cmd/cgo, cmd/internal/pkgpath: support gofrontend mangler v3

The gofrontend mangling scheme used by gccgo and GoLLVM has changed again.
Support the new version. This is a port of the relevant parts of
https://golang.org/cl/271726.

For #41862

Change-Id: I9c961c8e17ec960a83a23e1d49ea900962b63393
Reviewed-on: https://go-review.googlesource.com/c/go/+/272127
Trust: Ian Lance Taylor <[email protected]>
Run-TryBot: Ian Lance Taylor <[email protected]>
Reviewed-by: Than McIntosh <[email protected]>
TryBot-Result: Go Bot <[email protected]>

Author: ianlancetaylor

src/cmd/cgo/out.go

@@ -186,7 +186,7 @@ func (p *Package) writeDefs() {
 			panic(fmt.Errorf("invalid var kind %q", n.Kind))
 		}
 		if *gccgo {
-			fmt.Fprintf(fc, `extern void *%s __asm__("%s.%s");`, n.Mangle, gccgoSymbolPrefix, n.Mangle)
+			fmt.Fprintf(fc, `extern void *%s __asm__("%s.%s");`, n.Mangle, gccgoSymbolPrefix, gccgoToSymbol(n.Mangle))
 			fmt.Fprintf(&gccgoInit, "\t%s = &%s;\n", n.Mangle, n.C)
 			fmt.Fprintf(fc, "\n")
 		}
@@ -1148,7 +1148,7 @@ func (p *Package) writeGccgoExports(fgo2, fm, fgcc, fgcch io.Writer) {
 		// will not be able to link against it from the C
 		// code.
 		goName := "Cgoexp_" + exp.ExpName
-		fmt.Fprintf(fgcc, `extern %s %s %s __asm__("%s.%s");`, cRet, goName, cParams, gccgoSymbolPrefix, goName)
+		fmt.Fprintf(fgcc, `extern %s %s %s __asm__("%s.%s");`, cRet, goName, cParams, gccgoSymbolPrefix, gccgoToSymbol(goName))
 		fmt.Fprint(fgcc, "\n")
 
 		fmt.Fprint(fgcc, "\nCGO_NO_SANITIZE_THREAD\n")
@@ -1182,7 +1182,7 @@ func (p *Package) writeGccgoExports(fgo2, fm, fgcc, fgcch io.Writer) {
 		fmt.Fprint(fgcc, "}\n")
 
 		// Dummy declaration for _cgo_main.c
-		fmt.Fprintf(fm, `char %s[1] __asm__("%s.%s");`, goName, gccgoSymbolPrefix, goName)
+		fmt.Fprintf(fm, `char %s[1] __asm__("%s.%s");`, goName, gccgoSymbolPrefix, gccgoToSymbol(goName))
 		fmt.Fprint(fm, "\n")
 
 		// For gccgo we use a wrapper function in Go, in order
@@ -1266,9 +1266,8 @@ func (p *Package) writeExportHeader(fgcch io.Writer) {
 	fmt.Fprintf(fgcch, "%s\n", p.gccExportHeaderProlog())
 }
 
-// gccgoPkgpathToSymbol converts a package path to a mangled packagepath
-// symbol.
-func gccgoPkgpathToSymbol(ppath string) string {
+// gccgoToSymbol converts a name to a mangled symbol for gccgo.
+func gccgoToSymbol(ppath string) string {
 	if gccgoMangler == nil {
 		var err error
 		cmd := os.Getenv("GCCGO")
@@ -1293,12 +1292,12 @@ func (p *Package) gccgoSymbolPrefix() string {
 	}
 
 	if *gccgopkgpath != "" {
-		return gccgoPkgpathToSymbol(*gccgopkgpath)
+		return gccgoToSymbol(*gccgopkgpath)
 	}
 	if *gccgoprefix == "" && p.PackageName == "main" {
 		return "main"
 	}
-	prefix := gccgoPkgpathToSymbol(*gccgoprefix)
+	prefix := gccgoToSymbol(*gccgoprefix)
 	if prefix == "" {
 		prefix = "go"
 	}
@@ -1687,8 +1686,12 @@ void _cgoPREFIX_Cfunc__Cmalloc(void *v) {
 `
 
 func (p *Package) cPrologGccgo() string {
-	return strings.Replace(strings.Replace(cPrologGccgo, "PREFIX", cPrefix, -1),
-		"GCCGOSYMBOLPREF", p.gccgoSymbolPrefix(), -1)
+	r := strings.NewReplacer(
+		"PREFIX", cPrefix,
+		"GCCGOSYMBOLPREF", p.gccgoSymbolPrefix(),
+		"_cgoCheckPointer", gccgoToSymbol("_cgoCheckPointer"),
+		"_cgoCheckResult", gccgoToSymbol("_cgoCheckResult"))
+	return r.Replace(cPrologGccgo)
 }
 
 const cPrologGccgo = `

src/cmd/internal/pkgpath/pkgpath.go

@@ -50,9 +50,12 @@ func ToSymbolFunc(cmd, tmpdir string) (func(string) string, error) {
 		return nil, err
 	}
 
-	// New mangling: expect go.l..u00e4ufer.Run
-	// Old mangling: expect go.l__ufer.Run
-	if bytes.Contains(buf, []byte("go.l..u00e4ufer.Run")) {
+	// Original mangling: go.l__ufer.Run
+	// Mangling v2: go.l..u00e4ufer.Run
+	// Mangling v3: go_0l_u00e4ufer.Run
+	if bytes.Contains(buf, []byte("go_0l_u00e4ufer.Run")) {
+		return toSymbolV3, nil
+	} else if bytes.Contains(buf, []byte("go.l..u00e4ufer.Run")) {
 		return toSymbolV2, nil
 	} else if bytes.Contains(buf, []byte("go.l__ufer.Run")) {
 		return toSymbolV1, nil
@@ -82,7 +85,7 @@ func toSymbolV1(ppath string) string {
 	return strings.Map(clean, ppath)
 }
 
-// toSymbolV2 converts a package path using the newer mangling scheme.
+// toSymbolV2 converts a package path using the second mangling scheme.
 func toSymbolV2(ppath string) string {
 	// This has to build at boostrap time, so it has to build
 	// with Go 1.4, so we don't use strings.Builder.
@@ -112,3 +115,60 @@ func toSymbolV2(ppath string) string {
 	}
 	return string(bsl)
 }
+
+// v3UnderscoreCodes maps from a character that supports an underscore
+// encoding to the underscore encoding character.
+var v3UnderscoreCodes = map[byte]byte{
+	'_': '_',
+	'.': '0',
+	'/': '1',
+	'*': '2',
+	',': '3',
+	'{': '4',
+	'}': '5',
+	'[': '6',
+	']': '7',
+	'(': '8',
+	')': '9',
+	'"': 'a',
+	' ': 'b',
+	';': 'c',
+}
+
+// toSymbolV3 converts a package path using the third mangling scheme.
+func toSymbolV3(ppath string) string {
+	// This has to build at boostrap time, so it has to build
+	// with Go 1.4, so we don't use strings.Builder.
+	bsl := make([]byte, 0, len(ppath))
+	changed := false
+	for _, c := range ppath {
+		if ('A' <= c && c <= 'Z') || ('a' <= c && c <= 'z') || ('0' <= c && c <= '9') {
+			bsl = append(bsl, byte(c))
+			continue
+		}
+
+		if c < 0x80 {
+			if u, ok := v3UnderscoreCodes[byte(c)]; ok {
+				bsl = append(bsl, '_', u)
+				changed = true
+				continue
+			}
+		}
+
+		var enc string
+		switch {
+		case c < 0x80:
+			enc = fmt.Sprintf("_x%02x", c)
+		case c < 0x10000:
+			enc = fmt.Sprintf("_u%04x", c)
+		default:
+			enc = fmt.Sprintf("_U%08x", c)
+		}
+		bsl = append(bsl, enc...)
+		changed = true
+	}
+	if !changed {
+		return ppath
+	}
+	return string(bsl)
+}

src/cmd/internal/pkgpath/pkgpath_test.go

@@ -24,6 +24,9 @@ func init() {
 	case "v2":
 		os.Stdout.WriteString(`.string	"go.l..u00e4ufer.Run"`)
 		os.Exit(0)
+	case "v3":
+		os.Stdout.WriteString(`.string	"go_0l_u00e4ufer.Run"`)
+		os.Exit(0)
 	case "error":
 		os.Stdout.WriteString(`unknown string`)
 		os.Exit(0)
@@ -45,6 +48,10 @@ func TestToSymbolFunc(t *testing.T) {
 			env:     "v2",
 			mangled: "p..u00e4..u4e16..U0001f703",
 		},
+		{
+			env:     "v3",
+			mangled: "p_u00e4_u4e16_U0001f703",
+		},
 		{
 			env:  "error",
 			fail: true,
@@ -75,32 +82,37 @@ func TestToSymbolFunc(t *testing.T) {
 }
 
 var symbolTests = []struct {
-	input, v1, v2 string
+	input, v1, v2, v3 string
 }{
 	{
 		"",
 		"",
 		"",
+		"",
 	},
 	{
 		"bytes",
 		"bytes",
 		"bytes",
+		"bytes",
 	},
 	{
 		"net/http",
 		"net_http",
 		"net..z2fhttp",
+		"net_1http",
 	},
 	{
 		"golang.org/x/net/http",
 		"golang_org_x_net_http",
 		"golang.x2eorg..z2fx..z2fnet..z2fhttp",
+		"golang_0org_1x_1net_1http",
 	},
 	{
 		"pä世.🜃",
 		"p____",
 		"p..u00e4..u4e16.x2e..U0001f703",
+		"p_u00e4_u4e16_0_U0001f703",
 	},
 }
 
@@ -119,3 +131,11 @@ func TestV2(t *testing.T) {
 		}
 	}
 }
+
+func TestV3(t *testing.T) {
+	for _, test := range symbolTests {
+		if got, want := toSymbolV3(test.input), test.v3; got != want {
+			t.Errorf("toSymbolV3(%q) = %q, want %q", test.input, got, want)
+		}
+	}
+}