cmd/link: change -strictdups checking to handle mix of flags

Update the recently-added '-strictdups' sanity checking to avoid
failing the link in cases where we have objects feeding into the link
with a mix of command line flags (and in particular some with "-N" and
some without). This scenario will trigger errors/warnings due to
inlinable functions and wrapper functions that have different sizes
due to presence or lack of optimization.

Update #31034.

Change-Id: I1dd9e37c2f9bea5da0ab82e32e6fc210aebf6a65
Reviewed-on: https://go-review.googlesource.com/c/go/+/169160
Run-TryBot: Than McIntosh <thanm@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: David Chase <drchase@google.com>

diff --git a/src/cmd/link/internal/ld/dwarf.go b/src/cmd/link/internal/ld/dwarf.go
index d923b7599d68ffeef133d191f395051fddead87b..e86247dd04e11eaa6052989922a16618c5a76274 100644 (file)
--- a/src/cmd/link/internal/ld/dwarf.go
+++ b/src/cmd/link/internal/ld/dwarf.go
@@ -1797,6 +1797,7 @@ func dwarfGenerateDebugInfo(ctxt *Link) {
 
        // fake root DIE for compile unit DIEs
        var dwroot dwarf.DWDie
+       flagVariants := make(map[string]bool)
 
        for _, lib := range ctxt.Library {
                unit := &compilationUnit{lib: lib}
@@ -1825,7 +1826,11 @@ func dwarfGenerateDebugInfo(ctxt *Link) {
                        // version, so it should be safe for readers to scan
                        // forward to the semicolon.
                        producer += "; " + string(producerExtra.P)
+                       flagVariants[string(producerExtra.P)] = true
+               } else {
+                       flagVariants[""] = true
                }
+
                newattr(unit.dwinfo, dwarf.DW_AT_producer, dwarf.DW_CLS_STRING, int64(len(producer)), producer)
 
                if len(lib.Textp) == 0 {
@@ -1876,6 +1881,13 @@ func dwarfGenerateDebugInfo(ctxt *Link) {
                }
        }
 
+       // Fix for 31034: if the objects feeding into this link were compiled
+       // with different sets of flags, then don't issue an error if
+       // the -strictdups checks fail.
+       if checkStrictDups > 1 && len(flagVariants) > 1 {
+               checkStrictDups = 1
+       }
+
        // Create DIEs for global variables and the types they use.
        genasmsym(ctxt, defdwsymb)
 

diff --git a/src/cmd/link/internal/ld/lib.go b/src/cmd/link/internal/ld/lib.go
index f53e0273c6db43f1e7785e201eeafe94b0f2ec02..c5f35af254b37c6ed437c03406925671975ac3ee 100644 (file)
--- a/src/cmd/link/internal/ld/lib.go
+++ b/src/cmd/link/internal/ld/lib.go
@@ -200,6 +200,10 @@ var (
 
        nerrors  int
        liveness int64
+
+       // See -strictdups command line flag.
+       checkStrictDups   int // 0=off 1=warning 2=error
+       strictDupMsgCount int
 )
 
 var (
@@ -283,6 +287,9 @@ func errorexit() {
        if nerrors != 0 {
                Exit(2)
        }
+       if checkStrictDups > 1 && strictDupMsgCount > 0 {
+               Exit(2)
+       }
        Exit(0)
 }
 
@@ -1745,7 +1752,8 @@ func ldobj(ctxt *Link, f *bio.Reader, lib *sym.Library, length int64, pn string,
        default:
                log.Fatalf("invalid -strictdups flag value %d", *FlagStrictDups)
        }
-       objfile.Load(ctxt.Arch, ctxt.Syms, f, lib, eof-f.Offset(), pn, flags)
+       c := objfile.Load(ctxt.Arch, ctxt.Syms, f, lib, eof-f.Offset(), pn, flags)
+       strictDupMsgCount += c
        addImports(ctxt, lib, pn)
        return nil
 }

diff --git a/src/cmd/link/internal/ld/main.go b/src/cmd/link/internal/ld/main.go
index e5859868b7482fcbcbcb0f5615b5142953ede611..48a99538937d752376b4205ed262aea96edc6c47 100644 (file)
--- a/src/cmd/link/internal/ld/main.go
+++ b/src/cmd/link/internal/ld/main.go
@@ -148,6 +148,7 @@ func Main(arch *sys.Arch, theArch Arch) {
        if objabi.Fieldtrack_enabled != 0 {
                ctxt.Reachparent = make(map[*sym.Symbol]*sym.Symbol)
        }
+       checkStrictDups = *FlagStrictDups
 
        startProfile()
        if ctxt.BuildMode == BuildModeUnset {

diff --git a/src/cmd/link/internal/objfile/objfile.go b/src/cmd/link/internal/objfile/objfile.go
index 9b76f2801d1386765414e8be3411f0adce2ebb96..f3957822b03a9a2d25737465812b2535d64dd161 100644 (file)
--- a/src/cmd/link/internal/objfile/objfile.go
+++ b/src/cmd/link/internal/objfile/objfile.go
@@ -42,6 +42,7 @@ type objReader struct {
        dupSym          *sym.Symbol
        localSymVersion int
        flags           int
+       strictDupMsgs   int
 
        // rdBuf is used by readString and readSymName as scratch for reading strings.
        rdBuf []byte
@@ -72,7 +73,7 @@ const (
 
 // Load loads an object file f into library lib.
 // The symbols loaded are added to syms.
-func Load(arch *sys.Arch, syms *sym.Symbols, f *bio.Reader, lib *sym.Library, length int64, pn string, flags int) {
+func Load(arch *sys.Arch, syms *sym.Symbols, f *bio.Reader, lib *sym.Library, length int64, pn string, flags int) int {
        start := f.Offset()
        r := &objReader{
                rd:              f.Reader,
@@ -88,6 +89,7 @@ func Load(arch *sys.Arch, syms *sym.Symbols, f *bio.Reader, lib *sym.Library, le
        if f.Offset() != start+length {
                log.Fatalf("%s: unexpected end at %d, want %d", pn, f.Offset(), start+length)
        }
+       return r.strictDupMsgs
 }
 
 func (r *objReader) loadObjFile() {
@@ -376,9 +378,8 @@ overwrite:
                        // params; I am guessing that the pos is being inherited
                        // from the spot where the wrapper is needed.
                        whitelist := strings.HasPrefix(dup.Name, "go.info.go.interface")
-
-                       if r.flags&StrictDupsErrFlag != 0 && !whitelist {
-                               log.Fatalf("failed duplicate symbol check on '%s' reading %s", dup.Name, r.pn)
+                       if !whitelist {
+                               r.strictDupMsgs++
                        }
                }
        }