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

     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.
     4  
     5  package loader
     6  
     7  import (
     8  	"bytes"
     9  	"cmd/internal/bio"
    10  	"cmd/internal/goobj"
    11  	"cmd/internal/obj"
    12  	"cmd/internal/objabi"
    13  	"cmd/internal/sys"
    14  	"cmd/link/internal/sym"
    15  	"debug/elf"
    16  	"fmt"
    17  	"internal/abi"
    18  	"io"
    19  	"iter"
    20  	"log"
    21  	"math/bits"
    22  	"os"
    23  	"sort"
    24  	"strings"
    25  )
    26  
    27  var _ = fmt.Print
    28  
    29  // Sym encapsulates a global symbol index, used to identify a specific
    30  // Go symbol. The 0-valued Sym is corresponds to an invalid symbol.
    31  type Sym = sym.LoaderSym
    32  
    33  // Relocs encapsulates the set of relocations on a given symbol; an
    34  // instance of this type is returned by the Loader Relocs() method.
    35  type Relocs struct {
    36  	rs []goobj.Reloc
    37  
    38  	li uint32   // local index of symbol whose relocs we're examining
    39  	r  *oReader // object reader for containing package
    40  	l  *Loader  // loader
    41  }
    42  
    43  // ExtReloc contains the payload for an external relocation.
    44  type ExtReloc struct {
    45  	Xsym Sym
    46  	Xadd int64
    47  	Type objabi.RelocType
    48  	Size uint8
    49  }
    50  
    51  // Reloc holds a "handle" to access a relocation record from an
    52  // object file.
    53  type Reloc struct {
    54  	*goobj.Reloc
    55  	r *oReader
    56  	l *Loader
    57  }
    58  
    59  func (rel Reloc) Type() objabi.RelocType     { return objabi.RelocType(rel.Reloc.Type()) &^ objabi.R_WEAK }
    60  func (rel Reloc) Weak() bool                 { return objabi.RelocType(rel.Reloc.Type())&objabi.R_WEAK != 0 }
    61  func (rel Reloc) SetType(t objabi.RelocType) { rel.Reloc.SetType(uint16(t)) }
    62  func (rel Reloc) Sym() Sym                   { return rel.l.resolve(rel.r, rel.Reloc.Sym()) }
    63  func (rel Reloc) SetSym(s Sym)               { rel.Reloc.SetSym(goobj.SymRef{PkgIdx: 0, SymIdx: uint32(s)}) }
    64  func (rel Reloc) IsMarker() bool             { return rel.Siz() == 0 }
    65  
    66  // Aux holds a "handle" to access an aux symbol record from an
    67  // object file.
    68  type Aux struct {
    69  	*goobj.Aux
    70  	r *oReader
    71  	l *Loader
    72  }
    73  
    74  func (a Aux) Sym() Sym { return a.l.resolve(a.r, a.Aux.Sym()) }
    75  
    76  // oReader is a wrapper type of obj.Reader, along with some
    77  // extra information.
    78  type oReader struct {
    79  	*goobj.Reader
    80  	unit         *sym.CompilationUnit
    81  	version      int // version of static symbol
    82  	pkgprefix    string
    83  	syms         []Sym    // Sym's global index, indexed by local index
    84  	pkg          []uint32 // indices of referenced package by PkgIdx (index into loader.objs array)
    85  	ndef         int      // cache goobj.Reader.NSym()
    86  	nhashed64def int      // cache goobj.Reader.NHashed64Def()
    87  	nhasheddef   int      // cache goobj.Reader.NHashedDef()
    88  	objidx       uint32   // index of this reader in the objs slice
    89  }
    90  
    91  // Total number of defined symbols (package symbols, hashed symbols, and
    92  // non-package symbols).
    93  func (r *oReader) NAlldef() int { return r.ndef + r.nhashed64def + r.nhasheddef + r.NNonpkgdef() }
    94  
    95  // objSym represents a symbol in an object file. It is a tuple of
    96  // the object and the symbol's local index.
    97  // For external symbols, objidx is the index of l.extReader (extObj),
    98  // s is its index into the payload array.
    99  // {0, 0} represents the nil symbol.
   100  type objSym struct {
   101  	objidx uint32 // index of the object (in l.objs array)
   102  	s      uint32 // local index
   103  }
   104  
   105  type nameVer struct {
   106  	name string
   107  	v    int
   108  }
   109  
   110  type Bitmap []uint32
   111  
   112  // set the i-th bit.
   113  func (bm Bitmap) Set(i Sym) {
   114  	n, r := uint(i)/32, uint(i)%32
   115  	bm[n] |= 1 << r
   116  }
   117  
   118  // unset the i-th bit.
   119  func (bm Bitmap) Unset(i Sym) {
   120  	n, r := uint(i)/32, uint(i)%32
   121  	bm[n] &^= (1 << r)
   122  }
   123  
   124  // whether the i-th bit is set.
   125  func (bm Bitmap) Has(i Sym) bool {
   126  	n, r := uint(i)/32, uint(i)%32
   127  	return bm[n]&(1<<r) != 0
   128  }
   129  
   130  // return current length of bitmap in bits.
   131  func (bm Bitmap) Len() int {
   132  	return len(bm) * 32
   133  }
   134  
   135  // return the number of bits set.
   136  func (bm Bitmap) Count() int {
   137  	s := 0
   138  	for _, x := range bm {
   139  		s += bits.OnesCount32(x)
   140  	}
   141  	return s
   142  }
   143  
   144  func MakeBitmap(n int) Bitmap {
   145  	return make(Bitmap, (n+31)/32)
   146  }
   147  
   148  // growBitmap insures that the specified bitmap has enough capacity,
   149  // reallocating (doubling the size) if needed.
   150  func growBitmap(reqLen int, b Bitmap) Bitmap {
   151  	curLen := b.Len()
   152  	if reqLen > curLen {
   153  		b = append(b, MakeBitmap(reqLen+1-curLen)...)
   154  	}
   155  	return b
   156  }
   157  
   158  type symAndSize struct {
   159  	sym  Sym
   160  	size uint32
   161  }
   162  
   163  // A Loader loads new object files and resolves indexed symbol references.
   164  //
   165  // Notes on the layout of global symbol index space:
   166  //
   167  //   - Go object files are read before host object files; each Go object
   168  //     read adds its defined package symbols to the global index space.
   169  //     Nonpackage symbols are not yet added.
   170  //
   171  //   - In loader.LoadNonpkgSyms, add non-package defined symbols and
   172  //     references in all object files to the global index space.
   173  //
   174  //   - Host object file loading happens; the host object loader does a
   175  //     name/version lookup for each symbol it finds; this can wind up
   176  //     extending the external symbol index space range. The host object
   177  //     loader stores symbol payloads in loader.payloads using SymbolBuilder.
   178  //
   179  //   - Each symbol gets a unique global index. For duplicated and
   180  //     overwriting/overwritten symbols, the second (or later) appearance
   181  //     of the symbol gets the same global index as the first appearance.
   182  type Loader struct {
   183  	objs        []*oReader
   184  	extStart    Sym   // from this index on, the symbols are externally defined
   185  	builtinSyms []Sym // global index of builtin symbols
   186  
   187  	objSyms []objSym // global index mapping to local index
   188  
   189  	symsByName    [2]map[string]Sym // map symbol name to index, two maps are for ABI0 and ABIInternal
   190  	extStaticSyms map[nameVer]Sym   // externally defined static symbols, keyed by name
   191  
   192  	extReader    *oReader // a dummy oReader, for external symbols
   193  	payloadBatch []extSymPayload
   194  	payloads     []*extSymPayload // contents of linker-materialized external syms
   195  	values       []int64          // symbol values, indexed by global sym index
   196  
   197  	sects    []*sym.Section // sections
   198  	symSects []uint16       // symbol's section, index to sects array
   199  
   200  	align []uint8 // symbol 2^N alignment, indexed by global index
   201  
   202  	deferReturnTramp map[Sym]bool // whether the symbol is a trampoline of a deferreturn call
   203  
   204  	objByPkg map[string]uint32 // map package path to the index of its Go object reader
   205  
   206  	anonVersion int // most recently assigned ext static sym pseudo-version
   207  
   208  	// Bitmaps and other side structures used to store data used to store
   209  	// symbol flags/attributes; these are to be accessed via the
   210  	// corresponding loader "AttrXXX" and "SetAttrXXX" methods. Please
   211  	// visit the comments on these methods for more details on the
   212  	// semantics / interpretation of the specific flags or attribute.
   213  	attrReachable        Bitmap // reachable symbols, indexed by global index
   214  	attrOnList           Bitmap // "on list" symbols, indexed by global index
   215  	attrLocal            Bitmap // "local" symbols, indexed by global index
   216  	attrNotInSymbolTable Bitmap // "not in symtab" symbols, indexed by global idx
   217  	attrUsedInIface      Bitmap // "used in interface" symbols, indexed by global idx
   218  	attrSpecial          Bitmap // "special" frame symbols, indexed by global idx
   219  	attrVisibilityHidden Bitmap // hidden symbols, indexed by ext sym index
   220  	attrDuplicateOK      Bitmap // dupOK symbols, indexed by ext sym index
   221  	attrShared           Bitmap // shared symbols, indexed by ext sym index
   222  	attrExternal         Bitmap // external symbols, indexed by ext sym index
   223  	generatedSyms        Bitmap // symbols that generate their content, indexed by ext sym idx
   224  
   225  	attrReadOnly         map[Sym]bool     // readonly data for this sym
   226  	attrCgoExportDynamic map[Sym]struct{} // "cgo_export_dynamic" symbols
   227  	attrCgoExportStatic  map[Sym]struct{} // "cgo_export_static" symbols
   228  
   229  	// Outer and Sub relations for symbols.
   230  	outer []Sym // indexed by global index
   231  	sub   map[Sym]Sym
   232  
   233  	dynimplib   map[Sym]string      // stores Dynimplib symbol attribute
   234  	dynimpvers  map[Sym]string      // stores Dynimpvers symbol attribute
   235  	localentry  map[Sym]uint8       // stores Localentry symbol attribute
   236  	extname     map[Sym]string      // stores Extname symbol attribute
   237  	elfType     map[Sym]elf.SymType // stores elf type symbol property
   238  	elfSym      map[Sym]int32       // stores elf sym symbol property
   239  	localElfSym map[Sym]int32       // stores "local" elf sym symbol property
   240  	symPkg      map[Sym]string      // stores package for symbol, or library for shlib-derived syms
   241  	plt         map[Sym]int32       // stores dynimport for pe objects
   242  	got         map[Sym]int32       // stores got for pe objects
   243  	dynid       map[Sym]int32       // stores Dynid for symbol
   244  	weakBinding map[Sym]bool        // stores whether a symbol has a weak binding
   245  
   246  	relocVariant map[relocId]sym.RelocVariant // stores variant relocs
   247  
   248  	// Used to implement field tracking; created during deadcode if
   249  	// field tracking is enabled. Reachparent[K] contains the index of
   250  	// the symbol that triggered the marking of symbol K as live.
   251  	Reachparent []Sym
   252  
   253  	// CgoExports records cgo-exported symbols by SymName.
   254  	CgoExports map[string]Sym
   255  
   256  	WasmExports []Sym
   257  
   258  	// sizeFixups records symbols that we need to fix up the size
   259  	// after loading. It is very rarely needed, only for a DATA symbol
   260  	// and a BSS symbol with the same name, and the BSS symbol has
   261  	// larger size.
   262  	sizeFixups []symAndSize
   263  
   264  	flags uint32
   265  
   266  	strictDupMsgs int // number of strict-dup warning/errors, when FlagStrictDups is enabled
   267  
   268  	errorReporter *ErrorReporter
   269  
   270  	npkgsyms    int // number of package symbols, for accounting
   271  	nhashedsyms int // number of hashed symbols, for accounting
   272  }
   273  
   274  const (
   275  	pkgDef = iota
   276  	hashed64Def
   277  	hashedDef
   278  	nonPkgDef
   279  	nonPkgRef
   280  )
   281  
   282  // objidx
   283  const (
   284  	nilObj = iota
   285  	extObj
   286  	goObjStart
   287  )
   288  
   289  // extSymPayload holds the payload (data + relocations) for linker-synthesized
   290  // external symbols (note that symbol value is stored in a separate slice).
   291  type extSymPayload struct {
   292  	name   string // TODO: would this be better as offset into str table?
   293  	size   int64
   294  	ver    int
   295  	kind   sym.SymKind
   296  	objidx uint32 // index of original object if sym made by cloneToExternal
   297  	relocs []goobj.Reloc
   298  	data   []byte
   299  	auxs   []goobj.Aux
   300  }
   301  
   302  const (
   303  	// Loader.flags
   304  	FlagStrictDups = 1 << iota
   305  	FlagCheckLinkname
   306  )
   307  
   308  func NewLoader(flags uint32, reporter *ErrorReporter) *Loader {
   309  	nbuiltin := goobj.NBuiltin()
   310  	extReader := &oReader{objidx: extObj}
   311  	ldr := &Loader{
   312  		objs:                 []*oReader{nil, extReader}, // reserve index 0 for nil symbol, 1 for external symbols
   313  		objSyms:              make([]objSym, 1, 1),       // This will get overwritten later.
   314  		extReader:            extReader,
   315  		symsByName:           [2]map[string]Sym{make(map[string]Sym, 80000), make(map[string]Sym, 50000)}, // preallocate ~2MB for ABI0 and ~1MB for ABI1 symbols
   316  		objByPkg:             make(map[string]uint32),
   317  		sub:                  make(map[Sym]Sym),
   318  		dynimplib:            make(map[Sym]string),
   319  		dynimpvers:           make(map[Sym]string),
   320  		localentry:           make(map[Sym]uint8),
   321  		extname:              make(map[Sym]string),
   322  		attrReadOnly:         make(map[Sym]bool),
   323  		elfType:              make(map[Sym]elf.SymType),
   324  		elfSym:               make(map[Sym]int32),
   325  		localElfSym:          make(map[Sym]int32),
   326  		symPkg:               make(map[Sym]string),
   327  		plt:                  make(map[Sym]int32),
   328  		got:                  make(map[Sym]int32),
   329  		dynid:                make(map[Sym]int32),
   330  		weakBinding:          make(map[Sym]bool),
   331  		attrCgoExportDynamic: make(map[Sym]struct{}),
   332  		attrCgoExportStatic:  make(map[Sym]struct{}),
   333  		deferReturnTramp:     make(map[Sym]bool),
   334  		extStaticSyms:        make(map[nameVer]Sym),
   335  		builtinSyms:          make([]Sym, nbuiltin),
   336  		flags:                flags,
   337  		errorReporter:        reporter,
   338  		sects:                []*sym.Section{nil}, // reserve index 0 for nil section
   339  	}
   340  	reporter.ldr = ldr
   341  	return ldr
   342  }
   343  
   344  // Add object file r
   345  func (l *Loader) addObj(pkg string, r *oReader) {
   346  	pkg = objabi.PathToPrefix(pkg) // the object file contains escaped package path
   347  	if _, ok := l.objByPkg[pkg]; !ok {
   348  		l.objByPkg[pkg] = r.objidx
   349  	}
   350  	l.objs = append(l.objs, r)
   351  }
   352  
   353  // Add a symbol from an object file, return the global index.
   354  // If the symbol already exist, it returns the index of that symbol.
   355  func (st *loadState) addSym(name string, ver int, r *oReader, li uint32, kind int, osym *goobj.Sym) Sym {
   356  	l := st.l
   357  	if l.extStart != 0 {
   358  		panic("addSym called after external symbol is created")
   359  	}
   360  	i := Sym(len(l.objSyms))
   361  	if int(i) != len(l.objSyms) { // overflow
   362  		panic("too many symbols")
   363  	}
   364  	addToGlobal := func() {
   365  		l.objSyms = append(l.objSyms, objSym{r.objidx, li})
   366  	}
   367  	if name == "" && kind != hashed64Def && kind != hashedDef {
   368  		addToGlobal()
   369  		return i // unnamed aux symbol
   370  	}
   371  	if ver == r.version {
   372  		// Static symbol. Add its global index but don't
   373  		// add to name lookup table, as it cannot be
   374  		// referenced by name.
   375  		addToGlobal()
   376  		return i
   377  	}
   378  	switch kind {
   379  	case pkgDef:
   380  		// Defined package symbols cannot be dup to each other.
   381  		// We load all the package symbols first, so we don't need
   382  		// to check dup here.
   383  		// We still add it to the lookup table, as it may still be
   384  		// referenced by name (e.g. through linkname).
   385  		l.symsByName[ver][name] = i
   386  		addToGlobal()
   387  		return i
   388  	case hashed64Def, hashedDef:
   389  		// Hashed (content-addressable) symbol. Check the hash
   390  		// but don't add to name lookup table, as they are not
   391  		// referenced by name. Also no need to do overwriting
   392  		// check, as same hash indicates same content.
   393  		var checkHash func() (symAndSize, bool)
   394  		var addToHashMap func(symAndSize)
   395  		var h64 uint64        // only used for hashed64Def
   396  		var h *goobj.HashType // only used for hashedDef
   397  		if kind == hashed64Def {
   398  			checkHash = func() (symAndSize, bool) {
   399  				h64 = r.Hash64(li - uint32(r.ndef))
   400  				s, existed := st.hashed64Syms[h64]
   401  				return s, existed
   402  			}
   403  			addToHashMap = func(ss symAndSize) { st.hashed64Syms[h64] = ss }
   404  		} else {
   405  			checkHash = func() (symAndSize, bool) {
   406  				h = r.Hash(li - uint32(r.ndef+r.nhashed64def))
   407  				s, existed := st.hashedSyms[*h]
   408  				return s, existed
   409  			}
   410  			addToHashMap = func(ss symAndSize) { st.hashedSyms[*h] = ss }
   411  		}
   412  		siz := osym.Siz()
   413  		if s, existed := checkHash(); existed {
   414  			// The content hash is built from symbol data and relocations. In the
   415  			// object file, the symbol data may not always contain trailing zeros,
   416  			// e.g. for [5]int{1,2,3} and [100]int{1,2,3}, the data is same
   417  			// (although the size is different).
   418  			// Also, for short symbols, the content hash is the identity function of
   419  			// the 8 bytes, and trailing zeros doesn't change the hash value, e.g.
   420  			// hash("A") == hash("A\0\0\0").
   421  			// So when two symbols have the same hash, we need to use the one with
   422  			// larger size.
   423  			if siz > s.size {
   424  				// New symbol has larger size, use the new one. Rewrite the index mapping.
   425  				l.objSyms[s.sym] = objSym{r.objidx, li}
   426  				addToHashMap(symAndSize{s.sym, siz})
   427  			}
   428  			return s.sym
   429  		}
   430  		addToHashMap(symAndSize{i, siz})
   431  		addToGlobal()
   432  		return i
   433  	}
   434  
   435  	// Non-package (named) symbol.
   436  	// Check if it already exists.
   437  	oldi, existed := l.symsByName[ver][name]
   438  	if !existed {
   439  		l.symsByName[ver][name] = i
   440  		addToGlobal()
   441  		return i
   442  	}
   443  	// symbol already exists
   444  	// Fix for issue #47185 -- given two dupok or BSS symbols with
   445  	// different sizes, favor symbol with larger size. See also
   446  	// issue #46653 and #72032.
   447  	oldsz := l.SymSize(oldi)
   448  	sz := int64(r.Sym(li).Siz())
   449  	oldr, oldli := l.toLocal(oldi)
   450  	oldsym := oldr.Sym(oldli)
   451  	if osym.Dupok() {
   452  		if oldsym.Dupok() {
   453  			if l.flags&FlagStrictDups != 0 {
   454  				l.checkdup(name, r, li, oldi)
   455  			}
   456  			if oldsz < sz {
   457  				// new symbol overwrites old symbol.
   458  				l.objSyms[oldi] = objSym{r.objidx, li}
   459  			}
   460  		}
   461  		return oldi
   462  	}
   463  	if oldsym.Dupok() {
   464  		// oldsym is Dupok, new is not.
   465  		// new symbol overwrites old symbol.
   466  		l.objSyms[oldi] = objSym{r.objidx, li}
   467  		return oldi
   468  	}
   469  	// If one is a DATA symbol (i.e. has content, DataSize != 0,
   470  	// including RODATA) and the other is BSS, the one with content wins.
   471  	// If both are BSS, the one with larger size wins.
   472  	//
   473  	// For a special case, we allow a TEXT symbol overwrites a BSS symbol
   474  	// even if the BSS symbol has larger size. This is because there is
   475  	// code like below to take the address of a function
   476  	//
   477  	//	//go:linkname fn
   478  	//	var fn uintptr
   479  	//	var fnAddr = uintptr(unsafe.Pointer(&fn))
   480  	//
   481  	// TODO: maybe limit this case to just pointer sized variable?
   482  	//
   483  	// In summary, the "overwrite" variable and the final result are
   484  	//
   485  	// new sym       old sym       result
   486  	// -------------------------------------------------------
   487  	// TEXT          BSS           new wins
   488  	// DATA          DATA          ERROR
   489  	// DATA lg/eq    BSS  sm/eq    new wins
   490  	// DATA small    BSS  large    merge: new with larger size
   491  	// BSS  large    DATA small    merge: old with larger size
   492  	// BSS  large    BSS  small    new wins
   493  	// BSS  sm/eq    D/B  lg/eq    old wins
   494  	// BSS           TEXT          old wins
   495  	oldtyp := sym.AbiSymKindToSymKind[objabi.SymKind(oldsym.Type())]
   496  	newtyp := sym.AbiSymKindToSymKind[objabi.SymKind(osym.Type())]
   497  	newIsText := newtyp.IsText()
   498  	oldHasContent := oldr.DataSize(oldli) != 0
   499  	newHasContent := r.DataSize(li) != 0
   500  	oldIsBSS := oldtyp.IsData() && !oldHasContent
   501  	newIsBSS := newtyp.IsData() && !newHasContent
   502  	switch {
   503  	case newIsText && oldIsBSS,
   504  		newHasContent && oldIsBSS,
   505  		newIsBSS && oldIsBSS && sz > oldsz:
   506  		// new symbol overwrites old symbol.
   507  		l.objSyms[oldi] = objSym{r.objidx, li}
   508  		if oldsz > sz {
   509  			// If the BSS symbol has a larger size, expand the data
   510  			// symbol's size so access from the BSS side cannot overrun.
   511  			// It is hard to modify the symbol size until all Go objects
   512  			// (potentially read-only) are loaded, so we record it in
   513  			// a fixup table and apply them later. This is very rare.
   514  			// One case is a global variable with a Go declaration and an
   515  			// assembly definition, which typically have the same size,
   516  			// but in ASAN mode the Go declaration has a larger size due
   517  			// to the inserted red zone.
   518  			l.sizeFixups = append(l.sizeFixups, symAndSize{oldi, uint32(oldsz)})
   519  		}
   520  	case newIsBSS:
   521  		// old win, just ignore the new symbol.
   522  		if sz > oldsz {
   523  			// See the comment above for sizeFixups.
   524  			l.sizeFixups = append(l.sizeFixups, symAndSize{oldi, uint32(sz)})
   525  		}
   526  	default:
   527  		log.Fatalf("duplicated definition of symbol %s, from %s (type %s size %d) and %s (type %s size %d)", name, r.unit.Lib.Pkg, newtyp, sz, oldr.unit.Lib.Pkg, oldtyp, oldsz)
   528  	}
   529  	return oldi
   530  }
   531  
   532  // newExtSym creates a new external sym with the specified
   533  // name/version.
   534  func (l *Loader) newExtSym(name string, ver int) Sym {
   535  	i := Sym(len(l.objSyms))
   536  	if int(i) != len(l.objSyms) { // overflow
   537  		panic("too many symbols")
   538  	}
   539  	if l.extStart == 0 {
   540  		l.extStart = i
   541  	}
   542  	l.growValues(int(i) + 1)
   543  	l.growOuter(int(i) + 1)
   544  	l.growAttrBitmaps(int(i) + 1)
   545  	pi := l.newPayload(name, ver)
   546  	l.objSyms = append(l.objSyms, objSym{l.extReader.objidx, uint32(pi)})
   547  	l.extReader.syms = append(l.extReader.syms, i)
   548  	return i
   549  }
   550  
   551  // LookupOrCreateSym looks up the symbol with the specified name/version,
   552  // returning its Sym index if found. If the lookup fails, a new external
   553  // Sym will be created, entered into the lookup tables, and returned.
   554  func (l *Loader) LookupOrCreateSym(name string, ver int) Sym {
   555  	i := l.Lookup(name, ver)
   556  	if i != 0 {
   557  		return i
   558  	}
   559  	i = l.newExtSym(name, ver)
   560  	static := ver >= sym.SymVerStatic || ver < 0
   561  	if static {
   562  		l.extStaticSyms[nameVer{name, ver}] = i
   563  	} else {
   564  		l.symsByName[ver][name] = i
   565  	}
   566  	return i
   567  }
   568  
   569  // AddCgoExport records a cgo-exported symbol in l.CgoExports.
   570  // This table is used to identify the correct Go symbol ABI to use
   571  // to resolve references from host objects (which don't have ABIs).
   572  func (l *Loader) AddCgoExport(s Sym) {
   573  	if l.CgoExports == nil {
   574  		l.CgoExports = make(map[string]Sym)
   575  	}
   576  	l.CgoExports[l.SymName(s)] = s
   577  }
   578  
   579  // LookupOrCreateCgoExport is like LookupOrCreateSym, but if ver
   580  // indicates a global symbol, it uses the CgoExport table to determine
   581  // the appropriate symbol version (ABI) to use. ver must be either 0
   582  // or a static symbol version.
   583  func (l *Loader) LookupOrCreateCgoExport(name string, ver int) Sym {
   584  	if ver >= sym.SymVerStatic {
   585  		return l.LookupOrCreateSym(name, ver)
   586  	}
   587  	if ver != 0 {
   588  		panic("ver must be 0 or a static version")
   589  	}
   590  	// Look for a cgo-exported symbol from Go.
   591  	if s, ok := l.CgoExports[name]; ok {
   592  		return s
   593  	}
   594  	// Otherwise, this must just be a symbol in the host object.
   595  	// Create a version 0 symbol for it.
   596  	return l.LookupOrCreateSym(name, 0)
   597  }
   598  
   599  func (l *Loader) IsExternal(i Sym) bool {
   600  	r, _ := l.toLocal(i)
   601  	return l.isExtReader(r)
   602  }
   603  
   604  func (l *Loader) isExtReader(r *oReader) bool {
   605  	return r == l.extReader
   606  }
   607  
   608  // For external symbol, return its index in the payloads array.
   609  // XXX result is actually not a global index. We (ab)use the Sym type
   610  // so we don't need conversion for accessing bitmaps.
   611  func (l *Loader) extIndex(i Sym) Sym {
   612  	_, li := l.toLocal(i)
   613  	return Sym(li)
   614  }
   615  
   616  // Get a new payload for external symbol, return its index in
   617  // the payloads array.
   618  func (l *Loader) newPayload(name string, ver int) int {
   619  	pi := len(l.payloads)
   620  	pp := l.allocPayload()
   621  	pp.name = name
   622  	pp.ver = ver
   623  	l.payloads = append(l.payloads, pp)
   624  	l.growExtAttrBitmaps()
   625  	return pi
   626  }
   627  
   628  // getPayload returns a pointer to the extSymPayload struct for an
   629  // external symbol if the symbol has a payload. Will panic if the
   630  // symbol in question is bogus (zero or not an external sym).
   631  func (l *Loader) getPayload(i Sym) *extSymPayload {
   632  	if !l.IsExternal(i) {
   633  		panic(fmt.Sprintf("bogus symbol index %d in getPayload", i))
   634  	}
   635  	pi := l.extIndex(i)
   636  	return l.payloads[pi]
   637  }
   638  
   639  // allocPayload allocates a new payload.
   640  func (l *Loader) allocPayload() *extSymPayload {
   641  	batch := l.payloadBatch
   642  	if len(batch) == 0 {
   643  		batch = make([]extSymPayload, 1000)
   644  	}
   645  	p := &batch[0]
   646  	l.payloadBatch = batch[1:]
   647  	return p
   648  }
   649  
   650  func (ms *extSymPayload) Grow(siz int64) {
   651  	if int64(int(siz)) != siz {
   652  		log.Fatalf("symgrow size %d too long", siz)
   653  	}
   654  	if int64(len(ms.data)) >= siz {
   655  		return
   656  	}
   657  	if cap(ms.data) < int(siz) {
   658  		cl := len(ms.data)
   659  		ms.data = append(ms.data, make([]byte, int(siz)+1-cl)...)
   660  		ms.data = ms.data[0:cl]
   661  	}
   662  	ms.data = ms.data[:siz]
   663  }
   664  
   665  // Convert a local index to a global index.
   666  func (l *Loader) toGlobal(r *oReader, i uint32) Sym {
   667  	return r.syms[i]
   668  }
   669  
   670  // Convert a global index to a local index.
   671  func (l *Loader) toLocal(i Sym) (*oReader, uint32) {
   672  	return l.objs[l.objSyms[i].objidx], l.objSyms[i].s
   673  }
   674  
   675  // Resolve a local symbol reference. Return global index.
   676  func (l *Loader) resolve(r *oReader, s goobj.SymRef) Sym {
   677  	var rr *oReader
   678  	switch p := s.PkgIdx; p {
   679  	case goobj.PkgIdxInvalid:
   680  		// {0, X} with non-zero X is never a valid sym reference from a Go object.
   681  		// We steal this space for symbol references from external objects.
   682  		// In this case, X is just the global index.
   683  		if l.isExtReader(r) {
   684  			return Sym(s.SymIdx)
   685  		}
   686  		if s.SymIdx != 0 {
   687  			panic("bad sym ref")
   688  		}
   689  		return 0
   690  	case goobj.PkgIdxHashed64:
   691  		i := int(s.SymIdx) + r.ndef
   692  		return r.syms[i]
   693  	case goobj.PkgIdxHashed:
   694  		i := int(s.SymIdx) + r.ndef + r.nhashed64def
   695  		return r.syms[i]
   696  	case goobj.PkgIdxNone:
   697  		i := int(s.SymIdx) + r.ndef + r.nhashed64def + r.nhasheddef
   698  		return r.syms[i]
   699  	case goobj.PkgIdxBuiltin:
   700  		if bi := l.builtinSyms[s.SymIdx]; bi != 0 {
   701  			return bi
   702  		}
   703  		l.reportMissingBuiltin(int(s.SymIdx), r.unit.Lib.Pkg)
   704  		return 0
   705  	case goobj.PkgIdxSelf:
   706  		rr = r
   707  	default:
   708  		rr = l.objs[r.pkg[p]]
   709  	}
   710  	return l.toGlobal(rr, s.SymIdx)
   711  }
   712  
   713  // reportMissingBuiltin issues an error in the case where we have a
   714  // relocation against a runtime builtin whose definition is not found
   715  // when the runtime package is built. The canonical example is
   716  // "runtime.racefuncenter" -- currently if you do something like
   717  //
   718  //	go build -gcflags=-race myprogram.go
   719  //
   720  // the compiler will insert calls to the builtin runtime.racefuncenter,
   721  // but the version of the runtime used for linkage won't actually contain
   722  // definitions of that symbol. See issue #42396 for details.
   723  //
   724  // As currently implemented, this is a fatal error. This has drawbacks
   725  // in that if there are multiple missing builtins, the error will only
   726  // cite the first one. On the plus side, terminating the link here has
   727  // advantages in that we won't run the risk of panics or crashes later
   728  // on in the linker due to R_CALL relocations with 0-valued target
   729  // symbols.
   730  func (l *Loader) reportMissingBuiltin(bsym int, reflib string) {
   731  	bname, _ := goobj.BuiltinName(bsym)
   732  	log.Fatalf("reference to undefined builtin %q from package %q",
   733  		bname, reflib)
   734  }
   735  
   736  // Look up a symbol by name, return global index, or 0 if not found.
   737  // This is more like Syms.ROLookup than Lookup -- it doesn't create
   738  // new symbol.
   739  func (l *Loader) Lookup(name string, ver int) Sym {
   740  	if ver >= sym.SymVerStatic || ver < 0 {
   741  		return l.extStaticSyms[nameVer{name, ver}]
   742  	}
   743  	return l.symsByName[ver][name]
   744  }
   745  
   746  // Check that duplicate symbols have same contents.
   747  func (l *Loader) checkdup(name string, r *oReader, li uint32, dup Sym) {
   748  	p := r.Data(li)
   749  	rdup, ldup := l.toLocal(dup)
   750  	pdup := rdup.Data(ldup)
   751  	reason := "same length but different contents"
   752  	if len(p) != len(pdup) {
   753  		reason = fmt.Sprintf("new length %d != old length %d", len(p), len(pdup))
   754  	} else if bytes.Equal(p, pdup) {
   755  		// For BSS symbols, we need to check size as well, see issue 46653.
   756  		szdup := l.SymSize(dup)
   757  		sz := int64(r.Sym(li).Siz())
   758  		if szdup == sz {
   759  			return
   760  		}
   761  		reason = fmt.Sprintf("different sizes: new size %d != old size %d",
   762  			sz, szdup)
   763  	}
   764  	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)
   765  
   766  	// For the moment, allow DWARF subprogram DIEs for
   767  	// auto-generated wrapper functions. What seems to happen
   768  	// here is that we get different line numbers on formal
   769  	// params; I am guessing that the pos is being inherited
   770  	// from the spot where the wrapper is needed.
   771  	allowed := strings.HasPrefix(name, "go:info.go.interface") ||
   772  		strings.HasPrefix(name, "go:info.go.builtin") ||
   773  		strings.HasPrefix(name, "go:debuglines")
   774  	if !allowed {
   775  		l.strictDupMsgs++
   776  	}
   777  }
   778  
   779  func (l *Loader) NStrictDupMsgs() int { return l.strictDupMsgs }
   780  
   781  // Number of total symbols.
   782  func (l *Loader) NSym() int {
   783  	return len(l.objSyms)
   784  }
   785  
   786  // Number of defined Go symbols.
   787  func (l *Loader) NDef() int {
   788  	return int(l.extStart)
   789  }
   790  
   791  // Number of reachable symbols.
   792  func (l *Loader) NReachableSym() int {
   793  	return l.attrReachable.Count()
   794  }
   795  
   796  // Returns the name of the i-th symbol.
   797  func (l *Loader) SymName(i Sym) string {
   798  	if l.IsExternal(i) {
   799  		pp := l.getPayload(i)
   800  		return pp.name
   801  	}
   802  	r, li := l.toLocal(i)
   803  	if r == nil {
   804  		return "?"
   805  	}
   806  	return r.Sym(li).Name(r.Reader)
   807  }
   808  
   809  // Returns the version of the i-th symbol.
   810  func (l *Loader) SymVersion(i Sym) int {
   811  	if l.IsExternal(i) {
   812  		pp := l.getPayload(i)
   813  		return pp.ver
   814  	}
   815  	r, li := l.toLocal(i)
   816  	return abiToVer(r.Sym(li).ABI(), r.version)
   817  }
   818  
   819  func (l *Loader) IsFileLocal(i Sym) bool {
   820  	return l.SymVersion(i) >= sym.SymVerStatic
   821  }
   822  
   823  // IsFromAssembly returns true if this symbol is derived from an
   824  // object file generated by the Go assembler.
   825  func (l *Loader) IsFromAssembly(i Sym) bool {
   826  	if l.IsExternal(i) {
   827  		pp := l.getPayload(i)
   828  		if pp.objidx != 0 {
   829  			r := l.objs[pp.objidx]
   830  			return r.FromAssembly()
   831  		}
   832  		return false
   833  	}
   834  	r, _ := l.toLocal(i)
   835  	return r.FromAssembly()
   836  }
   837  
   838  // Returns the type of the i-th symbol.
   839  func (l *Loader) SymType(i Sym) sym.SymKind {
   840  	if l.IsExternal(i) {
   841  		pp := l.getPayload(i)
   842  		if pp != nil {
   843  			return pp.kind
   844  		}
   845  		return 0
   846  	}
   847  	r, li := l.toLocal(i)
   848  	return sym.AbiSymKindToSymKind[objabi.SymKind(r.Sym(li).Type())]
   849  }
   850  
   851  // Returns the attributes of the i-th symbol.
   852  func (l *Loader) SymAttr(i Sym) uint8 {
   853  	if l.IsExternal(i) {
   854  		// TODO: do something? External symbols have different representation of attributes.
   855  		// For now, ReflectMethod, NoSplit, GoType, and Typelink are used and they cannot be
   856  		// set by external symbol.
   857  		return 0
   858  	}
   859  	r, li := l.toLocal(i)
   860  	return r.Sym(li).Flag()
   861  }
   862  
   863  // Returns the size of the i-th symbol.
   864  func (l *Loader) SymSize(i Sym) int64 {
   865  	if l.IsExternal(i) {
   866  		pp := l.getPayload(i)
   867  		return pp.size
   868  	}
   869  	r, li := l.toLocal(i)
   870  	return int64(r.Sym(li).Siz())
   871  }
   872  
   873  // AttrReachable returns true for symbols that are transitively
   874  // referenced from the entry points. Unreachable symbols are not
   875  // written to the output.
   876  func (l *Loader) AttrReachable(i Sym) bool {
   877  	return l.attrReachable.Has(i)
   878  }
   879  
   880  // SetAttrReachable sets the reachability property for a symbol (see
   881  // AttrReachable).
   882  func (l *Loader) SetAttrReachable(i Sym, v bool) {
   883  	if v {
   884  		l.attrReachable.Set(i)
   885  	} else {
   886  		l.attrReachable.Unset(i)
   887  	}
   888  }
   889  
   890  // AttrOnList returns true for symbols that are on some list (such as
   891  // the list of all text symbols, or one of the lists of data symbols)
   892  // and is consulted to avoid bugs where a symbol is put on a list
   893  // twice.
   894  func (l *Loader) AttrOnList(i Sym) bool {
   895  	return l.attrOnList.Has(i)
   896  }
   897  
   898  // SetAttrOnList sets the "on list" property for a symbol (see
   899  // AttrOnList).
   900  func (l *Loader) SetAttrOnList(i Sym, v bool) {
   901  	if v {
   902  		l.attrOnList.Set(i)
   903  	} else {
   904  		l.attrOnList.Unset(i)
   905  	}
   906  }
   907  
   908  // AttrLocal returns true for symbols that are only visible within the
   909  // module (executable or shared library) being linked. This attribute
   910  // is applied to thunks and certain other linker-generated symbols.
   911  func (l *Loader) AttrLocal(i Sym) bool {
   912  	return l.attrLocal.Has(i)
   913  }
   914  
   915  // SetAttrLocal the "local" property for a symbol (see AttrLocal above).
   916  func (l *Loader) SetAttrLocal(i Sym, v bool) {
   917  	if v {
   918  		l.attrLocal.Set(i)
   919  	} else {
   920  		l.attrLocal.Unset(i)
   921  	}
   922  }
   923  
   924  // AttrUsedInIface returns true for a type symbol that is used in
   925  // an interface.
   926  func (l *Loader) AttrUsedInIface(i Sym) bool {
   927  	return l.attrUsedInIface.Has(i)
   928  }
   929  
   930  func (l *Loader) SetAttrUsedInIface(i Sym, v bool) {
   931  	if v {
   932  		l.attrUsedInIface.Set(i)
   933  	} else {
   934  		l.attrUsedInIface.Unset(i)
   935  	}
   936  }
   937  
   938  // SymAddr checks that a symbol is reachable, and returns its value.
   939  func (l *Loader) SymAddr(i Sym) int64 {
   940  	if !l.AttrReachable(i) {
   941  		panic("unreachable symbol in symaddr")
   942  	}
   943  	return l.values[i]
   944  }
   945  
   946  // AttrNotInSymbolTable returns true for symbols that should not be
   947  // added to the symbol table of the final generated load module.
   948  func (l *Loader) AttrNotInSymbolTable(i Sym) bool {
   949  	return l.attrNotInSymbolTable.Has(i)
   950  }
   951  
   952  // SetAttrNotInSymbolTable the "not in symtab" property for a symbol
   953  // (see AttrNotInSymbolTable above).
   954  func (l *Loader) SetAttrNotInSymbolTable(i Sym, v bool) {
   955  	if v {
   956  		l.attrNotInSymbolTable.Set(i)
   957  	} else {
   958  		l.attrNotInSymbolTable.Unset(i)
   959  	}
   960  }
   961  
   962  // AttrVisibilityHidden symbols returns true for ELF symbols with
   963  // visibility set to STV_HIDDEN. They become local symbols in
   964  // the final executable. Only relevant when internally linking
   965  // on an ELF platform.
   966  func (l *Loader) AttrVisibilityHidden(i Sym) bool {
   967  	if !l.IsExternal(i) {
   968  		return false
   969  	}
   970  	return l.attrVisibilityHidden.Has(l.extIndex(i))
   971  }
   972  
   973  // SetAttrVisibilityHidden sets the "hidden visibility" property for a
   974  // symbol (see AttrVisibilityHidden).
   975  func (l *Loader) SetAttrVisibilityHidden(i Sym, v bool) {
   976  	if !l.IsExternal(i) {
   977  		panic("tried to set visibility attr on non-external symbol")
   978  	}
   979  	if v {
   980  		l.attrVisibilityHidden.Set(l.extIndex(i))
   981  	} else {
   982  		l.attrVisibilityHidden.Unset(l.extIndex(i))
   983  	}
   984  }
   985  
   986  // AttrDuplicateOK returns true for a symbol that can be present in
   987  // multiple object files.
   988  func (l *Loader) AttrDuplicateOK(i Sym) bool {
   989  	if !l.IsExternal(i) {
   990  		// TODO: if this path winds up being taken frequently, it
   991  		// might make more sense to copy the flag value out of the object
   992  		// into a larger bitmap during preload.
   993  		r, li := l.toLocal(i)
   994  		return r.Sym(li).Dupok()
   995  	}
   996  	return l.attrDuplicateOK.Has(l.extIndex(i))
   997  }
   998  
   999  // SetAttrDuplicateOK sets the "duplicate OK" property for an external
  1000  // symbol (see AttrDuplicateOK).
  1001  func (l *Loader) SetAttrDuplicateOK(i Sym, v bool) {
  1002  	if !l.IsExternal(i) {
  1003  		panic("tried to set dupok attr on non-external symbol")
  1004  	}
  1005  	if v {
  1006  		l.attrDuplicateOK.Set(l.extIndex(i))
  1007  	} else {
  1008  		l.attrDuplicateOK.Unset(l.extIndex(i))
  1009  	}
  1010  }
  1011  
  1012  // AttrShared returns true for symbols compiled with the -shared option.
  1013  func (l *Loader) AttrShared(i Sym) bool {
  1014  	if !l.IsExternal(i) {
  1015  		// TODO: if this path winds up being taken frequently, it
  1016  		// might make more sense to copy the flag value out of the
  1017  		// object into a larger bitmap during preload.
  1018  		r, _ := l.toLocal(i)
  1019  		return r.Shared()
  1020  	}
  1021  	return l.attrShared.Has(l.extIndex(i))
  1022  }
  1023  
  1024  // SetAttrShared sets the "shared" property for an external
  1025  // symbol (see AttrShared).
  1026  func (l *Loader) SetAttrShared(i Sym, v bool) {
  1027  	if !l.IsExternal(i) {
  1028  		panic(fmt.Sprintf("tried to set shared attr on non-external symbol %d %s", i, l.SymName(i)))
  1029  	}
  1030  	if v {
  1031  		l.attrShared.Set(l.extIndex(i))
  1032  	} else {
  1033  		l.attrShared.Unset(l.extIndex(i))
  1034  	}
  1035  }
  1036  
  1037  // AttrExternal returns true for function symbols loaded from host
  1038  // object files.
  1039  func (l *Loader) AttrExternal(i Sym) bool {
  1040  	if !l.IsExternal(i) {
  1041  		return false
  1042  	}
  1043  	return l.attrExternal.Has(l.extIndex(i))
  1044  }
  1045  
  1046  // SetAttrExternal sets the "external" property for a host object
  1047  // symbol (see AttrExternal).
  1048  func (l *Loader) SetAttrExternal(i Sym, v bool) {
  1049  	if !l.IsExternal(i) {
  1050  		panic(fmt.Sprintf("tried to set external attr on non-external symbol %q", l.SymName(i)))
  1051  	}
  1052  	if v {
  1053  		l.attrExternal.Set(l.extIndex(i))
  1054  	} else {
  1055  		l.attrExternal.Unset(l.extIndex(i))
  1056  	}
  1057  }
  1058  
  1059  // AttrSpecial returns true for a symbols that do not have their
  1060  // address (i.e. Value) computed by the usual mechanism of
  1061  // data.go:dodata() & data.go:address().
  1062  func (l *Loader) AttrSpecial(i Sym) bool {
  1063  	return l.attrSpecial.Has(i)
  1064  }
  1065  
  1066  // SetAttrSpecial sets the "special" property for a symbol (see
  1067  // AttrSpecial).
  1068  func (l *Loader) SetAttrSpecial(i Sym, v bool) {
  1069  	if v {
  1070  		l.attrSpecial.Set(i)
  1071  	} else {
  1072  		l.attrSpecial.Unset(i)
  1073  	}
  1074  }
  1075  
  1076  // AttrCgoExportDynamic returns true for a symbol that has been
  1077  // specially marked via the "cgo_export_dynamic" compiler directive
  1078  // written by cgo (in response to //export directives in the source).
  1079  func (l *Loader) AttrCgoExportDynamic(i Sym) bool {
  1080  	_, ok := l.attrCgoExportDynamic[i]
  1081  	return ok
  1082  }
  1083  
  1084  // SetAttrCgoExportDynamic sets the "cgo_export_dynamic" for a symbol
  1085  // (see AttrCgoExportDynamic).
  1086  func (l *Loader) SetAttrCgoExportDynamic(i Sym, v bool) {
  1087  	if v {
  1088  		l.attrCgoExportDynamic[i] = struct{}{}
  1089  	} else {
  1090  		delete(l.attrCgoExportDynamic, i)
  1091  	}
  1092  }
  1093  
  1094  // ForAllCgoExportDynamic calls f for every symbol that has been
  1095  // marked with the "cgo_export_dynamic" compiler directive.
  1096  func (l *Loader) ForAllCgoExportDynamic(f func(Sym)) {
  1097  	for s := range l.attrCgoExportDynamic {
  1098  		f(s)
  1099  	}
  1100  }
  1101  
  1102  // AttrCgoExportStatic returns true for a symbol that has been
  1103  // specially marked via the "cgo_export_static" directive
  1104  // written by cgo.
  1105  func (l *Loader) AttrCgoExportStatic(i Sym) bool {
  1106  	_, ok := l.attrCgoExportStatic[i]
  1107  	return ok
  1108  }
  1109  
  1110  // SetAttrCgoExportStatic sets the "cgo_export_static" for a symbol
  1111  // (see AttrCgoExportStatic).
  1112  func (l *Loader) SetAttrCgoExportStatic(i Sym, v bool) {
  1113  	if v {
  1114  		l.attrCgoExportStatic[i] = struct{}{}
  1115  	} else {
  1116  		delete(l.attrCgoExportStatic, i)
  1117  	}
  1118  }
  1119  
  1120  // ForAllCgoExportStatic returns an iterator over all symbols
  1121  // marked with the "cgo_export_static" compiler directive.
  1122  func (l *Loader) ForAllCgoExportStatic() iter.Seq[Sym] {
  1123  	return func(yield func(Sym) bool) {
  1124  		for s := range l.attrCgoExportStatic {
  1125  			if !yield(s) {
  1126  				break
  1127  			}
  1128  		}
  1129  	}
  1130  }
  1131  
  1132  // IsGeneratedSym returns true if a symbol's been previously marked as a
  1133  // generator symbol through the SetIsGeneratedSym. The functions for generator
  1134  // symbols are kept in the Link context.
  1135  func (l *Loader) IsGeneratedSym(i Sym) bool {
  1136  	if !l.IsExternal(i) {
  1137  		return false
  1138  	}
  1139  	return l.generatedSyms.Has(l.extIndex(i))
  1140  }
  1141  
  1142  // SetIsGeneratedSym marks symbols as generated symbols. Data shouldn't be
  1143  // stored in generated symbols, and a function is registered and called for
  1144  // each of these symbols.
  1145  func (l *Loader) SetIsGeneratedSym(i Sym, v bool) {
  1146  	if !l.IsExternal(i) {
  1147  		panic("only external symbols can be generated")
  1148  	}
  1149  	if v {
  1150  		l.generatedSyms.Set(l.extIndex(i))
  1151  	} else {
  1152  		l.generatedSyms.Unset(l.extIndex(i))
  1153  	}
  1154  }
  1155  
  1156  func (l *Loader) AttrCgoExport(i Sym) bool {
  1157  	return l.AttrCgoExportDynamic(i) || l.AttrCgoExportStatic(i)
  1158  }
  1159  
  1160  // AttrReadOnly returns true for a symbol whose underlying data
  1161  // is stored via a read-only mmap.
  1162  func (l *Loader) AttrReadOnly(i Sym) bool {
  1163  	if v, ok := l.attrReadOnly[i]; ok {
  1164  		return v
  1165  	}
  1166  	if l.IsExternal(i) {
  1167  		pp := l.getPayload(i)
  1168  		if pp.objidx != 0 {
  1169  			return l.objs[pp.objidx].ReadOnly()
  1170  		}
  1171  		return false
  1172  	}
  1173  	r, _ := l.toLocal(i)
  1174  	return r.ReadOnly()
  1175  }
  1176  
  1177  // SetAttrReadOnly sets the "data is read only" property for a symbol
  1178  // (see AttrReadOnly).
  1179  func (l *Loader) SetAttrReadOnly(i Sym, v bool) {
  1180  	l.attrReadOnly[i] = v
  1181  }
  1182  
  1183  // AttrSubSymbol returns true for symbols that are listed as a
  1184  // sub-symbol of some other outer symbol. The sub/outer mechanism is
  1185  // used when loading host objects (sections from the host object
  1186  // become regular linker symbols and symbols go on the Sub list of
  1187  // their section) and for constructing the global offset table when
  1188  // internally linking a dynamic executable.
  1189  //
  1190  // Note that in later stages of the linker, we set Outer(S) to some
  1191  // container symbol C, but don't set Sub(C). Thus we have two
  1192  // distinct scenarios:
  1193  //
  1194  // - Outer symbol covers the address ranges of its sub-symbols.
  1195  //   Outer.Sub is set in this case.
  1196  // - Outer symbol doesn't cover the address ranges. It is zero-sized
  1197  //   and doesn't have sub-symbols. In the case, the inner symbol is
  1198  //   not actually a "SubSymbol". (Tricky!)
  1199  //
  1200  // This method returns TRUE only for sub-symbols in the first scenario.
  1201  //
  1202  // FIXME: would be better to do away with this and have a better way
  1203  // to represent container symbols.
  1204  
  1205  func (l *Loader) AttrSubSymbol(i Sym) bool {
  1206  	// we don't explicitly store this attribute any more -- return
  1207  	// a value based on the sub-symbol setting.
  1208  	o := l.OuterSym(i)
  1209  	if o == 0 {
  1210  		return false
  1211  	}
  1212  	return l.SubSym(o) != 0
  1213  }
  1214  
  1215  // Note that we don't have a 'SetAttrSubSymbol' method in the loader;
  1216  // clients should instead use the AddInteriorSym method to establish
  1217  // containment relationships for host object symbols.
  1218  
  1219  // Returns whether the i-th symbol has ReflectMethod attribute set.
  1220  func (l *Loader) IsReflectMethod(i Sym) bool {
  1221  	return l.SymAttr(i)&goobj.SymFlagReflectMethod != 0
  1222  }
  1223  
  1224  // Returns whether the i-th symbol is nosplit.
  1225  func (l *Loader) IsNoSplit(i Sym) bool {
  1226  	return l.SymAttr(i)&goobj.SymFlagNoSplit != 0
  1227  }
  1228  
  1229  // Returns whether this is a Go type symbol.
  1230  func (l *Loader) IsGoType(i Sym) bool {
  1231  	return l.SymAttr(i)&goobj.SymFlagGoType != 0
  1232  }
  1233  
  1234  // Returns whether this symbol should be included in typelink.
  1235  func (l *Loader) IsTypelink(i Sym) bool {
  1236  	return l.SymAttr(i)&goobj.SymFlagTypelink != 0
  1237  }
  1238  
  1239  // Returns whether this symbol is an itab symbol.
  1240  func (l *Loader) IsItab(i Sym) bool {
  1241  	if l.IsExternal(i) {
  1242  		return false
  1243  	}
  1244  	r, li := l.toLocal(i)
  1245  	return r.Sym(li).IsItab()
  1246  }
  1247  
  1248  // Returns whether this symbol is a dictionary symbol.
  1249  func (l *Loader) IsDict(i Sym) bool {
  1250  	if l.IsExternal(i) {
  1251  		return false
  1252  	}
  1253  	r, li := l.toLocal(i)
  1254  	return r.Sym(li).IsDict()
  1255  }
  1256  
  1257  // Returns whether this symbol is a compiler-generated package init func.
  1258  func (l *Loader) IsPkgInit(i Sym) bool {
  1259  	if l.IsExternal(i) {
  1260  		return false
  1261  	}
  1262  	r, li := l.toLocal(i)
  1263  	return r.Sym(li).IsPkgInit()
  1264  }
  1265  
  1266  // Return whether this is a trampoline of a deferreturn call.
  1267  func (l *Loader) IsDeferReturnTramp(i Sym) bool {
  1268  	return l.deferReturnTramp[i]
  1269  }
  1270  
  1271  // Set that i is a trampoline of a deferreturn call.
  1272  func (l *Loader) SetIsDeferReturnTramp(i Sym, v bool) {
  1273  	l.deferReturnTramp[i] = v
  1274  }
  1275  
  1276  // growValues grows the slice used to store symbol values.
  1277  func (l *Loader) growValues(reqLen int) {
  1278  	curLen := len(l.values)
  1279  	if reqLen > curLen {
  1280  		l.values = append(l.values, make([]int64, reqLen+1-curLen)...)
  1281  	}
  1282  }
  1283  
  1284  // SymValue returns the value of the i-th symbol. i is global index.
  1285  func (l *Loader) SymValue(i Sym) int64 {
  1286  	return l.values[i]
  1287  }
  1288  
  1289  // SetSymValue sets the value of the i-th symbol. i is global index.
  1290  func (l *Loader) SetSymValue(i Sym, val int64) {
  1291  	l.values[i] = val
  1292  }
  1293  
  1294  // AddToSymValue adds to the value of the i-th symbol. i is the global index.
  1295  func (l *Loader) AddToSymValue(i Sym, val int64) {
  1296  	l.values[i] += val
  1297  }
  1298  
  1299  // Returns the symbol content of the i-th symbol. i is global index.
  1300  func (l *Loader) Data(i Sym) []byte {
  1301  	if l.IsExternal(i) {
  1302  		pp := l.getPayload(i)
  1303  		if pp != nil {
  1304  			return pp.data
  1305  		}
  1306  		return nil
  1307  	}
  1308  	r, li := l.toLocal(i)
  1309  	return r.Data(li)
  1310  }
  1311  
  1312  // Returns the symbol content of the i-th symbol as a string. i is global index.
  1313  func (l *Loader) DataString(i Sym) string {
  1314  	if l.IsExternal(i) {
  1315  		pp := l.getPayload(i)
  1316  		return string(pp.data)
  1317  	}
  1318  	r, li := l.toLocal(i)
  1319  	return r.DataString(li)
  1320  }
  1321  
  1322  // FreeData clears the symbol data of an external symbol, allowing the memory
  1323  // to be freed earlier. No-op for non-external symbols.
  1324  // i is global index.
  1325  func (l *Loader) FreeData(i Sym) {
  1326  	if l.IsExternal(i) {
  1327  		pp := l.getPayload(i)
  1328  		if pp != nil {
  1329  			pp.data = nil
  1330  		}
  1331  	}
  1332  }
  1333  
  1334  // SymAlign returns the alignment for a symbol.
  1335  func (l *Loader) SymAlign(i Sym) int32 {
  1336  	if int(i) >= len(l.align) {
  1337  		// align is extended lazily -- it the sym in question is
  1338  		// outside the range of the existing slice, then we assume its
  1339  		// alignment has not yet been set.
  1340  		return 0
  1341  	}
  1342  	// TODO: would it make sense to return an arch-specific
  1343  	// alignment depending on section type? E.g. STEXT => 32,
  1344  	// SDATA => 1, etc?
  1345  	abits := l.align[i]
  1346  	if abits == 0 {
  1347  		return 0
  1348  	}
  1349  	return int32(1 << (abits - 1))
  1350  }
  1351  
  1352  // SetSymAlign sets the alignment for a symbol.
  1353  func (l *Loader) SetSymAlign(i Sym, align int32) {
  1354  	// Reject nonsense alignments.
  1355  	if align < 0 || align&(align-1) != 0 {
  1356  		panic("bad alignment value")
  1357  	}
  1358  	if int(i) >= len(l.align) {
  1359  		l.align = append(l.align, make([]uint8, l.NSym()-len(l.align))...)
  1360  	}
  1361  	l.align[i] = uint8(bits.Len32(uint32(align)))
  1362  }
  1363  
  1364  // SymSect returns the section of the i-th symbol. i is global index.
  1365  func (l *Loader) SymSect(i Sym) *sym.Section {
  1366  	if int(i) >= len(l.symSects) {
  1367  		// symSects is extended lazily -- it the sym in question is
  1368  		// outside the range of the existing slice, then we assume its
  1369  		// section has not yet been set.
  1370  		return nil
  1371  	}
  1372  	return l.sects[l.symSects[i]]
  1373  }
  1374  
  1375  // SetSymSect sets the section of the i-th symbol. i is global index.
  1376  func (l *Loader) SetSymSect(i Sym, sect *sym.Section) {
  1377  	if int(i) >= len(l.symSects) {
  1378  		l.symSects = append(l.symSects, make([]uint16, l.NSym()-len(l.symSects))...)
  1379  	}
  1380  	l.symSects[i] = sect.Index
  1381  }
  1382  
  1383  // NewSection creates a new (output) section.
  1384  func (l *Loader) NewSection() *sym.Section {
  1385  	sect := new(sym.Section)
  1386  	idx := len(l.sects)
  1387  	if idx != int(uint16(idx)) {
  1388  		panic("too many sections created")
  1389  	}
  1390  	sect.Index = uint16(idx)
  1391  	l.sects = append(l.sects, sect)
  1392  	return sect
  1393  }
  1394  
  1395  // SymDynimplib returns the "dynimplib" attribute for the specified
  1396  // symbol, making up a portion of the info for a symbol specified
  1397  // on a "cgo_import_dynamic" compiler directive.
  1398  func (l *Loader) SymDynimplib(i Sym) string {
  1399  	return l.dynimplib[i]
  1400  }
  1401  
  1402  // SetSymDynimplib sets the "dynimplib" attribute for a symbol.
  1403  func (l *Loader) SetSymDynimplib(i Sym, value string) {
  1404  	// reject bad symbols
  1405  	if i >= Sym(len(l.objSyms)) || i == 0 {
  1406  		panic("bad symbol index in SetDynimplib")
  1407  	}
  1408  	if value == "" {
  1409  		delete(l.dynimplib, i)
  1410  	} else {
  1411  		l.dynimplib[i] = value
  1412  	}
  1413  }
  1414  
  1415  // SymDynimpvers returns the "dynimpvers" attribute for the specified
  1416  // symbol, making up a portion of the info for a symbol specified
  1417  // on a "cgo_import_dynamic" compiler directive.
  1418  func (l *Loader) SymDynimpvers(i Sym) string {
  1419  	return l.dynimpvers[i]
  1420  }
  1421  
  1422  // SetSymDynimpvers sets the "dynimpvers" attribute for a symbol.
  1423  func (l *Loader) SetSymDynimpvers(i Sym, value string) {
  1424  	// reject bad symbols
  1425  	if i >= Sym(len(l.objSyms)) || i == 0 {
  1426  		panic("bad symbol index in SetDynimpvers")
  1427  	}
  1428  	if value == "" {
  1429  		delete(l.dynimpvers, i)
  1430  	} else {
  1431  		l.dynimpvers[i] = value
  1432  	}
  1433  }
  1434  
  1435  // SymExtname returns the "extname" value for the specified
  1436  // symbol.
  1437  func (l *Loader) SymExtname(i Sym) string {
  1438  	if s, ok := l.extname[i]; ok {
  1439  		return s
  1440  	}
  1441  	return l.SymName(i)
  1442  }
  1443  
  1444  // SetSymExtname sets the  "extname" attribute for a symbol.
  1445  func (l *Loader) SetSymExtname(i Sym, value string) {
  1446  	// reject bad symbols
  1447  	if i >= Sym(len(l.objSyms)) || i == 0 {
  1448  		panic("bad symbol index in SetExtname")
  1449  	}
  1450  	if value == "" {
  1451  		delete(l.extname, i)
  1452  	} else {
  1453  		l.extname[i] = value
  1454  	}
  1455  }
  1456  
  1457  func (l *Loader) SymWeakBinding(i Sym) bool {
  1458  	return l.weakBinding[i]
  1459  }
  1460  
  1461  func (l *Loader) SetSymWeakBinding(i Sym, v bool) {
  1462  	// reject bad symbols
  1463  	if i >= Sym(len(l.objSyms)) || i == 0 {
  1464  		panic("bad symbol index in SetSymWeakBinding")
  1465  	}
  1466  	l.weakBinding[i] = v
  1467  }
  1468  
  1469  // SymElfType returns the previously recorded ELF type for a symbol
  1470  // (used only for symbols read from shared libraries by ldshlibsyms).
  1471  // It is not set for symbols defined by the packages being linked or
  1472  // by symbols read by ldelf (and so is left as elf.STT_NOTYPE).
  1473  func (l *Loader) SymElfType(i Sym) elf.SymType {
  1474  	if et, ok := l.elfType[i]; ok {
  1475  		return et
  1476  	}
  1477  	return elf.STT_NOTYPE
  1478  }
  1479  
  1480  // SetSymElfType sets the elf type attribute for a symbol.
  1481  func (l *Loader) SetSymElfType(i Sym, et elf.SymType) {
  1482  	// reject bad symbols
  1483  	if i >= Sym(len(l.objSyms)) || i == 0 {
  1484  		panic("bad symbol index in SetSymElfType")
  1485  	}
  1486  	if et == elf.STT_NOTYPE {
  1487  		delete(l.elfType, i)
  1488  	} else {
  1489  		l.elfType[i] = et
  1490  	}
  1491  }
  1492  
  1493  // SymElfSym returns the ELF symbol index for a given loader
  1494  // symbol, assigned during ELF symtab generation.
  1495  func (l *Loader) SymElfSym(i Sym) int32 {
  1496  	return l.elfSym[i]
  1497  }
  1498  
  1499  // SetSymElfSym sets the elf symbol index for a symbol.
  1500  func (l *Loader) SetSymElfSym(i Sym, es int32) {
  1501  	if i == 0 {
  1502  		panic("bad sym index")
  1503  	}
  1504  	if es == 0 {
  1505  		delete(l.elfSym, i)
  1506  	} else {
  1507  		l.elfSym[i] = es
  1508  	}
  1509  }
  1510  
  1511  // SymLocalElfSym returns the "local" ELF symbol index for a given loader
  1512  // symbol, assigned during ELF symtab generation.
  1513  func (l *Loader) SymLocalElfSym(i Sym) int32 {
  1514  	return l.localElfSym[i]
  1515  }
  1516  
  1517  // SetSymLocalElfSym sets the "local" elf symbol index for a symbol.
  1518  func (l *Loader) SetSymLocalElfSym(i Sym, es int32) {
  1519  	if i == 0 {
  1520  		panic("bad sym index")
  1521  	}
  1522  	if es == 0 {
  1523  		delete(l.localElfSym, i)
  1524  	} else {
  1525  		l.localElfSym[i] = es
  1526  	}
  1527  }
  1528  
  1529  // SymPlt returns the PLT offset of symbol s.
  1530  func (l *Loader) SymPlt(s Sym) int32 {
  1531  	if v, ok := l.plt[s]; ok {
  1532  		return v
  1533  	}
  1534  	return -1
  1535  }
  1536  
  1537  // SetPlt sets the PLT offset of symbol i.
  1538  func (l *Loader) SetPlt(i Sym, v int32) {
  1539  	if i >= Sym(len(l.objSyms)) || i == 0 {
  1540  		panic("bad symbol for SetPlt")
  1541  	}
  1542  	if v == -1 {
  1543  		delete(l.plt, i)
  1544  	} else {
  1545  		l.plt[i] = v
  1546  	}
  1547  }
  1548  
  1549  // SymGot returns the GOT offset of symbol s.
  1550  func (l *Loader) SymGot(s Sym) int32 {
  1551  	if v, ok := l.got[s]; ok {
  1552  		return v
  1553  	}
  1554  	return -1
  1555  }
  1556  
  1557  // SetGot sets the GOT offset of symbol i.
  1558  func (l *Loader) SetGot(i Sym, v int32) {
  1559  	if i >= Sym(len(l.objSyms)) || i == 0 {
  1560  		panic("bad symbol for SetGot")
  1561  	}
  1562  	if v == -1 {
  1563  		delete(l.got, i)
  1564  	} else {
  1565  		l.got[i] = v
  1566  	}
  1567  }
  1568  
  1569  // SymDynid returns the "dynid" property for the specified symbol.
  1570  func (l *Loader) SymDynid(i Sym) int32 {
  1571  	if s, ok := l.dynid[i]; ok {
  1572  		return s
  1573  	}
  1574  	return -1
  1575  }
  1576  
  1577  // SetSymDynid sets the "dynid" property for a symbol.
  1578  func (l *Loader) SetSymDynid(i Sym, val int32) {
  1579  	// reject bad symbols
  1580  	if i >= Sym(len(l.objSyms)) || i == 0 {
  1581  		panic("bad symbol index in SetSymDynid")
  1582  	}
  1583  	if val == -1 {
  1584  		delete(l.dynid, i)
  1585  	} else {
  1586  		l.dynid[i] = val
  1587  	}
  1588  }
  1589  
  1590  // DynidSyms returns the set of symbols for which dynID is set to an
  1591  // interesting (non-default) value. This is expected to be a fairly
  1592  // small set.
  1593  func (l *Loader) DynidSyms() []Sym {
  1594  	sl := make([]Sym, 0, len(l.dynid))
  1595  	for s := range l.dynid {
  1596  		sl = append(sl, s)
  1597  	}
  1598  	sort.Slice(sl, func(i, j int) bool { return sl[i] < sl[j] })
  1599  	return sl
  1600  }
  1601  
  1602  // SymGoType returns the 'Gotype' property for a given symbol (set by
  1603  // the Go compiler for variable symbols). This version relies on
  1604  // reading aux symbols for the target sym -- it could be that a faster
  1605  // approach would be to check for gotype during preload and copy the
  1606  // results in to a map (might want to try this at some point and see
  1607  // if it helps speed things up).
  1608  func (l *Loader) SymGoType(i Sym) Sym { return l.aux1(i, goobj.AuxGotype) }
  1609  
  1610  // SymUnit returns the compilation unit for a given symbol (which will
  1611  // typically be nil for external or linker-manufactured symbols).
  1612  func (l *Loader) SymUnit(i Sym) *sym.CompilationUnit {
  1613  	if l.IsExternal(i) {
  1614  		pp := l.getPayload(i)
  1615  		if pp.objidx != 0 {
  1616  			r := l.objs[pp.objidx]
  1617  			return r.unit
  1618  		}
  1619  		return nil
  1620  	}
  1621  	r, _ := l.toLocal(i)
  1622  	return r.unit
  1623  }
  1624  
  1625  // SymPkg returns the package where the symbol came from (for
  1626  // regular compiler-generated Go symbols), but in the case of
  1627  // building with "-linkshared" (when a symbol is read from a
  1628  // shared library), will hold the library name.
  1629  // NOTE: this corresponds to sym.Symbol.File field.
  1630  func (l *Loader) SymPkg(i Sym) string {
  1631  	if f, ok := l.symPkg[i]; ok {
  1632  		return f
  1633  	}
  1634  	if l.IsExternal(i) {
  1635  		pp := l.getPayload(i)
  1636  		if pp.objidx != 0 {
  1637  			r := l.objs[pp.objidx]
  1638  			return r.unit.Lib.Pkg
  1639  		}
  1640  		return ""
  1641  	}
  1642  	r, _ := l.toLocal(i)
  1643  	return r.unit.Lib.Pkg
  1644  }
  1645  
  1646  // SetSymPkg sets the package/library for a symbol. This is
  1647  // needed mainly for external symbols, specifically those imported
  1648  // from shared libraries.
  1649  func (l *Loader) SetSymPkg(i Sym, pkg string) {
  1650  	// reject bad symbols
  1651  	if i >= Sym(len(l.objSyms)) || i == 0 {
  1652  		panic("bad symbol index in SetSymPkg")
  1653  	}
  1654  	l.symPkg[i] = pkg
  1655  }
  1656  
  1657  // SymLocalentry returns an offset in bytes of the "local entry" of a symbol.
  1658  //
  1659  // On PPC64, a value of 1 indicates the symbol does not use or preserve a TOC
  1660  // pointer in R2, nor does it have a distinct local entry.
  1661  func (l *Loader) SymLocalentry(i Sym) uint8 {
  1662  	return l.localentry[i]
  1663  }
  1664  
  1665  // SetSymLocalentry sets the "local entry" offset attribute for a symbol.
  1666  func (l *Loader) SetSymLocalentry(i Sym, value uint8) {
  1667  	// reject bad symbols
  1668  	if i >= Sym(len(l.objSyms)) || i == 0 {
  1669  		panic("bad symbol index in SetSymLocalentry")
  1670  	}
  1671  	if value == 0 {
  1672  		delete(l.localentry, i)
  1673  	} else {
  1674  		l.localentry[i] = value
  1675  	}
  1676  }
  1677  
  1678  // Returns the number of aux symbols given a global index.
  1679  func (l *Loader) NAux(i Sym) int {
  1680  	if l.IsExternal(i) {
  1681  		return 0
  1682  	}
  1683  	r, li := l.toLocal(i)
  1684  	return r.NAux(li)
  1685  }
  1686  
  1687  // Returns the "handle" to the j-th aux symbol of the i-th symbol.
  1688  func (l *Loader) Aux(i Sym, j int) Aux {
  1689  	if l.IsExternal(i) {
  1690  		return Aux{}
  1691  	}
  1692  	r, li := l.toLocal(i)
  1693  	if j >= r.NAux(li) {
  1694  		return Aux{}
  1695  	}
  1696  	return Aux{r.Aux(li, j), r, l}
  1697  }
  1698  
  1699  // WasmImportSym returns the auxiliary WebAssembly import symbol associated with
  1700  // a given function symbol. The aux sym only exists for Go function stubs that
  1701  // have been annotated with the //go:wasmimport directive.  The aux sym
  1702  // contains the information necessary for the linker to add a WebAssembly
  1703  // import statement.
  1704  // (https://webassembly.github.io/spec/core/syntax/modules.html#imports)
  1705  func (l *Loader) WasmImportSym(fnSymIdx Sym) Sym {
  1706  	if !l.SymType(fnSymIdx).IsText() {
  1707  		log.Fatalf("error: non-function sym %d/%s t=%s passed to WasmImportSym", fnSymIdx, l.SymName(fnSymIdx), l.SymType(fnSymIdx).String())
  1708  	}
  1709  	return l.aux1(fnSymIdx, goobj.AuxWasmImport)
  1710  }
  1711  
  1712  func (l *Loader) WasmTypeSym(s Sym) Sym {
  1713  	return l.aux1(s, goobj.AuxWasmType)
  1714  }
  1715  
  1716  // SEHUnwindSym returns the auxiliary SEH unwind symbol associated with
  1717  // a given function symbol.
  1718  func (l *Loader) SEHUnwindSym(fnSymIdx Sym) Sym {
  1719  	if !l.SymType(fnSymIdx).IsText() {
  1720  		log.Fatalf("error: non-function sym %d/%s t=%s passed to SEHUnwindSym", fnSymIdx, l.SymName(fnSymIdx), l.SymType(fnSymIdx).String())
  1721  	}
  1722  
  1723  	return l.aux1(fnSymIdx, goobj.AuxSehUnwindInfo)
  1724  }
  1725  
  1726  // GetFuncDwarfAuxSyms collects and returns the auxiliary DWARF
  1727  // symbols associated with a given function symbol.  Prior to the
  1728  // introduction of the loader, this was done purely using name
  1729  // lookups, e.f. for function with name XYZ we would then look up
  1730  // go.info.XYZ, etc.
  1731  func (l *Loader) GetFuncDwarfAuxSyms(fnSymIdx Sym) (auxDwarfInfo, auxDwarfLoc, auxDwarfRanges, auxDwarfLines Sym) {
  1732  	if !l.SymType(fnSymIdx).IsText() {
  1733  		log.Fatalf("error: non-function sym %d/%s t=%s passed to GetFuncDwarfAuxSyms", fnSymIdx, l.SymName(fnSymIdx), l.SymType(fnSymIdx).String())
  1734  	}
  1735  	r, auxs := l.auxs(fnSymIdx)
  1736  
  1737  	for i := range auxs {
  1738  		a := &auxs[i]
  1739  		switch a.Type() {
  1740  		case goobj.AuxDwarfInfo:
  1741  			auxDwarfInfo = l.resolve(r, a.Sym())
  1742  			if l.SymType(auxDwarfInfo) != sym.SDWARFFCN {
  1743  				panic("aux dwarf info sym with wrong type")
  1744  			}
  1745  		case goobj.AuxDwarfLoc:
  1746  			auxDwarfLoc = l.resolve(r, a.Sym())
  1747  			if l.SymType(auxDwarfLoc) != sym.SDWARFLOC {
  1748  				panic("aux dwarf loc sym with wrong type")
  1749  			}
  1750  		case goobj.AuxDwarfRanges:
  1751  			auxDwarfRanges = l.resolve(r, a.Sym())
  1752  			if l.SymType(auxDwarfRanges) != sym.SDWARFRANGE {
  1753  				panic("aux dwarf ranges sym with wrong type")
  1754  			}
  1755  		case goobj.AuxDwarfLines:
  1756  			auxDwarfLines = l.resolve(r, a.Sym())
  1757  			if l.SymType(auxDwarfLines) != sym.SDWARFLINES {
  1758  				panic("aux dwarf lines sym with wrong type")
  1759  			}
  1760  		}
  1761  	}
  1762  	return
  1763  }
  1764  
  1765  func (l *Loader) GetVarDwarfAuxSym(i Sym) Sym {
  1766  	aux := l.aux1(i, goobj.AuxDwarfInfo)
  1767  	if aux != 0 && l.SymType(aux) != sym.SDWARFVAR {
  1768  		fmt.Println(l.SymName(i), l.SymType(i), l.SymType(aux), sym.SDWARFVAR)
  1769  		panic("aux dwarf info sym with wrong type")
  1770  	}
  1771  	return aux
  1772  }
  1773  
  1774  // AddInteriorSym sets up 'interior' as an interior symbol of
  1775  // container/payload symbol 'container'. An interior symbol does not
  1776  // itself have data, but gives a name to a subrange of the data in its
  1777  // container symbol. The container itself may or may not have a name.
  1778  // This method is intended primarily for use in the host object
  1779  // loaders, to capture the semantics of symbols and sections in an
  1780  // object file. When reading a host object file, we'll typically
  1781  // encounter a static section symbol (ex: ".text") containing content
  1782  // for a collection of functions, then a series of ELF (or macho, etc)
  1783  // symbol table entries each of which points into a sub-section
  1784  // (offset and length) of its corresponding container symbol. Within
  1785  // the go linker we create a loader.Sym for the container (which is
  1786  // expected to have the actual content/payload) and then a set of
  1787  // interior loader.Sym's that point into a portion of the container.
  1788  func (l *Loader) AddInteriorSym(container Sym, interior Sym) {
  1789  	// The interior symbols for a container are not expected to have
  1790  	// content/data or relocations.
  1791  	if len(l.Data(interior)) != 0 {
  1792  		panic("unexpected non-empty interior symbol")
  1793  	}
  1794  	// Interior symbol is expected to be in the symbol table.
  1795  	if l.AttrNotInSymbolTable(interior) {
  1796  		panic("interior symbol must be in symtab")
  1797  	}
  1798  	// Only a single level of containment is allowed.
  1799  	if l.OuterSym(container) != 0 {
  1800  		panic("outer has outer itself")
  1801  	}
  1802  	// Interior sym should not already have a sibling.
  1803  	if l.SubSym(interior) != 0 {
  1804  		panic("sub set for subsym")
  1805  	}
  1806  	// Interior sym should not already point at a container.
  1807  	if l.OuterSym(interior) != 0 {
  1808  		panic("outer already set for subsym")
  1809  	}
  1810  	l.sub[interior] = l.sub[container]
  1811  	l.sub[container] = interior
  1812  	l.outer[interior] = container
  1813  }
  1814  
  1815  // OuterSym gets the outer/container symbol.
  1816  func (l *Loader) OuterSym(i Sym) Sym {
  1817  	return l.outer[i]
  1818  }
  1819  
  1820  // SubSym gets the subsymbol for host object loaded symbols.
  1821  func (l *Loader) SubSym(i Sym) Sym {
  1822  	return l.sub[i]
  1823  }
  1824  
  1825  // growOuter grows the slice used to store outer symbol.
  1826  func (l *Loader) growOuter(reqLen int) {
  1827  	curLen := len(l.outer)
  1828  	if reqLen > curLen {
  1829  		l.outer = append(l.outer, make([]Sym, reqLen-curLen)...)
  1830  	}
  1831  }
  1832  
  1833  // SetCarrierSym declares that 'c' is the carrier or container symbol
  1834  // for 's'. Carrier symbols are used in the linker to as a container
  1835  // for a collection of sub-symbols where the content of the
  1836  // sub-symbols is effectively concatenated to form the content of the
  1837  // carrier. The carrier is given a name in the output symbol table
  1838  // while the sub-symbol names are not. For example, the Go compiler
  1839  // emits named string symbols (type SGOSTRING) when compiling a
  1840  // package; after being deduplicated, these symbols are collected into
  1841  // a single unit by assigning them a new carrier symbol named
  1842  // "go:string.*" (which appears in the final symbol table for the
  1843  // output load module).
  1844  func (l *Loader) SetCarrierSym(s Sym, c Sym) {
  1845  	if c == 0 {
  1846  		panic("invalid carrier in SetCarrierSym")
  1847  	}
  1848  	if s == 0 {
  1849  		panic("invalid sub-symbol in SetCarrierSym")
  1850  	}
  1851  	// Carrier symbols are not expected to have content/data. It is
  1852  	// ok for them to have non-zero size (to allow for use of generator
  1853  	// symbols).
  1854  	if len(l.Data(c)) != 0 {
  1855  		panic("unexpected non-empty carrier symbol")
  1856  	}
  1857  	l.outer[s] = c
  1858  	// relocsym's foldSubSymbolOffset requires that we only
  1859  	// have a single level of containment-- enforce here.
  1860  	if l.outer[c] != 0 {
  1861  		panic("invalid nested carrier sym")
  1862  	}
  1863  }
  1864  
  1865  // Initialize Reachable bitmap and its siblings for running deadcode pass.
  1866  func (l *Loader) InitReachable() {
  1867  	l.growAttrBitmaps(l.NSym() + 1)
  1868  }
  1869  
  1870  type symWithVal struct {
  1871  	s Sym
  1872  	v int64
  1873  }
  1874  type bySymValue []symWithVal
  1875  
  1876  func (s bySymValue) Len() int           { return len(s) }
  1877  func (s bySymValue) Swap(i, j int)      { s[i], s[j] = s[j], s[i] }
  1878  func (s bySymValue) Less(i, j int) bool { return s[i].v < s[j].v }
  1879  
  1880  // SortSub walks through the sub-symbols for 's' and sorts them
  1881  // in place by increasing value. Return value is the new
  1882  // sub symbol for the specified outer symbol.
  1883  func (l *Loader) SortSub(s Sym) Sym {
  1884  
  1885  	if s == 0 || l.sub[s] == 0 {
  1886  		return s
  1887  	}
  1888  
  1889  	// Sort symbols using a slice first. Use a stable sort on the off
  1890  	// chance that there's more than once symbol with the same value,
  1891  	// so as to preserve reproducible builds.
  1892  	sl := []symWithVal{}
  1893  	for ss := l.sub[s]; ss != 0; ss = l.sub[ss] {
  1894  		sl = append(sl, symWithVal{s: ss, v: l.SymValue(ss)})
  1895  	}
  1896  	sort.Stable(bySymValue(sl))
  1897  
  1898  	// Then apply any changes needed to the sub map.
  1899  	ns := Sym(0)
  1900  	for i := len(sl) - 1; i >= 0; i-- {
  1901  		s := sl[i].s
  1902  		l.sub[s] = ns
  1903  		ns = s
  1904  	}
  1905  
  1906  	// Update sub for outer symbol, then return
  1907  	l.sub[s] = sl[0].s
  1908  	return sl[0].s
  1909  }
  1910  
  1911  // SortSyms sorts a list of symbols by their value.
  1912  func (l *Loader) SortSyms(ss []Sym) {
  1913  	sort.SliceStable(ss, func(i, j int) bool { return l.SymValue(ss[i]) < l.SymValue(ss[j]) })
  1914  }
  1915  
  1916  // Insure that reachable bitmap and its siblings have enough size.
  1917  func (l *Loader) growAttrBitmaps(reqLen int) {
  1918  	if reqLen > l.attrReachable.Len() {
  1919  		// These are indexed by global symbol
  1920  		l.attrReachable = growBitmap(reqLen, l.attrReachable)
  1921  		l.attrOnList = growBitmap(reqLen, l.attrOnList)
  1922  		l.attrLocal = growBitmap(reqLen, l.attrLocal)
  1923  		l.attrNotInSymbolTable = growBitmap(reqLen, l.attrNotInSymbolTable)
  1924  		l.attrUsedInIface = growBitmap(reqLen, l.attrUsedInIface)
  1925  		l.attrSpecial = growBitmap(reqLen, l.attrSpecial)
  1926  	}
  1927  	l.growExtAttrBitmaps()
  1928  }
  1929  
  1930  func (l *Loader) growExtAttrBitmaps() {
  1931  	// These are indexed by external symbol index (e.g. l.extIndex(i))
  1932  	extReqLen := len(l.payloads)
  1933  	if extReqLen > l.attrVisibilityHidden.Len() {
  1934  		l.attrVisibilityHidden = growBitmap(extReqLen, l.attrVisibilityHidden)
  1935  		l.attrDuplicateOK = growBitmap(extReqLen, l.attrDuplicateOK)
  1936  		l.attrShared = growBitmap(extReqLen, l.attrShared)
  1937  		l.attrExternal = growBitmap(extReqLen, l.attrExternal)
  1938  		l.generatedSyms = growBitmap(extReqLen, l.generatedSyms)
  1939  	}
  1940  }
  1941  
  1942  func (relocs *Relocs) Count() int { return len(relocs.rs) }
  1943  
  1944  // At returns the j-th reloc for a global symbol.
  1945  func (relocs *Relocs) At(j int) Reloc {
  1946  	if relocs.l.isExtReader(relocs.r) {
  1947  		return Reloc{&relocs.rs[j], relocs.r, relocs.l}
  1948  	}
  1949  	return Reloc{&relocs.rs[j], relocs.r, relocs.l}
  1950  }
  1951  
  1952  // Relocs returns a Relocs object for the given global sym.
  1953  func (l *Loader) Relocs(i Sym) Relocs {
  1954  	r, li := l.toLocal(i)
  1955  	if r == nil {
  1956  		panic(fmt.Sprintf("trying to get oreader for invalid sym %d\n\n", i))
  1957  	}
  1958  	return l.relocs(r, li)
  1959  }
  1960  
  1961  // relocs returns a Relocs object given a local sym index and reader.
  1962  func (l *Loader) relocs(r *oReader, li uint32) Relocs {
  1963  	var rs []goobj.Reloc
  1964  	if l.isExtReader(r) {
  1965  		pp := l.payloads[li]
  1966  		rs = pp.relocs
  1967  	} else {
  1968  		rs = r.Relocs(li)
  1969  	}
  1970  	return Relocs{
  1971  		rs: rs,
  1972  		li: li,
  1973  		r:  r,
  1974  		l:  l,
  1975  	}
  1976  }
  1977  
  1978  func (l *Loader) auxs(i Sym) (*oReader, []goobj.Aux) {
  1979  	if l.IsExternal(i) {
  1980  		pp := l.getPayload(i)
  1981  		return l.objs[pp.objidx], pp.auxs
  1982  	} else {
  1983  		r, li := l.toLocal(i)
  1984  		return r, r.Auxs(li)
  1985  	}
  1986  }
  1987  
  1988  // Returns a specific aux symbol of type t for symbol i.
  1989  func (l *Loader) aux1(i Sym, t uint8) Sym {
  1990  	r, auxs := l.auxs(i)
  1991  	for j := range auxs {
  1992  		a := &auxs[j]
  1993  		if a.Type() == t {
  1994  			return l.resolve(r, a.Sym())
  1995  		}
  1996  	}
  1997  	return 0
  1998  }
  1999  
  2000  func (l *Loader) Pcsp(i Sym) Sym { return l.aux1(i, goobj.AuxPcsp) }
  2001  
  2002  // Returns all aux symbols of per-PC data for symbol i.
  2003  // tmp is a scratch space for the pcdata slice.
  2004  func (l *Loader) PcdataAuxs(i Sym, tmp []Sym) (pcsp, pcfile, pcline, pcinline Sym, pcdata []Sym) {
  2005  	pcdata = tmp[:0]
  2006  	r, auxs := l.auxs(i)
  2007  	for j := range auxs {
  2008  		a := &auxs[j]
  2009  		switch a.Type() {
  2010  		case goobj.AuxPcsp:
  2011  			pcsp = l.resolve(r, a.Sym())
  2012  		case goobj.AuxPcline:
  2013  			pcline = l.resolve(r, a.Sym())
  2014  		case goobj.AuxPcfile:
  2015  			pcfile = l.resolve(r, a.Sym())
  2016  		case goobj.AuxPcinline:
  2017  			pcinline = l.resolve(r, a.Sym())
  2018  		case goobj.AuxPcdata:
  2019  			pcdata = append(pcdata, l.resolve(r, a.Sym()))
  2020  		}
  2021  	}
  2022  	return
  2023  }
  2024  
  2025  // Returns the number of pcdata for symbol i.
  2026  func (l *Loader) NumPcdata(i Sym) int {
  2027  	n := 0
  2028  	_, auxs := l.auxs(i)
  2029  	for j := range auxs {
  2030  		a := &auxs[j]
  2031  		if a.Type() == goobj.AuxPcdata {
  2032  			n++
  2033  		}
  2034  	}
  2035  	return n
  2036  }
  2037  
  2038  // Returns all funcdata symbols of symbol i.
  2039  // tmp is a scratch space.
  2040  func (l *Loader) Funcdata(i Sym, tmp []Sym) []Sym {
  2041  	fd := tmp[:0]
  2042  	r, auxs := l.auxs(i)
  2043  	for j := range auxs {
  2044  		a := &auxs[j]
  2045  		if a.Type() == goobj.AuxFuncdata {
  2046  			fd = append(fd, l.resolve(r, a.Sym()))
  2047  		}
  2048  	}
  2049  	return fd
  2050  }
  2051  
  2052  // Returns the number of funcdata for symbol i.
  2053  func (l *Loader) NumFuncdata(i Sym) int {
  2054  	n := 0
  2055  	_, auxs := l.auxs(i)
  2056  	for j := range auxs {
  2057  		a := &auxs[j]
  2058  		if a.Type() == goobj.AuxFuncdata {
  2059  			n++
  2060  		}
  2061  	}
  2062  	return n
  2063  }
  2064  
  2065  // FuncInfo provides hooks to access goobj.FuncInfo in the objects.
  2066  type FuncInfo struct {
  2067  	l       *Loader
  2068  	r       *oReader
  2069  	data    []byte
  2070  	lengths goobj.FuncInfoLengths
  2071  }
  2072  
  2073  func (fi *FuncInfo) Valid() bool { return fi.r != nil }
  2074  
  2075  func (fi *FuncInfo) Args() int {
  2076  	return int((*goobj.FuncInfo)(nil).ReadArgs(fi.data))
  2077  }
  2078  
  2079  func (fi *FuncInfo) Locals() int {
  2080  	return int((*goobj.FuncInfo)(nil).ReadLocals(fi.data))
  2081  }
  2082  
  2083  func (fi *FuncInfo) FuncID() abi.FuncID {
  2084  	return (*goobj.FuncInfo)(nil).ReadFuncID(fi.data)
  2085  }
  2086  
  2087  func (fi *FuncInfo) FuncFlag() abi.FuncFlag {
  2088  	return (*goobj.FuncInfo)(nil).ReadFuncFlag(fi.data)
  2089  }
  2090  
  2091  func (fi *FuncInfo) StartLine() int32 {
  2092  	return (*goobj.FuncInfo)(nil).ReadStartLine(fi.data)
  2093  }
  2094  
  2095  // Preload has to be called prior to invoking the various methods
  2096  // below related to pcdata, funcdataoff, files, and inltree nodes.
  2097  func (fi *FuncInfo) Preload() {
  2098  	fi.lengths = (*goobj.FuncInfo)(nil).ReadFuncInfoLengths(fi.data)
  2099  }
  2100  
  2101  func (fi *FuncInfo) NumFile() uint32 {
  2102  	if !fi.lengths.Initialized {
  2103  		panic("need to call Preload first")
  2104  	}
  2105  	return fi.lengths.NumFile
  2106  }
  2107  
  2108  func (fi *FuncInfo) File(k int) goobj.CUFileIndex {
  2109  	if !fi.lengths.Initialized {
  2110  		panic("need to call Preload first")
  2111  	}
  2112  	return (*goobj.FuncInfo)(nil).ReadFile(fi.data, fi.lengths.FileOff, uint32(k))
  2113  }
  2114  
  2115  // TopFrame returns true if the function associated with this FuncInfo
  2116  // is an entry point, meaning that unwinders should stop when they hit
  2117  // this function.
  2118  func (fi *FuncInfo) TopFrame() bool {
  2119  	return (fi.FuncFlag() & abi.FuncFlagTopFrame) != 0
  2120  }
  2121  
  2122  type InlTreeNode struct {
  2123  	Parent   int32
  2124  	File     goobj.CUFileIndex
  2125  	Line     int32
  2126  	Func     Sym
  2127  	ParentPC int32
  2128  }
  2129  
  2130  func (fi *FuncInfo) NumInlTree() uint32 {
  2131  	if !fi.lengths.Initialized {
  2132  		panic("need to call Preload first")
  2133  	}
  2134  	return fi.lengths.NumInlTree
  2135  }
  2136  
  2137  func (fi *FuncInfo) InlTree(k int) InlTreeNode {
  2138  	if !fi.lengths.Initialized {
  2139  		panic("need to call Preload first")
  2140  	}
  2141  	node := (*goobj.FuncInfo)(nil).ReadInlTree(fi.data, fi.lengths.InlTreeOff, uint32(k))
  2142  	return InlTreeNode{
  2143  		Parent:   node.Parent,
  2144  		File:     node.File,
  2145  		Line:     node.Line,
  2146  		Func:     fi.l.resolve(fi.r, node.Func),
  2147  		ParentPC: node.ParentPC,
  2148  	}
  2149  }
  2150  
  2151  func (l *Loader) FuncInfo(i Sym) FuncInfo {
  2152  	r, auxs := l.auxs(i)
  2153  	for j := range auxs {
  2154  		a := &auxs[j]
  2155  		if a.Type() == goobj.AuxFuncInfo {
  2156  			b := r.Data(a.Sym().SymIdx)
  2157  			return FuncInfo{l, r, b, goobj.FuncInfoLengths{}}
  2158  		}
  2159  	}
  2160  	return FuncInfo{}
  2161  }
  2162  
  2163  // Preload a package: adds autolib.
  2164  // Does not add defined package or non-packaged symbols to the symbol table.
  2165  // These are done in LoadSyms.
  2166  // Does not read symbol data.
  2167  // Returns the fingerprint of the object.
  2168  func (l *Loader) Preload(localSymVersion int, f *bio.Reader, lib *sym.Library, unit *sym.CompilationUnit, length int64) goobj.FingerprintType {
  2169  	roObject, readonly, err := f.Slice(uint64(length)) // TODO: no need to map blocks that are for tools only (e.g. RefName)
  2170  	if err != nil {
  2171  		log.Fatal("cannot read object file:", err)
  2172  	}
  2173  	r := goobj.NewReaderFromBytes(roObject, readonly)
  2174  	if r == nil {
  2175  		if len(roObject) >= 8 && bytes.Equal(roObject[:8], []byte("\x00go114ld")) {
  2176  			log.Fatalf("found object file %s in old format", f.File().Name())
  2177  		}
  2178  		panic("cannot read object file")
  2179  	}
  2180  	pkgprefix := objabi.PathToPrefix(lib.Pkg) + "."
  2181  	ndef := r.NSym()
  2182  	nhashed64def := r.NHashed64def()
  2183  	nhasheddef := r.NHasheddef()
  2184  	or := &oReader{
  2185  		Reader:       r,
  2186  		unit:         unit,
  2187  		version:      localSymVersion,
  2188  		pkgprefix:    pkgprefix,
  2189  		syms:         make([]Sym, ndef+nhashed64def+nhasheddef+r.NNonpkgdef()+r.NNonpkgref()),
  2190  		ndef:         ndef,
  2191  		nhasheddef:   nhasheddef,
  2192  		nhashed64def: nhashed64def,
  2193  		objidx:       uint32(len(l.objs)),
  2194  	}
  2195  
  2196  	if r.Unlinkable() {
  2197  		log.Fatalf("link: unlinkable object (from package %s) - compiler requires -p flag", lib.Pkg)
  2198  	}
  2199  
  2200  	// Autolib
  2201  	lib.Autolib = append(lib.Autolib, r.Autolib()...)
  2202  
  2203  	// DWARF file table
  2204  	nfile := r.NFile()
  2205  	unit.FileTable = make([]string, nfile)
  2206  	for i := range unit.FileTable {
  2207  		unit.FileTable[i] = r.File(i)
  2208  	}
  2209  
  2210  	l.addObj(lib.Pkg, or)
  2211  
  2212  	// The caller expects us consuming all the data
  2213  	f.MustSeek(length, io.SeekCurrent)
  2214  
  2215  	return r.Fingerprint()
  2216  }
  2217  
  2218  // Holds the loader along with temporary states for loading symbols.
  2219  type loadState struct {
  2220  	l            *Loader
  2221  	hashed64Syms map[uint64]symAndSize         // short hashed (content-addressable) symbols, keyed by content hash
  2222  	hashedSyms   map[goobj.HashType]symAndSize // hashed (content-addressable) symbols, keyed by content hash
  2223  
  2224  	linknameVarRefs []linknameVarRef // linknamed var refererces
  2225  }
  2226  
  2227  type linknameVarRef struct {
  2228  	pkg  *oReader // package of reference (not definition)
  2229  	name string
  2230  	sym  Sym
  2231  }
  2232  
  2233  // Preload symbols of given kind from an object.
  2234  func (st *loadState) preloadSyms(r *oReader, kind int) {
  2235  	l := st.l
  2236  	var start, end uint32
  2237  	switch kind {
  2238  	case pkgDef:
  2239  		start = 0
  2240  		end = uint32(r.ndef)
  2241  	case hashed64Def:
  2242  		start = uint32(r.ndef)
  2243  		end = uint32(r.ndef + r.nhashed64def)
  2244  	case hashedDef:
  2245  		start = uint32(r.ndef + r.nhashed64def)
  2246  		end = uint32(r.ndef + r.nhashed64def + r.nhasheddef)
  2247  	case nonPkgDef:
  2248  		start = uint32(r.ndef + r.nhashed64def + r.nhasheddef)
  2249  		end = uint32(r.ndef + r.nhashed64def + r.nhasheddef + r.NNonpkgdef())
  2250  	default:
  2251  		panic("preloadSyms: bad kind")
  2252  	}
  2253  	l.growAttrBitmaps(len(l.objSyms) + int(end-start))
  2254  	loadingRuntimePkg := r.unit.Lib.Pkg == "runtime"
  2255  	for i := start; i < end; i++ {
  2256  		osym := r.Sym(i)
  2257  		var name string
  2258  		var v int
  2259  		if kind != hashed64Def && kind != hashedDef { // we don't need the name, etc. for hashed symbols
  2260  			name = osym.Name(r.Reader)
  2261  			v = abiToVer(osym.ABI(), r.version)
  2262  		}
  2263  		gi := st.addSym(name, v, r, i, kind, osym)
  2264  		r.syms[i] = gi
  2265  		if kind == nonPkgDef && (osym.IsLinkname() || osym.IsLinknameStd()) && r.DataSize(i) == 0 && strings.Contains(name, ".") {
  2266  			// This is a linknamed "var" "reference" (var x T with no data and //go:linkname x).
  2267  			// We want to check if a linkname reference is allowed. Here we haven't loaded all
  2268  			// symbol definitions, so we don't yet know all the push linknames. So we add to a
  2269  			// list and check later after all symbol defs are loaded. Linknamed vars are rare,
  2270  			// so this list won't be long.
  2271  			// Only check references (pull), not definitions (push, with non-zero size),
  2272  			// so push is always allowed.
  2273  			// This use of linkname is usually for referencing C symbols, so allow symbols
  2274  			// with no "." in its name (not a regular Go symbol).
  2275  			// Linkname is always a non-package reference.
  2276  			st.linknameVarRefs = append(st.linknameVarRefs, linknameVarRef{r, name, gi})
  2277  		}
  2278  		if osym.Local() {
  2279  			l.SetAttrLocal(gi, true)
  2280  		}
  2281  		if osym.UsedInIface() {
  2282  			l.SetAttrUsedInIface(gi, true)
  2283  		}
  2284  		if strings.HasPrefix(name, "runtime.") ||
  2285  			(loadingRuntimePkg && strings.HasPrefix(name, "type:")) {
  2286  			if bi := goobj.BuiltinIdx(name, int(osym.ABI())); bi != -1 {
  2287  				// This is a definition of a builtin symbol. Record where it is.
  2288  				l.builtinSyms[bi] = gi
  2289  			}
  2290  		}
  2291  		if a := int32(osym.Align()); a != 0 && a > l.SymAlign(gi) {
  2292  			l.SetSymAlign(gi, a)
  2293  		}
  2294  		if osym.WasmExport() {
  2295  			l.WasmExports = append(l.WasmExports, gi)
  2296  		}
  2297  	}
  2298  }
  2299  
  2300  // Add syms, hashed (content-addressable) symbols, non-package symbols, and
  2301  // references to external symbols (which are always named).
  2302  func (l *Loader) LoadSyms(arch *sys.Arch) {
  2303  	// Allocate space for symbols, making a guess as to how much space we need.
  2304  	// This function was determined empirically by looking at the cmd/compile on
  2305  	// Darwin, and picking factors for hashed and hashed64 syms.
  2306  	var symSize, hashedSize, hashed64Size int
  2307  	for _, r := range l.objs[goObjStart:] {
  2308  		symSize += r.ndef + r.nhasheddef/2 + r.nhashed64def/2 + r.NNonpkgdef()
  2309  		hashedSize += r.nhasheddef / 2
  2310  		hashed64Size += r.nhashed64def / 2
  2311  	}
  2312  	// Index 0 is invalid for symbols.
  2313  	l.objSyms = make([]objSym, 1, symSize)
  2314  
  2315  	st := loadState{
  2316  		l:            l,
  2317  		hashed64Syms: make(map[uint64]symAndSize, hashed64Size),
  2318  		hashedSyms:   make(map[goobj.HashType]symAndSize, hashedSize),
  2319  	}
  2320  
  2321  	for _, r := range l.objs[goObjStart:] {
  2322  		st.preloadSyms(r, pkgDef)
  2323  	}
  2324  	l.npkgsyms = l.NSym()
  2325  	for _, r := range l.objs[goObjStart:] {
  2326  		st.preloadSyms(r, hashed64Def)
  2327  		st.preloadSyms(r, hashedDef)
  2328  		st.preloadSyms(r, nonPkgDef)
  2329  	}
  2330  	for _, vr := range st.linknameVarRefs {
  2331  		l.checkLinkname(vr.pkg, vr.name, vr.sym)
  2332  	}
  2333  	l.nhashedsyms = len(st.hashed64Syms) + len(st.hashedSyms)
  2334  	for _, r := range l.objs[goObjStart:] {
  2335  		loadObjRefs(l, r, arch)
  2336  	}
  2337  	for _, sf := range l.sizeFixups {
  2338  		pp := l.cloneToExternal(sf.sym)
  2339  		pp.size = int64(sf.size)
  2340  	}
  2341  	l.values = make([]int64, l.NSym(), l.NSym()+1000) // +1000 make some room for external symbols
  2342  	l.outer = make([]Sym, l.NSym(), l.NSym()+1000)
  2343  }
  2344  
  2345  func loadObjRefs(l *Loader, r *oReader, arch *sys.Arch) {
  2346  	// load non-package refs
  2347  	ndef := uint32(r.NAlldef())
  2348  	for i, n := uint32(0), uint32(r.NNonpkgref()); i < n; i++ {
  2349  		osym := r.Sym(ndef + i)
  2350  		name := osym.Name(r.Reader)
  2351  		v := abiToVer(osym.ABI(), r.version)
  2352  		gi := l.LookupOrCreateSym(name, v)
  2353  		r.syms[ndef+i] = gi
  2354  		if osym.IsLinkname() || osym.IsLinknameStd() {
  2355  			// Check if a linkname reference is allowed.
  2356  			// Only check references (pull), not definitions (push),
  2357  			// so push is always allowed.
  2358  			// Linkname is always a non-package reference.
  2359  			l.checkLinkname(r, name, gi)
  2360  		}
  2361  		if osym.Local() {
  2362  			l.SetAttrLocal(gi, true)
  2363  		}
  2364  		if osym.UsedInIface() {
  2365  			l.SetAttrUsedInIface(gi, true)
  2366  		}
  2367  	}
  2368  
  2369  	// referenced packages
  2370  	npkg := r.NPkg()
  2371  	r.pkg = make([]uint32, npkg)
  2372  	for i := 1; i < npkg; i++ { // PkgIdx 0 is a dummy invalid package
  2373  		pkg := r.Pkg(i)
  2374  		objidx, ok := l.objByPkg[pkg]
  2375  		if !ok {
  2376  			log.Fatalf("%v: reference to nonexistent package %s", r.unit.Lib, pkg)
  2377  		}
  2378  		r.pkg[i] = objidx
  2379  	}
  2380  
  2381  	// load flags of package refs
  2382  	for i, n := 0, r.NRefFlags(); i < n; i++ {
  2383  		rf := r.RefFlags(i)
  2384  		gi := l.resolve(r, rf.Sym())
  2385  		if rf.Flag2()&goobj.SymFlagUsedInIface != 0 {
  2386  			l.SetAttrUsedInIface(gi, true)
  2387  		}
  2388  	}
  2389  }
  2390  
  2391  func abiToVer(abi uint16, localSymVersion int) int {
  2392  	var v int
  2393  	if abi == goobj.SymABIstatic {
  2394  		// Static
  2395  		v = localSymVersion
  2396  	} else if abiver := sym.ABIToVersion(obj.ABI(abi)); abiver != -1 {
  2397  		// Note that data symbols are "ABI0", which maps to version 0.
  2398  		v = abiver
  2399  	} else {
  2400  		log.Fatalf("invalid symbol ABI: %d", abi)
  2401  	}
  2402  	return v
  2403  }
  2404  
  2405  // A list of blocked linknames. Some linknames are allowed only
  2406  // in specific packages. This maps symbol names to allowed packages.
  2407  // If a name is not in this map, it is allowed iff the definition
  2408  // has a linkname (push).
  2409  // If a name is in this map, it is allowed only in listed packages,
  2410  // even if it has a linknamed definition.
  2411  var blockedLinknames = map[string][]string{
  2412  	// coroutines
  2413  	"runtime.newcoro": {"iter"},
  2414  	// fips info
  2415  	"go:fipsinfo": {"crypto/internal/fips140/check"},
  2416  	// New internal linknames in Go 1.24
  2417  	// Pushed from runtime
  2418  	"crypto/internal/fips140.fatal":         {"crypto/internal/fips140"},
  2419  	"crypto/internal/fips140.getIndicator":  {"crypto/internal/fips140"},
  2420  	"crypto/internal/fips140.setIndicator":  {"crypto/internal/fips140"},
  2421  	"crypto/internal/sysrand.fatal":         {"crypto/internal/sysrand"},
  2422  	"crypto/rand.fatal":                     {"crypto/rand"},
  2423  	"internal/runtime/maps.errNilAssign":    {"internal/runtime/maps"},
  2424  	"internal/runtime/maps.fatal":           {"internal/runtime/maps"},
  2425  	"internal/runtime/maps.newarray":        {"internal/runtime/maps"},
  2426  	"internal/runtime/maps.newobject":       {"internal/runtime/maps"},
  2427  	"internal/runtime/maps.rand":            {"internal/runtime/maps"},
  2428  	"internal/runtime/maps.typedmemclr":     {"internal/runtime/maps"},
  2429  	"internal/runtime/maps.typedmemmove":    {"internal/runtime/maps"},
  2430  	"internal/sync.fatal":                   {"internal/sync"},
  2431  	"internal/sync.runtime_canSpin":         {"internal/sync"},
  2432  	"internal/sync.runtime_doSpin":          {"internal/sync"},
  2433  	"internal/sync.runtime_nanotime":        {"internal/sync"},
  2434  	"internal/sync.runtime_Semrelease":      {"internal/sync"},
  2435  	"internal/sync.runtime_SemacquireMutex": {"internal/sync"},
  2436  	"internal/sync.throw":                   {"internal/sync"},
  2437  	"internal/synctest.Run":                 {"internal/synctest"},
  2438  	"internal/synctest.Wait":                {"internal/synctest"},
  2439  	"internal/synctest.acquire":             {"internal/synctest"},
  2440  	"internal/synctest.release":             {"internal/synctest"},
  2441  	"internal/synctest.inBubble":            {"internal/synctest"},
  2442  	"runtime.getStaticuint64s":              {"reflect"},
  2443  	"sync.runtime_SemacquireWaitGroup":      {"sync"},
  2444  	"time.runtimeNow":                       {"time"},
  2445  	"time.runtimeNano":                      {"time"},
  2446  	// Pushed to runtime from internal/runtime/maps
  2447  	// (other map functions are already linknamed in Go 1.23)
  2448  	"runtime.mapaccess1":         {"runtime"},
  2449  	"runtime.mapaccess1_fast32":  {"runtime"},
  2450  	"runtime.mapaccess1_fast64":  {"runtime"},
  2451  	"runtime.mapaccess1_faststr": {"runtime"},
  2452  	"runtime.mapdelete_fast32":   {"runtime"},
  2453  	"runtime.mapdelete_fast64":   {"runtime"},
  2454  	"runtime.mapdelete_faststr":  {"runtime"},
  2455  	// New internal linknames in Go 1.25
  2456  	// Pushed from runtime
  2457  	"internal/cpu.riscvHWProbe":                      {"internal/cpu"},
  2458  	"internal/runtime/cgroup.throw":                  {"internal/runtime/cgroup"},
  2459  	"internal/runtime/maps.typeString":               {"internal/runtime/maps"},
  2460  	"internal/synctest.IsInBubble":                   {"internal/synctest"},
  2461  	"internal/synctest.associate":                    {"internal/synctest"},
  2462  	"internal/synctest.disassociate":                 {"internal/synctest"},
  2463  	"internal/synctest.isAssociated":                 {"internal/synctest"},
  2464  	"runtime/trace.runtime_readTrace":                {"runtime/trace"},
  2465  	"runtime/trace.runtime_traceClockUnitsPerSecond": {"runtime/trace"},
  2466  	"sync_test.runtime_blockUntilEmptyCleanupQueue":  {"sync_test"},
  2467  	"time.runtimeIsBubbled":                          {"time"},
  2468  	"unique.runtime_blockUntilEmptyCleanupQueue":     {"unique"},
  2469  	// Others
  2470  	"net.newWindowsFile":                   {"net"},              // pushed from os
  2471  	"testing/synctest.testingSynctestTest": {"testing/synctest"}, // pushed from testing
  2472  	// New internal linknames in Go 1.26
  2473  	// Pushed from runtime
  2474  	"crypto/fips140.isBypassed":                    {"crypto/fips140"},
  2475  	"crypto/fips140.setBypass":                     {"crypto/fips140"},
  2476  	"crypto/fips140.unsetBypass":                   {"crypto/fips140"},
  2477  	"crypto/subtle.setDITEnabled":                  {"crypto/subtle"},
  2478  	"crypto/subtle.setDITDisabled":                 {"crypto/subtle"},
  2479  	"internal/cpu.sysctlbynameBytes":               {"internal/cpu"},
  2480  	"internal/cpu.sysctlbynameInt32":               {"internal/cpu"},
  2481  	"runtime.pprof_goroutineLeakProfileWithLabels": {"runtime/pprof"},
  2482  	"runtime/pprof.runtime_goroutineLeakGC":        {"runtime/pprof"},
  2483  	"runtime/pprof.runtime_goroutineleakcount":     {"runtime/pprof"},
  2484  	"runtime/secret.appendSignalStacks":            {"runtime/secret"},
  2485  	"runtime/secret.count":                         {"runtime/secret"},
  2486  	"runtime/secret.dec":                           {"runtime/secret"},
  2487  	"runtime/secret.eraseSecrets":                  {"runtime/secret"},
  2488  	"runtime/secret.getStack":                      {"runtime/secret"},
  2489  	"runtime/secret.inc":                           {"runtime/secret"},
  2490  	"syscall.rawsyscalln":                          {"syscall"},
  2491  	"syscall.runtimeClearenv":                      {"syscall"},
  2492  	"syscall.syscalln":                             {"syscall"},
  2493  	// Others
  2494  	"crypto/internal/rand.SetTestingReader": {"testing/cryptotest"}, // pushed from crypto/internal/rand
  2495  	"testing.checkParallel":                 {"testing/cryptotest"}, // pushed from testing
  2496  	"runtime.addmoduledata":                 {},                     // assembly symbol, disallow all packages
  2497  }
  2498  
  2499  // check if a linkname reference to symbol s from refpkg is allowed
  2500  func (l *Loader) checkLinkname(refpkg *oReader, name string, s Sym) {
  2501  	if l.flags&FlagCheckLinkname == 0 {
  2502  		return
  2503  	}
  2504  
  2505  	pkg := refpkg.unit.Lib.Pkg
  2506  	error := func() {
  2507  		log.Fatalf("%s: invalid reference to %s", pkg, name)
  2508  	}
  2509  	pkgs, ok := blockedLinknames[name]
  2510  	if ok {
  2511  		for _, p := range pkgs {
  2512  			if pkg == p {
  2513  				return // pkg is allowed
  2514  			}
  2515  			// crypto/internal/fips140/vX.Y.Z/... is the frozen version of
  2516  			// crypto/internal/fips140/... and is similarly allowed.
  2517  			if strings.HasPrefix(pkg, "crypto/internal/fips140/v") {
  2518  				parts := strings.Split(pkg, "/")
  2519  				parts = append(parts[:3], parts[4:]...)
  2520  				pkg := strings.Join(parts, "/")
  2521  				if pkg == p {
  2522  					return
  2523  				}
  2524  			}
  2525  		}
  2526  		error()
  2527  	}
  2528  	r, li := l.toLocal(s)
  2529  	if r == l.extReader { // referencing external symbol is okay
  2530  		return
  2531  	}
  2532  	if !r.Std() { // For now, only check for symbols defined in std
  2533  		return
  2534  	}
  2535  	if r.unit.Lib.Pkg == pkg { // assembly reference from same package
  2536  		return
  2537  	}
  2538  	osym := r.Sym(li)
  2539  	if osym.IsLinknameStd() {
  2540  		// It is pushed with linknamestd. Allow only pulls from the
  2541  		// standard library.
  2542  		if refpkg.Std() {
  2543  			return
  2544  		}
  2545  	}
  2546  	if osym.IsLinkname() || osym.ABIWrapper() {
  2547  		// Allow if the def has a linkname (push).
  2548  		// ABI wrapper usually wraps an assembly symbol, a linknamed symbol,
  2549  		// or an external symbol, or provide access of a Go symbol to assembly.
  2550  		// For now, allow ABI wrappers.
  2551  		// TODO: check the wrapped symbol?
  2552  		return
  2553  	}
  2554  	error()
  2555  }
  2556  
  2557  // TopLevelSym tests a symbol (by name and kind) to determine whether
  2558  // the symbol first class sym (participating in the link) or is an
  2559  // anonymous aux or sub-symbol containing some sub-part or payload of
  2560  // another symbol.
  2561  func (l *Loader) TopLevelSym(s Sym) bool {
  2562  	return topLevelSym(l.SymName(s), l.SymType(s))
  2563  }
  2564  
  2565  // topLevelSym tests a symbol name and kind to determine whether
  2566  // the symbol first class sym (participating in the link) or is an
  2567  // anonymous aux or sub-symbol containing some sub-part or payload of
  2568  // another symbol.
  2569  func topLevelSym(sname string, skind sym.SymKind) bool {
  2570  	if sname != "" {
  2571  		return true
  2572  	}
  2573  	switch skind {
  2574  	case sym.SDWARFFCN, sym.SDWARFABSFCN, sym.SDWARFTYPE, sym.SDWARFCONST, sym.SDWARFCUINFO, sym.SDWARFRANGE, sym.SDWARFLOC, sym.SDWARFLINES, sym.SGOFUNC:
  2575  		return true
  2576  	default:
  2577  		return false
  2578  	}
  2579  }
  2580  
  2581  // cloneToExternal takes the existing object file symbol (symIdx)
  2582  // and creates a new external symbol payload that is a clone with
  2583  // respect to name, version, type, relocations, etc. The idea here
  2584  // is that if the linker decides it wants to update the contents of
  2585  // a symbol originally discovered as part of an object file, it's
  2586  // easier to do this if we make the updates to an external symbol
  2587  // payload.
  2588  func (l *Loader) cloneToExternal(symIdx Sym) *extSymPayload {
  2589  	if l.IsExternal(symIdx) {
  2590  		panic("sym is already external, no need for clone")
  2591  	}
  2592  
  2593  	// Read the particulars from object.
  2594  	r, li := l.toLocal(symIdx)
  2595  	osym := r.Sym(li)
  2596  	sname := osym.Name(r.Reader)
  2597  	sver := abiToVer(osym.ABI(), r.version)
  2598  	skind := sym.AbiSymKindToSymKind[objabi.SymKind(osym.Type())]
  2599  
  2600  	// Create new symbol, update version and kind.
  2601  	pi := l.newPayload(sname, sver)
  2602  	pp := l.payloads[pi]
  2603  	pp.kind = skind
  2604  	pp.ver = sver
  2605  	pp.size = int64(osym.Siz())
  2606  	pp.objidx = r.objidx
  2607  
  2608  	// If this is a def, then copy the guts. We expect this case
  2609  	// to be very rare (one case it may come up is with -X).
  2610  	if li < uint32(r.NAlldef()) {
  2611  
  2612  		// Copy relocations
  2613  		relocs := l.Relocs(symIdx)
  2614  		pp.relocs = make([]goobj.Reloc, relocs.Count())
  2615  		for i := range pp.relocs {
  2616  			// Copy the relocs slice.
  2617  			// Convert local reference to global reference.
  2618  			rel := relocs.At(i)
  2619  			pp.relocs[i].Set(rel.Off(), rel.Siz(), uint16(rel.Type()), rel.Add(), goobj.SymRef{PkgIdx: 0, SymIdx: uint32(rel.Sym())})
  2620  		}
  2621  
  2622  		// Copy data
  2623  		pp.data = r.Data(li)
  2624  	}
  2625  
  2626  	// If we're overriding a data symbol, collect the associated
  2627  	// Gotype, so as to propagate it to the new symbol.
  2628  	auxs := r.Auxs(li)
  2629  	pp.auxs = auxs
  2630  
  2631  	// Install new payload to global index space.
  2632  	// (This needs to happen at the end, as the accessors above
  2633  	// need to access the old symbol content.)
  2634  	l.objSyms[symIdx] = objSym{l.extReader.objidx, uint32(pi)}
  2635  	l.extReader.syms = append(l.extReader.syms, symIdx)
  2636  
  2637  	// Some attributes were encoded in the object file. Copy them over.
  2638  	l.SetAttrDuplicateOK(symIdx, r.Sym(li).Dupok())
  2639  	l.SetAttrShared(symIdx, r.Shared())
  2640  
  2641  	return pp
  2642  }
  2643  
  2644  // Copy the payload of symbol src to dst. Both src and dst must be external
  2645  // symbols.
  2646  // The intended use case is that when building/linking against a shared library,
  2647  // where we do symbol name mangling, the Go object file may have reference to
  2648  // the original symbol name whereas the shared library provides a symbol with
  2649  // the mangled name. When we do mangling, we copy payload of mangled to original.
  2650  func (l *Loader) CopySym(src, dst Sym) {
  2651  	if !l.IsExternal(dst) {
  2652  		panic("dst is not external") //l.newExtSym(l.SymName(dst), l.SymVersion(dst))
  2653  	}
  2654  	if !l.IsExternal(src) {
  2655  		panic("src is not external") //l.cloneToExternal(src)
  2656  	}
  2657  	l.payloads[l.extIndex(dst)] = l.payloads[l.extIndex(src)]
  2658  	l.SetSymPkg(dst, l.SymPkg(src))
  2659  	// TODO: other attributes?
  2660  }
  2661  
  2662  // CreateExtSym creates a new external symbol with the specified name
  2663  // without adding it to any lookup tables, returning a Sym index for it.
  2664  func (l *Loader) CreateExtSym(name string, ver int) Sym {
  2665  	return l.newExtSym(name, ver)
  2666  }
  2667  
  2668  // CreateStaticSym creates a new static symbol with the specified name
  2669  // without adding it to any lookup tables, returning a Sym index for it.
  2670  func (l *Loader) CreateStaticSym(name string) Sym {
  2671  	// Assign a new unique negative version -- this is to mark the
  2672  	// symbol so that it is not included in the name lookup table.
  2673  	l.anonVersion--
  2674  	return l.newExtSym(name, l.anonVersion)
  2675  }
  2676  
  2677  func (l *Loader) FreeSym(i Sym) {
  2678  	if l.IsExternal(i) {
  2679  		pp := l.getPayload(i)
  2680  		*pp = extSymPayload{}
  2681  	}
  2682  }
  2683  
  2684  // relocId is essentially a <S,R> tuple identifying the Rth
  2685  // relocation of symbol S.
  2686  type relocId struct {
  2687  	sym  Sym
  2688  	ridx int
  2689  }
  2690  
  2691  // SetRelocVariant sets the 'variant' property of a relocation on
  2692  // some specific symbol.
  2693  func (l *Loader) SetRelocVariant(s Sym, ri int, v sym.RelocVariant) {
  2694  	// sanity check
  2695  	if relocs := l.Relocs(s); ri >= relocs.Count() {
  2696  		panic("invalid relocation ID")
  2697  	}
  2698  	if l.relocVariant == nil {
  2699  		l.relocVariant = make(map[relocId]sym.RelocVariant)
  2700  	}
  2701  	if v != 0 {
  2702  		l.relocVariant[relocId{s, ri}] = v
  2703  	} else {
  2704  		delete(l.relocVariant, relocId{s, ri})
  2705  	}
  2706  }
  2707  
  2708  // RelocVariant returns the 'variant' property of a relocation on
  2709  // some specific symbol.
  2710  func (l *Loader) RelocVariant(s Sym, ri int) sym.RelocVariant {
  2711  	return l.relocVariant[relocId{s, ri}]
  2712  }
  2713  
  2714  // UndefinedRelocTargets iterates through the global symbol index
  2715  // space, looking for symbols with relocations targeting undefined
  2716  // references. The linker's loadlib method uses this to determine if
  2717  // there are unresolved references to functions in system libraries
  2718  // (for example, libgcc.a), presumably due to CGO code. Return value
  2719  // is a pair of lists of loader.Sym's. First list corresponds to the
  2720  // corresponding to the undefined symbols themselves, the second list
  2721  // is the symbol that is making a reference to the undef. The "limit"
  2722  // param controls the maximum number of results returned; if "limit"
  2723  // is -1, then all undefs are returned.
  2724  func (l *Loader) UndefinedRelocTargets(limit int) ([]Sym, []Sym) {
  2725  	result, fromr := []Sym{}, []Sym{}
  2726  outerloop:
  2727  	for si := Sym(1); si < Sym(len(l.objSyms)); si++ {
  2728  		relocs := l.Relocs(si)
  2729  		for ri := 0; ri < relocs.Count(); ri++ {
  2730  			r := relocs.At(ri)
  2731  			rs := r.Sym()
  2732  			if rs != 0 && l.SymType(rs) == sym.SXREF && l.SymName(rs) != ".got" {
  2733  				result = append(result, rs)
  2734  				fromr = append(fromr, si)
  2735  				if limit != -1 && len(result) >= limit {
  2736  					break outerloop
  2737  				}
  2738  			}
  2739  		}
  2740  	}
  2741  	return result, fromr
  2742  }
  2743  
  2744  // AssignTextSymbolOrder populates the Textp slices within each
  2745  // library and compilation unit, insuring that packages are laid down
  2746  // in dependency order (internal first, then everything else). Return value
  2747  // is a slice of all text syms.
  2748  func (l *Loader) AssignTextSymbolOrder(libs []*sym.Library, intlibs []bool, extsyms []Sym) []Sym {
  2749  
  2750  	// Library Textp lists should be empty at this point.
  2751  	for _, lib := range libs {
  2752  		if len(lib.Textp) != 0 {
  2753  			panic("expected empty Textp slice for library")
  2754  		}
  2755  		if len(lib.DupTextSyms) != 0 {
  2756  			panic("expected empty DupTextSyms slice for library")
  2757  		}
  2758  	}
  2759  
  2760  	// Used to record which dupok symbol we've assigned to a unit.
  2761  	// Can't use the onlist attribute here because it will need to
  2762  	// clear for the later assignment of the sym.Symbol to a unit.
  2763  	// NB: we can convert to using onList once we no longer have to
  2764  	// call the regular addToTextp.
  2765  	assignedToUnit := MakeBitmap(l.NSym() + 1)
  2766  
  2767  	// Start off textp with reachable external syms.
  2768  	textp := []Sym{}
  2769  	for _, sym := range extsyms {
  2770  		if !l.attrReachable.Has(sym) {
  2771  			continue
  2772  		}
  2773  		textp = append(textp, sym)
  2774  	}
  2775  
  2776  	// Walk through all text symbols from Go object files and append
  2777  	// them to their corresponding library's textp list.
  2778  	for _, r := range l.objs[goObjStart:] {
  2779  		lib := r.unit.Lib
  2780  		for i, n := uint32(0), uint32(r.NAlldef()); i < n; i++ {
  2781  			gi := l.toGlobal(r, i)
  2782  			if !l.attrReachable.Has(gi) {
  2783  				continue
  2784  			}
  2785  			osym := r.Sym(i)
  2786  			st := sym.AbiSymKindToSymKind[objabi.SymKind(osym.Type())]
  2787  			if !st.IsText() {
  2788  				continue
  2789  			}
  2790  			dupok := osym.Dupok()
  2791  			if r2, i2 := l.toLocal(gi); r2 != r || i2 != i {
  2792  				// A dupok text symbol is resolved to another package.
  2793  				// We still need to record its presence in the current
  2794  				// package, as the trampoline pass expects packages
  2795  				// are laid out in dependency order.
  2796  				lib.DupTextSyms = append(lib.DupTextSyms, gi)
  2797  				continue // symbol in different object
  2798  			}
  2799  			if dupok {
  2800  				lib.DupTextSyms = append(lib.DupTextSyms, gi)
  2801  				continue
  2802  			}
  2803  
  2804  			lib.Textp = append(lib.Textp, gi)
  2805  		}
  2806  	}
  2807  
  2808  	// Now assemble global textp, and assign text symbols to units.
  2809  	for _, doInternal := range [2]bool{true, false} {
  2810  		for idx, lib := range libs {
  2811  			if intlibs[idx] != doInternal {
  2812  				continue
  2813  			}
  2814  			lists := [2][]sym.LoaderSym{lib.Textp, lib.DupTextSyms}
  2815  			for i, list := range lists {
  2816  				for _, s := range list {
  2817  					sym := s
  2818  					if !assignedToUnit.Has(sym) {
  2819  						textp = append(textp, sym)
  2820  						unit := l.SymUnit(sym)
  2821  						if unit != nil {
  2822  							unit.Textp = append(unit.Textp, s)
  2823  							assignedToUnit.Set(sym)
  2824  						}
  2825  						// Dupok symbols may be defined in multiple packages; the
  2826  						// associated package for a dupok sym is chosen sort of
  2827  						// arbitrarily (the first containing package that the linker
  2828  						// loads). Canonicalizes its Pkg to the package with which
  2829  						// it will be laid down in text.
  2830  						if i == 1 /* DupTextSyms2 */ && l.SymPkg(sym) != lib.Pkg {
  2831  							l.SetSymPkg(sym, lib.Pkg)
  2832  						}
  2833  					}
  2834  				}
  2835  			}
  2836  			lib.Textp = nil
  2837  			lib.DupTextSyms = nil
  2838  		}
  2839  	}
  2840  
  2841  	return textp
  2842  }
  2843  
  2844  // ErrorReporter is a helper class for reporting errors.
  2845  type ErrorReporter struct {
  2846  	ldr              *Loader
  2847  	AfterErrorAction func()
  2848  }
  2849  
  2850  // Errorf method logs an error message.
  2851  //
  2852  // After each error, the error actions function will be invoked; this
  2853  // will either terminate the link immediately (if -h option given)
  2854  // or it will keep a count and exit if more than 20 errors have been printed.
  2855  //
  2856  // Logging an error means that on exit cmd/link will delete any
  2857  // output file and return a non-zero error code.
  2858  func (reporter *ErrorReporter) Errorf(s Sym, format string, args ...any) {
  2859  	if s != 0 && reporter.ldr.SymName(s) != "" {
  2860  		// Note: Replace is needed here because symbol names might have % in them,
  2861  		// due to the use of LinkString for names of instantiating types.
  2862  		format = strings.ReplaceAll(reporter.ldr.SymName(s), "%", "%%") + ": " + format
  2863  	} else {
  2864  		format = fmt.Sprintf("sym %d: %s", s, format)
  2865  	}
  2866  	format += "\n"
  2867  	fmt.Fprintf(os.Stderr, format, args...)
  2868  	reporter.AfterErrorAction()
  2869  }
  2870  
  2871  // GetErrorReporter returns the loader's associated error reporter.
  2872  func (l *Loader) GetErrorReporter() *ErrorReporter {
  2873  	return l.errorReporter
  2874  }
  2875  
  2876  // Errorf method logs an error message. See ErrorReporter.Errorf for details.
  2877  func (l *Loader) Errorf(s Sym, format string, args ...any) {
  2878  	l.errorReporter.Errorf(s, format, args...)
  2879  }
  2880  
  2881  // Symbol statistics.
  2882  func (l *Loader) Stat() string {
  2883  	s := fmt.Sprintf("%d symbols, %d reachable\n", l.NSym(), l.NReachableSym())
  2884  	s += fmt.Sprintf("\t%d package symbols, %d hashed symbols, %d non-package symbols, %d external symbols\n",
  2885  		l.npkgsyms, l.nhashedsyms, int(l.extStart)-l.npkgsyms-l.nhashedsyms, l.NSym()-int(l.extStart))
  2886  	return s
  2887  }
  2888  
  2889  // For debugging.
  2890  func (l *Loader) Dump() {
  2891  	fmt.Println("objs")
  2892  	for _, r := range l.objs[goObjStart:] {
  2893  		if r != nil {
  2894  			fmt.Println(r.unit.Lib)
  2895  		}
  2896  	}
  2897  	fmt.Println("extStart:", l.extStart)
  2898  	fmt.Println("Nsyms:", len(l.objSyms))
  2899  	fmt.Println("syms")
  2900  	for i := Sym(1); i < Sym(len(l.objSyms)); i++ {
  2901  		pi := ""
  2902  		if l.IsExternal(i) {
  2903  			pi = fmt.Sprintf("<ext %d>", l.extIndex(i))
  2904  		}
  2905  		sect := ""
  2906  		if l.SymSect(i) != nil {
  2907  			sect = l.SymSect(i).Name
  2908  		}
  2909  		fmt.Printf("%v %v %v %v %x %v\n", i, l.SymName(i), l.SymType(i), pi, l.SymValue(i), sect)
  2910  	}
  2911  	fmt.Println("symsByName")
  2912  	for name, i := range l.symsByName[0] {
  2913  		fmt.Println(i, name, 0)
  2914  	}
  2915  	for name, i := range l.symsByName[1] {
  2916  		fmt.Println(i, name, 1)
  2917  	}
  2918  	fmt.Println("payloads:")
  2919  	for i := range l.payloads {
  2920  		pp := l.payloads[i]
  2921  		fmt.Println(i, pp.name, pp.ver, pp.kind)
  2922  	}
  2923  }
  2924  

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