| // Copyright 2013 The Go Authors. All rights reserved. |
| // Use of this source code is governed by a BSD-style |
| // license that can be found in the LICENSE file. |
| |
| package obj |
| |
| import ( |
| "cmd/internal/objabi" |
| "fmt" |
| "strings" |
| ) |
| |
| type Plist struct { |
| Firstpc *Prog |
| Curfn interface{} // holds a *gc.Node, if non-nil |
| } |
| |
| // ProgAlloc is a function that allocates Progs. |
| // It is used to provide access to cached/bulk-allocated Progs to the assemblers. |
| type ProgAlloc func() *Prog |
| |
| func Flushplist(ctxt *Link, plist *Plist, newprog ProgAlloc, myimportpath string) { |
| // Build list of symbols, and assign instructions to lists. |
| var curtext *LSym |
| var etext *Prog |
| var text []*LSym |
| |
| var plink *Prog |
| for p := plist.Firstpc; p != nil; p = plink { |
| if ctxt.Debugasm > 0 && ctxt.Debugvlog { |
| fmt.Printf("obj: %v\n", p) |
| } |
| plink = p.Link |
| p.Link = nil |
| |
| switch p.As { |
| case AEND: |
| continue |
| |
| case ATEXT: |
| s := p.From.Sym |
| if s == nil { |
| // func _() { } |
| curtext = nil |
| continue |
| } |
| text = append(text, s) |
| etext = p |
| curtext = s |
| continue |
| |
| case AFUNCDATA: |
| // Rewrite reference to go_args_stackmap(SB) to the Go-provided declaration information. |
| if curtext == nil { // func _() {} |
| continue |
| } |
| if p.To.Sym.Name == "go_args_stackmap" { |
| if p.From.Type != TYPE_CONST || p.From.Offset != objabi.FUNCDATA_ArgsPointerMaps { |
| ctxt.Diag("FUNCDATA use of go_args_stackmap(SB) without FUNCDATA_ArgsPointerMaps") |
| } |
| p.To.Sym = ctxt.LookupDerived(curtext, curtext.Name+".args_stackmap") |
| } |
| |
| } |
| |
| if curtext == nil { |
| etext = nil |
| continue |
| } |
| etext.Link = p |
| etext = p |
| } |
| |
| if newprog == nil { |
| newprog = ctxt.NewProg |
| } |
| |
| // Add reference to Go arguments for C or assembly functions without them. |
| for _, s := range text { |
| if !strings.HasPrefix(s.Name, "\"\".") { |
| continue |
| } |
| found := false |
| for p := s.Func().Text; p != nil; p = p.Link { |
| if p.As == AFUNCDATA && p.From.Type == TYPE_CONST && p.From.Offset == objabi.FUNCDATA_ArgsPointerMaps { |
| found = true |
| break |
| } |
| } |
| |
| if !found { |
| p := Appendp(s.Func().Text, newprog) |
| p.As = AFUNCDATA |
| p.From.Type = TYPE_CONST |
| p.From.Offset = objabi.FUNCDATA_ArgsPointerMaps |
| p.To.Type = TYPE_MEM |
| p.To.Name = NAME_EXTERN |
| p.To.Sym = ctxt.LookupDerived(s, s.Name+".args_stackmap") |
| } |
| } |
| |
| // Turn functions into machine code images. |
| for _, s := range text { |
| mkfwd(s) |
| linkpatch(ctxt, s, newprog) |
| ctxt.Arch.Preprocess(ctxt, s, newprog) |
| ctxt.Arch.Assemble(ctxt, s, newprog) |
| if ctxt.Errors > 0 { |
| continue |
| } |
| linkpcln(ctxt, s) |
| if myimportpath != "" { |
| ctxt.populateDWARF(plist.Curfn, s, myimportpath) |
| } |
| } |
| } |
| |
| func (ctxt *Link) InitTextSym(s *LSym, flag int) { |
| if s == nil { |
| // func _() { } |
| return |
| } |
| if s.Func() != nil { |
| ctxt.Diag("InitTextSym double init for %s", s.Name) |
| } |
| s.NewFuncInfo() |
| if s.OnList() { |
| ctxt.Diag("symbol %s listed multiple times", s.Name) |
| } |
| name := strings.Replace(s.Name, "\"\"", ctxt.Pkgpath, -1) |
| s.Func().FuncID = objabi.GetFuncID(name, flag&WRAPPER != 0) |
| s.Set(AttrOnList, true) |
| s.Set(AttrDuplicateOK, flag&DUPOK != 0) |
| s.Set(AttrNoSplit, flag&NOSPLIT != 0) |
| s.Set(AttrReflectMethod, flag&REFLECTMETHOD != 0) |
| s.Set(AttrWrapper, flag&WRAPPER != 0) |
| s.Set(AttrNeedCtxt, flag&NEEDCTXT != 0) |
| s.Set(AttrNoFrame, flag&NOFRAME != 0) |
| s.Set(AttrTopFrame, flag&TOPFRAME != 0) |
| s.Type = objabi.STEXT |
| ctxt.Text = append(ctxt.Text, s) |
| |
| // Set up DWARF entries for s |
| ctxt.dwarfSym(s) |
| } |
| |
| func (ctxt *Link) Globl(s *LSym, size int64, flag int) { |
| if s.OnList() { |
| ctxt.Diag("symbol %s listed multiple times", s.Name) |
| } |
| s.Set(AttrOnList, true) |
| ctxt.Data = append(ctxt.Data, s) |
| s.Size = size |
| if s.Type == 0 { |
| s.Type = objabi.SBSS |
| } |
| if flag&DUPOK != 0 { |
| s.Set(AttrDuplicateOK, true) |
| } |
| if flag&RODATA != 0 { |
| s.Type = objabi.SRODATA |
| } else if flag&NOPTR != 0 { |
| if s.Type == objabi.SDATA { |
| s.Type = objabi.SNOPTRDATA |
| } else { |
| s.Type = objabi.SNOPTRBSS |
| } |
| } else if flag&TLSBSS != 0 { |
| s.Type = objabi.STLSBSS |
| } |
| if strings.HasPrefix(s.Name, "\"\"."+StaticNamePref) { |
| s.Set(AttrStatic, true) |
| } |
| } |
| |
| // EmitEntryLiveness generates PCDATA Progs after p to switch to the |
| // liveness map active at the entry of function s. It returns the last |
| // Prog generated. |
| func (ctxt *Link) EmitEntryLiveness(s *LSym, p *Prog, newprog ProgAlloc) *Prog { |
| pcdata := ctxt.EmitEntryStackMap(s, p, newprog) |
| pcdata = ctxt.EmitEntryUnsafePoint(s, pcdata, newprog) |
| return pcdata |
| } |
| |
| // Similar to EmitEntryLiveness, but just emit stack map. |
| func (ctxt *Link) EmitEntryStackMap(s *LSym, p *Prog, newprog ProgAlloc) *Prog { |
| pcdata := Appendp(p, newprog) |
| pcdata.Pos = s.Func().Text.Pos |
| pcdata.As = APCDATA |
| pcdata.From.Type = TYPE_CONST |
| pcdata.From.Offset = objabi.PCDATA_StackMapIndex |
| pcdata.To.Type = TYPE_CONST |
| pcdata.To.Offset = -1 // pcdata starts at -1 at function entry |
| |
| return pcdata |
| } |
| |
| // Similar to EmitEntryLiveness, but just emit unsafe point map. |
| func (ctxt *Link) EmitEntryUnsafePoint(s *LSym, p *Prog, newprog ProgAlloc) *Prog { |
| pcdata := Appendp(p, newprog) |
| pcdata.Pos = s.Func().Text.Pos |
| pcdata.As = APCDATA |
| pcdata.From.Type = TYPE_CONST |
| pcdata.From.Offset = objabi.PCDATA_UnsafePoint |
| pcdata.To.Type = TYPE_CONST |
| pcdata.To.Offset = -1 |
| |
| return pcdata |
| } |
| |
| // StartUnsafePoint generates PCDATA Progs after p to mark the |
| // beginning of an unsafe point. The unsafe point starts immediately |
| // after p. |
| // It returns the last Prog generated. |
| func (ctxt *Link) StartUnsafePoint(p *Prog, newprog ProgAlloc) *Prog { |
| pcdata := Appendp(p, newprog) |
| pcdata.As = APCDATA |
| pcdata.From.Type = TYPE_CONST |
| pcdata.From.Offset = objabi.PCDATA_UnsafePoint |
| pcdata.To.Type = TYPE_CONST |
| pcdata.To.Offset = objabi.PCDATA_UnsafePointUnsafe |
| |
| return pcdata |
| } |
| |
| // EndUnsafePoint generates PCDATA Progs after p to mark the end of an |
| // unsafe point, restoring the register map index to oldval. |
| // The unsafe point ends right after p. |
| // It returns the last Prog generated. |
| func (ctxt *Link) EndUnsafePoint(p *Prog, newprog ProgAlloc, oldval int64) *Prog { |
| pcdata := Appendp(p, newprog) |
| pcdata.As = APCDATA |
| pcdata.From.Type = TYPE_CONST |
| pcdata.From.Offset = objabi.PCDATA_UnsafePoint |
| pcdata.To.Type = TYPE_CONST |
| pcdata.To.Offset = oldval |
| |
| return pcdata |
| } |
| |
| // MarkUnsafePoints inserts PCDATAs to mark nonpreemptible and restartable |
| // instruction sequences, based on isUnsafePoint and isRestartable predicate. |
| // p0 is the start of the instruction stream. |
| // isUnsafePoint(p) returns true if p is not safe for async preemption. |
| // isRestartable(p) returns true if we can restart at the start of p (this Prog) |
| // upon async preemption. (Currently multi-Prog restartable sequence is not |
| // supported.) |
| // isRestartable can be nil. In this case it is treated as always returning false. |
| // If isUnsafePoint(p) and isRestartable(p) are both true, it is treated as |
| // an unsafe point. |
| func MarkUnsafePoints(ctxt *Link, p0 *Prog, newprog ProgAlloc, isUnsafePoint, isRestartable func(*Prog) bool) { |
| if isRestartable == nil { |
| // Default implementation: nothing is restartable. |
| isRestartable = func(*Prog) bool { return false } |
| } |
| prev := p0 |
| prevPcdata := int64(-1) // entry PC data value |
| prevRestart := int64(0) |
| for p := prev.Link; p != nil; p, prev = p.Link, p { |
| if p.As == APCDATA && p.From.Offset == objabi.PCDATA_UnsafePoint { |
| prevPcdata = p.To.Offset |
| continue |
| } |
| if prevPcdata == objabi.PCDATA_UnsafePointUnsafe { |
| continue // already unsafe |
| } |
| if isUnsafePoint(p) { |
| q := ctxt.StartUnsafePoint(prev, newprog) |
| q.Pc = p.Pc |
| q.Link = p |
| // Advance to the end of unsafe point. |
| for p.Link != nil && isUnsafePoint(p.Link) { |
| p = p.Link |
| } |
| if p.Link == nil { |
| break // Reached the end, don't bother marking the end |
| } |
| p = ctxt.EndUnsafePoint(p, newprog, prevPcdata) |
| p.Pc = p.Link.Pc |
| continue |
| } |
| if isRestartable(p) { |
| val := int64(objabi.PCDATA_Restart1) |
| if val == prevRestart { |
| val = objabi.PCDATA_Restart2 |
| } |
| prevRestart = val |
| q := Appendp(prev, newprog) |
| q.As = APCDATA |
| q.From.Type = TYPE_CONST |
| q.From.Offset = objabi.PCDATA_UnsafePoint |
| q.To.Type = TYPE_CONST |
| q.To.Offset = val |
| q.Pc = p.Pc |
| q.Link = p |
| |
| if p.Link == nil { |
| break // Reached the end, don't bother marking the end |
| } |
| if isRestartable(p.Link) { |
| // Next Prog is also restartable. No need to mark the end |
| // of this sequence. We'll just go ahead mark the next one. |
| continue |
| } |
| p = Appendp(p, newprog) |
| p.As = APCDATA |
| p.From.Type = TYPE_CONST |
| p.From.Offset = objabi.PCDATA_UnsafePoint |
| p.To.Type = TYPE_CONST |
| p.To.Offset = prevPcdata |
| p.Pc = p.Link.Pc |
| } |
| } |
| } |
