Index: include/llvm/IR/ModuleSummaryIndex.h
===================================================================
--- include/llvm/IR/ModuleSummaryIndex.h
+++ include/llvm/IR/ModuleSummaryIndex.h
@@ -197,6 +197,9 @@
   }
 
   bool isDSOLocal() const;
+
+  /// Checks if all copies are eligible for auto-hiding (have flag set).
+  bool canAutoHide() const;
 };
 
 inline raw_ostream &operator<<(raw_ostream &OS, const ValueInfo &VI) {
@@ -279,11 +282,23 @@
     /// within the same linkage unit.
     unsigned DSOLocal : 1;
 
+    /// In the per-module summary, indicates that the global value is
+    /// linkonce_odr and global unnamed addr (so eligible for auto-hiding
+    /// via hidden visibility). In the combined summary, indicates that the
+    /// prevailing linkonce_odr copy can be auto-hidden via hidden visibility
+    /// when it is upgraded to weak_odr in the backend. This is legal when
+    /// all copies are eligible for auto-hiding (i.e. all copies were
+    /// linkonce_odr global unnamed addr. If any copy is not (e.g. it was
+    /// originally weak_odr, we cannot auto-hide the prevailing copy as it
+    /// means the symbol was externally visible.
+    unsigned CanAutoHide : 1;
+
     /// Convenience Constructors
     explicit GVFlags(GlobalValue::LinkageTypes Linkage,
-                     bool NotEligibleToImport, bool Live, bool IsLocal)
+                     bool NotEligibleToImport, bool Live, bool IsLocal,
+                     bool CanAutoHide)
         : Linkage(Linkage), NotEligibleToImport(NotEligibleToImport),
-          Live(Live), DSOLocal(IsLocal) {}
+          Live(Live), DSOLocal(IsLocal), CanAutoHide(CanAutoHide) {}
   };
 
 private:
@@ -364,6 +379,10 @@
 
   bool isDSOLocal() const { return Flags.DSOLocal; }
 
+  void setCanAutoHide(bool CanAutoHide) { Flags.CanAutoHide = CanAutoHide; }
+
+  bool canAutoHide() const { return Flags.CanAutoHide; }
+
   /// Flag that this global value cannot be imported.
   void setNotEligibleToImport() { Flags.NotEligibleToImport = true; }
 
@@ -512,7 +531,8 @@
     return FunctionSummary(
         FunctionSummary::GVFlags(
             GlobalValue::LinkageTypes::AvailableExternallyLinkage,
-            /*NotEligibleToImport=*/true, /*Live=*/true, /*IsLocal=*/false),
+            /*NotEligibleToImport=*/true, /*Live=*/true, /*IsLocal=*/false,
+            /*CanAutoHide=*/false),
         /*InsCount=*/0, FunctionSummary::FFlags{}, /*EntryCount=*/0,
         std::vector<ValueInfo>(), std::move(Edges),
         std::vector<GlobalValue::GUID>(),
Index: include/llvm/IR/ModuleSummaryIndexYAML.h
===================================================================
--- include/llvm/IR/ModuleSummaryIndexYAML.h
+++ include/llvm/IR/ModuleSummaryIndexYAML.h
@@ -136,7 +136,7 @@
 
 struct FunctionSummaryYaml {
   unsigned Linkage;
-  bool NotEligibleToImport, Live, IsLocal;
+  bool NotEligibleToImport, Live, IsLocal, CanAutoHide;
   std::vector<uint64_t> Refs;
   std::vector<uint64_t> TypeTests;
   std::vector<FunctionSummary::VFuncId> TypeTestAssumeVCalls,
@@ -180,6 +180,7 @@
     io.mapOptional("NotEligibleToImport", summary.NotEligibleToImport);
     io.mapOptional("Live", summary.Live);
     io.mapOptional("Local", summary.IsLocal);
+    io.mapOptional("CanAutoHide", summary.CanAutoHide);
     io.mapOptional("Refs", summary.Refs);
     io.mapOptional("TypeTests", summary.TypeTests);
     io.mapOptional("TypeTestAssumeVCalls", summary.TypeTestAssumeVCalls);
@@ -222,7 +223,7 @@
       Elem.SummaryList.push_back(llvm::make_unique<FunctionSummary>(
           GlobalValueSummary::GVFlags(
               static_cast<GlobalValue::LinkageTypes>(FSum.Linkage),
-              FSum.NotEligibleToImport, FSum.Live, FSum.IsLocal),
+              FSum.NotEligibleToImport, FSum.Live, FSum.IsLocal, FSum.CanAutoHide),
           /*NumInsts=*/0, FunctionSummary::FFlags{}, /*EntryCount=*/0, Refs,
           ArrayRef<FunctionSummary::EdgeTy>{}, std::move(FSum.TypeTests),
           std::move(FSum.TypeTestAssumeVCalls),
@@ -243,7 +244,8 @@
               FSum->flags().Linkage,
               static_cast<bool>(FSum->flags().NotEligibleToImport),
               static_cast<bool>(FSum->flags().Live),
-              static_cast<bool>(FSum->flags().DSOLocal), Refs,
+              static_cast<bool>(FSum->flags().DSOLocal),
+              static_cast<bool>(FSum->flags().CanAutoHide), Refs,
               FSum->type_tests(), FSum->type_test_assume_vcalls(),
               FSum->type_checked_load_vcalls(),
               FSum->type_test_assume_const_vcalls(),
Index: include/llvm/LTO/LTO.h
===================================================================
--- include/llvm/LTO/LTO.h
+++ include/llvm/LTO/LTO.h
@@ -50,7 +50,8 @@
     function_ref<bool(GlobalValue::GUID, const GlobalValueSummary *)>
         isPrevailing,
     function_ref<void(StringRef, GlobalValue::GUID, GlobalValue::LinkageTypes)>
-        recordNewLinkage);
+        recordNewLinkage,
+    const DenseSet<GlobalValue::GUID> &GUIDPreservedSymbols);
 
 /// Update the linkages in the given \p Index to mark exported values
 /// as external and non-exported values as internal. The ThinLTO backends
@@ -398,7 +399,8 @@
                    const SymbolResolution *&ResI, const SymbolResolution *ResE);
 
   Error runRegularLTO(AddStreamFn AddStream);
-  Error runThinLTO(AddStreamFn AddStream, NativeObjectCache Cache);
+  Error runThinLTO(AddStreamFn AddStream, NativeObjectCache Cache,
+                   const DenseSet<GlobalValue::GUID> &GUIDPreservedSymbols);
 
   Error checkPartiallySplit();
 
Index: lib/Analysis/ModuleSummaryAnalysis.cpp
===================================================================
--- lib/Analysis/ModuleSummaryAnalysis.cpp
+++ lib/Analysis/ModuleSummaryAnalysis.cpp
@@ -391,7 +391,8 @@
   bool NotEligibleForImport =
       NonRenamableLocal || HasInlineAsmMaybeReferencingInternal;
   GlobalValueSummary::GVFlags Flags(F.getLinkage(), NotEligibleForImport,
-                                    /* Live = */ false, F.isDSOLocal());
+                                    /* Live = */ false, F.isDSOLocal(),
+                                    F.hasLinkOnceODRLinkage() && F.hasGlobalUnnamedAddr());
   FunctionSummary::FFlags FunFlags{
       F.hasFnAttribute(Attribute::ReadNone),
       F.hasFnAttribute(Attribute::ReadOnly),
@@ -418,7 +419,8 @@
   bool HasBlockAddress = findRefEdges(Index, &V, RefEdges, Visited);
   bool NonRenamableLocal = isNonRenamableLocal(V);
   GlobalValueSummary::GVFlags Flags(V.getLinkage(), NonRenamableLocal,
-                                    /* Live = */ false, V.isDSOLocal());
+                                    /* Live = */ false, V.isDSOLocal(),
+                                    V.hasLinkOnceODRLinkage() && V.hasGlobalUnnamedAddr());
 
   // Don't mark variables we won't be able to internalize as read-only.
   GlobalVarSummary::GVarFlags VarFlags(
@@ -438,7 +440,8 @@
                     DenseSet<GlobalValue::GUID> &CantBePromoted) {
   bool NonRenamableLocal = isNonRenamableLocal(A);
   GlobalValueSummary::GVFlags Flags(A.getLinkage(), NonRenamableLocal,
-                                    /* Live = */ false, A.isDSOLocal());
+                                    /* Live = */ false, A.isDSOLocal(),
+                                    A.hasLinkOnceODRLinkage() && A.hasGlobalUnnamedAddr());
   auto AS = llvm::make_unique<AliasSummary>(Flags);
   auto *Aliasee = A.getBaseObject();
   auto AliaseeVI = Index.getValueInfo(Aliasee->getGUID());
@@ -513,7 +516,8 @@
           GlobalValueSummary::GVFlags GVFlags(GlobalValue::InternalLinkage,
                                               /* NotEligibleToImport = */ true,
                                               /* Live = */ true,
-                                              /* Local */ GV->isDSOLocal());
+                                              /* Local */ GV->isDSOLocal(),
+                                              GV->hasLinkOnceODRLinkage() && GV->hasGlobalUnnamedAddr());
           CantBePromoted.insert(GV->getGUID());
           // Create the appropriate summary type.
           if (Function *F = dyn_cast<Function>(GV)) {
Index: lib/AsmParser/LLLexer.cpp
===================================================================
--- lib/AsmParser/LLLexer.cpp
+++ lib/AsmParser/LLLexer.cpp
@@ -733,6 +733,7 @@
   KEYWORD(notEligibleToImport);
   KEYWORD(live);
   KEYWORD(dsoLocal);
+  KEYWORD(canAutoHide);
   KEYWORD(function);
   KEYWORD(insts);
   KEYWORD(funcFlags);
Index: lib/AsmParser/LLParser.cpp
===================================================================
--- lib/AsmParser/LLParser.cpp
+++ lib/AsmParser/LLParser.cpp
@@ -7846,7 +7846,7 @@
   StringRef ModulePath;
   GlobalValueSummary::GVFlags GVFlags = GlobalValueSummary::GVFlags(
       /*Linkage=*/GlobalValue::ExternalLinkage, /*NotEligibleToImport=*/false,
-      /*Live=*/false, /*IsLocal=*/false);
+      /*Live=*/false, /*IsLocal=*/false, /*CanAutoHide=*/false);
   unsigned InstCount;
   std::vector<FunctionSummary::EdgeTy> Calls;
   FunctionSummary::TypeIdInfo TypeIdInfo;
@@ -7916,7 +7916,7 @@
   StringRef ModulePath;
   GlobalValueSummary::GVFlags GVFlags = GlobalValueSummary::GVFlags(
       /*Linkage=*/GlobalValue::ExternalLinkage, /*NotEligibleToImport=*/false,
-      /*Live=*/false, /*IsLocal=*/false);
+      /*Live=*/false, /*IsLocal=*/false, /*CanAutoHide=*/false);
   GlobalVarSummary::GVarFlags GVarFlags(/*ReadOnly*/ false);
   std::vector<ValueInfo> Refs;
   if (ParseToken(lltok::colon, "expected ':' here") ||
@@ -7959,7 +7959,7 @@
   StringRef ModulePath;
   GlobalValueSummary::GVFlags GVFlags = GlobalValueSummary::GVFlags(
       /*Linkage=*/GlobalValue::ExternalLinkage, /*NotEligibleToImport=*/false,
-      /*Live=*/false, /*IsLocal=*/false);
+      /*Live=*/false, /*IsLocal=*/false, /*CanAutoHide=*/false);
   if (ParseToken(lltok::colon, "expected ':' here") ||
       ParseToken(lltok::lparen, "expected '(' here") ||
       ParseModuleReference(ModulePath) ||
@@ -8449,41 +8449,55 @@
 /// GVFlags
 ///   ::= 'flags' ':' '(' 'linkage' ':' OptionalLinkageAux ','
 ///         'notEligibleToImport' ':' Flag ',' 'live' ':' Flag ','
-///         'dsoLocal' ':' Flag ')'
+///         'dsoLocal' ':' Flag ',' 'canAutoHide' ':' Flag ')'
 bool LLParser::ParseGVFlags(GlobalValueSummary::GVFlags &GVFlags) {
   assert(Lex.getKind() == lltok::kw_flags);
   Lex.Lex();
 
-  bool HasLinkage;
   if (ParseToken(lltok::colon, "expected ':' here") ||
-      ParseToken(lltok::lparen, "expected '(' here") ||
-      ParseToken(lltok::kw_linkage, "expected 'linkage' here") ||
-      ParseToken(lltok::colon, "expected ':' here"))
-    return true;
-
-  GVFlags.Linkage = parseOptionalLinkageAux(Lex.getKind(), HasLinkage);
-  assert(HasLinkage && "Linkage not optional in summary entry");
-  Lex.Lex();
-
-  unsigned Flag;
-  if (ParseToken(lltok::comma, "expected ',' here") ||
-      ParseToken(lltok::kw_notEligibleToImport,
-                 "expected 'notEligibleToImport' here") ||
-      ParseToken(lltok::colon, "expected ':' here") || ParseFlag(Flag))
-    return true;
-  GVFlags.NotEligibleToImport = Flag;
-
-  if (ParseToken(lltok::comma, "expected ',' here") ||
-      ParseToken(lltok::kw_live, "expected 'live' here") ||
-      ParseToken(lltok::colon, "expected ':' here") || ParseFlag(Flag))
+      ParseToken(lltok::lparen, "expected '(' here"))
     return true;
-  GVFlags.Live = Flag;
 
-  if (ParseToken(lltok::comma, "expected ',' here") ||
-      ParseToken(lltok::kw_dsoLocal, "expected 'dsoLocal' here") ||
-      ParseToken(lltok::colon, "expected ':' here") || ParseFlag(Flag))
-    return true;
-  GVFlags.DSOLocal = Flag;
+  do {
+    unsigned Flag;
+    switch (Lex.getKind()) {
+    case lltok::kw_linkage:
+      Lex.Lex();
+      if (ParseToken(lltok::colon, "expected ':'"))
+        return true;
+      bool HasLinkage;
+      GVFlags.Linkage = parseOptionalLinkageAux(Lex.getKind(), HasLinkage);
+      assert(HasLinkage && "Linkage not optional in summary entry");
+      Lex.Lex();
+      break;
+    case lltok::kw_notEligibleToImport:
+      Lex.Lex();
+      if (ParseToken(lltok::colon, "expected ':'") || ParseFlag(Flag))
+        return true;
+      GVFlags.NotEligibleToImport = Flag;
+      break;
+    case lltok::kw_live:
+      Lex.Lex();
+      if (ParseToken(lltok::colon, "expected ':'") || ParseFlag(Flag))
+        return true;
+      GVFlags.Live = Flag;
+      break;
+    case lltok::kw_dsoLocal:
+      Lex.Lex();
+      if (ParseToken(lltok::colon, "expected ':'") || ParseFlag(Flag))
+        return true;
+      GVFlags.DSOLocal = Flag;
+      break;
+    case lltok::kw_canAutoHide:
+      Lex.Lex();
+      if (ParseToken(lltok::colon, "expected ':'") || ParseFlag(Flag))
+        return true;
+      GVFlags.CanAutoHide = Flag;
+      break;
+    default:
+      return Error(Lex.getLoc(), "expected gv flag type");
+    }
+  } while (EatIfPresent(lltok::comma));
 
   if (ParseToken(lltok::rparen, "expected ')' here"))
     return true;
Index: lib/AsmParser/LLToken.h
===================================================================
--- lib/AsmParser/LLToken.h
+++ lib/AsmParser/LLToken.h
@@ -364,6 +364,7 @@
   kw_notEligibleToImport,
   kw_live,
   kw_dsoLocal,
+  kw_canAutoHide,
   kw_function,
   kw_insts,
   kw_funcFlags,
Index: lib/Bitcode/Reader/BitcodeReader.cpp
===================================================================
--- lib/Bitcode/Reader/BitcodeReader.cpp
+++ lib/Bitcode/Reader/BitcodeReader.cpp
@@ -893,8 +893,9 @@
   // values as live.
   bool Live = (RawFlags & 0x2) || Version < 3;
   bool Local = (RawFlags & 0x4);
+  bool AutoHide = (RawFlags & 0x8);
 
-  return GlobalValueSummary::GVFlags(Linkage, NotEligibleToImport, Live, Local);
+  return GlobalValueSummary::GVFlags(Linkage, NotEligibleToImport, Live, Local, AutoHide);
 }
 
 // Decode the flags for GlobalVariable in the summary
Index: lib/Bitcode/Writer/BitcodeWriter.cpp
===================================================================
--- lib/Bitcode/Writer/BitcodeWriter.cpp
+++ lib/Bitcode/Writer/BitcodeWriter.cpp
@@ -994,6 +994,7 @@
   RawFlags |= Flags.NotEligibleToImport; // bool
   RawFlags |= (Flags.Live << 1);
   RawFlags |= (Flags.DSOLocal << 2);
+  RawFlags |= (Flags.CanAutoHide << 3);
 
   // Linkage don't need to be remapped at that time for the summary. Any future
   // change to the getEncodedLinkage() function will need to be taken into
Index: lib/IR/AsmWriter.cpp
===================================================================
--- lib/IR/AsmWriter.cpp
+++ lib/IR/AsmWriter.cpp
@@ -3028,6 +3028,7 @@
   Out << ", notEligibleToImport: " << GVFlags.NotEligibleToImport;
   Out << ", live: " << GVFlags.Live;
   Out << ", dsoLocal: " << GVFlags.DSOLocal;
+  Out << ", canAutoHide: " << GVFlags.CanAutoHide;
   Out << ")";
 
   if (Summary.getSummaryKind() == GlobalValueSummary::AliasKind)
Index: lib/IR/ModuleSummaryIndex.cpp
===================================================================
--- lib/IR/ModuleSummaryIndex.cpp
+++ lib/IR/ModuleSummaryIndex.cpp
@@ -26,6 +26,7 @@
 
 FunctionSummary FunctionSummary::ExternalNode =
     FunctionSummary::makeDummyFunctionSummary({});
+
 bool ValueInfo::isDSOLocal() const {
   // Need to check all summaries are local in case of hash collisions.
   return getSummaryList().size() &&
@@ -35,6 +36,15 @@
                       });
 }
 
+bool ValueInfo::canAutoHide() const {
+  // Can only auto hide if all copies are eligible to auto hide.
+  return getSummaryList().size() &&
+         llvm::all_of(getSummaryList(),
+                      [](const std::unique_ptr<GlobalValueSummary> &Summary) {
+                        return Summary->canAutoHide();
+                      });
+}
+
 // Gets the number of immutable refs in RefEdgeList
 unsigned FunctionSummary::immutableRefCount() const {
   // Here we take advantage of having all readonly references
@@ -399,6 +409,10 @@
         if (Flags.Live && hasReadOnlyFlag(SummaryIt.second))
           A.addComment("immutable");
       }
+      if (Flags.DSOLocal)
+        A.addComment("dsoLocal");
+      if (Flags.CanAutoHide)
+        A.addComment("canAutoHide");
 
       auto VI = getValueInfo(SummaryIt.first);
       A.add("label", getNodeLabel(VI, SummaryIt.second));
Index: lib/LTO/LTO.cpp
===================================================================
--- lib/LTO/LTO.cpp
+++ lib/LTO/LTO.cpp
@@ -187,6 +187,7 @@
   auto AddUsedThings = [&](GlobalValueSummary *GS) {
     if (!GS) return;
     AddUnsigned(GS->isLive());
+    AddUnsigned(GS->canAutoHide());
     for (const ValueInfo &VI : GS->refs()) {
       AddUnsigned(VI.isDSOLocal());
       AddUsedCfiGlobal(VI.getGUID());
@@ -295,13 +296,13 @@
 }
 
 static void thinLTOResolvePrevailingGUID(
-    GlobalValueSummaryList &GVSummaryList, GlobalValue::GUID GUID,
-    DenseSet<GlobalValueSummary *> &GlobalInvolvedWithAlias,
+    ValueInfo VI, DenseSet<GlobalValueSummary *> &GlobalInvolvedWithAlias,
     function_ref<bool(GlobalValue::GUID, const GlobalValueSummary *)>
         isPrevailing,
     function_ref<void(StringRef, GlobalValue::GUID, GlobalValue::LinkageTypes)>
-        recordNewLinkage) {
-  for (auto &S : GVSummaryList) {
+        recordNewLinkage,
+    const DenseSet<GlobalValue::GUID> &GUIDPreservedSymbols) {
+  for (auto &S : VI.getSummaryList()) {
     GlobalValue::LinkageTypes OriginalLinkage = S->linkage();
     // Ignore local and appending linkage values since the linker
     // doesn't resolve them.
@@ -316,17 +317,29 @@
     // ensure a copy is kept to satisfy the exported reference.
     // FIXME: We may want to split the compile time and correctness
     // aspects into separate routines.
-    if (isPrevailing(GUID, S.get())) {
-      if (GlobalValue::isLinkOnceLinkage(OriginalLinkage))
+    if (isPrevailing(VI.getGUID(), S.get())) {
+      if (GlobalValue::isLinkOnceLinkage(OriginalLinkage)) {
         S->setLinkage(GlobalValue::getWeakLinkage(
             GlobalValue::isLinkOnceODRLinkage(OriginalLinkage)));
+        // The kept copy is eligible for auto-hiding (hidden visibility) if all
+        // copies were (i.e. they were all linkonce_odr global unnamed addr).
+        // If any copy is not (e.g. it was originally weak_odr), then the symbol
+        // must remain externally available (e.g. a weak_odr from an explicitly
+        // instantiated template). Additionally, if it is in the
+        // GUIDPreservedSymbols set, that means that it is visibile outside
+        // the summary (e.g. in a native object or a bitcode file without
+        // summary), and in that case we cannot hide it as it isn't possible to
+        // check all copies.
+        S->setCanAutoHide(VI.canAutoHide() &&
+                          !GUIDPreservedSymbols.count(VI.getGUID()));
+      }
     }
     // Alias and aliasee can't be turned into available_externally.
     else if (!isa<AliasSummary>(S.get()) &&
              !GlobalInvolvedWithAlias.count(S.get()))
       S->setLinkage(GlobalValue::AvailableExternallyLinkage);
     if (S->linkage() != OriginalLinkage)
-      recordNewLinkage(S->modulePath(), GUID, S->linkage());
+      recordNewLinkage(S->modulePath(), VI.getGUID(), S->linkage());
   }
 }
 
@@ -341,7 +354,8 @@
     function_ref<bool(GlobalValue::GUID, const GlobalValueSummary *)>
         isPrevailing,
     function_ref<void(StringRef, GlobalValue::GUID, GlobalValue::LinkageTypes)>
-        recordNewLinkage) {
+        recordNewLinkage,
+    const DenseSet<GlobalValue::GUID> &GUIDPreservedSymbols) {
   // We won't optimize the globals that are referenced by an alias for now
   // Ideally we should turn the alias into a global and duplicate the definition
   // when needed.
@@ -352,9 +366,9 @@
         GlobalInvolvedWithAlias.insert(&AS->getAliasee());
 
   for (auto &I : Index)
-    thinLTOResolvePrevailingGUID(I.second.SummaryList, I.first,
-                                 GlobalInvolvedWithAlias, isPrevailing,
-                                 recordNewLinkage);
+    thinLTOResolvePrevailingGUID(Index.getValueInfo(I), GlobalInvolvedWithAlias,
+                                 isPrevailing, recordNewLinkage,
+                                 GUIDPreservedSymbols);
 }
 
 static void thinLTOInternalizeAndPromoteGUID(
@@ -904,7 +918,7 @@
 
   Error Result = runRegularLTO(AddStream);
   if (!Result)
-    Result = runThinLTO(AddStream, Cache);
+    Result = runThinLTO(AddStream, Cache, GUIDPreservedSymbols);
 
   if (StatsFile)
     PrintStatisticsJSON(StatsFile->os());
@@ -1207,7 +1221,8 @@
   };
 }
 
-Error LTO::runThinLTO(AddStreamFn AddStream, NativeObjectCache Cache) {
+Error LTO::runThinLTO(AddStreamFn AddStream, NativeObjectCache Cache,
+                      const DenseSet<GlobalValue::GUID> &GUIDPreservedSymbols) {
   if (ThinLTO.ModuleMap.empty())
     return Error::success();
 
@@ -1289,7 +1304,7 @@
     ResolvedODR[ModuleIdentifier][GUID] = NewLinkage;
   };
   thinLTOResolvePrevailingInIndex(ThinLTO.CombinedIndex, isPrevailing,
-                                  recordNewLinkage);
+                                  recordNewLinkage, GUIDPreservedSymbols);
 
   std::unique_ptr<ThinBackendProc> BackendProc =
       ThinLTO.Backend(Conf, ThinLTO.CombinedIndex, ModuleToDefinedGVSummaries,
Index: lib/LTO/ThinLTOCodeGenerator.cpp
===================================================================
--- lib/LTO/ThinLTOCodeGenerator.cpp
+++ lib/LTO/ThinLTOCodeGenerator.cpp
@@ -447,7 +447,8 @@
 static void resolvePrevailingInIndex(
     ModuleSummaryIndex &Index,
     StringMap<std::map<GlobalValue::GUID, GlobalValue::LinkageTypes>>
-        &ResolvedODR) {
+        &ResolvedODR,
+    const DenseSet<GlobalValue::GUID> &GUIDPreservedSymbols) {
 
   DenseMap<GlobalValue::GUID, const GlobalValueSummary *> PrevailingCopy;
   computePrevailingCopies(Index, PrevailingCopy);
@@ -466,7 +467,8 @@
     ResolvedODR[ModuleIdentifier][GUID] = NewLinkage;
   };
 
-  thinLTOResolvePrevailingInIndex(Index, isPrevailing, recordNewLinkage);
+  thinLTOResolvePrevailingInIndex(Index, isPrevailing, recordNewLinkage,
+                                  GUIDPreservedSymbols);
 }
 
 // Initialize the TargetMachine builder for a given Triple
@@ -617,7 +619,7 @@
 
   // Resolve prevailing symbols
   StringMap<std::map<GlobalValue::GUID, GlobalValue::LinkageTypes>> ResolvedODR;
-  resolvePrevailingInIndex(Index, ResolvedODR);
+  resolvePrevailingInIndex(Index, ResolvedODR, GUIDPreservedSymbols);
 
   thinLTOResolvePrevailingInModule(
       TheModule, ModuleToDefinedGVSummaries[ModuleIdentifier]);
@@ -902,7 +904,7 @@
 
   // Resolve prevailing symbols, this has to be computed early because it
   // impacts the caching.
-  resolvePrevailingInIndex(*Index, ResolvedODR);
+  resolvePrevailingInIndex(*Index, ResolvedODR, GUIDPreservedSymbols);
 
   // Use global summary-based analysis to identify symbols that can be
   // internalized (because they aren't exported or preserved as per callback).
Index: lib/Transforms/IPO/FunctionImport.cpp
===================================================================
--- lib/Transforms/IPO/FunctionImport.cpp
+++ lib/Transforms/IPO/FunctionImport.cpp
@@ -976,12 +976,15 @@
         // changed to enable this for aliases.
         llvm_unreachable("Expected GV to be converted");
     } else {
-      // If the original symbols has global unnamed addr and linkonce_odr linkage,
-      // it should be an auto hide symbol. Add hidden visibility to the symbol to
-      // preserve the property.
-      if (GV.hasLinkOnceODRLinkage() && GV.hasGlobalUnnamedAddr() &&
-          NewLinkage == GlobalValue::WeakODRLinkage)
+      // If all copies of the original symbol had global unnamed addr and
+      // linkonce_odr linkage, it should be an auto hide symbol. In that case
+      // the thin link would have marked it as CanAutoHide. Add hidden visibility
+      // to the symbol to preserve the property.
+      if (NewLinkage == GlobalValue::WeakODRLinkage &&
+          GS->second->canAutoHide()) {
+        assert(GV.hasLinkOnceODRLinkage() && GV.hasGlobalUnnamedAddr());
         GV.setVisibility(GlobalValue::HiddenVisibility);
+      }
 
       LLVM_DEBUG(dbgs() << "ODR fixing up linkage for `" << GV.getName()
                         << "` from " << GV.getLinkage() << " to " << NewLinkage
Index: test/Assembler/thinlto-summary.ll
===================================================================
--- test/Assembler/thinlto-summary.ll
+++ test/Assembler/thinlto-summary.ll
@@ -22,7 +22,7 @@
 ^6 = gv: (guid: 5, summaries: (function: (module: ^0, flags: (linkage: available_externally, notEligibleToImport: 0, live: 0, dsoLocal: 0), insts: 1)))
 ^7 = gv: (guid: 6, summaries: (function: (module: ^0, flags: (linkage: linkonce, notEligibleToImport: 0, live: 0, dsoLocal: 0), insts: 1)))
 ^8 = gv: (guid: 7, summaries: (function: (module: ^0, flags: (linkage: linkonce_odr, notEligibleToImport: 0, live: 0, dsoLocal: 0), insts: 1)))
-^9 = gv: (guid: 8, summaries: (function: (module: ^0, flags: (linkage: weak_odr, notEligibleToImport: 0, live: 0, dsoLocal: 0), insts: 1)))
+^9 = gv: (guid: 8, summaries: (function: (module: ^0, flags: (linkage: weak_odr, notEligibleToImport: 0, live: 0, dsoLocal: 0, canAutoHide: 1), insts: 1)))
 ^10 = gv: (guid: 9, summaries: (function: (module: ^0, flags: (linkage: weak, notEligibleToImport: 0, live: 0, dsoLocal: 0), insts: 1)))
 ^11 = gv: (guid: 10, summaries: (variable: (module: ^0, flags: (linkage: common, notEligibleToImport: 0, live: 0, dsoLocal: 0), varFlags: (readonly: 0))))
 ; Test appending globel variable with reference (tests backward reference on
@@ -67,28 +67,28 @@
 ; Make sure we get back from llvm-dis essentially what we put in via llvm-as.
 ; CHECK: ^0 = module: (path: "thinlto-summary1.o", hash: (1369602428, 2747878711, 259090915, 2507395659, 1141468049))
 ; CHECK: ^1 = module: (path: "thinlto-summary2.o", hash: (2998369023, 4283347029, 1195487472, 2757298015, 1852134156))
-; CHECK: ^2 = gv: (guid: 1, summaries: (function: (module: ^0, flags: (linkage: external, notEligibleToImport: 0, live: 0, dsoLocal: 0), insts: 10, calls: ((callee: ^15, hotness: hot), (callee: ^17, hotness: cold), (callee: ^16, hotness: none)), refs: (^14, readonly ^13))))
-; CHECK: ^3 = gv: (guid: 2, summaries: (function: (module: ^1, flags: (linkage: external, notEligibleToImport: 0, live: 0, dsoLocal: 0), insts: 10, calls: ((callee: ^15)))))
-; CHECK: ^4 = gv: (guid: 3, summaries: (function: (module: ^0, flags: (linkage: internal, notEligibleToImport: 0, live: 0, dsoLocal: 1), insts: 1)))
-; CHECK: ^5 = gv: (guid: 4, summaries: (alias: (module: ^0, flags: (linkage: private, notEligibleToImport: 0, live: 0, dsoLocal: 1), aliasee: ^14)))
-; CHECK: ^6 = gv: (guid: 5, summaries: (function: (module: ^0, flags: (linkage: available_externally, notEligibleToImport: 0, live: 0, dsoLocal: 0), insts: 1)))
-; CHECK: ^7 = gv: (guid: 6, summaries: (function: (module: ^0, flags: (linkage: linkonce, notEligibleToImport: 0, live: 0, dsoLocal: 0), insts: 1)))
-; CHECK: ^8 = gv: (guid: 7, summaries: (function: (module: ^0, flags: (linkage: linkonce_odr, notEligibleToImport: 0, live: 0, dsoLocal: 0), insts: 1)))
-; CHECK: ^9 = gv: (guid: 8, summaries: (function: (module: ^0, flags: (linkage: weak_odr, notEligibleToImport: 0, live: 0, dsoLocal: 0), insts: 1)))
-; CHECK: ^10 = gv: (guid: 9, summaries: (function: (module: ^0, flags: (linkage: weak, notEligibleToImport: 0, live: 0, dsoLocal: 0), insts: 1)))
-; CHECK: ^11 = gv: (guid: 10, summaries: (variable: (module: ^0, flags: (linkage: common, notEligibleToImport: 0, live: 0, dsoLocal: 0), varFlags: (readonly: 0))))
-; CHECK: ^12 = gv: (guid: 11, summaries: (variable: (module: ^0, flags: (linkage: appending, notEligibleToImport: 0, live: 0, dsoLocal: 0), varFlags: (readonly: 0), refs: (^4))))
-; CHECK: ^13 = gv: (guid: 12, summaries: (variable: (module: ^0, flags: (linkage: external, notEligibleToImport: 0, live: 0, dsoLocal: 0), varFlags: (readonly: 1))))
-; CHECK: ^14 = gv: (guid: 13, summaries: (variable: (module: ^0, flags: (linkage: external, notEligibleToImport: 0, live: 0, dsoLocal: 1), varFlags: (readonly: 0))))
-; CHECK: ^15 = gv: (guid: 14, summaries: (function: (module: ^1, flags: (linkage: external, notEligibleToImport: 1, live: 1, dsoLocal: 0), insts: 1)))
-; CHECK: ^16 = gv: (guid: 15, summaries: (function: (module: ^1, flags: (linkage: external, notEligibleToImport: 0, live: 0, dsoLocal: 0), insts: 1, funcFlags: (readNone: 1, readOnly: 0, noRecurse: 1, returnDoesNotAlias: 0, noInline: 0))))
-; CHECK: ^17 = gv: (guid: 16, summaries: (function: (module: ^1, flags: (linkage: external, notEligibleToImport: 0, live: 0, dsoLocal: 0), insts: 1, funcFlags: (readNone: 0, readOnly: 1, noRecurse: 0, returnDoesNotAlias: 1, noInline: 0), calls: ((callee: ^15)))))
-; CHECK: ^18 = gv: (guid: 17, summaries: (alias: (module: ^0, flags: (linkage: external, notEligibleToImport: 0, live: 0, dsoLocal: 1), aliasee: ^14)))
-; CHECK: ^19 = gv: (guid: 18, summaries: (function: (module: ^0, flags: (linkage: external, notEligibleToImport: 0, live: 0, dsoLocal: 0), insts: 4, typeIdInfo: (typeTests: (^24, ^26)))))
-; CHECK: ^20 = gv: (guid: 19, summaries: (function: (module: ^0, flags: (linkage: external, notEligibleToImport: 0, live: 0, dsoLocal: 0), insts: 8, typeIdInfo: (typeTestAssumeVCalls: (vFuncId: (^27, offset: 16))))))
-; CHECK: ^21 = gv: (guid: 20, summaries: (function: (module: ^0, flags: (linkage: external, notEligibleToImport: 0, live: 0, dsoLocal: 0), insts: 5, typeIdInfo: (typeCheckedLoadVCalls: (vFuncId: (^25, offset: 16))))))
-; CHECK: ^22 = gv: (guid: 21, summaries: (function: (module: ^0, flags: (linkage: external, notEligibleToImport: 0, live: 0, dsoLocal: 0), insts: 15, typeIdInfo: (typeTestAssumeConstVCalls: ((vFuncId: (^27, offset: 16), args: (42)), (vFuncId: (^27, offset: 24)))))))
-; CHECK: ^23 = gv: (guid: 22, summaries: (function: (module: ^0, flags: (linkage: external, notEligibleToImport: 0, live: 0, dsoLocal: 0), insts: 5, typeIdInfo: (typeCheckedLoadConstVCalls: ((vFuncId: (^28, offset: 16), args: (42)))))))
+; CHECK: ^2 = gv: (guid: 1, summaries: (function: (module: ^0, flags: (linkage: external, notEligibleToImport: 0, live: 0, dsoLocal: 0, canAutoHide: 0), insts: 10, calls: ((callee: ^15, hotness: hot), (callee: ^17, hotness: cold), (callee: ^16, hotness: none)), refs: (^14, readonly ^13))))
+; CHECK: ^3 = gv: (guid: 2, summaries: (function: (module: ^1, flags: (linkage: external, notEligibleToImport: 0, live: 0, dsoLocal: 0, canAutoHide: 0), insts: 10, calls: ((callee: ^15)))))
+; CHECK: ^4 = gv: (guid: 3, summaries: (function: (module: ^0, flags: (linkage: internal, notEligibleToImport: 0, live: 0, dsoLocal: 1, canAutoHide: 0), insts: 1)))
+; CHECK: ^5 = gv: (guid: 4, summaries: (alias: (module: ^0, flags: (linkage: private, notEligibleToImport: 0, live: 0, dsoLocal: 1, canAutoHide: 0), aliasee: ^14)))
+; CHECK: ^6 = gv: (guid: 5, summaries: (function: (module: ^0, flags: (linkage: available_externally, notEligibleToImport: 0, live: 0, dsoLocal: 0, canAutoHide: 0), insts: 1)))
+; CHECK: ^7 = gv: (guid: 6, summaries: (function: (module: ^0, flags: (linkage: linkonce, notEligibleToImport: 0, live: 0, dsoLocal: 0, canAutoHide: 0), insts: 1)))
+; CHECK: ^8 = gv: (guid: 7, summaries: (function: (module: ^0, flags: (linkage: linkonce_odr, notEligibleToImport: 0, live: 0, dsoLocal: 0, canAutoHide: 0), insts: 1)))
+; CHECK: ^9 = gv: (guid: 8, summaries: (function: (module: ^0, flags: (linkage: weak_odr, notEligibleToImport: 0, live: 0, dsoLocal: 0, canAutoHide: 1), insts: 1)))
+; CHECK: ^10 = gv: (guid: 9, summaries: (function: (module: ^0, flags: (linkage: weak, notEligibleToImport: 0, live: 0, dsoLocal: 0, canAutoHide: 0), insts: 1)))
+; CHECK: ^11 = gv: (guid: 10, summaries: (variable: (module: ^0, flags: (linkage: common, notEligibleToImport: 0, live: 0, dsoLocal: 0, canAutoHide: 0), varFlags: (readonly: 0))))
+; CHECK: ^12 = gv: (guid: 11, summaries: (variable: (module: ^0, flags: (linkage: appending, notEligibleToImport: 0, live: 0, dsoLocal: 0, canAutoHide: 0), varFlags: (readonly: 0), refs: (^4))))
+; CHECK: ^13 = gv: (guid: 12, summaries: (variable: (module: ^0, flags: (linkage: external, notEligibleToImport: 0, live: 0, dsoLocal: 0, canAutoHide: 0), varFlags: (readonly: 1))))
+; CHECK: ^14 = gv: (guid: 13, summaries: (variable: (module: ^0, flags: (linkage: external, notEligibleToImport: 0, live: 0, dsoLocal: 1, canAutoHide: 0), varFlags: (readonly: 0))))
+; CHECK: ^15 = gv: (guid: 14, summaries: (function: (module: ^1, flags: (linkage: external, notEligibleToImport: 1, live: 1, dsoLocal: 0, canAutoHide: 0), insts: 1)))
+; CHECK: ^16 = gv: (guid: 15, summaries: (function: (module: ^1, flags: (linkage: external, notEligibleToImport: 0, live: 0, dsoLocal: 0, canAutoHide: 0), insts: 1, funcFlags: (readNone: 1, readOnly: 0, noRecurse: 1, returnDoesNotAlias: 0, noInline: 0))))
+; CHECK: ^17 = gv: (guid: 16, summaries: (function: (module: ^1, flags: (linkage: external, notEligibleToImport: 0, live: 0, dsoLocal: 0, canAutoHide: 0), insts: 1, funcFlags: (readNone: 0, readOnly: 1, noRecurse: 0, returnDoesNotAlias: 1, noInline: 0), calls: ((callee: ^15)))))
+; CHECK: ^18 = gv: (guid: 17, summaries: (alias: (module: ^0, flags: (linkage: external, notEligibleToImport: 0, live: 0, dsoLocal: 1, canAutoHide: 0), aliasee: ^14)))
+; CHECK: ^19 = gv: (guid: 18, summaries: (function: (module: ^0, flags: (linkage: external, notEligibleToImport: 0, live: 0, dsoLocal: 0, canAutoHide: 0), insts: 4, typeIdInfo: (typeTests: (^24, ^26)))))
+; CHECK: ^20 = gv: (guid: 19, summaries: (function: (module: ^0, flags: (linkage: external, notEligibleToImport: 0, live: 0, dsoLocal: 0, canAutoHide: 0), insts: 8, typeIdInfo: (typeTestAssumeVCalls: (vFuncId: (^27, offset: 16))))))
+; CHECK: ^21 = gv: (guid: 20, summaries: (function: (module: ^0, flags: (linkage: external, notEligibleToImport: 0, live: 0, dsoLocal: 0, canAutoHide: 0), insts: 5, typeIdInfo: (typeCheckedLoadVCalls: (vFuncId: (^25, offset: 16))))))
+; CHECK: ^22 = gv: (guid: 21, summaries: (function: (module: ^0, flags: (linkage: external, notEligibleToImport: 0, live: 0, dsoLocal: 0, canAutoHide: 0), insts: 15, typeIdInfo: (typeTestAssumeConstVCalls: ((vFuncId: (^27, offset: 16), args: (42)), (vFuncId: (^27, offset: 24)))))))
+; CHECK: ^23 = gv: (guid: 22, summaries: (function: (module: ^0, flags: (linkage: external, notEligibleToImport: 0, live: 0, dsoLocal: 0, canAutoHide: 0), insts: 5, typeIdInfo: (typeCheckedLoadConstVCalls: ((vFuncId: (^28, offset: 16), args: (42)))))))
 ; CHECK: ^24 = typeid: (name: "_ZTS1C", summary: (typeTestRes: (kind: single, sizeM1BitWidth: 0))) ; guid = 1884921850105019584
 ; CHECK: ^25 = typeid: (name: "_ZTS1B", summary: (typeTestRes: (kind: inline, sizeM1BitWidth: 0, alignLog2: 1, sizeM1: 2, bitMask: 3, inlineBits: 4))) ; guid = 6203814149063363976
 ; CHECK: ^26 = typeid: (name: "_ZTS1A", summary: (typeTestRes: (kind: allOnes, sizeM1BitWidth: 7), wpdResolutions: ((offset: 0, wpdRes: (kind: branchFunnel)), (offset: 8, wpdRes: (kind: singleImpl, singleImplName: "_ZN1A1nEi")), (offset: 16, wpdRes: (kind: indir, resByArg: (args: (1, 2), byArg: (kind: indir, byte: 2, bit: 3), args: (3), byArg: (kind: uniformRetVal, info: 1), args: (4), byArg: (kind: uniqueRetVal, info: 1), args: (5), byArg: (kind: virtualConstProp))))))) ; guid = 7004155349499253778
Index: test/Bitcode/thinlto-alias.ll
===================================================================
--- test/Bitcode/thinlto-alias.ll
+++ test/Bitcode/thinlto-alias.ll
@@ -53,11 +53,11 @@
 declare void @analias(...)
 
 ; DIS: ^0 = module: (path: "{{.*}}", hash: (0, 0, 0, 0, 0))
-; DIS: ^1 = gv: (name: "analias", summaries: (alias: (module: ^0, flags: (linkage: external, notEligibleToImport: 0, live: 0, dsoLocal: 0), aliasee: ^2))) ; guid = 12695095382722328222
-; DIS: ^2 = gv: (name: "aliasee", summaries: (function: (module: ^0, flags: (linkage: external, notEligibleToImport: 0, live: 0, dsoLocal: 0), insts: 1))) ; guid = 17407585008595848568
+; DIS: ^1 = gv: (name: "analias", summaries: (alias: (module: ^0, flags: (linkage: external, notEligibleToImport: 0, live: 0, dsoLocal: 0, canAutoHide: 0), aliasee: ^2))) ; guid = 12695095382722328222
+; DIS: ^2 = gv: (name: "aliasee", summaries: (function: (module: ^0, flags: (linkage: external, notEligibleToImport: 0, live: 0, dsoLocal: 0, canAutoHide: 0), insts: 1))) ; guid = 17407585008595848568
 
 ; COMBINED-DIS: ^0 = module: (path: "{{.*}}thinlto-alias.ll.tmp.o", hash: (0, 0, 0, 0, 0))
 ; COMBINED-DIS: ^1 = module: (path: "{{.*}}thinlto-alias.ll.tmp2.o", hash: (0, 0, 0, 0, 0))
-; COMBINED-DIS: ^2 = gv: (guid: 12695095382722328222, summaries: (alias: (module: ^1, flags: (linkage: external, notEligibleToImport: 0, live: 0, dsoLocal: 0), aliasee: ^4)))
-; COMBINED-DIS: ^3 = gv: (guid: 15822663052811949562, summaries: (function: (module: ^0, flags: (linkage: external, notEligibleToImport: 0, live: 0, dsoLocal: 0), insts: 2, calls: ((callee: ^2)))))
-; COMBINED-DIS: ^4 = gv: (guid: 17407585008595848568, summaries: (function: (module: ^1, flags: (linkage: external, notEligibleToImport: 0, live: 0, dsoLocal: 0), insts: 1)))
+; COMBINED-DIS: ^2 = gv: (guid: 12695095382722328222, summaries: (alias: (module: ^1, flags: (linkage: external, notEligibleToImport: 0, live: 0, dsoLocal: 0, canAutoHide: 0), aliasee: ^4)))
+; COMBINED-DIS: ^3 = gv: (guid: 15822663052811949562, summaries: (function: (module: ^0, flags: (linkage: external, notEligibleToImport: 0, live: 0, dsoLocal: 0, canAutoHide: 0), insts: 2, calls: ((callee: ^2)))))
+; COMBINED-DIS: ^4 = gv: (guid: 17407585008595848568, summaries: (function: (module: ^1, flags: (linkage: external, notEligibleToImport: 0, live: 0, dsoLocal: 0, canAutoHide: 0), insts: 1)))
Index: test/Bitcode/thinlto-function-summary-callgraph-profile-summary.ll
===================================================================
--- test/Bitcode/thinlto-function-summary-callgraph-profile-summary.ll
+++ test/Bitcode/thinlto-function-summary-callgraph-profile-summary.ll
@@ -150,16 +150,16 @@
 ; DIS: ^6 = gv: (name: "cold") ; guid = 11668175513417606517
 ; DIS: ^7 = gv: (name: "hot4") ; guid = 13161834114071272798
 ; DIS: ^8 = gv: (name: "none3") ; guid = 16213681105727317812
-; DIS: ^9 = gv: (name: "hot_function", summaries: (function: (module: ^0, flags: (linkage: external, notEligibleToImport: 0, live: 0, dsoLocal: 0), insts: 16, calls: ((callee: ^5, hotness: hot), (callee: ^6, hotness: cold), (callee: ^4, hotness: hot), (callee: ^7, hotness: cold), (callee: ^10, hotness: none), (callee: ^3, hotness: hot), (callee: ^2, hotness: none), (callee: ^8, hotness: none), (callee: ^1, hotness: critical))))) ; guid = 17381606045411660303
+; DIS: ^9 = gv: (name: "hot_function", summaries: (function: (module: ^0, flags: (linkage: external, notEligibleToImport: 0, live: 0, dsoLocal: 0, canAutoHide: 0), insts: 16, calls: ((callee: ^5, hotness: hot), (callee: ^6, hotness: cold), (callee: ^4, hotness: hot), (callee: ^7, hotness: cold), (callee: ^10, hotness: none), (callee: ^3, hotness: hot), (callee: ^2, hotness: none), (callee: ^8, hotness: none), (callee: ^1, hotness: critical))))) ; guid = 17381606045411660303
 ; DIS: ^10 = gv: (name: "none1") ; guid = 17712061229457633252
 
 ; COMBINED-DIS: ^0 = module: (path: "{{.*}}thinlto-function-summary-callgraph-profile-summary.ll.tmp.o", hash: (0, 0, 0, 0, 0))
 ; COMBINED-DIS: ^1 = module: (path: "{{.*}}thinlto-function-summary-callgraph-profile-summary.ll.tmp2.o", hash: (0, 0, 0, 0, 0))
-; COMBINED-DIS: ^2 = gv: (guid: 3741006263754194003, summaries: (function: (module: ^1, flags: (linkage: external, notEligibleToImport: 0, live: 0, dsoLocal: 0), insts: 1)))
-; COMBINED-DIS: ^3 = gv: (guid: 5026609803865204483, summaries: (function: (module: ^1, flags: (linkage: external, notEligibleToImport: 0, live: 0, dsoLocal: 0), insts: 1)))
-; COMBINED-DIS: ^4 = gv: (guid: 8117347573235780485, summaries: (function: (module: ^1, flags: (linkage: external, notEligibleToImport: 0, live: 0, dsoLocal: 0), insts: 1)))
-; COMBINED-DIS: ^5 = gv: (guid: 9453975128311291976, summaries: (function: (module: ^1, flags: (linkage: external, notEligibleToImport: 0, live: 0, dsoLocal: 0), insts: 1)))
-; COMBINED-DIS: ^6 = gv: (guid: 11668175513417606517, summaries: (function: (module: ^1, flags: (linkage: external, notEligibleToImport: 0, live: 0, dsoLocal: 0), insts: 1)))
-; COMBINED-DIS: ^7 = gv: (guid: 16213681105727317812, summaries: (function: (module: ^1, flags: (linkage: external, notEligibleToImport: 0, live: 0, dsoLocal: 0), insts: 1)))
-; COMBINED-DIS: ^8 = gv: (guid: 17381606045411660303, summaries: (function: (module: ^0, flags: (linkage: external, notEligibleToImport: 0, live: 0, dsoLocal: 0), insts: 16, calls: ((callee: ^5, hotness: hot), (callee: ^6, hotness: cold), (callee: ^4, hotness: hot), (callee: ^9, hotness: none), (callee: ^3, hotness: hot), (callee: ^2, hotness: none), (callee: ^7, hotness: none)))))
-; COMBINED-DIS: ^9 = gv: (guid: 17712061229457633252, summaries: (function: (module: ^1, flags: (linkage: external, notEligibleToImport: 0, live: 0, dsoLocal: 0), insts: 1)))
+; COMBINED-DIS: ^2 = gv: (guid: 3741006263754194003, summaries: (function: (module: ^1, flags: (linkage: external, notEligibleToImport: 0, live: 0, dsoLocal: 0, canAutoHide: 0), insts: 1)))
+; COMBINED-DIS: ^3 = gv: (guid: 5026609803865204483, summaries: (function: (module: ^1, flags: (linkage: external, notEligibleToImport: 0, live: 0, dsoLocal: 0, canAutoHide: 0), insts: 1)))
+; COMBINED-DIS: ^4 = gv: (guid: 8117347573235780485, summaries: (function: (module: ^1, flags: (linkage: external, notEligibleToImport: 0, live: 0, dsoLocal: 0, canAutoHide: 0), insts: 1)))
+; COMBINED-DIS: ^5 = gv: (guid: 9453975128311291976, summaries: (function: (module: ^1, flags: (linkage: external, notEligibleToImport: 0, live: 0, dsoLocal: 0, canAutoHide: 0), insts: 1)))
+; COMBINED-DIS: ^6 = gv: (guid: 11668175513417606517, summaries: (function: (module: ^1, flags: (linkage: external, notEligibleToImport: 0, live: 0, dsoLocal: 0, canAutoHide: 0), insts: 1)))
+; COMBINED-DIS: ^7 = gv: (guid: 16213681105727317812, summaries: (function: (module: ^1, flags: (linkage: external, notEligibleToImport: 0, live: 0, dsoLocal: 0, canAutoHide: 0), insts: 1)))
+; COMBINED-DIS: ^8 = gv: (guid: 17381606045411660303, summaries: (function: (module: ^0, flags: (linkage: external, notEligibleToImport: 0, live: 0, dsoLocal: 0, canAutoHide: 0), insts: 16, calls: ((callee: ^5, hotness: hot), (callee: ^6, hotness: cold), (callee: ^4, hotness: hot), (callee: ^9, hotness: none), (callee: ^3, hotness: hot), (callee: ^2, hotness: none), (callee: ^7, hotness: none)))))
+; COMBINED-DIS: ^9 = gv: (guid: 17712061229457633252, summaries: (function: (module: ^1, flags: (linkage: external, notEligibleToImport: 0, live: 0, dsoLocal: 0, canAutoHide: 0), insts: 1)))
Index: test/Bitcode/thinlto-function-summary-callgraph-relbf.ll
===================================================================
--- test/Bitcode/thinlto-function-summary-callgraph-relbf.ll
+++ test/Bitcode/thinlto-function-summary-callgraph-relbf.ll
@@ -39,5 +39,5 @@
 
 ; DIS: ^0 = module: (path: "{{.*}}", hash: (0, 0, 0, 0, 0))
 ; DIS: ^1 = gv: (name: "func") ; guid = 7289175272376759421
-; DIS: ^2 = gv: (name: "main", summaries: (function: (module: ^0, flags: (linkage: external, notEligibleToImport: 0, live: 0, dsoLocal: 0), insts: 3, calls: ((callee: ^1, relbf: 256)), refs: (readonly ^3)))) ; guid = 15822663052811949562
+; DIS: ^2 = gv: (name: "main", summaries: (function: (module: ^0, flags: (linkage: external, notEligibleToImport: 0, live: 0, dsoLocal: 0, canAutoHide: 0), insts: 3, calls: ((callee: ^1, relbf: 256)), refs: (readonly ^3)))) ; guid = 15822663052811949562
 ; DIS: ^3 = gv: (name: "undefinedglob") ; guid = 18036901804029949403
Index: test/Bitcode/thinlto-function-summary-refgraph.ll
===================================================================
--- test/Bitcode/thinlto-function-summary-refgraph.ll
+++ test/Bitcode/thinlto-function-summary-refgraph.ll
@@ -148,17 +148,17 @@
 ; order, which depends on GUID, and the private function Y GUID will depend
 ; on the path to the test.
 ; DIS: ^0 = module: (path: "{{.*}}", hash: (0, 0, 0, 0, 0))
-; DIS-DAG: = gv: (name: "Z", summaries: (function: (module: ^0, flags: (linkage: linkonce_odr, notEligibleToImport: 0, live: 0, dsoLocal: 0), insts: 2, calls: ((callee: ^{{.*}}))))) ; guid = 104084381700047393
-; DIS-DAG: = gv: (name: "X", summaries: (function: (module: ^0, flags: (linkage: available_externally, notEligibleToImport: 0, live: 0, dsoLocal: 0), insts: 2, calls: ((callee: ^{{.*}})), refs: (^{{.*}})))) ; guid = 1881667236089500162
-; DIS-DAG: = gv: (name: "W", summaries: (function: (module: ^0, flags: (linkage: weak_odr, notEligibleToImport: 0, live: 0, dsoLocal: 0), insts: 2, calls: ((callee: ^{{.*}})), refs: (^{{.*}})))) ; guid = 5790125716599269729
+; DIS-DAG: = gv: (name: "Z", summaries: (function: (module: ^0, flags: (linkage: linkonce_odr, notEligibleToImport: 0, live: 0, dsoLocal: 0, canAutoHide: 0), insts: 2, calls: ((callee: ^{{.*}}))))) ; guid = 104084381700047393
+; DIS-DAG: = gv: (name: "X", summaries: (function: (module: ^0, flags: (linkage: available_externally, notEligibleToImport: 0, live: 0, dsoLocal: 0, canAutoHide: 0), insts: 2, calls: ((callee: ^{{.*}})), refs: (^{{.*}})))) ; guid = 1881667236089500162
+; DIS-DAG: = gv: (name: "W", summaries: (function: (module: ^0, flags: (linkage: weak_odr, notEligibleToImport: 0, live: 0, dsoLocal: 0, canAutoHide: 0), insts: 2, calls: ((callee: ^{{.*}})), refs: (^{{.*}})))) ; guid = 5790125716599269729
 ; DIS-DAG: = gv: (name: "foo") ; guid = 6699318081062747564
 ; DIS-DAG: = gv: (name: "func") ; guid = 7289175272376759421
 ; DIS-DAG: = gv: (name: "func3") ; guid = 11517462787082255043
-; DIS-DAG: = gv: (name: "globalvar", summaries: (variable: (module: ^0, flags: (linkage: external, notEligibleToImport: 0, live: 0, dsoLocal: 0), varFlags: (readonly: 1)))) ; guid = 12887606300320728018
+; DIS-DAG: = gv: (name: "globalvar", summaries: (variable: (module: ^0, flags: (linkage: external, notEligibleToImport: 0, live: 0, dsoLocal: 0, canAutoHide: 0), varFlags: (readonly: 1)))) ; guid = 12887606300320728018
 ; DIS-DAG: = gv: (name: "func2") ; guid = 14069196320850861797
 ; DIS-DAG: = gv: (name: "llvm.ctpop.i8") ; guid = 15254915475081819833
-; DIS-DAG: = gv: (name: "main", summaries: (function: (module: ^0, flags: (linkage: external, notEligibleToImport: 0, live: 0, dsoLocal: 0), insts: 9, calls: ((callee: ^{{.*}})), refs: (^{{.*}})))) ; guid = 15822663052811949562
-; DIS-DAG: = gv: (name: "bar", summaries: (variable: (module: ^0, flags: (linkage: external, notEligibleToImport: 0, live: 0, dsoLocal: 0), varFlags: (readonly: 1),  refs: (^{{.*}})))) ; guid = 16434608426314478903
+; DIS-DAG: = gv: (name: "main", summaries: (function: (module: ^0, flags: (linkage: external, notEligibleToImport: 0, live: 0, dsoLocal: 0, canAutoHide: 0), insts: 9, calls: ((callee: ^{{.*}})), refs: (^{{.*}})))) ; guid = 15822663052811949562
+; DIS-DAG: = gv: (name: "bar", summaries: (variable: (module: ^0, flags: (linkage: external, notEligibleToImport: 0, live: 0, dsoLocal: 0, canAutoHide: 0), varFlags: (readonly: 1),  refs: (^{{.*}})))) ; guid = 16434608426314478903
 ; Don't try to match the exact GUID. Since it is private, the file path
 ; will get hashed, and that will be test dependent.
-; DIS-DAG: = gv: (name: "Y", summaries: (function: (module: ^0, flags: (linkage: private, notEligibleToImport: 0, live: 0, dsoLocal: 1), insts: 14, calls: ((callee: ^{{.*}}))))) ; guid =
+; DIS-DAG: = gv: (name: "Y", summaries: (function: (module: ^0, flags: (linkage: private, notEligibleToImport: 0, live: 0, dsoLocal: 1, canAutoHide: 0), insts: 14, calls: ((callee: ^{{.*}}))))) ; guid =
Index: test/Bitcode/thinlto-type-tests.ll
===================================================================
--- test/Bitcode/thinlto-type-tests.ll
+++ test/Bitcode/thinlto-type-tests.ll
@@ -37,11 +37,11 @@
 
 ; DIS: ^0 = module: (path: "{{.*}}", hash: (0, 0, 0, 0, 0))
 ; DIS: ^1 = gv: (name: "llvm.type.test") ; guid = 608142985856744218
-; DIS: ^2 = gv: (name: "h", summaries: (function: (module: ^0, flags: (linkage: external, notEligibleToImport: 0, live: 0, dsoLocal: 0), insts: 2, typeIdInfo: (typeTests: (16434608426314478903))))) ; guid = 8124147457056772133
-; DIS: ^3 = gv: (name: "g", summaries: (function: (module: ^0, flags: (linkage: external, notEligibleToImport: 0, live: 0, dsoLocal: 0), insts: 4, typeIdInfo: (typeTests: (6699318081062747564, 16434608426314478903))))) ; guid = 13146401226427987378
-; DIS: ^4 = gv: (name: "f", summaries: (function: (module: ^0, flags: (linkage: external, notEligibleToImport: 0, live: 0, dsoLocal: 0), insts: 2, typeIdInfo: (typeTests: (6699318081062747564))))) ; guid = 14740650423002898831
+; DIS: ^2 = gv: (name: "h", summaries: (function: (module: ^0, flags: (linkage: external, notEligibleToImport: 0, live: 0, dsoLocal: 0, canAutoHide: 0), insts: 2, typeIdInfo: (typeTests: (16434608426314478903))))) ; guid = 8124147457056772133
+; DIS: ^3 = gv: (name: "g", summaries: (function: (module: ^0, flags: (linkage: external, notEligibleToImport: 0, live: 0, dsoLocal: 0, canAutoHide: 0), insts: 4, typeIdInfo: (typeTests: (6699318081062747564, 16434608426314478903))))) ; guid = 13146401226427987378
+; DIS: ^4 = gv: (name: "f", summaries: (function: (module: ^0, flags: (linkage: external, notEligibleToImport: 0, live: 0, dsoLocal: 0, canAutoHide: 0), insts: 2, typeIdInfo: (typeTests: (6699318081062747564))))) ; guid = 14740650423002898831
 
 ; COMBINED-DIS: ^0 = module: (path: "{{.*}}thinlto-type-tests.ll.tmp.o", hash: (0, 0, 0, 0, 0))
-; COMBINED-DIS: ^1 = gv: (guid: 8124147457056772133, summaries: (function: (module: ^0, flags: (linkage: external, notEligibleToImport: 0, live: 0, dsoLocal: 0), insts: 2, typeIdInfo: (typeTests: (16434608426314478903)))))
-; COMBINED-DIS: ^2 = gv: (guid: 13146401226427987378, summaries: (function: (module: ^0, flags: (linkage: external, notEligibleToImport: 0, live: 0, dsoLocal: 0), insts: 4, typeIdInfo: (typeTests: (6699318081062747564, 16434608426314478903)))))
-; COMBINED-DIS: ^3 = gv: (guid: 14740650423002898831, summaries: (function: (module: ^0, flags: (linkage: external, notEligibleToImport: 0, live: 0, dsoLocal: 0), insts: 2, typeIdInfo: (typeTests: (6699318081062747564)))))
+; COMBINED-DIS: ^1 = gv: (guid: 8124147457056772133, summaries: (function: (module: ^0, flags: (linkage: external, notEligibleToImport: 0, live: 0, dsoLocal: 0, canAutoHide: 0), insts: 2, typeIdInfo: (typeTests: (16434608426314478903)))))
+; COMBINED-DIS: ^2 = gv: (guid: 13146401226427987378, summaries: (function: (module: ^0, flags: (linkage: external, notEligibleToImport: 0, live: 0, dsoLocal: 0, canAutoHide: 0), insts: 4, typeIdInfo: (typeTests: (6699318081062747564, 16434608426314478903)))))
+; COMBINED-DIS: ^3 = gv: (guid: 14740650423002898831, summaries: (function: (module: ^0, flags: (linkage: external, notEligibleToImport: 0, live: 0, dsoLocal: 0, canAutoHide: 0), insts: 2, typeIdInfo: (typeTests: (6699318081062747564)))))
Index: test/Bitcode/thinlto-type-vcalls.ll
===================================================================
--- test/Bitcode/thinlto-type-vcalls.ll
+++ test/Bitcode/thinlto-type-vcalls.ll
@@ -112,19 +112,19 @@
 
 ; DIS: ^0 = module: (path: "{{.*}}", hash: (0, 0, 0, 0, 0))
 ; DIS: ^1 = gv: (name: "llvm.type.test") ; guid = 608142985856744218
-; DIS: ^2 = gv: (name: "f1", summaries: (function: (module: ^0, flags: (linkage: external, notEligibleToImport: 0, live: 0, dsoLocal: 0), insts: 8, typeIdInfo: (typeTestAssumeVCalls: (vFuncId: (guid: 6699318081062747564, offset: 16)))))) ; guid = 2072045998141807037
-; DIS: ^3 = gv: (name: "f3", summaries: (function: (module: ^0, flags: (linkage: external, notEligibleToImport: 0, live: 0, dsoLocal: 0), insts: 5, typeIdInfo: (typeCheckedLoadVCalls: (vFuncId: (guid: 6699318081062747564, offset: 16)))))) ; guid = 4197650231481825559
+; DIS: ^2 = gv: (name: "f1", summaries: (function: (module: ^0, flags: (linkage: external, notEligibleToImport: 0, live: 0, dsoLocal: 0, canAutoHide: 0), insts: 8, typeIdInfo: (typeTestAssumeVCalls: (vFuncId: (guid: 6699318081062747564, offset: 16)))))) ; guid = 2072045998141807037
+; DIS: ^3 = gv: (name: "f3", summaries: (function: (module: ^0, flags: (linkage: external, notEligibleToImport: 0, live: 0, dsoLocal: 0, canAutoHide: 0), insts: 5, typeIdInfo: (typeCheckedLoadVCalls: (vFuncId: (guid: 6699318081062747564, offset: 16)))))) ; guid = 4197650231481825559
 ; DIS: ^4 = gv: (name: "llvm.type.checked.load") ; guid = 5568222536364573403
 ; DIS: ^5 = gv: (name: "llvm.assume") ; guid = 6385187066495850096
-; DIS: ^6 = gv: (name: "f2", summaries: (function: (module: ^0, flags: (linkage: external, notEligibleToImport: 0, live: 0, dsoLocal: 0), insts: 15, typeIdInfo: (typeTestAssumeVCalls: (vFuncId: (guid: 6699318081062747564, offset: 24), vFuncId: (guid: 16434608426314478903, offset: 32)))))) ; guid = 8471399308421654326
-; DIS: ^7 = gv: (name: "f4", summaries: (function: (module: ^0, flags: (linkage: external, notEligibleToImport: 0, live: 0, dsoLocal: 0), insts: 15, typeIdInfo: (typeTestAssumeConstVCalls: ((vFuncId: (guid: 6699318081062747564, offset: 16), args: (42)), (vFuncId: (guid: 6699318081062747564, offset: 24), args: (43))))))) ; guid = 10064745020953272174
-; DIS: ^8 = gv: (name: "f5", summaries: (function: (module: ^0, flags: (linkage: external, notEligibleToImport: 0, live: 0, dsoLocal: 0), insts: 5, typeIdInfo: (typeCheckedLoadConstVCalls: ((vFuncId: (guid: 6699318081062747564, offset: 16), args: (42))))))) ; guid = 11686717102184386164
-; DIS: ^9 = gv: (name: "f6", summaries: (function: (module: ^0, flags: (linkage: external, notEligibleToImport: 0, live: 0, dsoLocal: 0), insts: 2, typeIdInfo: (typeTests: (7546896869197086323))))) ; guid = 11834966808443348068
+; DIS: ^6 = gv: (name: "f2", summaries: (function: (module: ^0, flags: (linkage: external, notEligibleToImport: 0, live: 0, dsoLocal: 0, canAutoHide: 0), insts: 15, typeIdInfo: (typeTestAssumeVCalls: (vFuncId: (guid: 6699318081062747564, offset: 24), vFuncId: (guid: 16434608426314478903, offset: 32)))))) ; guid = 8471399308421654326
+; DIS: ^7 = gv: (name: "f4", summaries: (function: (module: ^0, flags: (linkage: external, notEligibleToImport: 0, live: 0, dsoLocal: 0, canAutoHide: 0), insts: 15, typeIdInfo: (typeTestAssumeConstVCalls: ((vFuncId: (guid: 6699318081062747564, offset: 16), args: (42)), (vFuncId: (guid: 6699318081062747564, offset: 24), args: (43))))))) ; guid = 10064745020953272174
+; DIS: ^8 = gv: (name: "f5", summaries: (function: (module: ^0, flags: (linkage: external, notEligibleToImport: 0, live: 0, dsoLocal: 0, canAutoHide: 0), insts: 5, typeIdInfo: (typeCheckedLoadConstVCalls: ((vFuncId: (guid: 6699318081062747564, offset: 16), args: (42))))))) ; guid = 11686717102184386164
+; DIS: ^9 = gv: (name: "f6", summaries: (function: (module: ^0, flags: (linkage: external, notEligibleToImport: 0, live: 0, dsoLocal: 0, canAutoHide: 0), insts: 2, typeIdInfo: (typeTests: (7546896869197086323))))) ; guid = 11834966808443348068
 
 ; COMBINED-DIS: ^0 = module: (path: "{{.*}}thinlto-type-vcalls.ll.tmp.o", hash: (0, 0, 0, 0, 0))
-; COMBINED-DIS: ^1 = gv: (guid: 2072045998141807037, summaries: (function: (module: ^0, flags: (linkage: external, notEligibleToImport: 0, live: 0, dsoLocal: 0), insts: 8, typeIdInfo: (typeTestAssumeVCalls: (vFuncId: (guid: 6699318081062747564, offset: 16))))))
-; COMBINED-DIS: ^2 = gv: (guid: 4197650231481825559, summaries: (function: (module: ^0, flags: (linkage: external, notEligibleToImport: 0, live: 0, dsoLocal: 0), insts: 5, typeIdInfo: (typeCheckedLoadVCalls: (vFuncId: (guid: 6699318081062747564, offset: 16))))))
-; COMBINED-DIS: ^3 = gv: (guid: 8471399308421654326, summaries: (function: (module: ^0, flags: (linkage: external, notEligibleToImport: 0, live: 0, dsoLocal: 0), insts: 15, typeIdInfo: (typeTestAssumeVCalls: (vFuncId: (guid: 6699318081062747564, offset: 24), vFuncId: (guid: 16434608426314478903, offset: 32))))))
-; COMBINED-DIS: ^4 = gv: (guid: 10064745020953272174, summaries: (function: (module: ^0, flags: (linkage: external, notEligibleToImport: 0, live: 0, dsoLocal: 0), insts: 15, typeIdInfo: (typeTestAssumeConstVCalls: ((vFuncId: (guid: 6699318081062747564, offset: 16), args: (42)), (vFuncId: (guid: 6699318081062747564, offset: 24), args: (43)))))))
-; COMBINED-DIS: ^5 = gv: (guid: 11686717102184386164, summaries: (function: (module: ^0, flags: (linkage: external, notEligibleToImport: 0, live: 0, dsoLocal: 0), insts: 5, typeIdInfo: (typeCheckedLoadConstVCalls: ((vFuncId: (guid: 6699318081062747564, offset: 16), args: (42)))))))
-; COMBINED-DIS: ^6 = gv: (guid: 11834966808443348068, summaries: (function: (module: ^0, flags: (linkage: external, notEligibleToImport: 0, live: 0, dsoLocal: 0), insts: 2, typeIdInfo: (typeTests: (7546896869197086323)))))
+; COMBINED-DIS: ^1 = gv: (guid: 2072045998141807037, summaries: (function: (module: ^0, flags: (linkage: external, notEligibleToImport: 0, live: 0, dsoLocal: 0, canAutoHide: 0), insts: 8, typeIdInfo: (typeTestAssumeVCalls: (vFuncId: (guid: 6699318081062747564, offset: 16))))))
+; COMBINED-DIS: ^2 = gv: (guid: 4197650231481825559, summaries: (function: (module: ^0, flags: (linkage: external, notEligibleToImport: 0, live: 0, dsoLocal: 0, canAutoHide: 0), insts: 5, typeIdInfo: (typeCheckedLoadVCalls: (vFuncId: (guid: 6699318081062747564, offset: 16))))))
+; COMBINED-DIS: ^3 = gv: (guid: 8471399308421654326, summaries: (function: (module: ^0, flags: (linkage: external, notEligibleToImport: 0, live: 0, dsoLocal: 0, canAutoHide: 0), insts: 15, typeIdInfo: (typeTestAssumeVCalls: (vFuncId: (guid: 6699318081062747564, offset: 24), vFuncId: (guid: 16434608426314478903, offset: 32))))))
+; COMBINED-DIS: ^4 = gv: (guid: 10064745020953272174, summaries: (function: (module: ^0, flags: (linkage: external, notEligibleToImport: 0, live: 0, dsoLocal: 0, canAutoHide: 0), insts: 15, typeIdInfo: (typeTestAssumeConstVCalls: ((vFuncId: (guid: 6699318081062747564, offset: 16), args: (42)), (vFuncId: (guid: 6699318081062747564, offset: 24), args: (43)))))))
+; COMBINED-DIS: ^5 = gv: (guid: 11686717102184386164, summaries: (function: (module: ^0, flags: (linkage: external, notEligibleToImport: 0, live: 0, dsoLocal: 0, canAutoHide: 0), insts: 5, typeIdInfo: (typeCheckedLoadConstVCalls: ((vFuncId: (guid: 6699318081062747564, offset: 16), args: (42)))))))
+; COMBINED-DIS: ^6 = gv: (guid: 11834966808443348068, summaries: (function: (module: ^0, flags: (linkage: external, notEligibleToImport: 0, live: 0, dsoLocal: 0, canAutoHide: 0), insts: 2, typeIdInfo: (typeTests: (7546896869197086323)))))
Index: test/ThinLTO/X86/Inputs/linkonce_odr_unnamed_addr.ll
===================================================================
--- /dev/null
+++ test/ThinLTO/X86/Inputs/linkonce_odr_unnamed_addr.ll
@@ -0,0 +1,5 @@
+target datalayout = "e-m:e-i64:64-f80:128-n8:16:32:64-S128"
+target triple = "x86_64-grtev4-linux-gnu"
+
+@linkonceodrunnamed = linkonce_odr unnamed_addr constant i32 0
+@odrunnamed = weak_odr unnamed_addr constant i32 0
Index: test/ThinLTO/X86/linkonce_odr_unnamed_addr.ll
===================================================================
--- test/ThinLTO/X86/linkonce_odr_unnamed_addr.ll
+++ test/ThinLTO/X86/linkonce_odr_unnamed_addr.ll
@@ -1,10 +1,31 @@
 ; This test ensures that when linkonce_odr + unnamed_addr symbols promoted to
-; weak symbols, it preserves the auto hide property.
+; weak symbols, it preserves the auto hide property when possible.
 
 ; RUN: opt -module-summary %s -o %t.bc
-; RUN: opt -module-summary %s -o %t2.bc
+; RUN: opt -module-summary %p/Inputs/linkonce_odr_unnamed_addr.ll -o %t2.bc
+; Check old LTO API
 ; RUN: llvm-lto -thinlto-action=thinlink -o %t3.bc %t.bc %t2.bc
 ; RUN: llvm-lto -thinlto-action=promote %t.bc -thinlto-index=%t3.bc -o - | llvm-dis -o - | FileCheck %s
+; Check new LTO API
+; RUN: llvm-lto2 run -save-temps -o %t6.bc %t.bc %t2.bc -r=%t.bc,linkonceodrunnamed,p -r=%t.bc,odrunnamed,p -r=%t2.bc,linkonceodrunnamed, -r=%t2.bc,odrunnamed,
+; RUN: llvm-dis %t6.bc.1.1.promote.bc -o - | FileCheck %s
 
+; Now test when one module does not have a summary. In that case we must be
+; conservative and not auto hide.
+; RUN: opt %p/Inputs/linkonce_odr_unnamed_addr.ll -o %t4.bc
+; Check new LTO API (old LTO API does not detect this case).
+; RUN: llvm-lto2 run -save-temps -o %t6.bc %t.bc %t4.bc -r=%t.bc,linkonceodrunnamed,p -r=%t.bc,odrunnamed,p -r=%t4.bc,linkonceodrunnamed, -r=%t4.bc,odrunnamed,
+; RUN: llvm-dis %t6.bc.1.1.promote.bc -o - | FileCheck %s --check-prefix=NOSUMMARY
+
+target datalayout = "e-m:e-i64:64-f80:128-n8:16:32:64-S128"
+target triple = "x86_64-grtev4-linux-gnu"
+
+; In this case all copies are linkonce_odr, so it may be hidden.
 ; CHECK: @linkonceodrunnamed = weak_odr hidden unnamed_addr constant i32 0
+; NOSUMMARY: @linkonceodrunnamed = weak_odr unnamed_addr constant i32 0
 @linkonceodrunnamed = linkonce_odr unnamed_addr constant i32 0
+
+; In this case, the other copy was weak_odr, so it may not be hidden.
+; CHECK: @odrunnamed = weak_odr unnamed_addr constant i32 0
+; NOSUMMARY: @odrunnamed = weak_odr unnamed_addr constant i32 0
+@odrunnamed = linkonce_odr unnamed_addr constant i32 0
Index: test/ThinLTO/X86/linkonce_resolution_comdat.ll
===================================================================
--- test/ThinLTO/X86/linkonce_resolution_comdat.ll
+++ test/ThinLTO/X86/linkonce_resolution_comdat.ll
@@ -10,7 +10,7 @@
 ; Copy from first module is prevailing and converted to weak_odr, copy
 ; from second module is preempted and converted to available_externally and
 ; removed from comdat.
-; IMPORT1: define weak_odr hidden i32 @f(i8*) unnamed_addr comdat($c1) {
+; IMPORT1: define weak_odr i32 @f(i8*) unnamed_addr comdat($c1) {
 ; IMPORT2: define available_externally i32 @f(i8*) unnamed_addr {
 
 ; RUN: llvm-nm -o - < %t1.bc.thinlto.o | FileCheck %s --check-prefix=NM1
Index: test/Transforms/LowerTypeTests/import-unsat.ll
===================================================================
--- test/Transforms/LowerTypeTests/import-unsat.ll
+++ test/Transforms/LowerTypeTests/import-unsat.ll
@@ -8,6 +8,7 @@
 ; SUMMARY-NEXT:      NotEligibleToImport: false
 ; SUMMARY-NEXT:      Live:                true
 ; SUMMARY-NEXT:      Local:               false
+; SUMMARY-NEXT:      CanAutoHide:         false
 ; SUMMARY-NEXT:      TypeTests: [ 123 ]
 ; SUMMARY-NEXT: TypeIdMap:
 ; SUMMARY-NEXT:   typeid1:
Index: test/Transforms/WholeProgramDevirt/import-indir.ll
===================================================================
--- test/Transforms/WholeProgramDevirt/import-indir.ll
+++ test/Transforms/WholeProgramDevirt/import-indir.ll
@@ -8,6 +8,7 @@
 ; SUMMARY-NEXT:      NotEligibleToImport: false
 ; SUMMARY-NEXT:      Live:                true
 ; SUMMARY-NEXT:      Local:               false
+; SUMMARY-NEXT:      CanAutoHide:         false
 ; SUMMARY-NEXT:      TypeTestAssumeVCalls:
 ; SUMMARY-NEXT:        - GUID:            123
 ; SUMMARY-NEXT:          Offset:          0
Index: test/tools/gold/X86/Inputs/linkonce_odr_unnamed_addr.ll
===================================================================
--- /dev/null
+++ test/tools/gold/X86/Inputs/linkonce_odr_unnamed_addr.ll
@@ -0,0 +1,5 @@
+target datalayout = "e-m:e-i64:64-f80:128-n8:16:32:64-S128"
+target triple = "x86_64-grtev4-linux-gnu"
+
+@linkonceodrunnamed = linkonce_odr unnamed_addr constant i32 0
+@odrunnamed = weak_odr unnamed_addr constant i32 0
Index: test/tools/gold/X86/linkonce_odr_unnamed_addr.ll
===================================================================
--- /dev/null
+++ test/tools/gold/X86/linkonce_odr_unnamed_addr.ll
@@ -0,0 +1,30 @@
+; This test ensures that when linkonce_odr + unnamed_addr symbols promoted to
+; weak symbols, it preserves the auto hide property when possible.
+
+; RUN: opt -module-summary %s -o %t.o
+; RUN: opt -module-summary %p/Inputs/linkonce_odr_unnamed_addr.ll -o %t2.o
+; RUN: %gold -plugin %llvmshlibdir/LLVMgold%shlibext \
+; RUN:    --plugin-opt=save-temps \
+; RUN:    %t.o %t2.o -o %t3.o
+; RUN: llvm-dis %t.o.1.promote.bc -o - | FileCheck %s
+
+; Now test when one module is a native object. In that case we must be
+; conservative and not auto hide.
+; RUN: llc %p/Inputs/linkonce_odr_unnamed_addr.ll -o %t2native.o -filetype=obj
+; RUN: %gold -plugin %llvmshlibdir/LLVMgold%shlibext \
+; RUN:    --plugin-opt=save-temps \
+; RUN:    %t.o %t2native.o -o %t3.o
+; RUN: llvm-dis %t.o.1.promote.bc -o - | FileCheck %s --check-prefix=NOSUMMARY
+
+target datalayout = "e-m:e-i64:64-f80:128-n8:16:32:64-S128"
+target triple = "x86_64-grtev4-linux-gnu"
+
+; In this case all copies are linkonce_odr, so it may be hidden.
+; CHECK: @linkonceodrunnamed = weak_odr hidden unnamed_addr constant i32 0
+; NOSUMMARY: @linkonceodrunnamed = weak_odr dso_local unnamed_addr constant i32 0
+@linkonceodrunnamed = linkonce_odr unnamed_addr constant i32 0
+
+; In this case, the other copy was weak_odr, so it may not be hidden.
+; CHECK: @odrunnamed = weak_odr dso_local unnamed_addr constant i32 0
+; NOSUMMARY: @odrunnamed = weak_odr dso_local unnamed_addr constant i32 0
+@odrunnamed = linkonce_odr unnamed_addr constant i32 0
Index: test/tools/gold/X86/thinlto.ll
===================================================================
--- test/tools/gold/X86/thinlto.ll
+++ test/tools/gold/X86/thinlto.ll
@@ -119,11 +119,11 @@
 
 ; DIS1: ^0 = module: (path: "{{.*}}thinlto.ll.tmp.o", hash: (0, 0, 0, 0, 0))
 ; DIS1: ^1 = module: (path: "{{.*}}thinlto.ll.tmp2.o", hash: (0, 0, 0, 0, 0))
-; DIS1: ^2 = gv: (guid: 13146401226427987378, summaries: (function: (module: ^1, flags: (linkage: external, notEligibleToImport: 0, live: 1, dsoLocal: 0), insts: 1)))
-; DIS1: ^3 = gv: (guid: 14740650423002898831, summaries: (function: (module: ^0, flags: (linkage: external, notEligibleToImport: 0, live: 1, dsoLocal: 0), insts: 2, calls: ((callee: ^2)))))
+; DIS1: ^2 = gv: (guid: 13146401226427987378, summaries: (function: (module: ^1, flags: (linkage: external, notEligibleToImport: 0, live: 1, dsoLocal: 0, canAutoHide: 0), insts: 1)))
+; DIS1: ^3 = gv: (guid: 14740650423002898831, summaries: (function: (module: ^0, flags: (linkage: external, notEligibleToImport: 0, live: 1, dsoLocal: 0, canAutoHide: 0), insts: 2, calls: ((callee: ^2)))))
 
 ; DIS2: ^0 = module: (path: "{{.*}}thinlto.ll.tmp2.o", hash: (0, 0, 0, 0, 0))
-; DIS2: ^1 = gv: (guid: 13146401226427987378, summaries: (function: (module: ^0, flags: (linkage: external, notEligibleToImport: 0, live: 1, dsoLocal: 0), insts: 1)))
+; DIS2: ^1 = gv: (guid: 13146401226427987378, summaries: (function: (module: ^0, flags: (linkage: external, notEligibleToImport: 0, live: 1, dsoLocal: 0, canAutoHide: 0), insts: 1)))
 
 ; COMBINED: <MODULE_STRTAB_BLOCK
 ; COMBINED-NEXT: <ENTRY {{.*}} record string = '{{.*}}/test/tools/gold/X86/Output/thinlto.ll.tmp{{.*}}.o'