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- // 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 (
- "github.com/twitchyliquid64/golang-asm/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.Func = new(FuncInfo)
- 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
- }
- }
- }
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