422 lines
12 KiB
Go
422 lines
12 KiB
Go
// Derived from Inferno utils/6l/obj.c and utils/6l/span.c
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// https://bitbucket.org/inferno-os/inferno-os/src/master/utils/6l/obj.c
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// https://bitbucket.org/inferno-os/inferno-os/src/master/utils/6l/span.c
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//
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// Copyright © 1994-1999 Lucent Technologies Inc. All rights reserved.
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// Portions Copyright © 1995-1997 C H Forsyth (forsyth@terzarima.net)
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// Portions Copyright © 1997-1999 Vita Nuova Limited
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// Portions Copyright © 2000-2007 Vita Nuova Holdings Limited (www.vitanuova.com)
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// Portions Copyright © 2004,2006 Bruce Ellis
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// Portions Copyright © 2005-2007 C H Forsyth (forsyth@terzarima.net)
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// Revisions Copyright © 2000-2007 Lucent Technologies Inc. and others
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// Portions Copyright © 2009 The Go Authors. All rights reserved.
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//
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// Permission is hereby granted, free of charge, to any person obtaining a copy
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// of this software and associated documentation files (the "Software"), to deal
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// in the Software without restriction, including without limitation the rights
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// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
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// copies of the Software, and to permit persons to whom the Software is
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// furnished to do so, subject to the following conditions:
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//
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// The above copyright notice and this permission notice shall be included in
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// all copies or substantial portions of the Software.
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//
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// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
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// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
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// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
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// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
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// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
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// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
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// THE SOFTWARE.
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package obj
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import (
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"github.com/twitchyliquid64/golang-asm/goobj"
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"github.com/twitchyliquid64/golang-asm/objabi"
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"fmt"
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"log"
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"math"
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"sort"
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)
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func Linknew(arch *LinkArch) *Link {
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ctxt := new(Link)
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ctxt.hash = make(map[string]*LSym)
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ctxt.funchash = make(map[string]*LSym)
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ctxt.statichash = make(map[string]*LSym)
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ctxt.Arch = arch
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ctxt.Pathname = objabi.WorkingDir()
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if err := ctxt.Headtype.Set(objabi.GOOS); err != nil {
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log.Fatalf("unknown goos %s", objabi.GOOS)
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}
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ctxt.Flag_optimize = true
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return ctxt
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}
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// LookupDerived looks up or creates the symbol with name name derived from symbol s.
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// The resulting symbol will be static iff s is.
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func (ctxt *Link) LookupDerived(s *LSym, name string) *LSym {
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if s.Static() {
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return ctxt.LookupStatic(name)
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}
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return ctxt.Lookup(name)
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}
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// LookupStatic looks up the static symbol with name name.
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// If it does not exist, it creates it.
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func (ctxt *Link) LookupStatic(name string) *LSym {
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s := ctxt.statichash[name]
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if s == nil {
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s = &LSym{Name: name, Attribute: AttrStatic}
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ctxt.statichash[name] = s
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}
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return s
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}
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// LookupABI looks up a symbol with the given ABI.
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// If it does not exist, it creates it.
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func (ctxt *Link) LookupABI(name string, abi ABI) *LSym {
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return ctxt.LookupABIInit(name, abi, nil)
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}
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// LookupABI looks up a symbol with the given ABI.
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// If it does not exist, it creates it and
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// passes it to init for one-time initialization.
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func (ctxt *Link) LookupABIInit(name string, abi ABI, init func(s *LSym)) *LSym {
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var hash map[string]*LSym
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switch abi {
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case ABI0:
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hash = ctxt.hash
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case ABIInternal:
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hash = ctxt.funchash
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default:
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panic("unknown ABI")
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}
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ctxt.hashmu.Lock()
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s := hash[name]
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if s == nil {
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s = &LSym{Name: name}
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s.SetABI(abi)
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hash[name] = s
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if init != nil {
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init(s)
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}
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}
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ctxt.hashmu.Unlock()
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return s
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}
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// Lookup looks up the symbol with name name.
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// If it does not exist, it creates it.
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func (ctxt *Link) Lookup(name string) *LSym {
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return ctxt.LookupInit(name, nil)
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}
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// LookupInit looks up the symbol with name name.
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// If it does not exist, it creates it and
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// passes it to init for one-time initialization.
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func (ctxt *Link) LookupInit(name string, init func(s *LSym)) *LSym {
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ctxt.hashmu.Lock()
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s := ctxt.hash[name]
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if s == nil {
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s = &LSym{Name: name}
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ctxt.hash[name] = s
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if init != nil {
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init(s)
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}
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}
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ctxt.hashmu.Unlock()
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return s
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}
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func (ctxt *Link) Float32Sym(f float32) *LSym {
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i := math.Float32bits(f)
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name := fmt.Sprintf("$f32.%08x", i)
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return ctxt.LookupInit(name, func(s *LSym) {
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s.Size = 4
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s.WriteFloat32(ctxt, 0, f)
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s.Type = objabi.SRODATA
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s.Set(AttrLocal, true)
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s.Set(AttrContentAddressable, true)
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ctxt.constSyms = append(ctxt.constSyms, s)
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})
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}
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func (ctxt *Link) Float64Sym(f float64) *LSym {
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i := math.Float64bits(f)
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name := fmt.Sprintf("$f64.%016x", i)
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return ctxt.LookupInit(name, func(s *LSym) {
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s.Size = 8
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s.WriteFloat64(ctxt, 0, f)
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s.Type = objabi.SRODATA
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s.Set(AttrLocal, true)
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s.Set(AttrContentAddressable, true)
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ctxt.constSyms = append(ctxt.constSyms, s)
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})
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}
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func (ctxt *Link) Int64Sym(i int64) *LSym {
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name := fmt.Sprintf("$i64.%016x", uint64(i))
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return ctxt.LookupInit(name, func(s *LSym) {
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s.Size = 8
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s.WriteInt(ctxt, 0, 8, i)
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s.Type = objabi.SRODATA
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s.Set(AttrLocal, true)
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s.Set(AttrContentAddressable, true)
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ctxt.constSyms = append(ctxt.constSyms, s)
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})
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}
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// Assign index to symbols.
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// asm is set to true if this is called by the assembler (i.e. not the compiler),
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// in which case all the symbols are non-package (for now).
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func (ctxt *Link) NumberSyms() {
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if ctxt.Headtype == objabi.Haix {
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// Data must be sorted to keep a constant order in TOC symbols.
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// As they are created during Progedit, two symbols can be switched between
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// two different compilations. Therefore, BuildID will be different.
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// TODO: find a better place and optimize to only sort TOC symbols
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sort.Slice(ctxt.Data, func(i, j int) bool {
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return ctxt.Data[i].Name < ctxt.Data[j].Name
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})
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}
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// Constant symbols are created late in the concurrent phase. Sort them
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// to ensure a deterministic order.
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sort.Slice(ctxt.constSyms, func(i, j int) bool {
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return ctxt.constSyms[i].Name < ctxt.constSyms[j].Name
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})
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ctxt.Data = append(ctxt.Data, ctxt.constSyms...)
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ctxt.constSyms = nil
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ctxt.pkgIdx = make(map[string]int32)
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ctxt.defs = []*LSym{}
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ctxt.hashed64defs = []*LSym{}
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ctxt.hasheddefs = []*LSym{}
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ctxt.nonpkgdefs = []*LSym{}
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var idx, hashedidx, hashed64idx, nonpkgidx int32
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ctxt.traverseSyms(traverseDefs, func(s *LSym) {
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// if Pkgpath is unknown, cannot hash symbols with relocations, as it
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// may reference named symbols whose names are not fully expanded.
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if s.ContentAddressable() && (ctxt.Pkgpath != "" || len(s.R) == 0) {
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if len(s.P) <= 8 && len(s.R) == 0 { // we can use short hash only for symbols without relocations
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s.PkgIdx = goobj.PkgIdxHashed64
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s.SymIdx = hashed64idx
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if hashed64idx != int32(len(ctxt.hashed64defs)) {
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panic("bad index")
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}
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ctxt.hashed64defs = append(ctxt.hashed64defs, s)
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hashed64idx++
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} else {
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s.PkgIdx = goobj.PkgIdxHashed
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s.SymIdx = hashedidx
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if hashedidx != int32(len(ctxt.hasheddefs)) {
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panic("bad index")
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}
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ctxt.hasheddefs = append(ctxt.hasheddefs, s)
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hashedidx++
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}
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} else if isNonPkgSym(ctxt, s) {
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s.PkgIdx = goobj.PkgIdxNone
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s.SymIdx = nonpkgidx
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if nonpkgidx != int32(len(ctxt.nonpkgdefs)) {
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panic("bad index")
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}
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ctxt.nonpkgdefs = append(ctxt.nonpkgdefs, s)
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nonpkgidx++
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} else {
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s.PkgIdx = goobj.PkgIdxSelf
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s.SymIdx = idx
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if idx != int32(len(ctxt.defs)) {
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panic("bad index")
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}
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ctxt.defs = append(ctxt.defs, s)
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idx++
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}
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s.Set(AttrIndexed, true)
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})
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ipkg := int32(1) // 0 is invalid index
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nonpkgdef := nonpkgidx
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ctxt.traverseSyms(traverseRefs|traverseAux, func(rs *LSym) {
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if rs.PkgIdx != goobj.PkgIdxInvalid {
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return
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}
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if !ctxt.Flag_linkshared {
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// Assign special index for builtin symbols.
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// Don't do it when linking against shared libraries, as the runtime
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// may be in a different library.
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if i := goobj.BuiltinIdx(rs.Name, int(rs.ABI())); i != -1 {
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rs.PkgIdx = goobj.PkgIdxBuiltin
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rs.SymIdx = int32(i)
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rs.Set(AttrIndexed, true)
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return
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}
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}
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pkg := rs.Pkg
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if rs.ContentAddressable() {
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// for now, only support content-addressable symbols that are always locally defined.
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panic("hashed refs unsupported for now")
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}
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if pkg == "" || pkg == "\"\"" || pkg == "_" || !rs.Indexed() {
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rs.PkgIdx = goobj.PkgIdxNone
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rs.SymIdx = nonpkgidx
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rs.Set(AttrIndexed, true)
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if nonpkgidx != nonpkgdef+int32(len(ctxt.nonpkgrefs)) {
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panic("bad index")
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}
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ctxt.nonpkgrefs = append(ctxt.nonpkgrefs, rs)
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nonpkgidx++
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return
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}
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if k, ok := ctxt.pkgIdx[pkg]; ok {
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rs.PkgIdx = k
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return
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}
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rs.PkgIdx = ipkg
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ctxt.pkgIdx[pkg] = ipkg
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ipkg++
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})
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}
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// Returns whether s is a non-package symbol, which needs to be referenced
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// by name instead of by index.
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func isNonPkgSym(ctxt *Link, s *LSym) bool {
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if ctxt.IsAsm && !s.Static() {
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// asm symbols are referenced by name only, except static symbols
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// which are file-local and can be referenced by index.
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return true
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}
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if ctxt.Flag_linkshared {
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// The referenced symbol may be in a different shared library so
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// the linker cannot see its index.
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return true
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}
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if s.Pkg == "_" {
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// The frontend uses package "_" to mark symbols that should not
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// be referenced by index, e.g. linkname'd symbols.
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return true
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}
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if s.DuplicateOK() {
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// Dupok symbol needs to be dedup'd by name.
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return true
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}
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return false
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}
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// StaticNamePref is the prefix the front end applies to static temporary
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// variables. When turned into LSyms, these can be tagged as static so
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// as to avoid inserting them into the linker's name lookup tables.
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const StaticNamePref = ".stmp_"
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type traverseFlag uint32
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const (
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traverseDefs traverseFlag = 1 << iota
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traverseRefs
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traverseAux
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traverseAll = traverseDefs | traverseRefs | traverseAux
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)
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// Traverse symbols based on flag, call fn for each symbol.
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func (ctxt *Link) traverseSyms(flag traverseFlag, fn func(*LSym)) {
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lists := [][]*LSym{ctxt.Text, ctxt.Data, ctxt.ABIAliases}
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for _, list := range lists {
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for _, s := range list {
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if flag&traverseDefs != 0 {
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fn(s)
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}
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if flag&traverseRefs != 0 {
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for _, r := range s.R {
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if r.Sym != nil {
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fn(r.Sym)
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}
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}
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}
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if flag&traverseAux != 0 {
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if s.Gotype != nil {
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fn(s.Gotype)
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}
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if s.Type == objabi.STEXT {
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f := func(parent *LSym, aux *LSym) {
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fn(aux)
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}
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ctxt.traverseFuncAux(flag, s, f)
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}
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}
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}
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}
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}
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func (ctxt *Link) traverseFuncAux(flag traverseFlag, fsym *LSym, fn func(parent *LSym, aux *LSym)) {
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pc := &fsym.Func.Pcln
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if flag&traverseAux == 0 {
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// NB: should it become necessary to walk aux sym reloc references
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// without walking the aux syms themselves, this can be changed.
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panic("should not be here")
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}
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for _, d := range pc.Funcdata {
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if d != nil {
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fn(fsym, d)
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}
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}
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files := ctxt.PosTable.FileTable()
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usedFiles := make([]goobj.CUFileIndex, 0, len(pc.UsedFiles))
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for f := range pc.UsedFiles {
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usedFiles = append(usedFiles, f)
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}
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sort.Slice(usedFiles, func(i, j int) bool { return usedFiles[i] < usedFiles[j] })
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for _, f := range usedFiles {
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if filesym := ctxt.Lookup(files[f]); filesym != nil {
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fn(fsym, filesym)
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}
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}
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for _, call := range pc.InlTree.nodes {
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if call.Func != nil {
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fn(fsym, call.Func)
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}
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f, _ := linkgetlineFromPos(ctxt, call.Pos)
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if filesym := ctxt.Lookup(f); filesym != nil {
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fn(fsym, filesym)
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}
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}
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dwsyms := []*LSym{fsym.Func.dwarfRangesSym, fsym.Func.dwarfLocSym, fsym.Func.dwarfDebugLinesSym, fsym.Func.dwarfInfoSym}
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for _, dws := range dwsyms {
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if dws == nil || dws.Size == 0 {
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continue
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}
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fn(fsym, dws)
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if flag&traverseRefs != 0 {
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for _, r := range dws.R {
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if r.Sym != nil {
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fn(dws, r.Sym)
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}
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}
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}
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}
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}
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// Traverse aux symbols, calling fn for each sym/aux pair.
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func (ctxt *Link) traverseAuxSyms(flag traverseFlag, fn func(parent *LSym, aux *LSym)) {
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lists := [][]*LSym{ctxt.Text, ctxt.Data, ctxt.ABIAliases}
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for _, list := range lists {
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for _, s := range list {
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if s.Gotype != nil {
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if flag&traverseDefs != 0 {
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fn(s, s.Gotype)
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}
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}
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if s.Type != objabi.STEXT {
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continue
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}
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ctxt.traverseFuncAux(flag, s, fn)
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}
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}
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}
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