInfoLengths
1859 func (fi *FuncInfo) Valid() bool { return fi.r != nil }
1861 func (fi *FuncInfo) Args() int {
1862 return int((*goobj.FuncInfo)(nil).ReadArgs(fi.data))
1865 func (fi *FuncInfo) Locals() int {
1866 return int((*goobj.FuncInfo)(nil).ReadLocals(fi.data))
1869 func (fi *FuncInfo) FuncID() objabi.FuncID {
1870 return (*goobj.FuncInfo)(nil).ReadFuncID(fi.data)
1873 func (fi *FuncInfo) FuncFlag() objabi.FuncFlag {
1874 return (*goobj.FuncInfo)(nil).ReadFuncFlag(fi.data)
1877 func (fi *FuncInfo) Pcsp() Sym {
1878 sym := (*goobj.FuncInfo)(nil).ReadPcsp(fi.data)
1879 return fi.l.resolve(fi.r, sym)
1882 func (fi *FuncInfo) Pcfile() Sym {
1883 sym := (*goobj.FuncInfo)(nil).ReadPcfile(fi.data)
1884 return fi.l.resolve(fi.r, sym)
1887 func (fi *FuncInfo) Pcline() Sym {
1888 sym := (*goobj.FuncInfo)(nil).ReadPcline(fi.data)
1889 return fi.l.resolve(fi.r, sym)
1892 func (fi *FuncInfo) Pcinline() Sym {
1893 sym := (*goobj.FuncInfo)(nil).ReadPcinline(fi.data)
1894 return fi.l.resolve(fi.r, sym)
1897 // Preload has to be called prior to invoking the various methods
1898 // below related to pcdata, funcdataoff, files, and inltree nodes.
1899 func (fi *FuncInfo) Preload() {
1900 fi.lengths = (*goobj.FuncInfo)(nil).ReadFuncInfoLengths(fi.data)
1903 func (fi *FuncInfo) Pcdata() []Sym {
1904 if !fi.lengths.Initialized {
1905 panic("need to call Preload first")
1907 syms := (*goobj.FuncInfo)(nil).ReadPcdata(fi.data)
1908 ret := make([]Sym, len(syms))
1909 for i := range ret {
1910 ret[i] = fi.l.resolve(fi.r, syms[i])
1915 func (fi *FuncInfo) NumFuncdataoff() uint32 {
1916 if !fi.lengths.Initialized {
1917 panic("need to call Preload first")
1919 return fi.lengths.NumFuncdataoff
1922 func (fi *FuncInfo) Funcdataoff(k int) int64 {
1923 if !fi.lengths.Initialized {
1924 panic("need to call Preload first")
1926 return (*goobj.FuncInfo)(nil).ReadFuncdataoff(fi.data, fi.lengths.FuncdataoffOff, uint32(k))
1929 func (fi *FuncInfo) Funcdata(syms []Sym) []Sym {
1930 if !fi.lengths.Initialized {
1931 panic("need to call Preload first")
1933 if int(fi.lengths.NumFuncdataoff) > cap(syms) {
1934 syms = make([]Sym, 0, fi.lengths.NumFuncdataoff)
1938 for j := range fi.auxs {
1940 if a.Type() == goobj.AuxFuncdata {
1941 syms = append(syms, fi.l.resolve(fi.r, a.Sym()))
1947 func (fi *FuncInfo) NumFile() uint32 {
1948 if !fi.lengths.Initialized {
1949 panic("need to call Preload first")
1951 return fi.lengths.NumFile
1954 func (fi *FuncInfo) File(k int) goobj.CUFileIndex {
1955 if !fi.lengths.Initialized {
1956 panic("need to call Preload first")
1958 return (*goobj.FuncInfo)(nil).ReadFile(fi.data, fi.lengths.FileOff, uint32(k))
1961 // TopFrame returns true if the function associated with this FuncInfo
1962 // is an entry point, meaning that unwinders should stop when they hit
1964 func (fi *FuncInfo) TopFrame() bool {
1965 return (fi.FuncFlag() & objabi.FuncFlag_TOPFRAME) != 0
1968 type InlTreeNode struct {
1970 File goobj.CUFileIndex
1976 func (fi *FuncInfo) NumInlTree() uint32 {
1977 if !fi.lengths.Initialized {
1978 panic("need to call Preload first")
1980 return fi.lengths.NumInlTree
1983 func (fi *FuncInfo) InlTree(k int) InlTreeNode {
1984 if !fi.lengths.Initialized {
1985 panic("need to call Preload first")
1987 node := (*goobj.FuncInfo)(nil).ReadInlTree(fi.data, fi.lengths.InlTreeOff, uint32(k))
1989 Parent: node.Parent,
1992 Func: fi.l.resolve(fi.r, node.Func),
1993 ParentPC: node.ParentPC,
1997 func (l *Loader) FuncInfo(i Sym) FuncInfo {
1999 var auxs []goobj.Aux
2000 if l.IsExternal(i) {
2001 pp := l.getPayload(i)
2005 r = l.objs[pp.objidx].r
2009 r, li = l.toLocal(i)
2012 for j := range auxs {
2014 if a.Type() == goobj.AuxFuncInfo {
2015 b := r.Data(a.Sym().SymIdx)
2016 return FuncInfo{l, r, b, auxs, goobj.FuncInfoLengths{}}
2022 // Preload a package: adds autolib.
2023 // Does not add defined package or non-packaged symbols to the symbol table.
2024 // These are done in LoadSyms.
2025 // Does not read symbol data.
2026 // Returns the fingerprint of the object.
2027 func (l *Loader) Preload(localSymVersion int, f *bio.Reader, lib *sym.Library, unit *sym.CompilationUnit, length int64) goobj.FingerprintType {
2028 roObject, readonly, err := f.Slice(uint64(length)) // TODO: no need to map blocks that are for tools only (e.g. RefName)
2030 log.Fatal("cannot read object file:", err)
2032 r := goobj.NewReaderFromBytes(roObject, readonly)
2034 if len(roObject) >= 8 && bytes.Equal(roObject[:8], []byte("\x00go114ld")) {
2035 log.Fatalf("found object file %s in old format", f.File().Name())
2037 panic("cannot read object file")
2039 pkgprefix := objabi.PathToPrefix(lib.Pkg) + "."
2041 nhashed64def := r.NHashed64def()
2042 nhasheddef := r.NHasheddef()
2046 version: localSymVersion,
2048 pkgprefix: pkgprefix,
2049 syms: make([]Sym, ndef+nhashed64def+nhasheddef+r.NNonpkgdef()+r.NNonpkgref()),
2051 nhasheddef: nhasheddef,
2052 nhashed64def: nhashed64def,
2053 objidx: uint32(len(l.objs)),
2057 lib.Autolib = append(lib.Autolib, r.Autolib()...)
2061 unit.FileTable = make([]string, nfile)
2062 for i := range unit.FileTable {
2063 unit.FileTable[i] = r.File(i)
2066 l.addObj(lib.Pkg, or)
2068 // The caller expects us consuming all the data
2069 f.MustSeek(length, os.SEEK_CUR)
2071 return r.Fingerprint()
2074 // Holds the loader along with temporary states for loading symbols.
2075 type loadState struct {
2077 hashed64Syms map[uint64]symAndSize // short hashed (content-addressable) symbols, keyed by content hash
2078 hashedSyms map[goobj.HashType]symAndSize // hashed (content-addressable) symbols, keyed by content hash
2081 // Preload symbols of given kind from an object.
2082 func (st *loadState) preloadSyms(r *oReader, kind int) {
2084 var start, end uint32
2088 end = uint32(r.ndef)
2090 start = uint32(r.ndef)
2091 end = uint32(r.ndef + r.nhashed64def)
2093 start = uint32(r.ndef + r.nhashed64def)
2094 end = uint32(r.ndef + r.nhashed64def + r.nhasheddef)
2095 if l.hasUnknownPkgPath {
2096 // The content hash depends on symbol name expansion. If any package is
2097 // built without fully expanded names, the content hash is unreliable.
2098 // Treat them as named symbols.
2100 // (We don't need to do this for hashed64Def case, as there the hash
2101 // function is simply the identity function, which doesn't depend on
2106 start = uint32(r.ndef + r.nhashed64def + r.nhasheddef)
2107 end = uint32(r.ndef + r.nhashed64def + r.nhasheddef + r.NNonpkgdef())
2109 panic("preloadSyms: bad kind")
2111 l.growAttrBitmaps(len(l.objSyms) + int(end-start))
2112 needNameExpansion := r.NeedNameExpansion()
2113 loadingRuntimePkg := r.unit.Lib.Pkg == "runtime"
2114 for i := start; i < end; i++ {
2118 if kind != hashed64Def && kind != hashedDef { // we don't need the name, etc. for hashed symbols
2119 name = osym.Name(r.Reader)
2120 if needNameExpansion {
2121 name = strings.Replace(name, "\"\".", r.pkgprefix, -1)
2123 v = abiToVer(osym.ABI(), r.version)
2125 gi := st.addSym(name, v, r, i, kind, osym)
2128 l.SetAttrLocal(gi, true)
2130 if osym.UsedInIface() {
2131 l.SetAttrUsedInIface(gi, true)
2133 if strings.HasPrefix(name, "runtime.") ||
2134 (loadingRuntimePkg && strings.HasPrefix(name, "type.")) {
2135 if bi := goobj.BuiltinIdx(name, v); bi != -1 {
2136 // This is a definition of a builtin symbol. Record where it is.
2137 l.builtinSyms[bi] = gi
2140 if a := int32(osym.Align()); a != 0 && a > l.SymAlign(gi) {
2141 l.SetSymAlign(gi, a)
2146 // Add syms, hashed (content-addressable) symbols, non-package symbols, and
2147 // references to external symbols (which are always named).
2148 func (l *Loader) LoadSyms(arch *sys.Arch) {
2149 // Allocate space for symbols, making a guess as to how much space we need.
2150 // This function was determined empirically by looking at the cmd/compile on
2151 // Darwin, and picking factors for hashed and hashed64 syms.
2152 var symSize, hashedSize, hashed64Size int
2153 for _, o := range l.objs[goObjStart:] {
2154 symSize += o.r.ndef + o.r.nhasheddef/2 + o.r.nhashed64def/2 + o.r.NNonpkgdef()
2155 hashedSize += o.r.nhasheddef / 2
2156 hashed64Size += o.r.nhashed64def / 2
2158 // Index 0 is invalid for symbols.
2159 l.objSyms = make([]objSym, 1, symSize)
2161 l.npkgsyms = l.NSym()
2164 hashed64Syms: make(map[uint64]symAndSize, hashed64Size),
2165 hashedSyms: make(map[goobj.HashType]symAndSize, hashedSize),
2168 for _, o := range l.objs[goObjStart:] {
2169 st.preloadSyms(o.r, pkgDef)
2171 for _, o := range l.objs[goObjStart:] {
2172 st.preloadSyms(o.r, hashed64Def)
2173 st.preloadSyms(o.r, hashedDef)
2174 st.preloadSyms(o.r, nonPkgDef)
2176 l.nhashedsyms = len(st.hashed64Syms) + len(st.hashedSyms)
2177 for _, o := range l.objs[goObjStart:] {
2178 loadObjRefs(l, o.r, arch)
2180 l.values = make([]int64, l.NSym(), l.NSym()+1000) // +1000 make some room for external symbols
2183 func loadObjRefs(l *Loader, r *oReader, arch *sys.Arch) {
2184 // load non-package refs
2185 ndef := uint32(r.NAlldef())
2186 needNameExpansion := r.NeedNameExpansion()
2187 for i, n := uint32(0), uint32(r.NNonpkgref()); i < n; i++ {
2188 osym := r.Sym(ndef + i)
2189 name := osym.Name(r.Reader)
2190 if needNameExpansion {
2191 name = strings.Replace(name, "\"\".", r.pkgprefix, -1)
2193 v := abiToVer(osym.ABI(), r.version)
2194 r.syms[ndef+i] = l.LookupOrCreateSym(name, v)
2195 gi := r.syms[ndef+i]
2197 l.SetAttrLocal(gi, true)
2199 if osym.UsedInIface() {
2200 l.SetAttrUsedInIface(gi, true)
2204 // referenced packages
2206 r.pkg = make([]uint32, npkg)
2207 for i := 1; i < npkg; i++ { // PkgIdx 0 is a dummy invalid package
2209 objidx, ok := l.objByPkg[pkg]
2211 log.Fatalf("%v: reference to nonexistent package %s", r.unit.Lib, pkg)
2216 // load flags of package refs
2217 for i, n := 0, r.NRefFlags(); i < n; i++ {
2219 gi := l.resolve(r, rf.Sym())
2220 if rf.Flag2()&goobj.SymFlagUsedInIface != 0 {
2221 l.SetAttrUsedInIface(gi, true)
2226 func abiToVer(abi uint16, localSymVersion int) int {
2228 if abi == goobj.SymABIstatic {
2231 } else if abiver := sym.ABIToVersion(obj.ABI(abi)); abiver != -1 {
2232 // Note that data symbols are "ABI0", which maps to version 0.
2235 log.Fatalf("invalid symbol ABI: %d", abi)
2240 // ResolveABIAlias given a symbol returns the ABI alias target of that
2241 // symbol. If the sym in question is not an alias, the sym itself is
2243 func (l *Loader) ResolveABIAlias(s Sym) Sym {
2244 if l.flags&FlagUseABIAlias == 0 {
2250 if l.SymType(s) != sym.SABIALIAS {
2253 relocs := l.Relocs(s)
2254 target := relocs.At(0).Sym()
2255 if l.SymType(target) == sym.SABIALIAS {
2256 panic(fmt.Sprintf("ABI alias %s references another ABI alias %s", l.SymName(s), l.SymName(target)))
2261 // TopLevelSym tests a symbol (by name and kind) to determine whether
2262 // the symbol first class sym (participating in the link) or is an
2263 // anonymous aux or sub-symbol containing some sub-part or payload of
2265 func (l *Loader) TopLevelSym(s Sym) bool {
2266 return topLevelSym(l.RawSymName(s), l.SymType(s))
2269 // topLevelSym tests a symbol name and kind to determine whether
2270 // the symbol first class sym (participating in the link) or is an
2271 // anonymous aux or sub-symbol containing some sub-part or payload of
2273 func topLevelSym(sname string, skind sym.SymKind) bool {
2278 case sym.SDWARFFCN, sym.SDWARFABSFCN, sym.SDWARFTYPE, sym.SDWARFCONST, sym.SDWARFCUINFO, sym.SDWARFRANGE, sym.SDWARFLOC, sym.SDWARFLINES, sym.SGOFUNC:
2285 // cloneToExternal takes the existing object file symbol (symIdx)
2286 // and creates a new external symbol payload that is a clone with
2287 // respect to name, version, type, relocations, etc. The idea here
2288 // is that if the linker decides it wants to update the contents of
2289 // a symbol originally discovered as part of an object file, it's
2290 // easier to do this if we make the updates to an external symbol
2292 func (l *Loader) cloneToExternal(symIdx Sym) {
2293 if l.IsExternal(symIdx) {
2294 panic("sym is already external, no need for clone")
2297 // Read the particulars from object.
2298 r, li := l.toLocal(symIdx)
2300 sname := osym.Name(r.Reader)
2301 if r.NeedNameExpansion() {
2302 sname = strings.Replace(sname, "\"\".", r.pkgprefix, -1)
2304 sver := abiToVer(osym.ABI(), r.version)
2305 skind := sym.AbiSymKindToSymKind[objabi.SymKind(osym.Type())]
2307 // Create new symbol, update version and kind.
2308 pi := l.newPayload(sname, sver)
2309 pp := l.payloads[pi]
2312 pp.size = int64(osym.Siz())
2313 pp.objidx = r.objidx
2315 // If this is a def, then copy the guts. We expect this case
2316 // to be very rare (one case it may come up is with -X).
2317 if li < uint32(r.NAlldef()) {
2320 relocs := l.Relocs(symIdx)
2321 pp.relocs = make([]goobj.Reloc, relocs.Count())
2322 for i := range pp.relocs {
2323 // Copy the relocs slice.
2324 // Convert local reference to global reference.
2326 pp.relocs[i].Set(rel.Off(), rel.Siz(), uint16(rel.Type()), rel.Add(), goobj.SymRef{PkgIdx: 0, SymIdx: uint32(rel.Sym())})
2330 pp.data = r.Data(li)
2333 // If we're overriding a data symbol, collect the associated
2334 // Gotype, so as to propagate it to the new symbol.
2338 // Install new payload to global index space.
2339 // (This needs to happen at the end, as the accessors above
2340 // need to access the old symbol content.)
2341 l.objSyms[symIdx] = objSym{l.extReader.objidx, uint32(pi)}
2342 l.extReader.syms = append(l.extReader.syms, symIdx)
2345 // Copy the payload of symbol src to dst. Both src and dst must be external
2347 // The intended use case is that when building/linking against a shared library,
2348 // where we do symbol name mangling, the Go object file may have reference to
2349 // the original symbol name whereas the shared library provides a symbol with
2350 // the mangled name. When we do mangling, we copy payload of mangled to original.
2351 func (l *Loader) CopySym(src, dst Sym) {
2352 if !l.IsExternal(dst) {
2353 panic("dst is not external") //l.newExtSym(l.SymName(dst), l.SymVersion(dst))
2355 if !l.IsExternal(src) {
2356 panic("src is not external") //l.cloneToExternal(src)
2358 l.payloads[l.extIndex(dst)] = l.payloads[l.extIndex(src)]
2359 l.SetSymPkg(dst, l.SymPkg(src))
2360 // TODO: other attributes?
2363 // CopyAttributes copies over all of the attributes of symbol 'src' to
2365 func (l *Loader) CopyAttributes(src Sym, dst Sym) {
2366 l.SetAttrReachable(dst, l.AttrReachable(src))
2367 l.SetAttrOnList(dst, l.AttrOnList(src))
2368 l.SetAttrLocal(dst, l.AttrLocal(src))
2369 l.SetAttrNotInSymbolTable(dst, l.AttrNotInSymbolTable(src))
2370 if l.IsExternal(dst) {
2371 l.SetAttrVisibilityHidden(dst, l.AttrVisibilityHidden(src))
2372 l.SetAttrDuplicateOK(dst, l.AttrDuplicateOK(src))
2373 l.SetAttrShared(dst, l.AttrShared(src))
2374 l.SetAttrExternal(dst, l.AttrExternal(src))
2376 // Some attributes are modifiable only for external symbols.
2377 // In such cases, don't try to transfer over the attribute
2378 // from the source even if there is a clash. This comes up
2379 // when copying attributes from a dupOK ABI wrapper symbol to
2380 // the real target symbol (which may not be marked dupOK).
2382 l.SetAttrSpecial(dst, l.AttrSpecial(src))
2383 l.SetAttrCgoExportDynamic(dst, l.AttrCgoExportDynamic(src))
2384 l.SetAttrCgoExportStatic(dst, l.AttrCgoExportStatic(src))
2385 l.SetAttrReadOnly(dst, l.AttrReadOnly(src))
2388 // CreateExtSym creates a new external symbol with the specified name
2389 // without adding it to any lookup tables, returning a Sym index for it.
2390 func (l *Loader) CreateExtSym(name string, ver int) Sym {
2391 return l.newExtSym(name, ver)
2394 // CreateStaticSym creates a new static symbol with the specified name
2395 // without adding it to any lookup tables, returning a Sym index for it.
2396 func (l *Loader) CreateStaticSym(name string) Sym {
2397 // Assign a new unique negative version -- this is to mark the
2398 // symbol so that it is not included in the name lookup table.
2400 return l.newExtSym(name, l.anonVersion)
2403 func (l *Loader) FreeSym(i Sym) {
2404 if l.IsExternal(i) {
2405 pp := l.getPayload(i)
2406 *pp = extSymPayload{}
2410 // relocId is essentially a <S,R> tuple identifying the Rth
2411 // relocation of symbol S.
2412 type relocId struct {
2417 // SetRelocVariant sets the 'variant' property of a relocation on
2418 // some specific symbol.
2419 func (l *Loader) SetRelocVariant(s Sym, ri int, v sym.RelocVariant) {
2421 if relocs := l.Relocs(s); ri >= relocs.Count() {
2422 panic("invalid relocation ID")
2424 if l.relocVariant == nil {
2425 l.relocVariant = make(map[relocId]sym.RelocVariant)
2428 l.relocVariant[relocId{s, ri}] = v
2430 delete(l.relocVariant, relocId{s, ri})
2434 // RelocVariant returns the 'variant' property of a relocation on
2435 // some specific symbol.
2436 func (l *Loader) RelocVariant(s Sym, ri int) sym.RelocVariant {
2437 return l.relocVariant[relocId{s, ri}]
2440 // UndefinedRelocTargets iterates through the global symbol index
2441 // space, looking for symbols with relocations targeting undefined
2442 // references. The linker's loadlib method uses this to determine if
2443 // there are unresolved references to functions in system libraries
2444 // (for example, libgcc.a), presumably due to CGO code. Return
2445 // value is a list of loader.Sym's corresponding to the undefined
2446 // cross-refs. The "limit" param controls the maximum number of
2447 // results returned; if "limit" is -1, then all undefs are returned.
2448 func (l *Loader) UndefinedRelocTargets(limit int) []Sym {
2450 for si := Sym(1); si < Sym(len(l.objSyms)); si++ {
2451 relocs := l.Relocs(si)
2452 for ri := 0; ri < relocs.Count(); ri++ {
2455 if rs != 0 && l.SymType(rs) == sym.SXREF && l.RawSymName(rs) != ".got" {
2456 result = append(result, rs)
2457 if limit != -1 && len(result) >= limit {
2466 // AssignTextSymbolOrder populates the Textp slices within each
2467 // library and compilation unit, insuring that packages are laid down
2468 // in dependency order (internal first, then everything else). Return value
2469 // is a slice of all text syms.
2470 func (l *Loader) AssignTextSymbolOrder(libs []*sym.Library, intlibs []bool, extsyms []Sym) []Sym {
2472 // Library Textp lists should be empty at this point.
2473 for _, lib := range libs {
2474 if len(lib.Textp) != 0 {
2475 panic("expected empty Textp slice for library")
2477 if len(lib.DupTextSyms) != 0 {
2478 panic("expected empty DupTextSyms slice for library")
2482 // Used to record which dupok symbol we've assigned to a unit.
2483 // Can't use the onlist attribute here because it will need to
2484 // clear for the later assignment of the sym.Symbol to a unit.
2485 // NB: we can convert to using onList once we no longer have to
2486 // call the regular addToTextp.
2487 assignedToUnit := MakeBitmap(l.NSym() + 1)
2489 // Start off textp with reachable external syms.
2491 for _, sym := range extsyms {
2492 if !l.attrReachable.Has(sym) {
2495 textp = append(textp, sym)
2498 // Walk through all text symbols from Go object files and append
2499 // them to their corresponding library's textp list.
2500 for _, o := range l.objs[goObjStart:] {
2503 for i, n := uint32(0), uint32(r.NAlldef()); i < n; i++ {
2504 gi := l.toGlobal(r, i)
2505 if !l.attrReachable.Has(gi) {
2509 st := sym.AbiSymKindToSymKind[objabi.SymKind(osym.Type())]
2510 if st != sym.STEXT {
2513 dupok := osym.Dupok()
2514 if r2, i2 := l.toLocal(gi); r2 != r || i2 != i {
2515 // A dupok text symbol is resolved to another package.
2516 // We still need to record its presence in the current
2517 // package, as the trampoline pass expects packages
2518 // are laid out in dependency order.
2519 lib.DupTextSyms = append(lib.DupTextSyms, sym.LoaderSym(gi))
2520 continue // symbol in different object
2523 lib.DupTextSyms = append(lib.DupTextSyms, sym.LoaderSym(gi))
2527 lib.Textp = append(lib.Textp, sym.LoaderSym(gi))
2531 // Now assemble global textp, and assign text symbols to units.
2532 for _, doInternal := range [2]bool{true, false} {
2533 for idx, lib := range libs {
2534 if intlibs[idx] != doInternal {
2537 lists := [2][]sym.LoaderSym{lib.Textp, lib.DupTextSyms}
2538 for i, list := range lists {
2539 for _, s := range list {
2541 if !assignedToUnit.Has(sym) {
2542 textp = append(textp, sym)
2543 unit := l.SymUnit(sym)
2545 unit.Textp = append(unit.Textp, s)
2546 assignedToUnit.Set(sym)
2548 // Dupok symbols may be defined in multiple packages; the
2549 // associated package for a dupok sym is chosen sort of
2550 // arbitrarily (the first containing package that the linker
2551 // loads). Canonicalizes its Pkg to the package with which
2552 // it will be laid down in text.
2553 if i == 1 /* DupTextSyms2 */ && l.SymPkg(sym) != lib.Pkg {
2554 l.SetSymPkg(sym, lib.Pkg)
2560 lib.DupTextSyms = nil
2567 // ErrorReporter is a helper class for reporting errors.
2568 type ErrorReporter struct {
2570 AfterErrorAction func()
2573 // Errorf method logs an error message.
2575 // After each error, the error actions function will be invoked; this
2576 // will either terminate the link immediately (if -h option given)
2577 // or it will keep a count and exit if more than 20 errors have been printed.
2579 // Logging an error means that on exit cmd/link will delete any
2580 // output file and return a non-zero error code.
2582 func (reporter *ErrorReporter) Errorf(s Sym, format string, args ...interface{}) {
2583 if s != 0 && reporter.ldr.SymName(s) != "" {
2584 format = reporter.ldr.SymName(s) + ": " + format
2586 format = fmt.Sprintf("sym %d: %s", s, format)
2589 fmt.Fprintf(os.Stderr, format, args...)
2590 reporter.AfterErrorAction()
2593 // GetErrorReporter returns the loader's associated error reporter.
2594 func (l *Loader) GetErrorReporter() *ErrorReporter {
2595 return l.errorReporter
2598 // Errorf method logs an error message. See ErrorReporter.Errorf for details.
2599 func (l *Loader) Errorf(s Sym, format string, args ...interface{}) {
2600 l.errorReporter.Errorf(s, format, args...)
2603 // Symbol statistics.
2604 func (l *Loader) Stat() string {
2605 s := fmt.Sprintf("%d symbols, %d reachable\n", l.NSym(), l.NReachableSym())
2606 s += fmt.Sprintf("\t%d package symbols, %d hashed symbols, %d non-package symbols, %d external symbols\n",
2607 l.npkgsyms, l.nhashedsyms, int(l.extStart)-l.npkgsyms-l.nhashedsyms, l.NSym()-int(l.extStart))
2612 func (l *Loader) Dump() {
2614 for _, obj := range l.objs[goObjStart:] {
2616 fmt.Println(obj.i, obj.r.unit.Lib)
2619 fmt.Println("extStart:", l.extStart)
2620 fmt.Println("Nsyms:", len(l.objSyms))
2622 for i := Sym(1); i < Sym(len(l.objSyms)); i++ {
2624 if l.IsExternal(i) {
2625 pi = fmt.Sprintf("<ext %d>", l.extIndex(i))
2628 if l.SymSect(i) != nil {
2629 sect = l.SymSect(i).Name
2631 fmt.Printf("%v %v %v %v %x %v\n", i, l.SymName(i), l.SymType(i), pi, l.SymValue(i), sect)
2633 fmt.Println("symsByName")
2634 for name, i := range l.symsByName[0] {
2635 fmt.Println(i, name, 0)
2637 for name, i := range l.symsByName[1] {
2638 fmt.Println(i, name, 1)
2640 fmt.Println("payloads:")
2641 for i := range l.payloads {
2643 fmt.Println(i, pp.name, pp.ver, pp.kind)