1 files changed, 639 insertions, 0 deletions
diff --git a/src/cmd/compile/internal/gc/obj.go b/src/cmd/compile/internal/gc/obj.go
new file mode 100644
index 0000000..da1869e
--- /dev/null
+++ b/src/cmd/compile/internal/gc/obj.go
@@ -0,0 +1,639 @@
+// Copyright 2009 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 gc
+
+import (
+	"cmd/compile/internal/types"
+	"cmd/internal/bio"
+	"cmd/internal/obj"
+	"cmd/internal/objabi"
+	"cmd/internal/src"
+	"crypto/sha256"
+	"encoding/json"
+	"fmt"
+	"io"
+	"io/ioutil"
+	"os"
+	"sort"
+	"strconv"
+)
+
+// architecture-independent object file output
+const ArhdrSize = 60
+
+func formathdr(arhdr []byte, name string, size int64) {
+	copy(arhdr[:], fmt.Sprintf("%-16s%-12d%-6d%-6d%-8o%-10d`\n", name, 0, 0, 0, 0644, size))
+}
+
+// These modes say which kind of object file to generate.
+// The default use of the toolchain is to set both bits,
+// generating a combined compiler+linker object, one that
+// serves to describe the package to both the compiler and the linker.
+// In fact the compiler and linker read nearly disjoint sections of
+// that file, though, so in a distributed build setting it can be more
+// efficient to split the output into two files, supplying the compiler
+// object only to future compilations and the linker object only to
+// future links.
+//
+// By default a combined object is written, but if -linkobj is specified
+// on the command line then the default -o output is a compiler object
+// and the -linkobj output is a linker object.
+const (
+	modeCompilerObj = 1 << iota
+	modeLinkerObj
+)
+
+func dumpobj() {
+	if linkobj == "" {
+		dumpobj1(outfile, modeCompilerObj|modeLinkerObj)
+		return
+	}
+	dumpobj1(outfile, modeCompilerObj)
+	dumpobj1(linkobj, modeLinkerObj)
+}
+
+func dumpobj1(outfile string, mode int) {
+	bout, err := bio.Create(outfile)
+	if err != nil {
+		flusherrors()
+		fmt.Printf("can't create %s: %v\n", outfile, err)
+		errorexit()
+	}
+	defer bout.Close()
+	bout.WriteString("!<arch>\n")
+
+	if mode&modeCompilerObj != 0 {
+		start := startArchiveEntry(bout)
+		dumpCompilerObj(bout)
+		finishArchiveEntry(bout, start, "__.PKGDEF")
+	}
+	if mode&modeLinkerObj != 0 {
+		start := startArchiveEntry(bout)
+		dumpLinkerObj(bout)
+		finishArchiveEntry(bout, start, "_go_.o")
+	}
+}
+
+func printObjHeader(bout *bio.Writer) {
+	fmt.Fprintf(bout, "go object %s %s %s %s\n", objabi.GOOS, objabi.GOARCH, objabi.Version, objabi.Expstring())
+	if buildid != "" {
+		fmt.Fprintf(bout, "build id %q\n", buildid)
+	}
+	if localpkg.Name == "main" {
+		fmt.Fprintf(bout, "main\n")
+	}
+	fmt.Fprintf(bout, "\n") // header ends with blank line
+}
+
+func startArchiveEntry(bout *bio.Writer) int64 {
+	var arhdr [ArhdrSize]byte
+	bout.Write(arhdr[:])
+	return bout.Offset()
+}
+
+func finishArchiveEntry(bout *bio.Writer, start int64, name string) {
+	bout.Flush()
+	size := bout.Offset() - start
+	if size&1 != 0 {
+		bout.WriteByte(0)
+	}
+	bout.MustSeek(start-ArhdrSize, 0)
+
+	var arhdr [ArhdrSize]byte
+	formathdr(arhdr[:], name, size)
+	bout.Write(arhdr[:])
+	bout.Flush()
+	bout.MustSeek(start+size+(size&1), 0)
+}
+
+func dumpCompilerObj(bout *bio.Writer) {
+	printObjHeader(bout)
+	dumpexport(bout)
+}
+
+func dumpdata() {
+	externs := len(externdcl)
+	xtops := len(xtop)
+
+	dumpglobls()
+	addptabs()
+	exportlistLen := len(exportlist)
+	addsignats(externdcl)
+	dumpsignats()
+	dumptabs()
+	ptabsLen := len(ptabs)
+	itabsLen := len(itabs)
+	dumpimportstrings()
+	dumpbasictypes()
+	dumpembeds()
+
+	// Calls to dumpsignats can generate functions,
+	// like method wrappers and hash and equality routines.
+	// Compile any generated functions, process any new resulting types, repeat.
+	// This can't loop forever, because there is no way to generate an infinite
+	// number of types in a finite amount of code.
+	// In the typical case, we loop 0 or 1 times.
+	// It was not until issue 24761 that we found any code that required a loop at all.
+	for {
+		for i := xtops; i < len(xtop); i++ {
+			n := xtop[i]
+			if n.Op == ODCLFUNC {
+				funccompile(n)
+			}
+		}
+		xtops = len(xtop)
+		compileFunctions()
+		dumpsignats()
+		if xtops == len(xtop) {
+			break
+		}
+	}
+
+	// Dump extra globals.
+	tmp := externdcl
+
+	if externdcl != nil {
+		externdcl = externdcl[externs:]
+	}
+	dumpglobls()
+	externdcl = tmp
+
+	if zerosize > 0 {
+		zero := mappkg.Lookup("zero")
+		ggloblsym(zero.Linksym(), int32(zerosize), obj.DUPOK|obj.RODATA)
+		zero.Linksym().Set(obj.AttrStatic, true)
+	}
+
+	addGCLocals()
+
+	if exportlistLen != len(exportlist) {
+		Fatalf("exportlist changed after compile functions loop")
+	}
+	if ptabsLen != len(ptabs) {
+		Fatalf("ptabs changed after compile functions loop")
+	}
+	if itabsLen != len(itabs) {
+		Fatalf("itabs changed after compile functions loop")
+	}
+}
+
+func dumpLinkerObj(bout *bio.Writer) {
+	printObjHeader(bout)
+
+	if len(pragcgobuf) != 0 {
+		// write empty export section; must be before cgo section
+		fmt.Fprintf(bout, "\n$$\n\n$$\n\n")
+		fmt.Fprintf(bout, "\n$$  // cgo\n")
+		if err := json.NewEncoder(bout).Encode(pragcgobuf); err != nil {
+			Fatalf("serializing pragcgobuf: %v", err)
+		}
+		fmt.Fprintf(bout, "\n$$\n\n")
+	}
+
+	fmt.Fprintf(bout, "\n!\n")
+
+	obj.WriteObjFile(Ctxt, bout)
+}
+
+func addptabs() {
+	if !Ctxt.Flag_dynlink || localpkg.Name != "main" {
+		return
+	}
+	for _, exportn := range exportlist {
+		s := exportn.Sym
+		n := asNode(s.Def)
+		if n == nil {
+			continue
+		}
+		if n.Op != ONAME {
+			continue
+		}
+		if !types.IsExported(s.Name) {
+			continue
+		}
+		if s.Pkg.Name != "main" {
+			continue
+		}
+		if n.Type.Etype == TFUNC && n.Class() == PFUNC {
+			// function
+			ptabs = append(ptabs, ptabEntry{s: s, t: asNode(s.Def).Type})
+		} else {
+			// variable
+			ptabs = append(ptabs, ptabEntry{s: s, t: types.NewPtr(asNode(s.Def).Type)})
+		}
+	}
+}
+
+func dumpGlobal(n *Node) {
+	if n.Type == nil {
+		Fatalf("external %v nil type\n", n)
+	}
+	if n.Class() == PFUNC {
+		return
+	}
+	if n.Sym.Pkg != localpkg {
+		return
+	}
+	dowidth(n.Type)
+	ggloblnod(n)
+}
+
+func dumpGlobalConst(n *Node) {
+	// only export typed constants
+	t := n.Type
+	if t == nil {
+		return
+	}
+	if n.Sym.Pkg != localpkg {
+		return
+	}
+	// only export integer constants for now
+	switch t.Etype {
+	case TINT8:
+	case TINT16:
+	case TINT32:
+	case TINT64:
+	case TINT:
+	case TUINT8:
+	case TUINT16:
+	case TUINT32:
+	case TUINT64:
+	case TUINT:
+	case TUINTPTR:
+		// ok
+	case TIDEAL:
+		if !Isconst(n, CTINT) {
+			return
+		}
+		x := n.Val().U.(*Mpint)
+		if x.Cmp(minintval[TINT]) < 0 || x.Cmp(maxintval[TINT]) > 0 {
+			return
+		}
+		// Ideal integers we export as int (if they fit).
+		t = types.Types[TINT]
+	default:
+		return
+	}
+	Ctxt.DwarfIntConst(myimportpath, n.Sym.Name, typesymname(t), n.Int64Val())
+}
+
+func dumpglobls() {
+	// add globals
+	for _, n := range externdcl {
+		switch n.Op {
+		case ONAME:
+			dumpGlobal(n)
+		case OLITERAL:
+			dumpGlobalConst(n)
+		}
+	}
+
+	sort.Slice(funcsyms, func(i, j int) bool {
+		return funcsyms[i].LinksymName() < funcsyms[j].LinksymName()
+	})
+	for _, s := range funcsyms {
+		sf := s.Pkg.Lookup(funcsymname(s)).Linksym()
+		dsymptr(sf, 0, s.Linksym(), 0)
+		ggloblsym(sf, int32(Widthptr), obj.DUPOK|obj.RODATA)
+	}
+
+	// Do not reprocess funcsyms on next dumpglobls call.
+	funcsyms = nil
+}
+
+// addGCLocals adds gcargs, gclocals, gcregs, and stack object symbols to Ctxt.Data.
+//
+// This is done during the sequential phase after compilation, since
+// global symbols can't be declared during parallel compilation.
+func addGCLocals() {
+	for _, s := range Ctxt.Text {
+		fn := s.Func()
+		if fn == nil {
+			continue
+		}
+		for _, gcsym := range []*obj.LSym{fn.GCArgs, fn.GCLocals} {
+			if gcsym != nil && !gcsym.OnList() {
+				ggloblsym(gcsym, int32(len(gcsym.P)), obj.RODATA|obj.DUPOK)
+			}
+		}
+		if x := fn.StackObjects; x != nil {
+			attr := int16(obj.RODATA)
+			ggloblsym(x, int32(len(x.P)), attr)
+			x.Set(obj.AttrStatic, true)
+		}
+		if x := fn.OpenCodedDeferInfo; x != nil {
+			ggloblsym(x, int32(len(x.P)), obj.RODATA|obj.DUPOK)
+		}
+	}
+}
+
+func duintxx(s *obj.LSym, off int, v uint64, wid int) int {
+	if off&(wid-1) != 0 {
+		Fatalf("duintxxLSym: misaligned: v=%d wid=%d off=%d", v, wid, off)
+	}
+	s.WriteInt(Ctxt, int64(off), wid, int64(v))
+	return off + wid
+}
+
+func duint8(s *obj.LSym, off int, v uint8) int {
+	return duintxx(s, off, uint64(v), 1)
+}
+
+func duint16(s *obj.LSym, off int, v uint16) int {
+	return duintxx(s, off, uint64(v), 2)
+}
+
+func duint32(s *obj.LSym, off int, v uint32) int {
+	return duintxx(s, off, uint64(v), 4)
+}
+
+func duintptr(s *obj.LSym, off int, v uint64) int {
+	return duintxx(s, off, v, Widthptr)
+}
+
+func dbvec(s *obj.LSym, off int, bv bvec) int {
+	// Runtime reads the bitmaps as byte arrays. Oblige.
+	for j := 0; int32(j) < bv.n; j += 8 {
+		word := bv.b[j/32]
+		off = duint8(s, off, uint8(word>>(uint(j)%32)))
+	}
+	return off
+}
+
+const (
+	stringSymPrefix  = "go.string."
+	stringSymPattern = ".gostring.%d.%x"
+)
+
+// stringsym returns a symbol containing the string s.
+// The symbol contains the string data, not a string header.
+func stringsym(pos src.XPos, s string) (data *obj.LSym) {
+	var symname string
+	if len(s) > 100 {
+		// Huge strings are hashed to avoid long names in object files.
+		// Indulge in some paranoia by writing the length of s, too,
+		// as protection against length extension attacks.
+		// Same pattern is known to fileStringSym below.
+		h := sha256.New()
+		io.WriteString(h, s)
+		symname = fmt.Sprintf(stringSymPattern, len(s), h.Sum(nil))
+	} else {
+		// Small strings get named directly by their contents.
+		symname = strconv.Quote(s)
+	}
+
+	symdata := Ctxt.Lookup(stringSymPrefix + symname)
+	if !symdata.OnList() {
+		off := dstringdata(symdata, 0, s, pos, "string")
+		ggloblsym(symdata, int32(off), obj.DUPOK|obj.RODATA|obj.LOCAL)
+		symdata.Set(obj.AttrContentAddressable, true)
+	}
+
+	return symdata
+}
+
+// fileStringSym returns a symbol for the contents and the size of file.
+// If readonly is true, the symbol shares storage with any literal string
+// or other file with the same content and is placed in a read-only section.
+// If readonly is false, the symbol is a read-write copy separate from any other,
+// for use as the backing store of a []byte.
+// The content hash of file is copied into hash. (If hash is nil, nothing is copied.)
+// The returned symbol contains the data itself, not a string header.
+func fileStringSym(pos src.XPos, file string, readonly bool, hash []byte) (*obj.LSym, int64, error) {
+	f, err := os.Open(file)
+	if err != nil {
+		return nil, 0, err
+	}
+	defer f.Close()
+	info, err := f.Stat()
+	if err != nil {
+		return nil, 0, err
+	}
+	if !info.Mode().IsRegular() {
+		return nil, 0, fmt.Errorf("not a regular file")
+	}
+	size := info.Size()
+	if size <= 1*1024 {
+		data, err := ioutil.ReadAll(f)
+		if err != nil {
+			return nil, 0, err
+		}
+		if int64(len(data)) != size {
+			return nil, 0, fmt.Errorf("file changed between reads")
+		}
+		var sym *obj.LSym
+		if readonly {
+			sym = stringsym(pos, string(data))
+		} else {
+			sym = slicedata(pos, string(data)).Sym.Linksym()
+		}
+		if len(hash) > 0 {
+			sum := sha256.Sum256(data)
+			copy(hash, sum[:])
+		}
+		return sym, size, nil
+	}
+	if size > 2e9 {
+		// ggloblsym takes an int32,
+		// and probably the rest of the toolchain
+		// can't handle such big symbols either.
+		// See golang.org/issue/9862.
+		return nil, 0, fmt.Errorf("file too large")
+	}
+
+	// File is too big to read and keep in memory.
+	// Compute hash if needed for read-only content hashing or if the caller wants it.
+	var sum []byte
+	if readonly || len(hash) > 0 {
+		h := sha256.New()
+		n, err := io.Copy(h, f)
+		if err != nil {
+			return nil, 0, err
+		}
+		if n != size {
+			return nil, 0, fmt.Errorf("file changed between reads")
+		}
+		sum = h.Sum(nil)
+		copy(hash, sum)
+	}
+
+	var symdata *obj.LSym
+	if readonly {
+		symname := fmt.Sprintf(stringSymPattern, size, sum)
+		symdata = Ctxt.Lookup(stringSymPrefix + symname)
+		if !symdata.OnList() {
+			info := symdata.NewFileInfo()
+			info.Name = file
+			info.Size = size
+			ggloblsym(symdata, int32(size), obj.DUPOK|obj.RODATA|obj.LOCAL)
+			// Note: AttrContentAddressable cannot be set here,
+			// because the content-addressable-handling code
+			// does not know about file symbols.
+		}
+	} else {
+		// Emit a zero-length data symbol
+		// and then fix up length and content to use file.
+		symdata = slicedata(pos, "").Sym.Linksym()
+		symdata.Size = size
+		symdata.Type = objabi.SNOPTRDATA
+		info := symdata.NewFileInfo()
+		info.Name = file
+		info.Size = size
+	}
+
+	return symdata, size, nil
+}
+
+var slicedataGen int
+
+func slicedata(pos src.XPos, s string) *Node {
+	slicedataGen++
+	symname := fmt.Sprintf(".gobytes.%d", slicedataGen)
+	sym := localpkg.Lookup(symname)
+	symnode := newname(sym)
+	sym.Def = asTypesNode(symnode)
+
+	lsym := sym.Linksym()
+	off := dstringdata(lsym, 0, s, pos, "slice")
+	ggloblsym(lsym, int32(off), obj.NOPTR|obj.LOCAL)
+
+	return symnode
+}
+
+func slicebytes(nam *Node, s string) {
+	if nam.Op != ONAME {
+		Fatalf("slicebytes %v", nam)
+	}
+	slicesym(nam, slicedata(nam.Pos, s), int64(len(s)))
+}
+
+func dstringdata(s *obj.LSym, off int, t string, pos src.XPos, what string) int {
+	// Objects that are too large will cause the data section to overflow right away,
+	// causing a cryptic error message by the linker. Check for oversize objects here
+	// and provide a useful error message instead.
+	if int64(len(t)) > 2e9 {
+		yyerrorl(pos, "%v with length %v is too big", what, len(t))
+		return 0
+	}
+
+	s.WriteString(Ctxt, int64(off), len(t), t)
+	return off + len(t)
+}
+
+func dsymptr(s *obj.LSym, off int, x *obj.LSym, xoff int) int {
+	off = int(Rnd(int64(off), int64(Widthptr)))
+	s.WriteAddr(Ctxt, int64(off), Widthptr, x, int64(xoff))
+	off += Widthptr
+	return off
+}
+
+func dsymptrOff(s *obj.LSym, off int, x *obj.LSym) int {
+	s.WriteOff(Ctxt, int64(off), x, 0)
+	off += 4
+	return off
+}
+
+func dsymptrWeakOff(s *obj.LSym, off int, x *obj.LSym) int {
+	s.WriteWeakOff(Ctxt, int64(off), x, 0)
+	off += 4
+	return off
+}
+
+// slicesym writes a static slice symbol {&arr, lencap, lencap} to n.
+// arr must be an ONAME. slicesym does not modify n.
+func slicesym(n, arr *Node, lencap int64) {
+	s := n.Sym.Linksym()
+	base := n.Xoffset
+	if arr.Op != ONAME {
+		Fatalf("slicesym non-name arr %v", arr)
+	}
+	s.WriteAddr(Ctxt, base, Widthptr, arr.Sym.Linksym(), arr.Xoffset)
+	s.WriteInt(Ctxt, base+sliceLenOffset, Widthptr, lencap)
+	s.WriteInt(Ctxt, base+sliceCapOffset, Widthptr, lencap)
+}
+
+// addrsym writes the static address of a to n. a must be an ONAME.
+// Neither n nor a is modified.
+func addrsym(n, a *Node) {
+	if n.Op != ONAME {
+		Fatalf("addrsym n op %v", n.Op)
+	}
+	if n.Sym == nil {
+		Fatalf("addrsym nil n sym")
+	}
+	if a.Op != ONAME {
+		Fatalf("addrsym a op %v", a.Op)
+	}
+	s := n.Sym.Linksym()
+	s.WriteAddr(Ctxt, n.Xoffset, Widthptr, a.Sym.Linksym(), a.Xoffset)
+}
+
+// pfuncsym writes the static address of f to n. f must be a global function.
+// Neither n nor f is modified.
+func pfuncsym(n, f *Node) {
+	if n.Op != ONAME {
+		Fatalf("pfuncsym n op %v", n.Op)
+	}
+	if n.Sym == nil {
+		Fatalf("pfuncsym nil n sym")
+	}
+	if f.Class() != PFUNC {
+		Fatalf("pfuncsym class not PFUNC %d", f.Class())
+	}
+	s := n.Sym.Linksym()
+	s.WriteAddr(Ctxt, n.Xoffset, Widthptr, funcsym(f.Sym).Linksym(), f.Xoffset)
+}
+
+// litsym writes the static literal c to n.
+// Neither n nor c is modified.
+func litsym(n, c *Node, wid int) {
+	if n.Op != ONAME {
+		Fatalf("litsym n op %v", n.Op)
+	}
+	if c.Op != OLITERAL {
+		Fatalf("litsym c op %v", c.Op)
+	}
+	if n.Sym == nil {
+		Fatalf("litsym nil n sym")
+	}
+	s := n.Sym.Linksym()
+	switch u := c.Val().U.(type) {
+	case bool:
+		i := int64(obj.Bool2int(u))
+		s.WriteInt(Ctxt, n.Xoffset, wid, i)
+
+	case *Mpint:
+		s.WriteInt(Ctxt, n.Xoffset, wid, u.Int64())
+
+	case *Mpflt:
+		f := u.Float64()
+		switch n.Type.Etype {
+		case TFLOAT32:
+			s.WriteFloat32(Ctxt, n.Xoffset, float32(f))
+		case TFLOAT64:
+			s.WriteFloat64(Ctxt, n.Xoffset, f)
+		}
+
+	case *Mpcplx:
+		r := u.Real.Float64()
+		i := u.Imag.Float64()
+		switch n.Type.Etype {
+		case TCOMPLEX64:
+			s.WriteFloat32(Ctxt, n.Xoffset, float32(r))
+			s.WriteFloat32(Ctxt, n.Xoffset+4, float32(i))
+		case TCOMPLEX128:
+			s.WriteFloat64(Ctxt, n.Xoffset, r)
+			s.WriteFloat64(Ctxt, n.Xoffset+8, i)
+		}
+
+	case string:
+		symdata := stringsym(n.Pos, u)
+		s.WriteAddr(Ctxt, n.Xoffset, Widthptr, symdata, 0)
+		s.WriteInt(Ctxt, n.Xoffset+int64(Widthptr), Widthptr, int64(len(u)))
+
+	default:
+		Fatalf("litsym unhandled OLITERAL %v", c)
+	}
+}