Stowage/go
2
0
Fork 0
mirror of https://github.com/golang/go.git synced 2025-12-08 06:10:04 +00:00
Code Issues Projects Releases Packages Wiki Activity

cmd/cgo: split gofrontend mangling checks into cmd/internal/pkgpath

Browse source 
This is a step toward porting https://golang.org/cl/219817 from the
gofrontend repo to the main repo.

Note that this also corrects the implementation of the v2 mangling
scheme to use ..u and ..U where appropriate.

For #37272

Change-Id: I64a1e7ca1c84348efcbf1cf62049eeb05c830ed8
Reviewed-on: https://go-review.googlesource.com/c/go/+/259298
Trust: Ian Lance Taylor <iant@golang.org>
Run-TryBot: Ian Lance Taylor <iant@golang.org>
TryBot-Result: Go Bot <gobot@golang.org>
Reviewed-by: Than McIntosh <thanm@google.com>
This commit is contained in:
Ian Lance Taylor 2020-10-02 16:03:37 -07:00
parent b064eb7e1b
commit 72ee5bad9f
5 changed files with 252 additions and 105 deletions
Download patch file Download diff file Expand all files Collapse all files

118
src/cmd/cgo/out.go
View file

@ -6,6 +6,7 @@ package main
import (
"bytes"
"cmd/internal/pkgpath"
"debug/elf"
"debug/macho"
"debug/pe"
@ -15,7 +16,6 @@ import (
"go/token"
"internal/xcoff"
"io"
"io/ioutil"
"os"
"os/exec"
"path/filepath"
@ -1282,112 +1282,24 @@ func (p *Package) writeExportHeader(fgcch io.Writer) {
fmt.Fprintf(fgcch, "%s\n", p.gccExportHeaderProlog())
}
// gccgoUsesNewMangling reports whether gccgo uses the new collision-free
// packagepath mangling scheme (see determineGccgoManglingScheme for more
// info).
func gccgoUsesNewMangling() bool {
if !gccgoMangleCheckDone {
gccgoNewmanglingInEffect = determineGccgoManglingScheme()
gccgoMangleCheckDone = true
}
return gccgoNewmanglingInEffect
}
const mangleCheckCode = `
package läufer
func Run(x int) int {
return 1
}
`
// determineGccgoManglingScheme performs a runtime test to see which
// flavor of packagepath mangling gccgo is using. Older versions of
// gccgo use a simple mangling scheme where there can be collisions
// between packages whose paths are different but mangle to the same
// string. More recent versions of gccgo use a new mangler that avoids
// these collisions. Return value is whether gccgo uses the new mangling.
func determineGccgoManglingScheme() bool {
// Emit a small Go file for gccgo to compile.
filepat := "*_gccgo_manglecheck.go"
var f *os.File
var err error
if f, err = ioutil.TempFile(*objDir, filepat); err != nil {
fatalf("%v", err)
}
gofilename := f.Name()
defer os.Remove(gofilename)
if err = ioutil.WriteFile(gofilename, []byte(mangleCheckCode), 0666); err != nil {
fatalf("%v", err)
}
// Compile with gccgo, capturing generated assembly.
gccgocmd := os.Getenv("GCCGO")
if gccgocmd == "" {
gpath, gerr := exec.LookPath("gccgo")
if gerr != nil {
fatalf("unable to locate gccgo: %v", gerr)
}
gccgocmd = gpath
}
cmd := exec.Command(gccgocmd, "-S", "-o", "-", gofilename)
buf, cerr := cmd.CombinedOutput()
if cerr != nil {
fatalf("%s", cerr)
}
// New mangling: expect go.l..u00e4ufer.Run
// Old mangling: expect go.l__ufer.Run
return regexp.MustCompile(`go\.l\.\.u00e4ufer\.Run`).Match(buf)
}
// gccgoPkgpathToSymbolNew converts a package path to a gccgo-style
// package symbol.
func gccgoPkgpathToSymbolNew(ppath string) string {
bsl := []byte{}
changed := false
for _, c := range []byte(ppath) {
switch {
case 'A' <= c && c <= 'Z', 'a' <= c && c <= 'z',
'0' <= c && c <= '9', c == '_':
bsl = append(bsl, c)
case c == '.':
bsl = append(bsl, ".x2e"...)
default:
changed = true
encbytes := []byte(fmt.Sprintf("..z%02x", c))
bsl = append(bsl, encbytes...)
}
}
if !changed {
return ppath
}
return string(bsl)
}
// gccgoPkgpathToSymbolOld converts a package path to a gccgo-style
// package symbol using the older mangling scheme.
func gccgoPkgpathToSymbolOld(ppath string) string {
clean := func(r rune) rune {
switch {
case 'A' <= r && r <= 'Z', 'a' <= r && r <= 'z',
'0' <= r && r <= '9':
return r
}
return '_'
}
return strings.Map(clean, ppath)
}
// gccgoPkgpathToSymbol converts a package path to a mangled packagepath
// symbol.
func gccgoPkgpathToSymbol(ppath string) string {
if gccgoUsesNewMangling() {
return gccgoPkgpathToSymbolNew(ppath)
} else {
return gccgoPkgpathToSymbolOld(ppath)
if gccgoMangler == nil {
var err error
cmd := os.Getenv("GCCGO")
if cmd == "" {
cmd, err = exec.LookPath("gccgo")
if err != nil {
fatalf("unable to locate gccgo: %v", err)
}
}
gccgoMangler, err = pkgpath.ToSymbolFunc(cmd, *objDir)
if err != nil {
fatalf("%v", err)
}
}
return gccgoMangler(ppath)
}
// Return the package prefix when using gccgo.