cmd/compile,cmd/link: remove statictmp variables from symbol table.

Removes statictmp variables from debug_info and the final symbol table.

Fixes #27800

Change-Id: I302c59a04bc3f460e7085fef241f937bbf30421d
Reviewed-on: https://go-review.googlesource.com/c/142577
Run-TryBot: Alessandro Arzilli <alessandro.arzilli@gmail.com>
Run-TryBot: Heschi Kreinick <heschi@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Heschi Kreinick <heschi@google.com>

diff --git a/src/cmd/link/internal/ld/dwarf.go b/src/cmd/link/internal/ld/dwarf.go
index 743f4cedd4bf77218f1f74f218e89621abc13165..827a1d931afadef5b5272eb1046d99d1f9943902 100644 (file)
--- a/src/cmd/link/internal/ld/dwarf.go
+++ b/src/cmd/link/internal/ld/dwarf.go
@@ -863,7 +863,9 @@ func defdwsymb(ctxt *Link, s *sym.Symbol, str string, t SymbolType, v int64, got
                default:
                        return
                }
-
+               if ctxt.LinkMode != LinkExternal && isStaticTemp(s.Name) {
+                       return
+               }
                dwarfDefineGlobal(ctxt, s, str, v, gotype)
 
        case AutoSym, ParamSym, DeletedAutoSym:

diff --git a/src/cmd/link/internal/ld/dwarf_test.go b/src/cmd/link/internal/ld/dwarf_test.go
index e5d99815909b26042e546d61aa63ff0ab06b642d..42b598efefa14d2bb40dc324bcfb65e14040216d 100644 (file)
--- a/src/cmd/link/internal/ld/dwarf_test.go
+++ b/src/cmd/link/internal/ld/dwarf_test.go
@@ -1062,3 +1062,76 @@ func main() {
                }
        }
 }
+
+func TestStaticTmp(t *testing.T) {
+       // Checks that statictmp variables do not appear in debug_info or the
+       // symbol table.
+       // Also checks that statictmp variables do not collide with user defined
+       // variables (issue #25113)
+
+       testenv.MustHaveGoBuild(t)
+
+       if runtime.GOOS == "plan9" {
+               t.Skip("skipping on plan9; no DWARF symbol table in executables")
+       }
+
+       dir, err := ioutil.TempDir("", "go-build")
+       if err != nil {
+               t.Fatal(err)
+       }
+       defer os.RemoveAll(dir)
+
+       const prog = `package main
+
+var stmp_0 string
+var a []int
+
+func init() {
+       a = []int{ 7 }
+}
+
+func main() {
+       println(a[0])
+}
+`
+
+       f := gobuild(t, dir, prog, NoOpt)
+
+       defer f.Close()
+
+       d, err := f.DWARF()
+       if err != nil {
+               t.Fatalf("error reading DWARF: %v", err)
+       }
+
+       rdr := d.Reader()
+       for {
+               e, err := rdr.Next()
+               if err != nil {
+                       t.Fatal(err)
+               }
+               if e == nil {
+                       break
+               }
+               if e.Tag != dwarf.TagVariable {
+                       continue
+               }
+               name, ok := e.Val(dwarf.AttrName).(string)
+               if !ok {
+                       continue
+               }
+               if strings.Contains(name, "stmp") {
+                       t.Errorf("statictmp variable found in debug_info: %s at %x", name, e.Offset)
+               }
+       }
+
+       syms, err := f.Symbols()
+       if err != nil {
+               t.Fatalf("error reading symbols: %v", err)
+       }
+       for _, sym := range syms {
+               if strings.Contains(sym.Name, "stmp") {
+                       t.Errorf("statictmp variable found in symbol table: %s", sym.Name)
+               }
+       }
+}

diff --git a/src/cmd/link/internal/ld/symtab.go b/src/cmd/link/internal/ld/symtab.go
index 2a04ef3824eba87345371e515a32c35f4691daf9..d2737deca56860bb4cb0a563e46d7b67eba96999 100644 (file)
--- a/src/cmd/link/internal/ld/symtab.go
+++ b/src/cmd/link/internal/ld/symtab.go
@@ -432,6 +432,10 @@ func (ctxt *Link) symtab() {
        // just defined above will be first.
        // hide the specific symbols.
        for _, s := range ctxt.Syms.Allsym {
+               if ctxt.LinkMode != LinkExternal && isStaticTemp(s.Name) {
+                       s.Attr |= sym.AttrNotInSymbolTable
+               }
+
                if !s.Attr.Reachable() || s.Attr.Special() || s.Type != sym.SRODATA {
                        continue
                }
@@ -676,3 +680,10 @@ func (ctxt *Link) symtab() {
                lastmoduledatap.AddAddr(ctxt.Arch, moduledata)
        }
 }
+
+func isStaticTemp(name string) bool {
+       if i := strings.LastIndex(name, "/"); i >= 0 {
+               name = name[i:]
+       }
+       return strings.Contains(name, "..stmp_")
+}