gtsocial-umbx

sym.go (12293B)

---

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