pcln.go

     1  // Copyright 2013 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 ld
     6  
     7  import (
     8  	"cmd/internal/goobj"
     9  	"cmd/internal/objabi"
    10  	"cmd/internal/sys"
    11  	"cmd/link/internal/loader"
    12  	"cmd/link/internal/sym"
    13  	"cmp"
    14  	"fmt"
    15  	"internal/abi"
    16  	"internal/buildcfg"
    17  	"path/filepath"
    18  	"slices"
    19  	"strings"
    20  )
    21  
    22  const funcSize = 11 * 4 // funcSize is the size of the _func object in runtime/runtime2.go
    23  
    24  // pclntab holds the state needed for pclntab generation.
    25  type pclntab struct {
    26  	// The first and last functions found.
    27  	firstFunc, lastFunc loader.Sym
    28  
    29  	// Running total size of pclntab.
    30  	size int64
    31  
    32  	// runtime.pclntab's symbols
    33  	carrier     loader.Sym
    34  	pclntab     loader.Sym
    35  	pcheader    loader.Sym
    36  	funcnametab loader.Sym
    37  	findfunctab loader.Sym
    38  	cutab       loader.Sym
    39  	filetab     loader.Sym
    40  	pctab       loader.Sym
    41  	funcdata    loader.Sym
    42  
    43  	// The number of functions + number of TEXT sections - 1. This is such an
    44  	// unexpected value because platforms that have more than one TEXT section
    45  	// get a dummy function inserted between because the external linker can place
    46  	// functions in those areas. We mark those areas as not covered by the Go
    47  	// runtime.
    48  	//
    49  	// On most platforms this is the number of reachable functions.
    50  	nfunc int32
    51  
    52  	// The number of filenames in runtime.filetab.
    53  	nfiles uint32
    54  }
    55  
    56  // addGeneratedSym adds a generator symbol to pclntab, returning the new Sym.
    57  // It is the caller's responsibility to save the symbol in state.
    58  func (state *pclntab) addGeneratedSym(ctxt *Link, name string, size int64, f generatorFunc) loader.Sym {
    59  	size = Rnd(size, int64(ctxt.Arch.PtrSize))
    60  	state.size += size
    61  	s := ctxt.createGeneratorSymbol(name, 0, sym.SPCLNTAB, size, f)
    62  	ctxt.loader.SetAttrReachable(s, true)
    63  	ctxt.loader.SetCarrierSym(s, state.carrier)
    64  	ctxt.loader.SetAttrNotInSymbolTable(s, true)
    65  	return s
    66  }
    67  
    68  // makePclntab makes a pclntab object, and assembles all the compilation units
    69  // we'll need to write pclntab. Returns the pclntab structure, a slice of the
    70  // CompilationUnits we need, and a slice of the function symbols we need to
    71  // generate pclntab.
    72  func makePclntab(ctxt *Link, container loader.Bitmap) (*pclntab, []*sym.CompilationUnit, []loader.Sym) {
    73  	ldr := ctxt.loader
    74  	state := new(pclntab)
    75  
    76  	// Gather some basic stats and info.
    77  	seenCUs := make(map[*sym.CompilationUnit]struct{})
    78  	compUnits := []*sym.CompilationUnit{}
    79  	funcs := []loader.Sym{}
    80  
    81  	for _, s := range ctxt.Textp {
    82  		if !emitPcln(ctxt, s, container) {
    83  			continue
    84  		}
    85  		funcs = append(funcs, s)
    86  		state.nfunc++
    87  		if state.firstFunc == 0 {
    88  			state.firstFunc = s
    89  		}
    90  		state.lastFunc = s
    91  
    92  		// We need to keep track of all compilation units we see. Some symbols
    93  		// (eg, go.buildid, _cgoexp_, etc) won't have a compilation unit.
    94  		cu := ldr.SymUnit(s)
    95  		if _, ok := seenCUs[cu]; cu != nil && !ok {
    96  			seenCUs[cu] = struct{}{}
    97  			cu.PclnIndex = len(compUnits)
    98  			compUnits = append(compUnits, cu)
    99  		}
   100  	}
   101  	return state, compUnits, funcs
   102  }
   103  
   104  func emitPcln(ctxt *Link, s loader.Sym, container loader.Bitmap) bool {
   105  	if ctxt.Target.IsRISCV64() {
   106  		// Avoid adding local symbols to the pcln table - RISC-V
   107  		// linking generates a very large number of these, particularly
   108  		// for HI20 symbols (which we need to load in order to be able
   109  		// to resolve relocations). Unnecessarily including all of
   110  		// these symbols quickly blows out the size of the pcln table
   111  		// and overflows hash buckets.
   112  		symName := ctxt.loader.SymName(s)
   113  		if symName == "" || strings.HasPrefix(symName, ".L") {
   114  			return false
   115  		}
   116  	}
   117  
   118  	// We want to generate func table entries only for the "lowest
   119  	// level" symbols, not containers of subsymbols.
   120  	return !container.Has(s)
   121  }
   122  
   123  func computeDeferReturn(ctxt *Link, deferReturnSym, s loader.Sym) uint32 {
   124  	ldr := ctxt.loader
   125  	target := ctxt.Target
   126  	deferreturn := uint32(0)
   127  	lastWasmAddr := uint32(0)
   128  
   129  	relocs := ldr.Relocs(s)
   130  	for ri := 0; ri < relocs.Count(); ri++ {
   131  		r := relocs.At(ri)
   132  		if target.IsWasm() && r.Type() == objabi.R_ADDR {
   133  			// wasm/ssa.go generates an ARESUMEPOINT just
   134  			// before the deferreturn call. The "PC" of
   135  			// the deferreturn call is stored in the
   136  			// R_ADDR relocation on the ARESUMEPOINT.
   137  			lastWasmAddr = uint32(r.Add())
   138  		}
   139  		if r.Type().IsDirectCall() && (r.Sym() == deferReturnSym || ldr.IsDeferReturnTramp(r.Sym())) {
   140  			if target.IsWasm() {
   141  				deferreturn = lastWasmAddr - 1
   142  			} else {
   143  				// Note: the relocation target is in the call instruction, but
   144  				// is not necessarily the whole instruction (for instance, on
   145  				// x86 the relocation applies to bytes [1:5] of the 5 byte call
   146  				// instruction).
   147  				deferreturn = uint32(r.Off())
   148  				switch target.Arch.Family {
   149  				case sys.I386:
   150  					deferreturn--
   151  					if ctxt.BuildMode == BuildModeShared || ctxt.linkShared || ctxt.BuildMode == BuildModePlugin {
   152  						// In this mode, we need to get the address from GOT,
   153  						// with two additional instructions like
   154  						//
   155  						// CALL    __x86.get_pc_thunk.bx(SB)       // 5 bytes
   156  						// LEAL    _GLOBAL_OFFSET_TABLE_<>(BX), BX // 6 bytes
   157  						//
   158  						// We need to back off to the get_pc_thunk call.
   159  						// (See progedit in cmd/internal/obj/x86/obj6.go)
   160  						deferreturn -= 11
   161  					}
   162  				case sys.AMD64:
   163  					deferreturn--
   164  
   165  				case sys.ARM, sys.ARM64, sys.Loong64, sys.MIPS, sys.MIPS64, sys.PPC64, sys.RISCV64:
   166  					// no change
   167  				case sys.S390X:
   168  					deferreturn -= 2
   169  				default:
   170  					panic(fmt.Sprint("Unhandled architecture:", target.Arch.Family))
   171  				}
   172  			}
   173  			break // only need one
   174  		}
   175  	}
   176  	return deferreturn
   177  }
   178  
   179  // genInlTreeSym generates the InlTree sym for a function with the
   180  // specified FuncInfo.
   181  func genInlTreeSym(ctxt *Link, cu *sym.CompilationUnit, fi loader.FuncInfo, arch *sys.Arch, nameOffsets map[loader.Sym]uint32) loader.Sym {
   182  	ldr := ctxt.loader
   183  	its := ldr.CreateExtSym("", 0)
   184  	inlTreeSym := ldr.MakeSymbolUpdater(its)
   185  	// Note: the generated symbol is given a type of sym.SGOFUNC, as a
   186  	// signal to the symtab() phase that it needs to be grouped in with
   187  	// other similar symbols (gcdata, etc); the dodata() phase will
   188  	// eventually switch the type back to SRODATA.
   189  	inlTreeSym.SetType(sym.SPCLNTAB)
   190  	ldr.SetAttrReachable(its, true)
   191  	ldr.SetSymAlign(its, 4) // it has 32-bit fields
   192  	ninl := fi.NumInlTree()
   193  	for i := 0; i < int(ninl); i++ {
   194  		call := fi.InlTree(i)
   195  		nameOff, ok := nameOffsets[call.Func]
   196  		if !ok {
   197  			panic("couldn't find function name offset")
   198  		}
   199  
   200  		inlFunc := ldr.FuncInfo(call.Func)
   201  		var funcID abi.FuncID
   202  		startLine := int32(0)
   203  		if inlFunc.Valid() {
   204  			funcID = inlFunc.FuncID()
   205  			startLine = inlFunc.StartLine()
   206  		} else if !ctxt.linkShared {
   207  			// Inlined functions are always Go functions, and thus
   208  			// must have FuncInfo.
   209  			//
   210  			// Unfortunately, with -linkshared, the inlined
   211  			// function may be external symbols (from another
   212  			// shared library), and we don't load FuncInfo from the
   213  			// shared library. We will report potentially incorrect
   214  			// FuncID in this case. See https://go.dev/issue/55954.
   215  			panic(fmt.Sprintf("inlined function %s missing func info", ldr.SymName(call.Func)))
   216  		}
   217  
   218  		// Construct runtime.inlinedCall value.
   219  		const size = 16
   220  		inlTreeSym.SetUint8(arch, int64(i*size+0), uint8(funcID))
   221  		// Bytes 1-3 are unused.
   222  		inlTreeSym.SetUint32(arch, int64(i*size+4), nameOff)
   223  		inlTreeSym.SetUint32(arch, int64(i*size+8), uint32(call.ParentPC))
   224  		inlTreeSym.SetUint32(arch, int64(i*size+12), uint32(startLine))
   225  	}
   226  	return its
   227  }
   228  
   229  // makeInlSyms returns a map of loader.Sym that are created inlSyms.
   230  func makeInlSyms(ctxt *Link, funcs []loader.Sym, nameOffsets map[loader.Sym]uint32) map[loader.Sym]loader.Sym {
   231  	ldr := ctxt.loader
   232  	// Create the inline symbols we need.
   233  	inlSyms := make(map[loader.Sym]loader.Sym)
   234  	for _, s := range funcs {
   235  		if fi := ldr.FuncInfo(s); fi.Valid() {
   236  			fi.Preload()
   237  			if fi.NumInlTree() > 0 {
   238  				inlSyms[s] = genInlTreeSym(ctxt, ldr.SymUnit(s), fi, ctxt.Arch, nameOffsets)
   239  			}
   240  		}
   241  	}
   242  	return inlSyms
   243  }
   244  
   245  // generatePCHeader creates the runtime.pcheader symbol, setting it up as a
   246  // generator to fill in its data later.
   247  func (state *pclntab) generatePCHeader(ctxt *Link) {
   248  	ldr := ctxt.loader
   249  	size := int64(8 + 8*ctxt.Arch.PtrSize)
   250  	writeHeader := func(ctxt *Link, s loader.Sym) {
   251  		header := ctxt.loader.MakeSymbolUpdater(s)
   252  
   253  		writeSymOffset := func(off int64, ws loader.Sym) int64 {
   254  			diff := ldr.SymValue(ws) - ldr.SymValue(s)
   255  			if diff <= 0 {
   256  				name := ldr.SymName(ws)
   257  				panic(fmt.Sprintf("expected runtime.pcheader(%x) to be placed before %s(%x)", ldr.SymValue(s), name, ldr.SymValue(ws)))
   258  			}
   259  			return header.SetUintptr(ctxt.Arch, off, uintptr(diff))
   260  		}
   261  
   262  		// Write header.
   263  		// Keep in sync with runtime/symtab.go:pcHeader and package debug/gosym.
   264  		header.SetUint32(ctxt.Arch, 0, uint32(abi.CurrentPCLnTabMagic))
   265  		header.SetUint8(ctxt.Arch, 6, uint8(ctxt.Arch.MinLC))
   266  		header.SetUint8(ctxt.Arch, 7, uint8(ctxt.Arch.PtrSize))
   267  		off := header.SetUint(ctxt.Arch, 8, uint64(state.nfunc))
   268  		off = header.SetUint(ctxt.Arch, off, uint64(state.nfiles))
   269  		off = header.SetUintptr(ctxt.Arch, off, 0) // unused
   270  		off = writeSymOffset(off, state.funcnametab)
   271  		off = writeSymOffset(off, state.cutab)
   272  		off = writeSymOffset(off, state.filetab)
   273  		off = writeSymOffset(off, state.pctab)
   274  		off = writeSymOffset(off, state.pclntab)
   275  		if off != size {
   276  			panic(fmt.Sprintf("pcHeader size: %d != %d", off, size))
   277  		}
   278  	}
   279  
   280  	state.pcheader = state.addGeneratedSym(ctxt, "runtime.pcheader", size, writeHeader)
   281  }
   282  
   283  // walkFuncs iterates over the funcs, calling a function for each unique
   284  // function and inlined function.
   285  func walkFuncs(ctxt *Link, funcs []loader.Sym, f func(loader.Sym)) {
   286  	ldr := ctxt.loader
   287  	seen := make(map[loader.Sym]struct{})
   288  	for _, s := range funcs {
   289  		if _, ok := seen[s]; !ok {
   290  			f(s)
   291  			seen[s] = struct{}{}
   292  		}
   293  
   294  		fi := ldr.FuncInfo(s)
   295  		if !fi.Valid() {
   296  			continue
   297  		}
   298  		fi.Preload()
   299  		for i, ni := 0, fi.NumInlTree(); i < int(ni); i++ {
   300  			call := fi.InlTree(i).Func
   301  			if _, ok := seen[call]; !ok {
   302  				f(call)
   303  				seen[call] = struct{}{}
   304  			}
   305  		}
   306  	}
   307  }
   308  
   309  // generateFuncnametab creates the function name table. Returns a map of
   310  // func symbol to the name offset in runtime.funcnamtab.
   311  func (state *pclntab) generateFuncnametab(ctxt *Link, funcs []loader.Sym) map[loader.Sym]uint32 {
   312  	nameOffsets := make(map[loader.Sym]uint32, state.nfunc)
   313  
   314  	// Write the null terminated strings.
   315  	writeFuncNameTab := func(ctxt *Link, s loader.Sym) {
   316  		symtab := ctxt.loader.MakeSymbolUpdater(s)
   317  		for s, off := range nameOffsets {
   318  			symtab.AddCStringAt(int64(off), ctxt.loader.SymName(s))
   319  		}
   320  	}
   321  
   322  	// Loop through the CUs, and calculate the size needed.
   323  	var size int64
   324  	walkFuncs(ctxt, funcs, func(s loader.Sym) {
   325  		nameOffsets[s] = uint32(size)
   326  		size += int64(len(ctxt.loader.SymName(s)) + 1) // NULL terminate
   327  	})
   328  
   329  	state.funcnametab = state.addGeneratedSym(ctxt, "runtime.funcnametab", size, writeFuncNameTab)
   330  	return nameOffsets
   331  }
   332  
   333  // walkFilenames walks funcs, calling a function for each filename used in each
   334  // function's line table.
   335  func walkFilenames(ctxt *Link, funcs []loader.Sym, f func(*sym.CompilationUnit, goobj.CUFileIndex)) {
   336  	ldr := ctxt.loader
   337  
   338  	// Loop through all functions, finding the filenames we need.
   339  	for _, s := range funcs {
   340  		fi := ldr.FuncInfo(s)
   341  		if !fi.Valid() {
   342  			continue
   343  		}
   344  		fi.Preload()
   345  
   346  		cu := ldr.SymUnit(s)
   347  		for i, nf := 0, int(fi.NumFile()); i < nf; i++ {
   348  			f(cu, fi.File(i))
   349  		}
   350  		for i, ninl := 0, int(fi.NumInlTree()); i < ninl; i++ {
   351  			call := fi.InlTree(i)
   352  			f(cu, call.File)
   353  		}
   354  	}
   355  }
   356  
   357  // generateFilenameTabs creates LUTs needed for filename lookup. Returns a slice
   358  // of the index at which each CU begins in runtime.cutab.
   359  //
   360  // Function objects keep track of the files they reference to print the stack.
   361  // This function creates a per-CU list of filenames if CU[M] references
   362  // files[1-N], the following is generated:
   363  //
   364  //	runtime.cutab:
   365  //	  CU[M]
   366  //	   offsetToFilename[0]
   367  //	   offsetToFilename[1]
   368  //	   ..
   369  //
   370  //	runtime.filetab
   371  //	   filename[0]
   372  //	   filename[1]
   373  //
   374  // Looking up a filename then becomes:
   375  //  0. Given a func, and filename index [K]
   376  //  1. Get Func.CUIndex:       M := func.cuOffset
   377  //  2. Find filename offset:   fileOffset := runtime.cutab[M+K]
   378  //  3. Get the filename:       getcstring(runtime.filetab[fileOffset])
   379  func (state *pclntab) generateFilenameTabs(ctxt *Link, compUnits []*sym.CompilationUnit, funcs []loader.Sym) []uint32 {
   380  	// On a per-CU basis, keep track of all the filenames we need.
   381  	//
   382  	// Note, that we store the filenames in a separate section in the object
   383  	// files, and deduplicate based on the actual value. It would be better to
   384  	// store the filenames as symbols, using content addressable symbols (and
   385  	// then not loading extra filenames), and just use the hash value of the
   386  	// symbol name to do this cataloging.
   387  	//
   388  	// TODO: Store filenames as symbols. (Note this would be easiest if you
   389  	// also move strings to ALWAYS using the larger content addressable hash
   390  	// function, and use that hash value for uniqueness testing.)
   391  	cuEntries := make([]goobj.CUFileIndex, len(compUnits))
   392  	fileOffsets := make(map[string]uint32)
   393  
   394  	// Walk the filenames.
   395  	// We store the total filename string length we need to load, and the max
   396  	// file index we've seen per CU so we can calculate how large the
   397  	// CU->global table needs to be.
   398  	var fileSize int64
   399  	walkFilenames(ctxt, funcs, func(cu *sym.CompilationUnit, i goobj.CUFileIndex) {
   400  		// Note we use the raw filename for lookup, but use the expanded filename
   401  		// when we save the size.
   402  		filename := cu.FileTable[i]
   403  		if _, ok := fileOffsets[filename]; !ok {
   404  			fileOffsets[filename] = uint32(fileSize)
   405  			fileSize += int64(len(expandFile(filename)) + 1) // NULL terminate
   406  		}
   407  
   408  		// Find the maximum file index we've seen.
   409  		if cuEntries[cu.PclnIndex] < i+1 {
   410  			cuEntries[cu.PclnIndex] = i + 1 // Store max + 1
   411  		}
   412  	})
   413  
   414  	// Calculate the size of the runtime.cutab variable.
   415  	var totalEntries uint32
   416  	cuOffsets := make([]uint32, len(cuEntries))
   417  	for i, entries := range cuEntries {
   418  		// Note, cutab is a slice of uint32, so an offset to a cu's entry is just the
   419  		// running total of all cu indices we've needed to store so far, not the
   420  		// number of bytes we've stored so far.
   421  		cuOffsets[i] = totalEntries
   422  		totalEntries += uint32(entries)
   423  	}
   424  
   425  	// Write cutab.
   426  	writeCutab := func(ctxt *Link, s loader.Sym) {
   427  		sb := ctxt.loader.MakeSymbolUpdater(s)
   428  
   429  		var off int64
   430  		for i, max := range cuEntries {
   431  			// Write the per CU LUT.
   432  			cu := compUnits[i]
   433  			for j := goobj.CUFileIndex(0); j < max; j++ {
   434  				fileOffset, ok := fileOffsets[cu.FileTable[j]]
   435  				if !ok {
   436  					// We're looping through all possible file indices. It's possible a file's
   437  					// been deadcode eliminated, and although it's a valid file in the CU, it's
   438  					// not needed in this binary. When that happens, use an invalid offset.
   439  					fileOffset = ^uint32(0)
   440  				}
   441  				off = sb.SetUint32(ctxt.Arch, off, fileOffset)
   442  			}
   443  		}
   444  	}
   445  	state.cutab = state.addGeneratedSym(ctxt, "runtime.cutab", int64(totalEntries*4), writeCutab)
   446  
   447  	// Write filetab.
   448  	writeFiletab := func(ctxt *Link, s loader.Sym) {
   449  		sb := ctxt.loader.MakeSymbolUpdater(s)
   450  
   451  		// Write the strings.
   452  		for filename, loc := range fileOffsets {
   453  			sb.AddStringAt(int64(loc), expandFile(filename))
   454  		}
   455  	}
   456  	state.nfiles = uint32(len(fileOffsets))
   457  	state.filetab = state.addGeneratedSym(ctxt, "runtime.filetab", fileSize, writeFiletab)
   458  
   459  	return cuOffsets
   460  }
   461  
   462  // generatePctab creates the runtime.pctab variable, holding all the
   463  // deduplicated pcdata.
   464  func (state *pclntab) generatePctab(ctxt *Link, funcs []loader.Sym) {
   465  	ldr := ctxt.loader
   466  
   467  	// Pctab offsets of 0 are considered invalid in the runtime. We respect
   468  	// that by just padding a single byte at the beginning of runtime.pctab,
   469  	// that way no real offsets can be zero.
   470  	size := int64(1)
   471  
   472  	// Walk the functions, finding offset to store each pcdata.
   473  	seen := make(map[loader.Sym]struct{})
   474  	saveOffset := func(pcSym loader.Sym) {
   475  		if _, ok := seen[pcSym]; !ok {
   476  			datSize := ldr.SymSize(pcSym)
   477  			if datSize != 0 {
   478  				ldr.SetSymValue(pcSym, size)
   479  			} else {
   480  				// Invalid PC data, record as zero.
   481  				ldr.SetSymValue(pcSym, 0)
   482  			}
   483  			size += datSize
   484  			seen[pcSym] = struct{}{}
   485  		}
   486  	}
   487  	var pcsp, pcline, pcfile, pcinline loader.Sym
   488  	var pcdata []loader.Sym
   489  	for _, s := range funcs {
   490  		fi := ldr.FuncInfo(s)
   491  		if !fi.Valid() {
   492  			continue
   493  		}
   494  		fi.Preload()
   495  		pcsp, pcfile, pcline, pcinline, pcdata = ldr.PcdataAuxs(s, pcdata)
   496  
   497  		pcSyms := []loader.Sym{pcsp, pcfile, pcline}
   498  		for _, pcSym := range pcSyms {
   499  			saveOffset(pcSym)
   500  		}
   501  		for _, pcSym := range pcdata {
   502  			saveOffset(pcSym)
   503  		}
   504  		if fi.NumInlTree() > 0 {
   505  			saveOffset(pcinline)
   506  		}
   507  	}
   508  
   509  	// TODO: There is no reason we need a generator for this variable, and it
   510  	// could be moved to a carrier symbol. However, carrier symbols containing
   511  	// carrier symbols don't work yet (as of Aug 2020). Once this is fixed,
   512  	// runtime.pctab could just be a carrier sym.
   513  	writePctab := func(ctxt *Link, s loader.Sym) {
   514  		ldr := ctxt.loader
   515  		sb := ldr.MakeSymbolUpdater(s)
   516  		for sym := range seen {
   517  			sb.SetBytesAt(ldr.SymValue(sym), ldr.Data(sym))
   518  		}
   519  	}
   520  
   521  	state.pctab = state.addGeneratedSym(ctxt, "runtime.pctab", size, writePctab)
   522  }
   523  
   524  // generateFuncdata writes out the funcdata information.
   525  func (state *pclntab) generateFuncdata(ctxt *Link, funcs []loader.Sym, inlsyms map[loader.Sym]loader.Sym) {
   526  	ldr := ctxt.loader
   527  
   528  	// Walk the functions and collect the funcdata.
   529  	seen := make(map[loader.Sym]struct{}, len(funcs))
   530  	fdSyms := make([]loader.Sym, 0, len(funcs))
   531  	fd := []loader.Sym{}
   532  	for _, s := range funcs {
   533  		fi := ldr.FuncInfo(s)
   534  		if !fi.Valid() {
   535  			continue
   536  		}
   537  		fi.Preload()
   538  		fd := funcData(ldr, s, fi, inlsyms[s], fd)
   539  		for j, fdSym := range fd {
   540  			if ignoreFuncData(ldr, s, j, fdSym) {
   541  				continue
   542  			}
   543  
   544  			if _, ok := seen[fdSym]; !ok {
   545  				fdSyms = append(fdSyms, fdSym)
   546  				seen[fdSym] = struct{}{}
   547  			}
   548  		}
   549  	}
   550  	seen = nil
   551  
   552  	// Sort the funcdata in reverse order by alignment
   553  	// to minimize alignment gaps. Use a stable sort
   554  	// for reproducible results.
   555  	var maxAlign int32
   556  	slices.SortStableFunc(fdSyms, func(a, b loader.Sym) int {
   557  		aAlign := symalign(ldr, a)
   558  		bAlign := symalign(ldr, b)
   559  
   560  		// Remember maximum alignment.
   561  		maxAlign = max(maxAlign, aAlign, bAlign)
   562  
   563  		// Negate to sort by decreasing alignment.
   564  		return -cmp.Compare(aAlign, bAlign)
   565  	})
   566  
   567  	// We will output the symbols in the order of fdSyms.
   568  	// Set the value of each symbol to its offset in the funcdata.
   569  	// This way when writeFuncs writes out the funcdata offset,
   570  	// it can simply write out the symbol value.
   571  
   572  	// Accumulated size of funcdata info.
   573  	size := int64(0)
   574  
   575  	for _, fdSym := range fdSyms {
   576  		datSize := ldr.SymSize(fdSym)
   577  		if datSize == 0 {
   578  			ctxt.Errorf(fdSym, "zero size funcdata")
   579  			continue
   580  		}
   581  
   582  		size = Rnd(size, int64(symalign(ldr, fdSym)))
   583  		ldr.SetSymValue(fdSym, size)
   584  		size += datSize
   585  
   586  		// We do not put the funcdata symbols in the symbol table.
   587  		ldr.SetAttrNotInSymbolTable(fdSym, true)
   588  
   589  		// Mark the symbol as special so that it does not get
   590  		// adjusted by the section offset.
   591  		ldr.SetAttrSpecial(fdSym, true)
   592  	}
   593  
   594  	// Funcdata symbols are permitted to have R_ADDROFF relocations,
   595  	// which the linker can fully resolve.
   596  	resolveRelocs := func(ldr *loader.Loader, fdSym loader.Sym, data []byte) {
   597  		relocs := ldr.Relocs(fdSym)
   598  		for i := 0; i < relocs.Count(); i++ {
   599  			r := relocs.At(i)
   600  			if r.Type() != objabi.R_ADDROFF {
   601  				ctxt.Errorf(fdSym, "unsupported reloc %d (%s) for funcdata symbol", r.Type(), sym.RelocName(ctxt.Target.Arch, r.Type()))
   602  				return
   603  			}
   604  			if r.Siz() != 4 {
   605  				ctxt.Errorf(fdSym, "unsupported ADDROFF reloc size %d for funcdata symbol", r.Siz())
   606  				return
   607  			}
   608  			rs := r.Sym()
   609  			if r.Weak() && !ldr.AttrReachable(rs) {
   610  				return
   611  			}
   612  			sect := ldr.SymSect(rs)
   613  			if sect == nil {
   614  				ctxt.Errorf(fdSym, "missing section for relocation target %s for funcdata symbol", ldr.SymName(rs))
   615  			}
   616  			o := ldr.SymValue(rs)
   617  			if sect.Name != ".text" {
   618  				o -= int64(sect.Vaddr)
   619  			} else {
   620  				// With multiple .text sections the offset
   621  				// is from the start of the first one.
   622  				o -= int64(Segtext.Sections[0].Vaddr)
   623  				if ctxt.Target.IsWasm() {
   624  					if o&(1<<16-1) != 0 {
   625  						ctxt.Errorf(fdSym, "textoff relocation does not target function entry for funcdata symbol: %s %#x", ldr.SymName(rs), o)
   626  					}
   627  					o >>= 16
   628  				}
   629  			}
   630  			o += r.Add()
   631  			if o != int64(int32(o)) && o != int64(uint32(o)) {
   632  				ctxt.Errorf(fdSym, "ADDROFF relocation out of range for funcdata symbol: %#x", o)
   633  			}
   634  			ctxt.Target.Arch.ByteOrder.PutUint32(data[r.Off():], uint32(o))
   635  		}
   636  	}
   637  
   638  	writeFuncData := func(ctxt *Link, s loader.Sym) {
   639  		ldr := ctxt.loader
   640  		sb := ldr.MakeSymbolUpdater(s)
   641  		for _, fdSym := range fdSyms {
   642  			off := ldr.SymValue(fdSym)
   643  			fdSymData := ldr.Data(fdSym)
   644  			sb.SetBytesAt(off, fdSymData)
   645  			// Resolve any R_ADDROFF relocations.
   646  			resolveRelocs(ldr, fdSym, sb.Data()[off:off+int64(len(fdSymData))])
   647  		}
   648  	}
   649  
   650  	state.funcdata = state.addGeneratedSym(ctxt, "go:func.*", size, writeFuncData)
   651  
   652  	// Because the funcdata previously was not in pclntab,
   653  	// we need to keep the visible symbol so that tools can find it.
   654  	ldr.SetAttrNotInSymbolTable(state.funcdata, false)
   655  }
   656  
   657  // ignoreFuncData reports whether we should ignore a funcdata symbol.
   658  //
   659  // cmd/internal/obj optimistically populates ArgsPointerMaps and
   660  // ArgInfo for assembly functions, hoping that the compiler will
   661  // emit appropriate symbols from their Go stub declarations. If
   662  // it didn't though, just ignore it.
   663  //
   664  // TODO(cherryyz): Fix arg map generation (see discussion on CL 523335).
   665  func ignoreFuncData(ldr *loader.Loader, s loader.Sym, j int, fdSym loader.Sym) bool {
   666  	if fdSym == 0 {
   667  		return true
   668  	}
   669  	if (j == abi.FUNCDATA_ArgsPointerMaps || j == abi.FUNCDATA_ArgInfo) && ldr.IsFromAssembly(s) && ldr.Data(fdSym) == nil {
   670  		return true
   671  	}
   672  	return false
   673  }
   674  
   675  // numPCData returns the number of PCData syms for the FuncInfo.
   676  // NB: Preload must be called on valid FuncInfos before calling this function.
   677  func numPCData(ldr *loader.Loader, s loader.Sym, fi loader.FuncInfo) uint32 {
   678  	if !fi.Valid() {
   679  		return 0
   680  	}
   681  	numPCData := uint32(ldr.NumPcdata(s))
   682  	if fi.NumInlTree() > 0 {
   683  		if numPCData < abi.PCDATA_InlTreeIndex+1 {
   684  			numPCData = abi.PCDATA_InlTreeIndex + 1
   685  		}
   686  	}
   687  	return numPCData
   688  }
   689  
   690  // generateFunctab creates the runtime.functab
   691  //
   692  // runtime.functab contains two things:
   693  //
   694  //   - pc->func look up table.
   695  //   - array of func objects, interleaved with pcdata and funcdata
   696  func (state *pclntab) generateFunctab(ctxt *Link, funcs []loader.Sym, inlSyms map[loader.Sym]loader.Sym, cuOffsets []uint32, nameOffsets map[loader.Sym]uint32) {
   697  	// Calculate the size of the table.
   698  	size, startLocations := state.calculateFunctabSize(ctxt, funcs)
   699  	writePcln := func(ctxt *Link, s loader.Sym) {
   700  		ldr := ctxt.loader
   701  		sb := ldr.MakeSymbolUpdater(s)
   702  		// Write the data.
   703  		writePCToFunc(ctxt, sb, funcs, startLocations)
   704  		writeFuncs(ctxt, sb, funcs, inlSyms, startLocations, cuOffsets, nameOffsets)
   705  	}
   706  	state.pclntab = state.addGeneratedSym(ctxt, "runtime.functab", size, writePcln)
   707  }
   708  
   709  // funcData returns the funcdata and offsets for the FuncInfo.
   710  // The funcdata are written into runtime.functab after each func
   711  // object. This is a helper function to make querying the FuncInfo object
   712  // cleaner.
   713  //
   714  // NB: Preload must be called on the FuncInfo before calling.
   715  // NB: fdSyms is used as scratch space.
   716  func funcData(ldr *loader.Loader, s loader.Sym, fi loader.FuncInfo, inlSym loader.Sym, fdSyms []loader.Sym) []loader.Sym {
   717  	fdSyms = fdSyms[:0]
   718  	if fi.Valid() {
   719  		fdSyms = ldr.Funcdata(s, fdSyms)
   720  		if fi.NumInlTree() > 0 {
   721  			if len(fdSyms) < abi.FUNCDATA_InlTree+1 {
   722  				fdSyms = append(fdSyms, make([]loader.Sym, abi.FUNCDATA_InlTree+1-len(fdSyms))...)
   723  			}
   724  			fdSyms[abi.FUNCDATA_InlTree] = inlSym
   725  		}
   726  	}
   727  	return fdSyms
   728  }
   729  
   730  // calculateFunctabSize calculates the size of the pclntab, and the offsets in
   731  // the output buffer for individual func entries.
   732  func (state pclntab) calculateFunctabSize(ctxt *Link, funcs []loader.Sym) (int64, []uint32) {
   733  	ldr := ctxt.loader
   734  	startLocations := make([]uint32, len(funcs))
   735  
   736  	// Allocate space for the pc->func table. This structure consists of a pc offset
   737  	// and an offset to the func structure. After that, we have a single pc
   738  	// value that marks the end of the last function in the binary.
   739  	size := int64(int(state.nfunc)*2*4 + 4)
   740  
   741  	// Now find the space for the func objects. We do this in a running manner,
   742  	// so that we can find individual starting locations.
   743  	for i, s := range funcs {
   744  		size = Rnd(size, int64(ctxt.Arch.PtrSize))
   745  		startLocations[i] = uint32(size)
   746  		fi := ldr.FuncInfo(s)
   747  		size += funcSize
   748  		if fi.Valid() {
   749  			fi.Preload()
   750  			numFuncData := ldr.NumFuncdata(s)
   751  			if fi.NumInlTree() > 0 {
   752  				if numFuncData < abi.FUNCDATA_InlTree+1 {
   753  					numFuncData = abi.FUNCDATA_InlTree + 1
   754  				}
   755  			}
   756  			size += int64(numPCData(ldr, s, fi) * 4)
   757  			size += int64(numFuncData * 4)
   758  		}
   759  	}
   760  
   761  	return size, startLocations
   762  }
   763  
   764  // textOff computes the offset of a text symbol, relative to textStart,
   765  // similar to an R_ADDROFF relocation,  for various runtime metadata and
   766  // tables (see runtime/symtab.go:(*moduledata).textAddr).
   767  func textOff(ctxt *Link, s loader.Sym, textStart int64) uint32 {
   768  	ldr := ctxt.loader
   769  	off := ldr.SymValue(s) - textStart
   770  	if off < 0 {
   771  		panic(fmt.Sprintf("expected func %s(%x) to be placed at or after textStart (%x)", ldr.SymName(s), ldr.SymValue(s), textStart))
   772  	}
   773  	if ctxt.IsWasm() {
   774  		// On Wasm, the function table contains just the function index, whereas
   775  		// the "PC" (s's Value) is function index << 16 + block index (see
   776  		// ../wasm/asm.go:assignAddress).
   777  		if off&(1<<16-1) != 0 {
   778  			ctxt.Errorf(s, "nonzero PC_B at function entry: %#x", off)
   779  		}
   780  		off >>= 16
   781  	}
   782  	if int64(uint32(off)) != off {
   783  		ctxt.Errorf(s, "textOff overflow: %#x", off)
   784  	}
   785  	return uint32(off)
   786  }
   787  
   788  // writePCToFunc writes the PC->func lookup table.
   789  func writePCToFunc(ctxt *Link, sb *loader.SymbolBuilder, funcs []loader.Sym, startLocations []uint32) {
   790  	ldr := ctxt.loader
   791  	textStart := ldr.SymValue(ldr.Lookup("runtime.text", 0))
   792  	pcOff := func(s loader.Sym) uint32 {
   793  		return textOff(ctxt, s, textStart)
   794  	}
   795  	for i, s := range funcs {
   796  		sb.SetUint32(ctxt.Arch, int64(i*2*4), pcOff(s))
   797  		sb.SetUint32(ctxt.Arch, int64((i*2+1)*4), startLocations[i])
   798  	}
   799  
   800  	// Final entry of table is just end pc offset.
   801  	lastFunc := funcs[len(funcs)-1]
   802  	lastPC := pcOff(lastFunc) + uint32(ldr.SymSize(lastFunc))
   803  	if ctxt.IsWasm() {
   804  		lastPC = pcOff(lastFunc) + 1 // On Wasm it is function index (see above)
   805  	}
   806  	sb.SetUint32(ctxt.Arch, int64(len(funcs))*2*4, lastPC)
   807  }
   808  
   809  // writeFuncs writes the func structures and pcdata to runtime.functab.
   810  func writeFuncs(ctxt *Link, sb *loader.SymbolBuilder, funcs []loader.Sym, inlSyms map[loader.Sym]loader.Sym, startLocations, cuOffsets []uint32, nameOffsets map[loader.Sym]uint32) {
   811  	ldr := ctxt.loader
   812  	deferReturnSym := ldr.Lookup("runtime.deferreturn", abiInternalVer)
   813  	textStart := ldr.SymValue(ldr.Lookup("runtime.text", 0))
   814  	funcdata := []loader.Sym{}
   815  	var pcsp, pcfile, pcline, pcinline loader.Sym
   816  	var pcdata []loader.Sym
   817  
   818  	// Write the individual func objects (runtime._func struct).
   819  	for i, s := range funcs {
   820  		startLine := int32(0)
   821  		fi := ldr.FuncInfo(s)
   822  		if fi.Valid() {
   823  			fi.Preload()
   824  			pcsp, pcfile, pcline, pcinline, pcdata = ldr.PcdataAuxs(s, pcdata)
   825  			startLine = fi.StartLine()
   826  		}
   827  
   828  		off := int64(startLocations[i])
   829  		// entryOff uint32 (offset of func entry PC from textStart)
   830  		entryOff := textOff(ctxt, s, textStart)
   831  		off = sb.SetUint32(ctxt.Arch, off, entryOff)
   832  
   833  		// nameOff int32
   834  		nameOff, ok := nameOffsets[s]
   835  		if !ok {
   836  			panic("couldn't find function name offset")
   837  		}
   838  		off = sb.SetUint32(ctxt.Arch, off, nameOff)
   839  
   840  		// args int32
   841  		// TODO: Move into funcinfo.
   842  		args := uint32(0)
   843  		if fi.Valid() {
   844  			args = uint32(fi.Args())
   845  		}
   846  		off = sb.SetUint32(ctxt.Arch, off, args)
   847  
   848  		// deferreturn
   849  		deferreturn := computeDeferReturn(ctxt, deferReturnSym, s)
   850  		off = sb.SetUint32(ctxt.Arch, off, deferreturn)
   851  
   852  		// pcdata
   853  		if fi.Valid() {
   854  			off = sb.SetUint32(ctxt.Arch, off, uint32(ldr.SymValue(pcsp)))
   855  			off = sb.SetUint32(ctxt.Arch, off, uint32(ldr.SymValue(pcfile)))
   856  			off = sb.SetUint32(ctxt.Arch, off, uint32(ldr.SymValue(pcline)))
   857  		} else {
   858  			off += 12
   859  		}
   860  		off = sb.SetUint32(ctxt.Arch, off, numPCData(ldr, s, fi))
   861  
   862  		// Store the offset to compilation unit's file table.
   863  		cuIdx := ^uint32(0)
   864  		if cu := ldr.SymUnit(s); cu != nil {
   865  			cuIdx = cuOffsets[cu.PclnIndex]
   866  		}
   867  		off = sb.SetUint32(ctxt.Arch, off, cuIdx)
   868  
   869  		// startLine int32
   870  		off = sb.SetUint32(ctxt.Arch, off, uint32(startLine))
   871  
   872  		// funcID uint8
   873  		var funcID abi.FuncID
   874  		if fi.Valid() {
   875  			funcID = fi.FuncID()
   876  		}
   877  		off = sb.SetUint8(ctxt.Arch, off, uint8(funcID))
   878  
   879  		// flag uint8
   880  		var flag abi.FuncFlag
   881  		if fi.Valid() {
   882  			flag = fi.FuncFlag()
   883  		}
   884  		off = sb.SetUint8(ctxt.Arch, off, uint8(flag))
   885  
   886  		off += 1 // pad
   887  
   888  		// nfuncdata must be the final entry.
   889  		funcdata = funcData(ldr, s, fi, 0, funcdata)
   890  		off = sb.SetUint8(ctxt.Arch, off, uint8(len(funcdata)))
   891  
   892  		// Output the pcdata.
   893  		if fi.Valid() {
   894  			for j, pcSym := range pcdata {
   895  				sb.SetUint32(ctxt.Arch, off+int64(j*4), uint32(ldr.SymValue(pcSym)))
   896  			}
   897  			if fi.NumInlTree() > 0 {
   898  				sb.SetUint32(ctxt.Arch, off+abi.PCDATA_InlTreeIndex*4, uint32(ldr.SymValue(pcinline)))
   899  			}
   900  		}
   901  
   902  		// Write funcdata refs as offsets from go:func.* and go:funcrel.*.
   903  		funcdata = funcData(ldr, s, fi, inlSyms[s], funcdata)
   904  		// Missing funcdata will be ^0. See runtime/symtab.go:funcdata.
   905  		off = int64(startLocations[i] + funcSize + numPCData(ldr, s, fi)*4)
   906  		for j := range funcdata {
   907  			dataoff := off + int64(4*j)
   908  			fdsym := funcdata[j]
   909  
   910  			if ignoreFuncData(ldr, s, j, fdsym) {
   911  				sb.SetUint32(ctxt.Arch, dataoff, ^uint32(0)) // ^0 is a sentinel for "no value"
   912  				continue
   913  			}
   914  
   915  			sb.SetUint32(ctxt.Arch, dataoff, uint32(ldr.SymValue(fdsym)))
   916  		}
   917  	}
   918  }
   919  
   920  // pclntab initializes the pclntab symbol with
   921  // runtime function and file name information.
   922  
   923  // pclntab generates the pcln table for the link output.
   924  func (ctxt *Link) pclntab(container loader.Bitmap) *pclntab {
   925  	// Go 1.2's symtab layout is documented in golang.org/s/go12symtab, but the
   926  	// layout and data has changed since that time.
   927  	//
   928  	// As of August 2020, here's the layout of pclntab:
   929  	//
   930  	//  .gopclntab/__gopclntab [elf/macho section]
   931  	//    runtime.pclntab
   932  	//      Carrier symbol for the entire pclntab section.
   933  	//
   934  	//      runtime.pcheader  (see: runtime/symtab.go:pcHeader)
   935  	//        8-byte magic
   936  	//        nfunc [thearch.ptrsize bytes]
   937  	//        offset to runtime.funcnametab from the beginning of runtime.pcheader
   938  	//        offset to runtime.pclntab_old from beginning of runtime.pcheader
   939  	//
   940  	//      runtime.funcnametab
   941  	//        []list of null terminated function names
   942  	//
   943  	//      runtime.cutab
   944  	//        for i=0..#CUs
   945  	//          for j=0..#max used file index in CU[i]
   946  	//            uint32 offset into runtime.filetab for the filename[j]
   947  	//
   948  	//      runtime.filetab
   949  	//        []null terminated filename strings
   950  	//
   951  	//      runtime.pctab
   952  	//        []byte of deduplicated pc data.
   953  	//
   954  	//      runtime.functab
   955  	//        function table, alternating PC and offset to func struct [each entry thearch.ptrsize bytes]
   956  	//        end PC [thearch.ptrsize bytes]
   957  	//        func structures, pcdata offsets, func data.
   958  	//
   959  	//      runtime.funcdata
   960  	//        []byte of deduplicated funcdata
   961  
   962  	state, compUnits, funcs := makePclntab(ctxt, container)
   963  
   964  	ldr := ctxt.loader
   965  	state.carrier = ldr.LookupOrCreateSym("runtime.pclntab", 0)
   966  	ldr.MakeSymbolUpdater(state.carrier).SetType(sym.SPCLNTAB)
   967  	ldr.SetAttrReachable(state.carrier, true)
   968  	setCarrierSym(sym.SPCLNTAB, state.carrier)
   969  
   970  	state.generatePCHeader(ctxt)
   971  	nameOffsets := state.generateFuncnametab(ctxt, funcs)
   972  	cuOffsets := state.generateFilenameTabs(ctxt, compUnits, funcs)
   973  	state.generatePctab(ctxt, funcs)
   974  	inlSyms := makeInlSyms(ctxt, funcs, nameOffsets)
   975  	state.generateFunctab(ctxt, funcs, inlSyms, cuOffsets, nameOffsets)
   976  	state.generateFuncdata(ctxt, funcs, inlSyms)
   977  
   978  	return state
   979  }
   980  
   981  func expandGoroot(s string) string {
   982  	const n = len("$GOROOT")
   983  	if len(s) >= n+1 && s[:n] == "$GOROOT" && (s[n] == '/' || s[n] == '\\') {
   984  		if final := buildcfg.GOROOT; final != "" {
   985  			return filepath.ToSlash(filepath.Join(final, s[n:]))
   986  		}
   987  	}
   988  	return s
   989  }
   990  
   991  const (
   992  	SUBBUCKETS    = 16
   993  	SUBBUCKETSIZE = abi.FuncTabBucketSize / SUBBUCKETS
   994  	NOIDX         = 0x7fffffff
   995  )
   996  
   997  // findfunctab generates a lookup table to quickly find the containing
   998  // function for a pc. See src/runtime/symtab.go:findfunc for details.
   999  func (ctxt *Link) findfunctab(state *pclntab, container loader.Bitmap) {
  1000  	ldr := ctxt.loader
  1001  
  1002  	// find min and max address
  1003  	min := ldr.SymValue(ctxt.Textp[0])
  1004  	lastp := ctxt.Textp[len(ctxt.Textp)-1]
  1005  	max := ldr.SymValue(lastp) + ldr.SymSize(lastp)
  1006  
  1007  	// for each subbucket, compute the minimum of all symbol indexes
  1008  	// that map to that subbucket.
  1009  	n := int32((max - min + SUBBUCKETSIZE - 1) / SUBBUCKETSIZE)
  1010  
  1011  	nbuckets := int32((max - min + abi.FuncTabBucketSize - 1) / abi.FuncTabBucketSize)
  1012  
  1013  	size := 4*int64(nbuckets) + int64(n)
  1014  
  1015  	writeFindFuncTab := func(_ *Link, s loader.Sym) {
  1016  		t := ldr.MakeSymbolUpdater(s)
  1017  
  1018  		indexes := make([]int32, n)
  1019  		for i := int32(0); i < n; i++ {
  1020  			indexes[i] = NOIDX
  1021  		}
  1022  		idx := int32(0)
  1023  		for i, s := range ctxt.Textp {
  1024  			if !emitPcln(ctxt, s, container) {
  1025  				continue
  1026  			}
  1027  			p := ldr.SymValue(s)
  1028  			var e loader.Sym
  1029  			i++
  1030  			if i < len(ctxt.Textp) {
  1031  				e = ctxt.Textp[i]
  1032  			}
  1033  			for e != 0 && !emitPcln(ctxt, e, container) && i < len(ctxt.Textp) {
  1034  				e = ctxt.Textp[i]
  1035  				i++
  1036  			}
  1037  			q := max
  1038  			if e != 0 {
  1039  				q = ldr.SymValue(e)
  1040  			}
  1041  
  1042  			//fmt.Printf("%d: [%x %x] %s\n", idx, p, q, ldr.SymName(s))
  1043  			for ; p < q; p += SUBBUCKETSIZE {
  1044  				i = int((p - min) / SUBBUCKETSIZE)
  1045  				if indexes[i] > idx {
  1046  					indexes[i] = idx
  1047  				}
  1048  			}
  1049  
  1050  			i = int((q - 1 - min) / SUBBUCKETSIZE)
  1051  			if indexes[i] > idx {
  1052  				indexes[i] = idx
  1053  			}
  1054  			idx++
  1055  		}
  1056  
  1057  		// fill in table
  1058  		for i := int32(0); i < nbuckets; i++ {
  1059  			base := indexes[i*SUBBUCKETS]
  1060  			if base == NOIDX {
  1061  				Errorf("hole in findfunctab")
  1062  			}
  1063  			t.SetUint32(ctxt.Arch, int64(i)*(4+SUBBUCKETS), uint32(base))
  1064  			for j := int32(0); j < SUBBUCKETS && i*SUBBUCKETS+j < n; j++ {
  1065  				idx = indexes[i*SUBBUCKETS+j]
  1066  				if idx == NOIDX {
  1067  					Errorf("hole in findfunctab")
  1068  				}
  1069  				if idx-base >= 256 {
  1070  					Errorf("too many functions in a findfunc bucket! %d/%d %d %d", i, nbuckets, j, idx-base)
  1071  				}
  1072  
  1073  				t.SetUint8(ctxt.Arch, int64(i)*(4+SUBBUCKETS)+4+int64(j), uint8(idx-base))
  1074  			}
  1075  		}
  1076  	}
  1077  
  1078  	state.findfunctab = ctxt.createGeneratorSymbol("runtime.findfunctab", 0, sym.SPCLNTAB, size, writeFindFuncTab)
  1079  	ldr.SetAttrReachable(state.findfunctab, true)
  1080  	ldr.SetAttrLocal(state.findfunctab, true)
  1081  }
  1082  
  1083  // findContainerSyms returns a bitmap, indexed by symbol number, where there's
  1084  // a 1 for every container symbol.
  1085  func (ctxt *Link) findContainerSyms() loader.Bitmap {
  1086  	ldr := ctxt.loader
  1087  	container := loader.MakeBitmap(ldr.NSym())
  1088  	// Find container symbols and mark them as such.
  1089  	for _, s := range ctxt.Textp {
  1090  		outer := ldr.OuterSym(s)
  1091  		if outer != 0 {
  1092  			container.Set(outer)
  1093  		}
  1094  	}
  1095  	return container
  1096  }
  1097
View as plain text