misc/cgo: enable testso and testsovar on aix/ppc64

On AIX, shared objects must be wrapped under an archive file.

For testso, creating libcgosotest with an extern symbol isn't
AIX-friendly. By default, ld will block such behavior. Rather than
forcing ld to work as on Linux and using the run-time linking,
goCallback became a function pointer which is set by setCallback().

Updates #30565

Change-Id: I455ab32faddd41f1b0c84cc9e503788044ad49b2
Reviewed-on: https://go-review.googlesource.com/c/go/+/169020
Run-TryBot: Ian Lance Taylor <iant@golang.org>
Reviewed-by: Ian Lance Taylor <iant@golang.org>

misc/cgo/testso/so_test.go

@@ -28,9 +28,6 @@ func requireTestSOSupported(t *testing.T) {
 		if runtime.GOOS == "linux" {
 			t.Skip("External linking not implemented on aix/ppc64 (issue #8912).")
 		}
-		if runtime.GOOS == "aix" {
-			t.Skip("Using shared object isn't yet available on aix/ppc64 (issue #30565)")
-		}
 	case "mips64le", "mips64":
 		t.Skip("External linking not implemented on mips64.")
 	}
@@ -85,6 +82,8 @@ func TestSO(t *testing.T) {
 	case "windows":
 		ext = "dll"
 		args = append(args, "-DEXPORT_DLL")
+	case "aix":
+		ext = "so.1"
 	}
 	sofname := "libcgosotest." + ext
 	args = append(args, "-o", sofname, "cgoso_c.c")
@@ -98,6 +97,16 @@ func TestSO(t *testing.T) {
 	}
 	t.Logf("%s:\n%s", strings.Join(cmd.Args, " "), out)
 
+	if runtime.GOOS == "aix" {
+		// Shared object must be wrapped by an archive
+		cmd = exec.Command("ar", "-X64", "-q", "libcgosotest.a", "libcgosotest.so.1")
+		cmd.Dir = modRoot
+		out, err = cmd.CombinedOutput()
+		if err != nil {
+			t.Fatalf("%s: %s\n%s", strings.Join(cmd.Args, " "), err, out)
+		}
+	}
+
 	cmd = exec.Command("go", "build", "-o", "main.exe", "main.go")
 	cmd.Dir = modRoot
 	cmd.Env = append(os.Environ(), "GOPATH="+GOPATH)

misc/cgo/testso/testdata/cgoso.c

@@ -4,7 +4,7 @@
 
 #include "_cgo_export.h"
 
-#ifdef WIN32
+#if defined(WIN32) || defined(_AIX)
 extern void setCallback(void *);
 void init() {
 	setCallback(goCallback);

misc/cgo/testso/testdata/cgoso.go

@@ -15,6 +15,7 @@ package cgosotest
 #cgo netbsd LDFLAGS: -L. libcgosotest.so
 #cgo darwin LDFLAGS: -L. libcgosotest.dylib
 #cgo windows LDFLAGS: -L. libcgosotest.dll
+#cgo aix LDFLAGS: -L. -l cgosotest
 
 void init(void);
 void sofunc(void);

misc/cgo/testso/testdata/cgoso_c.c

@@ -14,6 +14,15 @@ __declspec(dllexport) void setCallback(void *f)
 	goCallback = (void (*)())f;
 }
 __declspec(dllexport) void sofunc(void);
+#elif defined(_AIX)
+// AIX doesn't allow the creation of a shared object with an
+// undefined symbol. It's possible to bypass this problem by
+// using -Wl,-G and -Wl,-brtl option which allows run-time linking.
+// However, that's not how most of AIX shared object works.
+// Therefore, it's better to consider goCallback as a pointer and
+// to set up during an init function.
+void (*goCallback)(void);
+void setCallback(void *f) { goCallback = f; }
 #else
 extern void goCallback(void);
 void setCallback(void *f) { (void)f; }

misc/cgo/testso/testdata/cgoso_unix.go

@@ -2,7 +2,7 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
-// +build dragonfly freebsd linux netbsd solaris
+// +build aix dragonfly freebsd linux netbsd solaris
 
 package cgosotest
 

misc/cgo/testsovar/so_test.go

@@ -28,9 +28,6 @@ func requireTestSOSupported(t *testing.T) {
 		if runtime.GOOS == "linux" {
 			t.Skip("External linking not implemented on aix/ppc64 (issue #8912).")
 		}
-		if runtime.GOOS == "aix" {
-			t.Skip("Using shared object isn't yet available on aix/ppc64 (issue #30565)")
-		}
 	case "mips64le", "mips64":
 		t.Skip("External linking not implemented on mips64.")
 	}
@@ -85,6 +82,8 @@ func TestSO(t *testing.T) {
 	case "windows":
 		ext = "dll"
 		args = append(args, "-DEXPORT_DLL")
+	case "aix":
+		ext = "so.1"
 	}
 	sofname := "libcgosotest." + ext
 	args = append(args, "-o", sofname, "cgoso_c.c")
@@ -98,6 +97,16 @@ func TestSO(t *testing.T) {
 	}
 	t.Logf("%s:\n%s", strings.Join(cmd.Args, " "), out)
 
+	if runtime.GOOS == "aix" {
+		// Shared object must be wrapped by an archive
+		cmd = exec.Command("ar", "-X64", "-q", "libcgosotest.a", "libcgosotest.so.1")
+		cmd.Dir = modRoot
+		out, err = cmd.CombinedOutput()
+		if err != nil {
+			t.Fatalf("%s: %s\n%s", strings.Join(cmd.Args, " "), err, out)
+		}
+	}
+
 	cmd = exec.Command("go", "build", "-o", "main.exe", "main.go")
 	cmd.Dir = modRoot
 	cmd.Env = append(os.Environ(), "GOPATH="+GOPATH)

misc/cgo/testsovar/testdata/cgoso.go

@@ -19,6 +19,7 @@ package cgosotest
 #cgo netbsd LDFLAGS: -L. libcgosotest.so
 #cgo darwin LDFLAGS: -L. libcgosotest.dylib
 #cgo windows LDFLAGS: -L. libcgosotest.dll
+#cgo aix LDFLAGS: -L. -l cgosotest
 
 #include "cgoso_c.h"