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[dev.link] cmd: convert symbol "shared" flag to object file flag

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For the new object file format, don't tag individual symbols with a
"shared" flag, since that characteristic is better off as an attribute
of the containing object file as opposed to the individual symbol. Add
a new flags field in the object file header and put a bit in the flags
if the shared flags is in effect during compilation.

Change-Id: I2cf6d33bf7bf2fd8a7614ae0cd6ef03914777498
Reviewed-on: https://go-review.googlesource.com/c/go/+/201398
Run-TryBot: Than McIntosh <thanm@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Jeremy Faller <jeremy@golang.org>
Reviewed-by: Cherry Zhang <cherryyz@google.com>
This commit is contained in:
Than McIntosh 2019-10-16 08:54:58 -04:00
parent 2bbf2e0233
commit 15634a0230
3 changed files with 24 additions and 10 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

18
src/cmd/internal/goobj2/objfile.go
View File

@ -20,6 +20,7 @@ import (
//
// Header struct {
// Magic [...]byte // "\x00go114LD"
// Flags uint32
// // TODO: Fingerprint
// Offsets [...]uint32 // byte offset of each block below
// }
@ -148,6 +149,7 @@ const (
// TODO: probably no need to export this.
type Header struct {
Magic string
Flags uint32
Offsets [NBlk]uint32
}
@ -155,6 +157,7 @@ const Magic = "\x00go114LD"
func (h *Header) Write(w *Writer) {
w.RawString(h.Magic)
w.Uint32(h.Flags)
for _, x := range h.Offsets {
w.Uint32(x)
}
@ -167,6 +170,8 @@ func (h *Header) Read(r *Reader) error {
return errors.New("wrong magic, not a Go object file")
}
off := uint32(len(h.Magic))
h.Flags = r.uint32At(off)
off += 4
for i := range h.Offsets {
h.Offsets[i] = r.uint32At(off)
off += 4
@ -175,7 +180,7 @@ func (h *Header) Read(r *Reader) error {
}
func (h *Header) Size() int {
return len(h.Magic) + 4*len(h.Offsets)
return len(h.Magic) + 4 + 4*len(h.Offsets)
}
// Symbol definition.
@ -189,6 +194,10 @@ type Sym struct {
const SymABIstatic = ^uint16(0)
const (
ObjFlagShared = 1 << iota
)
const (
SymFlagDupok = 1 << iota
SymFlagLocal
@ -196,7 +205,6 @@ const (
SymFlagLeaf
SymFlagCFunc
SymFlagReflectMethod
SymFlagShared // This is really silly
SymFlagTopFrame
)
@ -226,7 +234,6 @@ func (s *Sym) Typelink() bool { return s.Flag&SymFlagTypelink != 0 }
func (s *Sym) Leaf() bool { return s.Flag&SymFlagLeaf != 0 }
func (s *Sym) CFunc() bool { return s.Flag&SymFlagCFunc != 0 }
func (s *Sym) ReflectMethod() bool { return s.Flag&SymFlagReflectMethod != 0 }
func (s *Sym) Shared() bool { return s.Flag&SymFlagShared != 0 }
func (s *Sym) TopFrame() bool { return s.Flag&SymFlagTopFrame != 0 }
// Symbol reference.
@ -596,3 +603,8 @@ func (r *Reader) PcdataBase() uint32 {
func (r *Reader) ReadOnly() bool {
return r.readonly
}
// Flags returns the flag bits read from the object file header.
func (r *Reader) Flags() uint32 {
return r.h.Flags
}

9
src/cmd/internal/obj/objfile2.go
View File

@ -35,7 +35,11 @@ func WriteObjFile2(ctxt *Link, b *bio.Writer, pkgpath string) {
// Header
// We just reserve the space. We'll fill in the offsets later.
h := goobj2.Header{Magic: goobj2.Magic}
flags := uint32(0)
if ctxt.Flag_shared {
flags |= goobj2.ObjFlagShared
}
h := goobj2.Header{Magic: goobj2.Magic, Flags: flags}
h.Write(w.Writer)
// String table
@ -231,9 +235,6 @@ func (w *writer) Sym(s *LSym) {
if s.ReflectMethod() {
flag |= goobj2.SymFlagReflectMethod
}
if w.ctxt.Flag_shared { // This is really silly
flag |= goobj2.SymFlagShared
}
if s.TopFrame() {
flag |= goobj2.SymFlagTopFrame
}

5
src/cmd/link/internal/loader/loader.go
View File

@ -57,6 +57,7 @@ type oReader struct {
*goobj2.Reader
unit *sym.CompilationUnit
version int // version of static symbol
flags uint32 // read from object file
pkgprefix string
}
@ -460,7 +461,7 @@ func (l *Loader) Preload(arch *sys.Arch, syms *sym.Symbols, f *bio.Reader, lib *
}
localSymVersion := syms.IncVersion()
pkgprefix := objabi.PathToPrefix(lib.Pkg) + "."
or := &oReader{r, unit, localSymVersion, pkgprefix}
or := &oReader{r, unit, localSymVersion, r.Flags(), pkgprefix}
// Autolib
lib.ImportStrings = append(lib.ImportStrings, r.Autolib()...)
@ -770,7 +771,7 @@ func loadObjFull(l *Loader, r *oReader) {
if osym.ReflectMethod() {
s.Attr |= sym.AttrReflectMethod
}
if osym.Shared() {
if r.Flags()&goobj2.ObjFlagShared != 0 {
s.Attr |= sym.AttrShared
}
if osym.TopFrame() {