| // 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.EmitEntryRegMap(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 register map. | |
| func (ctxt *Link) EmitEntryRegMap(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_RegMapIndex | |
| 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_RegMapIndex | |
| pcdata.To.Type = TYPE_CONST | |
| pcdata.To.Offset = objabi.PCDATA_RegMapUnsafe | |
| 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_RegMapIndex | |
| 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_RegMapIndex { | |
| prevPcdata = p.To.Offset | |
| continue | |
| } | |
| if prevPcdata == objabi.PCDATA_RegMapUnsafe { | |
| 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_RegMapIndex | |
| 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_RegMapIndex | |
| p.To.Type = TYPE_CONST | |
| p.To.Offset = prevPcdata | |
| p.Pc = p.Link.Pc | |
| } | |
| } | |
| } |