[dev.link] cmd/link: invoke oldlink if old object format is chosen

Now we can choose the old object file format by setting
-gcflags=all=-go115newobj=false -asmflags=all=-go115newobj=false -ldflags=all=-go115newobj=false

Tested that setting all three to default false and it still works.

Change-Id: I9514b62a676916cc383b8afa389489fe7b8fa2bf
Reviewed-on: https://go-review.googlesource.com/c/go/+/224625
Reviewed-by: Than McIntosh <thanm@google.com>

diff --git a/src/cmd/link/internal/ld/main.go b/src/cmd/link/internal/ld/main.go
index 1d2a764db908d01667c7d4b79c24a39bf975c880..af1f6d763d961947eb272b5dbfdb5a7a3902ad45 100644 (file)
--- a/src/cmd/link/internal/ld/main.go
+++ b/src/cmd/link/internal/ld/main.go
@@ -39,6 +39,7 @@ import (
        "flag"
        "log"
        "os"
+       "os/exec"
        "runtime"
        "runtime/pprof"
        "strings"
@@ -98,6 +99,8 @@ var (
 
        benchmarkFlag     = flag.String("benchmark", "", "set to 'mem' or 'cpu' to enable phase benchmarking")
        benchmarkFileFlag = flag.String("benchmarkprofile", "", "emit phase profiles to `base`_phase.{cpu,mem}prof")
+
+       flagGo115Newobj = flag.Bool("go115newobj", true, "use new object file format")
 )
 
 // Main is the main entry point for the linker code.
@@ -137,6 +140,10 @@ func Main(arch *sys.Arch, theArch Arch) {
 
        objabi.Flagparse(usage)
 
+       if !*flagGo115Newobj {
+               oldlink()
+       }
+
        switch *flagHeadType {
        case "":
        case "windowsgui":
@@ -401,3 +408,48 @@ func startProfile() {
                })
        }
 }
+
+// Invoke the old linker and exit.
+func oldlink() {
+       linker := os.Args[0]
+       if strings.HasSuffix(linker, "link") {
+               linker = linker[:len(linker)-4] + "oldlink"
+       } else if strings.HasSuffix(linker, "link.exe") {
+               linker = linker[:len(linker)-8] + "oldlink.exe"
+       } else {
+               log.Fatal("cannot find oldlink. arg0=", linker)
+       }
+
+       // Copy args, filter out -go115newobj flag
+       args := make([]string, 0, len(os.Args)-1)
+       skipNext := false
+       for i, a := range os.Args {
+               if i == 0 {
+                       continue // skip arg0
+               }
+               if skipNext {
+                       skipNext = false
+                       continue
+               }
+               if a == "-go115newobj" {
+                       skipNext = true
+                       continue
+               }
+               if strings.HasPrefix(a, "-go115newobj=") {
+                       continue
+               }
+               args = append(args, a)
+       }
+
+       cmd := exec.Command(linker, args...)
+       cmd.Stdout = os.Stdout
+       cmd.Stderr = os.Stderr
+       err := cmd.Run()
+       if err == nil {
+               os.Exit(0)
+       }
+       if _, ok := err.(*exec.ExitError); ok {
+               os.Exit(2) // would be nice to use ExitError.ExitCode(), but that is too new
+       }
+       log.Fatal("invoke oldlink failed:", err)
+}

diff --git a/src/cmd/link/link_test.go b/src/cmd/link/link_test.go
index 4f792bd1f19c0512888ae4f1ba2dc1c1f36d2803..5e19cb5de1858edfb0c75ce861f1b9c72f45ad7c 100644 (file)
--- a/src/cmd/link/link_test.go
+++ b/src/cmd/link/link_test.go
@@ -447,3 +447,27 @@ func TestStrictDup(t *testing.T) {
                t.Errorf("unexpected output:\n%s", out)
        }
 }
+
+func TestOldLink(t *testing.T) {
+       // Test that old object file format still works.
+       // TODO(go115newobj): delete.
+
+       testenv.MustHaveGoBuild(t)
+
+       tmpdir, err := ioutil.TempDir("", "TestOldLink")
+       if err != nil {
+               t.Fatal(err)
+       }
+       defer os.RemoveAll(tmpdir)
+
+       src := filepath.Join(tmpdir, "main.go")
+       err = ioutil.WriteFile(src, []byte("package main; func main(){}\n"), 0666)
+       if err != nil {
+               t.Fatal(err)
+       }
+
+       cmd := exec.Command(testenv.GoToolPath(t), "run", "-gcflags=all=-go115newobj=false", "-asmflags=all=-go115newobj=false", "-ldflags=-go115newobj=false", src)
+       if out, err := cmd.CombinedOutput(); err != nil {
+               t.Errorf("%v: %v:\n%s", cmd.Args, err, out)
+       }
+}