| // 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" |
| "cmd/internal/src" |
| "fmt" |
| "internal/abi" |
| "strings" |
| ) |
| |
| type Plist struct { |
| Firstpc *Prog |
| Curfn Func |
| } |
| |
| // 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) { |
| if ctxt.Pkgpath == "" { |
| panic("Flushplist called without Pkgpath") |
| } |
| |
| // 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 |
| } |
| switch p.To.Sym.Name { |
| case "go_args_stackmap": |
| if p.From.Type != TYPE_CONST || p.From.Offset != abi.FUNCDATA_ArgsPointerMaps { |
| ctxt.Diag("%s: FUNCDATA use of go_args_stackmap(SB) without FUNCDATA_ArgsPointerMaps", p.Pos) |
| } |
| p.To.Sym = ctxt.LookupDerived(curtext, curtext.Name+".args_stackmap") |
| case "no_pointers_stackmap": |
| if p.From.Type != TYPE_CONST || p.From.Offset != abi.FUNCDATA_LocalsPointerMaps { |
| ctxt.Diag("%s: FUNCDATA use of no_pointers_stackmap(SB) without FUNCDATA_LocalsPointerMaps", p.Pos) |
| } |
| // funcdata for functions with no local variables in frame. |
| // Define two zero-length bitmaps, because the same index is used |
| // for the local variables as for the argument frame, and assembly |
| // frames have two argument bitmaps, one without results and one with results. |
| // Write []uint32{2, 0}. |
| b := make([]byte, 8) |
| ctxt.Arch.ByteOrder.PutUint32(b, 2) |
| s := ctxt.GCLocalsSym(b) |
| if !s.OnList() { |
| ctxt.Globl(s, int64(len(s.P)), int(RODATA|DUPOK)) |
| } |
| p.To.Sym = s |
| } |
| |
| } |
| |
| if curtext == nil { |
| etext = nil |
| continue |
| } |
| etext.Link = p |
| etext = p |
| } |
| |
| if newprog == nil { |
| newprog = ctxt.NewProg |
| } |
| |
| // Add reference to Go arguments for assembly functions without them. |
| if ctxt.IsAsm { |
| pkgPrefix := objabi.PathToPrefix(ctxt.Pkgpath) + "." |
| for _, s := range text { |
| if !strings.HasPrefix(s.Name, pkgPrefix) { |
| continue |
| } |
| // The current args_stackmap generation in the compiler assumes |
| // that the function in question is ABI0, so avoid introducing |
| // an args_stackmap reference if the func is not ABI0 (better to |
| // have no stackmap than an incorrect/lying stackmap). |
| if s.ABI() != ABI0 { |
| continue |
| } |
| // runtime.addmoduledata is a host ABI function, so it doesn't |
| // need FUNCDATA anyway. Moreover, cmd/link has special logic |
| // for linking it in eccentric build modes, which breaks if it |
| // has FUNCDATA references (e.g., cmd/cgo/internal/testplugin). |
| // |
| // TODO(cherryyz): Fix cmd/link's handling of plugins (see |
| // discussion on CL 523355). |
| if s.Name == "runtime.addmoduledata" { |
| continue |
| } |
| foundArgMap, foundArgInfo := false, false |
| for p := s.Func().Text; p != nil; p = p.Link { |
| if p.As == AFUNCDATA && p.From.Type == TYPE_CONST { |
| if p.From.Offset == abi.FUNCDATA_ArgsPointerMaps { |
| foundArgMap = true |
| } |
| if p.From.Offset == abi.FUNCDATA_ArgInfo { |
| foundArgInfo = true |
| } |
| if foundArgMap && foundArgInfo { |
| break |
| } |
| } |
| } |
| if !foundArgMap { |
| p := Appendp(s.Func().Text, newprog) |
| p.As = AFUNCDATA |
| p.From.Type = TYPE_CONST |
| p.From.Offset = abi.FUNCDATA_ArgsPointerMaps |
| p.To.Type = TYPE_MEM |
| p.To.Name = NAME_EXTERN |
| p.To.Sym = ctxt.LookupDerived(s, s.Name+".args_stackmap") |
| } |
| if !foundArgInfo { |
| p := Appendp(s.Func().Text, newprog) |
| p.As = AFUNCDATA |
| p.From.Type = TYPE_CONST |
| p.From.Offset = abi.FUNCDATA_ArgInfo |
| p.To.Type = TYPE_MEM |
| p.To.Name = NAME_EXTERN |
| p.To.Sym = ctxt.LookupDerived(s, fmt.Sprintf("%s.arginfo%d", s.Name, s.ABI())) |
| } |
| } |
| } |
| |
| // Turn functions into machine code images. |
| for _, s := range text { |
| mkfwd(s) |
| if ctxt.Arch.ErrorCheck != nil { |
| ctxt.Arch.ErrorCheck(ctxt, 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) |
| ctxt.populateDWARF(plist.Curfn, s) |
| if ctxt.Headtype == objabi.Hwindows && ctxt.Arch.SEH != nil { |
| s.Func().sehUnwindInfoSym = ctxt.Arch.SEH(ctxt, s) |
| } |
| } |
| } |
| |
| func (ctxt *Link) InitTextSym(s *LSym, flag int, start src.XPos) { |
| if s == nil { |
| // func _() { } |
| return |
| } |
| if s.Func() != nil { |
| ctxt.Diag("%s: symbol %s redeclared\n\t%s: other declaration of symbol %s", ctxt.PosTable.Pos(start), s.Name, ctxt.PosTable.Pos(s.Func().Text.Pos), s.Name) |
| return |
| } |
| s.NewFuncInfo() |
| if s.OnList() { |
| ctxt.Diag("%s: symbol %s redeclared", ctxt.PosTable.Pos(start), s.Name) |
| return |
| } |
| if strings.HasPrefix(s.Name, `"".`) { |
| ctxt.Diag("%s: unqualified symbol name: %s", ctxt.PosTable.Pos(start), s.Name) |
| } |
| |
| // startLine should be the same line number that would be displayed via |
| // pcln, etc for the declaration (i.e., relative line number, as |
| // adjusted by //line). |
| _, startLine := ctxt.getFileIndexAndLine(start) |
| |
| s.Func().FuncID = objabi.GetFuncID(s.Name, flag&WRAPPER != 0 || flag&ABIWRAPPER != 0) |
| s.Func().FuncFlag = ctxt.toFuncFlag(flag) |
| s.Func().StartLine = startLine |
| 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(AttrABIWrapper, flag&ABIWRAPPER != 0) |
| s.Set(AttrNeedCtxt, flag&NEEDCTXT != 0) |
| s.Set(AttrNoFrame, flag&NOFRAME != 0) |
| s.Set(AttrPkgInit, flag&PKGINIT != 0) |
| s.Type = objabi.STEXT |
| ctxt.Text = append(ctxt.Text, s) |
| |
| // Set up DWARF entries for s |
| ctxt.dwarfSym(s) |
| } |
| |
| func (ctxt *Link) toFuncFlag(flag int) abi.FuncFlag { |
| var out abi.FuncFlag |
| if flag&TOPFRAME != 0 { |
| out |= abi.FuncFlagTopFrame |
| } |
| if ctxt.IsAsm { |
| out |= abi.FuncFlagAsm |
| } |
| return out |
| } |
| |
| func (ctxt *Link) Globl(s *LSym, size int64, flag int) { |
| ctxt.GloblPos(s, size, flag, src.NoXPos) |
| } |
| func (ctxt *Link) GloblPos(s *LSym, size int64, flag int, pos src.XPos) { |
| if s.OnList() { |
| // TODO: print where the first declaration was. |
| ctxt.Diag("%s: symbol %s redeclared", ctxt.PosTable.Pos(pos), 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 |
| } |
| } |
| |
| // 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 = abi.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 = abi.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 = abi.PCDATA_UnsafePoint |
| pcdata.To.Type = TYPE_CONST |
| pcdata.To.Offset = abi.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 = abi.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 == abi.PCDATA_UnsafePoint { |
| prevPcdata = p.To.Offset |
| continue |
| } |
| if prevPcdata == abi.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(abi.UnsafePointRestart1) |
| if val == prevRestart { |
| val = abi.UnsafePointRestart2 |
| } |
| prevRestart = val |
| q := Appendp(prev, newprog) |
| q.As = APCDATA |
| q.From.Type = TYPE_CONST |
| q.From.Offset = abi.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 = abi.PCDATA_UnsafePoint |
| p.To.Type = TYPE_CONST |
| p.To.Offset = prevPcdata |
| p.Pc = p.Link.Pc |
| } |
| } |
| } |
