315 lines
8.4 KiB
Go
315 lines
8.4 KiB
Go
// Copyright 2013 The Go Authors. All rights reserved.
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// Use of this source code is governed by a BSD-style
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// license that can be found in the LICENSE file.
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package obj
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import (
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"github.com/twitchyliquid64/golang-asm/objabi"
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"fmt"
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"strings"
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)
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type Plist struct {
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Firstpc *Prog
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Curfn interface{} // holds a *gc.Node, if non-nil
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}
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// ProgAlloc is a function that allocates Progs.
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// It is used to provide access to cached/bulk-allocated Progs to the assemblers.
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type ProgAlloc func() *Prog
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func Flushplist(ctxt *Link, plist *Plist, newprog ProgAlloc, myimportpath string) {
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// Build list of symbols, and assign instructions to lists.
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var curtext *LSym
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var etext *Prog
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var text []*LSym
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var plink *Prog
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for p := plist.Firstpc; p != nil; p = plink {
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if ctxt.Debugasm > 0 && ctxt.Debugvlog {
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fmt.Printf("obj: %v\n", p)
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}
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plink = p.Link
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p.Link = nil
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switch p.As {
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case AEND:
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continue
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case ATEXT:
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s := p.From.Sym
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if s == nil {
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// func _() { }
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curtext = nil
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continue
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}
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text = append(text, s)
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etext = p
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curtext = s
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continue
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case AFUNCDATA:
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// Rewrite reference to go_args_stackmap(SB) to the Go-provided declaration information.
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if curtext == nil { // func _() {}
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continue
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}
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if p.To.Sym.Name == "go_args_stackmap" {
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if p.From.Type != TYPE_CONST || p.From.Offset != objabi.FUNCDATA_ArgsPointerMaps {
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ctxt.Diag("FUNCDATA use of go_args_stackmap(SB) without FUNCDATA_ArgsPointerMaps")
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}
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p.To.Sym = ctxt.LookupDerived(curtext, curtext.Name+".args_stackmap")
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}
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}
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if curtext == nil {
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etext = nil
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continue
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}
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etext.Link = p
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etext = p
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}
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if newprog == nil {
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newprog = ctxt.NewProg
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}
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// Add reference to Go arguments for C or assembly functions without them.
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for _, s := range text {
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if !strings.HasPrefix(s.Name, "\"\".") {
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continue
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}
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found := false
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for p := s.Func.Text; p != nil; p = p.Link {
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if p.As == AFUNCDATA && p.From.Type == TYPE_CONST && p.From.Offset == objabi.FUNCDATA_ArgsPointerMaps {
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found = true
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break
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}
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}
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if !found {
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p := Appendp(s.Func.Text, newprog)
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p.As = AFUNCDATA
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p.From.Type = TYPE_CONST
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p.From.Offset = objabi.FUNCDATA_ArgsPointerMaps
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p.To.Type = TYPE_MEM
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p.To.Name = NAME_EXTERN
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p.To.Sym = ctxt.LookupDerived(s, s.Name+".args_stackmap")
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}
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}
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// Turn functions into machine code images.
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for _, s := range text {
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mkfwd(s)
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linkpatch(ctxt, s, newprog)
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ctxt.Arch.Preprocess(ctxt, s, newprog)
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ctxt.Arch.Assemble(ctxt, s, newprog)
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if ctxt.Errors > 0 {
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continue
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}
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linkpcln(ctxt, s)
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if myimportpath != "" {
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ctxt.populateDWARF(plist.Curfn, s, myimportpath)
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}
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}
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}
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func (ctxt *Link) InitTextSym(s *LSym, flag int) {
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if s == nil {
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// func _() { }
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return
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}
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if s.Func != nil {
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ctxt.Diag("InitTextSym double init for %s", s.Name)
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}
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s.Func = new(FuncInfo)
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if s.OnList() {
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ctxt.Diag("symbol %s listed multiple times", s.Name)
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}
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name := strings.Replace(s.Name, "\"\"", ctxt.Pkgpath, -1)
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s.Func.FuncID = objabi.GetFuncID(name, flag&WRAPPER != 0)
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s.Set(AttrOnList, true)
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s.Set(AttrDuplicateOK, flag&DUPOK != 0)
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s.Set(AttrNoSplit, flag&NOSPLIT != 0)
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s.Set(AttrReflectMethod, flag&REFLECTMETHOD != 0)
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s.Set(AttrWrapper, flag&WRAPPER != 0)
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s.Set(AttrNeedCtxt, flag&NEEDCTXT != 0)
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s.Set(AttrNoFrame, flag&NOFRAME != 0)
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s.Set(AttrTopFrame, flag&TOPFRAME != 0)
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s.Type = objabi.STEXT
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ctxt.Text = append(ctxt.Text, s)
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// Set up DWARF entries for s
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ctxt.dwarfSym(s)
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}
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func (ctxt *Link) Globl(s *LSym, size int64, flag int) {
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if s.OnList() {
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ctxt.Diag("symbol %s listed multiple times", s.Name)
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}
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s.Set(AttrOnList, true)
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ctxt.Data = append(ctxt.Data, s)
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s.Size = size
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if s.Type == 0 {
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s.Type = objabi.SBSS
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}
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if flag&DUPOK != 0 {
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s.Set(AttrDuplicateOK, true)
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}
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if flag&RODATA != 0 {
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s.Type = objabi.SRODATA
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} else if flag&NOPTR != 0 {
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if s.Type == objabi.SDATA {
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s.Type = objabi.SNOPTRDATA
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} else {
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s.Type = objabi.SNOPTRBSS
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}
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} else if flag&TLSBSS != 0 {
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s.Type = objabi.STLSBSS
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}
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if strings.HasPrefix(s.Name, "\"\"."+StaticNamePref) {
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s.Set(AttrStatic, true)
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}
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}
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// EmitEntryLiveness generates PCDATA Progs after p to switch to the
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// liveness map active at the entry of function s. It returns the last
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// Prog generated.
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func (ctxt *Link) EmitEntryLiveness(s *LSym, p *Prog, newprog ProgAlloc) *Prog {
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pcdata := ctxt.EmitEntryStackMap(s, p, newprog)
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pcdata = ctxt.EmitEntryRegMap(s, pcdata, newprog)
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return pcdata
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}
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// Similar to EmitEntryLiveness, but just emit stack map.
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func (ctxt *Link) EmitEntryStackMap(s *LSym, p *Prog, newprog ProgAlloc) *Prog {
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pcdata := Appendp(p, newprog)
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pcdata.Pos = s.Func.Text.Pos
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pcdata.As = APCDATA
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pcdata.From.Type = TYPE_CONST
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pcdata.From.Offset = objabi.PCDATA_StackMapIndex
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pcdata.To.Type = TYPE_CONST
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pcdata.To.Offset = -1 // pcdata starts at -1 at function entry
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return pcdata
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}
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// Similar to EmitEntryLiveness, but just emit register map.
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func (ctxt *Link) EmitEntryRegMap(s *LSym, p *Prog, newprog ProgAlloc) *Prog {
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pcdata := Appendp(p, newprog)
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pcdata.Pos = s.Func.Text.Pos
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pcdata.As = APCDATA
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pcdata.From.Type = TYPE_CONST
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pcdata.From.Offset = objabi.PCDATA_RegMapIndex
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pcdata.To.Type = TYPE_CONST
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pcdata.To.Offset = -1
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return pcdata
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}
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// StartUnsafePoint generates PCDATA Progs after p to mark the
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// beginning of an unsafe point. The unsafe point starts immediately
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// after p.
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// It returns the last Prog generated.
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func (ctxt *Link) StartUnsafePoint(p *Prog, newprog ProgAlloc) *Prog {
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pcdata := Appendp(p, newprog)
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pcdata.As = APCDATA
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pcdata.From.Type = TYPE_CONST
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pcdata.From.Offset = objabi.PCDATA_RegMapIndex
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pcdata.To.Type = TYPE_CONST
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pcdata.To.Offset = objabi.PCDATA_RegMapUnsafe
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return pcdata
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}
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// EndUnsafePoint generates PCDATA Progs after p to mark the end of an
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// unsafe point, restoring the register map index to oldval.
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// The unsafe point ends right after p.
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// It returns the last Prog generated.
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func (ctxt *Link) EndUnsafePoint(p *Prog, newprog ProgAlloc, oldval int64) *Prog {
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pcdata := Appendp(p, newprog)
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pcdata.As = APCDATA
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pcdata.From.Type = TYPE_CONST
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pcdata.From.Offset = objabi.PCDATA_RegMapIndex
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pcdata.To.Type = TYPE_CONST
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pcdata.To.Offset = oldval
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return pcdata
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}
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// MarkUnsafePoints inserts PCDATAs to mark nonpreemptible and restartable
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// instruction sequences, based on isUnsafePoint and isRestartable predicate.
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// p0 is the start of the instruction stream.
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// isUnsafePoint(p) returns true if p is not safe for async preemption.
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// isRestartable(p) returns true if we can restart at the start of p (this Prog)
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// upon async preemption. (Currently multi-Prog restartable sequence is not
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// supported.)
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// isRestartable can be nil. In this case it is treated as always returning false.
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// If isUnsafePoint(p) and isRestartable(p) are both true, it is treated as
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// an unsafe point.
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func MarkUnsafePoints(ctxt *Link, p0 *Prog, newprog ProgAlloc, isUnsafePoint, isRestartable func(*Prog) bool) {
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if isRestartable == nil {
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// Default implementation: nothing is restartable.
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isRestartable = func(*Prog) bool { return false }
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}
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prev := p0
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prevPcdata := int64(-1) // entry PC data value
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prevRestart := int64(0)
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for p := prev.Link; p != nil; p, prev = p.Link, p {
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if p.As == APCDATA && p.From.Offset == objabi.PCDATA_RegMapIndex {
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prevPcdata = p.To.Offset
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continue
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}
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if prevPcdata == objabi.PCDATA_RegMapUnsafe {
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continue // already unsafe
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}
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if isUnsafePoint(p) {
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q := ctxt.StartUnsafePoint(prev, newprog)
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q.Pc = p.Pc
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q.Link = p
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// Advance to the end of unsafe point.
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for p.Link != nil && isUnsafePoint(p.Link) {
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p = p.Link
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}
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if p.Link == nil {
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break // Reached the end, don't bother marking the end
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}
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p = ctxt.EndUnsafePoint(p, newprog, prevPcdata)
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p.Pc = p.Link.Pc
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continue
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}
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if isRestartable(p) {
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val := int64(objabi.PCDATA_Restart1)
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if val == prevRestart {
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val = objabi.PCDATA_Restart2
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}
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prevRestart = val
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q := Appendp(prev, newprog)
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q.As = APCDATA
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q.From.Type = TYPE_CONST
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q.From.Offset = objabi.PCDATA_RegMapIndex
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q.To.Type = TYPE_CONST
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q.To.Offset = val
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q.Pc = p.Pc
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q.Link = p
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if p.Link == nil {
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break // Reached the end, don't bother marking the end
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}
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if isRestartable(p.Link) {
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// Next Prog is also restartable. No need to mark the end
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// of this sequence. We'll just go ahead mark the next one.
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continue
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}
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p = Appendp(p, newprog)
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p.As = APCDATA
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p.From.Type = TYPE_CONST
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p.From.Offset = objabi.PCDATA_RegMapIndex
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p.To.Type = TYPE_CONST
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p.To.Offset = prevPcdata
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p.Pc = p.Link.Pc
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}
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}
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}
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