cmd/compile: fix spurious R_TLE_LE reloc on android/386

When compiling for GOARCH=386 GOOS=android, the compiler was attaching
R_TLS_LE relocations inappropriately -- as of Go 1.13 the TLS access
recipe for Android refers to a runtime symbol and no longer needs this
type of relocation (which was causing a crash when the linker tried to
process it).

Updates #29674.
Fixes #34788.

Change-Id: Ida01875011b524586597b1f7e273aa14e11815d6
Reviewed-on: https://go-review.googlesource.com/c/go/+/200337
Run-TryBot: Than McIntosh <thanm@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Elias Naur <mail@eliasnaur.com>
Reviewed-by: Cherry Zhang <cherryyz@google.com>

diff --git a/src/cmd/internal/obj/x86/asm6.go b/src/cmd/internal/obj/x86/asm6.go
index 618e88212cff0c970607498f7c794e5d0b7446ce..3a33bc3c3cc83655f98a836739770eff0d294909 100644 (file)
--- a/src/cmd/internal/obj/x86/asm6.go
+++ b/src/cmd/internal/obj/x86/asm6.go
@@ -3468,7 +3468,7 @@ func (ab *AsmBuf) asmandsz(ctxt *obj.Link, cursym *obj.LSym, p *obj.Prog, a *obj
        }
 
        if REG_AX <= base && base <= REG_R15 {
-               if a.Index == REG_TLS && !ctxt.Flag_shared {
+               if a.Index == REG_TLS && !ctxt.Flag_shared && !isAndroid {
                        rel = obj.Reloc{}
                        rel.Type = objabi.R_TLS_LE
                        rel.Siz = 4

diff --git a/src/cmd/link/link_test.go b/src/cmd/link/link_test.go
index 29b98e9c320ea8fd18ef46a9ac298f18aa5bf9c7..155fd8bce3b305afb8b7193338bfee99f2ac39fc 100644 (file)
--- a/src/cmd/link/link_test.go
+++ b/src/cmd/link/link_test.go
@@ -1,6 +1,8 @@
 package main
 
 import (
+       "bufio"
+       "bytes"
        "debug/macho"
        "internal/testenv"
        "io/ioutil"
@@ -315,3 +317,62 @@ func TestMacOSVersion(t *testing.T) {
                t.Errorf("no LC_VERSION_MIN_MACOSX load command found")
        }
 }
+
+const Issue34788src = `
+
+package blah
+
+func Blah(i int) int {
+       a := [...]int{1, 2, 3, 4, 5, 6, 7, 8}
+       return a[i&7]
+}
+`
+
+func TestIssue34788Android386TLSSequence(t *testing.T) {
+       testenv.MustHaveGoBuild(t)
+
+       // This is a cross-compilation test, so it doesn't make
+       // sense to run it on every GOOS/GOARCH combination. Limit
+       // the test to amd64 + darwin/linux.
+       if runtime.GOARCH != "amd64" ||
+               (runtime.GOOS != "darwin" && runtime.GOOS != "linux") {
+               t.Skip("skipping on non-{linux,darwin}/amd64 platform")
+       }
+
+       tmpdir, err := ioutil.TempDir("", "TestIssue34788Android386TLSSequence")
+       if err != nil {
+               t.Fatal(err)
+       }
+       defer os.RemoveAll(tmpdir)
+
+       src := filepath.Join(tmpdir, "blah.go")
+       err = ioutil.WriteFile(src, []byte(Issue34788src), 0666)
+       if err != nil {
+               t.Fatal(err)
+       }
+
+       obj := filepath.Join(tmpdir, "blah.o")
+       cmd := exec.Command(testenv.GoToolPath(t), "tool", "compile", "-o", obj, src)
+       cmd.Env = append(os.Environ(), "GOARCH=386", "GOOS=android")
+       if out, err := cmd.CombinedOutput(); err != nil {
+               if err != nil {
+                       t.Fatalf("failed to compile blah.go: %v, output: %s\n", err, out)
+               }
+       }
+
+       // Run objdump on the resulting object.
+       cmd = exec.Command(testenv.GoToolPath(t), "tool", "objdump", obj)
+       out, oerr := cmd.CombinedOutput()
+       if oerr != nil {
+               t.Fatalf("failed to objdump blah.o: %v, output: %s\n", oerr, out)
+       }
+
+       // Sift through the output; we should not be seeing any R_TLS_LE relocs.
+       scanner := bufio.NewScanner(bytes.NewReader(out))
+       for scanner.Scan() {
+               line := scanner.Text()
+               if strings.Contains(line, "R_TLS_LE") {
+                       t.Errorf("objdump output contains unexpected R_TLS_LE reloc: %s", line)
+               }
+       }
+}