llvm · teresajohnson · Oct 21, 2025 · Oct 21, 2025
diff --git a/llvm/include/llvm/IR/ModuleSummaryIndex.h b/llvm/include/llvm/IR/ModuleSummaryIndex.h
@@ -164,9 +164,24 @@ struct alignas(8) GlobalValueSummaryInfo {
 
   inline GlobalValueSummaryInfo(bool HaveGVs);
 
+  /// Access a read-only list of global value summary structures for a
+  /// particular value held in the GlobalValueMap.
+  ArrayRef<std::unique_ptr<GlobalValueSummary>> getSummaryList() const {
+    return SummaryList;
+  }
+
+  /// Add a summary corresponding to a global value definition in a module with
+  /// the corresponding GUID.
+  void addSummary(std::unique_ptr<GlobalValueSummary> Summary) {
+    return SummaryList.push_back(std::move(Summary));
+  }
+
+private:
   /// List of global value summary structures for a particular value held
   /// in the GlobalValueMap. Requires a vector in the case of multiple
-  /// COMDAT values of the same name.
+  /// COMDAT values of the same name, weak symbols, locals of the same name when
+  /// compiling without sufficient distinguishing path, or (theoretically) hash
+  /// collisions. Each summary is from a different module.
   GlobalValueSummaryList SummaryList;
 };
 
@@ -201,7 +216,7 @@ struct ValueInfo {
   }
 
   ArrayRef<std::unique_ptr<GlobalValueSummary>> getSummaryList() const {
-    return getRef()->second.SummaryList;
+    return getRef()->second.getSummaryList();
   }
 
   // Even if the index is built with GVs available, we may not have one for
@@ -1607,8 +1622,8 @@ class ModuleSummaryIndex {
 
     for (auto &S : *this) {
       // Skip external functions
-      if (!S.second.SummaryList.size() ||
-          !isa<FunctionSummary>(S.second.SummaryList.front().get()))
+      if (!S.second.getSummaryList().size() ||
+          !isa<FunctionSummary>(S.second.getSummaryList().front().get()))
         continue;
       discoverNodes(ValueInfo(HaveGVs, &S), FunctionHasParent);
     }
@@ -1748,7 +1763,7 @@ class ModuleSummaryIndex {
     // Here we have a notionally const VI, but the value it points to is owned
     // by the non-const *this.
     const_cast<GlobalValueSummaryMapTy::value_type *>(VI.getRef())
-        ->second.SummaryList.push_back(std::move(Summary));
+        ->second.addSummary(std::move(Summary));
   }
 
   /// Add an original name for the value of the given GUID.
@@ -1937,7 +1952,7 @@ class ModuleSummaryIndex {
   collectDefinedGVSummariesPerModule(Map &ModuleToDefinedGVSummaries) const {
     for (const auto &GlobalList : *this) {
       auto GUID = GlobalList.first;
-      for (const auto &Summary : GlobalList.second.SummaryList) {
+      for (const auto &Summary : GlobalList.second.getSummaryList()) {
         ModuleToDefinedGVSummaries[Summary->modulePath()][GUID] = Summary.get();
       }
     }
@@ -2035,7 +2050,7 @@ struct GraphTraits<ModuleSummaryIndex *> : public GraphTraits<ValueInfo> {
     std::unique_ptr<GlobalValueSummary> Root =
         std::make_unique<FunctionSummary>(I->calculateCallGraphRoot());
     GlobalValueSummaryInfo G(I->haveGVs());
-    G.SummaryList.push_back(std::move(Root));
+    G.addSummary(std::move(Root));
     static auto P =
         GlobalValueSummaryMapTy::value_type(GlobalValue::GUID(0), std::move(G));
     return ValueInfo(I->haveGVs(), &P);

diff --git a/llvm/include/llvm/IR/ModuleSummaryIndexYAML.h b/llvm/include/llvm/IR/ModuleSummaryIndexYAML.h
@@ -237,7 +237,7 @@ template <> struct CustomMappingTraits<GlobalValueSummaryMapTy> {
         // This is done in fixAliaseeLinks() which is called in
         // MappingTraits<ModuleSummaryIndex>::mapping().
         ASum->setAliasee(AliaseeVI, /*Aliasee=*/nullptr);
-        Elem.SummaryList.push_back(std::move(ASum));
+        Elem.addSummary(std::move(ASum));
         continue;
       }
       SmallVector<ValueInfo, 0> Refs;
@@ -246,7 +246,7 @@ template <> struct CustomMappingTraits<GlobalValueSummaryMapTy> {
         auto It = V.try_emplace(RefGUID, /*IsAnalysis=*/false).first;
         Refs.push_back(ValueInfo(/*IsAnalysis=*/false, &*It));
       }
-      Elem.SummaryList.push_back(std::make_unique<FunctionSummary>(
+      Elem.addSummary(std::make_unique<FunctionSummary>(
           GVFlags, /*NumInsts=*/0, FunctionSummary::FFlags{}, std::move(Refs),
           SmallVector<FunctionSummary::EdgeTy, 0>{}, std::move(GVSum.TypeTests),
           std::move(GVSum.TypeTestAssumeVCalls),
@@ -260,7 +260,7 @@ template <> struct CustomMappingTraits<GlobalValueSummaryMapTy> {
   static void output(IO &io, GlobalValueSummaryMapTy &V) {
     for (auto &P : V) {
       std::vector<GlobalValueSummaryYaml> GVSums;
-      for (auto &Sum : P.second.SummaryList) {
+      for (auto &Sum : P.second.getSummaryList()) {
         if (auto *FSum = dyn_cast<FunctionSummary>(Sum.get())) {
           std::vector<uint64_t> Refs;
           Refs.reserve(FSum->refs().size());
@@ -295,7 +295,7 @@ template <> struct CustomMappingTraits<GlobalValueSummaryMapTy> {
   }
   static void fixAliaseeLinks(GlobalValueSummaryMapTy &V) {
     for (auto &P : V) {
-      for (auto &Sum : P.second.SummaryList) {
+      for (auto &Sum : P.second.getSummaryList()) {
         if (auto *Alias = dyn_cast<AliasSummary>(Sum.get())) {
           ValueInfo AliaseeVI = Alias->getAliaseeVI();
           auto AliaseeSL = AliaseeVI.getSummaryList();

diff --git a/llvm/lib/Analysis/ModuleSummaryAnalysis.cpp b/llvm/lib/Analysis/ModuleSummaryAnalysis.cpp
@@ -1100,12 +1100,12 @@ ModuleSummaryIndex llvm::buildModuleSummaryIndex(
 
   for (auto &GlobalList : Index) {
     // Ignore entries for references that are undefined in the current module.
-    if (GlobalList.second.SummaryList.empty())
+    if (GlobalList.second.getSummaryList().empty())
       continue;
 
-    assert(GlobalList.second.SummaryList.size() == 1 &&
+    assert(GlobalList.second.getSummaryList().size() == 1 &&
            "Expected module's index to have one summary per GUID");
-    auto &Summary = GlobalList.second.SummaryList[0];
+    auto &Summary = GlobalList.second.getSummaryList()[0];
     if (!IsThinLTO) {
       Summary->setNotEligibleToImport();
       continue;

diff --git a/llvm/lib/Analysis/StackSafetyAnalysis.cpp b/llvm/lib/Analysis/StackSafetyAnalysis.cpp
@@ -1136,7 +1136,7 @@ void llvm::generateParamAccessSummary(ModuleSummaryIndex &Index) {
     if (!AreStatisticsEnabled())
       return;
     for (auto &GVS : Index)
-      for (auto &GV : GVS.second.SummaryList)
+      for (auto &GV : GVS.second.getSummaryList())
         if (FunctionSummary *FS = dyn_cast<FunctionSummary>(GV.get()))
           Stat += FS->paramAccesses().size();
   };
@@ -1147,7 +1147,7 @@ void llvm::generateParamAccessSummary(ModuleSummaryIndex &Index) {
 
   // Convert the ModuleSummaryIndex to a FunctionMap
   for (auto &GVS : Index) {
-    for (auto &GV : GVS.second.SummaryList) {
+    for (auto &GV : GVS.second.getSummaryList()) {
       FunctionSummary *FS = dyn_cast<FunctionSummary>(GV.get());
       if (!FS || FS->paramAccesses().empty())
         continue;

diff --git a/llvm/lib/Bitcode/Writer/BitcodeWriter.cpp b/llvm/lib/Bitcode/Writer/BitcodeWriter.cpp
@@ -235,7 +235,7 @@ class ModuleBitcodeWriterBase : public BitcodeWriterBase {
       return;
     for (const auto &GUIDSummaryLists : *Index)
       // Examine all summaries for this GUID.
-      for (auto &Summary : GUIDSummaryLists.second.SummaryList)
+      for (auto &Summary : GUIDSummaryLists.second.getSummaryList())
         if (auto FS = dyn_cast<FunctionSummary>(Summary.get())) {
           // For each call in the function summary, see if the call
           // is to a GUID (which means it is for an indirect call,
@@ -587,7 +587,7 @@ class IndexBitcodeWriter : public BitcodeWriterBase {
         }
     } else {
       for (auto &Summaries : Index)
-        for (auto &Summary : Summaries.second.SummaryList)
+        for (auto &Summary : Summaries.second.getSummaryList())
           Callback({Summaries.first, Summary.get()}, false);
     }
   }

diff --git a/llvm/lib/IR/AsmWriter.cpp b/llvm/lib/IR/AsmWriter.cpp
@@ -3196,7 +3196,7 @@ void AssemblyWriter::printModuleSummaryIndex() {
   // for aliasee (then update BitcodeWriter.cpp and remove get/setAliaseeGUID).
   for (auto &GlobalList : *TheIndex) {
     auto GUID = GlobalList.first;
-    for (auto &Summary : GlobalList.second.SummaryList)
+    for (auto &Summary : GlobalList.second.getSummaryList())
       SummaryToGUIDMap[Summary.get()] = GUID;
   }
 

diff --git a/llvm/lib/IR/ModuleSummaryIndex.cpp b/llvm/lib/IR/ModuleSummaryIndex.cpp
@@ -162,7 +162,7 @@ void ModuleSummaryIndex::collectDefinedFunctionsForModule(
     StringRef ModulePath, GVSummaryMapTy &GVSummaryMap) const {
   for (auto &GlobalList : *this) {
     auto GUID = GlobalList.first;
-    for (auto &GlobSummary : GlobalList.second.SummaryList) {
+    for (auto &GlobSummary : GlobalList.second.getSummaryList()) {
       auto *Summary = dyn_cast_or_null<FunctionSummary>(GlobSummary.get());
       if (!Summary)
         // Ignore global variable, focus on functions
@@ -263,7 +263,7 @@ void ModuleSummaryIndex::propagateAttributes(
   DenseSet<ValueInfo> MarkedNonReadWriteOnly;
   for (auto &P : *this) {
     bool IsDSOLocal = true;
-    for (auto &S : P.second.SummaryList) {
+    for (auto &S : P.second.getSummaryList()) {
       if (!isGlobalValueLive(S.get())) {
         // computeDeadSymbolsAndUpdateIndirectCalls should have marked all
         // copies live. Note that it is possible that there is a GUID collision
@@ -273,7 +273,7 @@ void ModuleSummaryIndex::propagateAttributes(
         // all copies live we can assert here that all are dead if any copy is
         // dead.
         assert(llvm::none_of(
-            P.second.SummaryList,
+            P.second.getSummaryList(),
             [&](const std::unique_ptr<GlobalValueSummary> &Summary) {
               return isGlobalValueLive(Summary.get());
             }));
@@ -308,16 +308,16 @@ void ModuleSummaryIndex::propagateAttributes(
       // Mark the flag in all summaries false so that we can do quick check
       // without going through the whole list.
       for (const std::unique_ptr<GlobalValueSummary> &Summary :
-           P.second.SummaryList)
+           P.second.getSummaryList())
         Summary->setDSOLocal(false);
   }
   setWithAttributePropagation();
   setWithDSOLocalPropagation();
   if (llvm::AreStatisticsEnabled())
     for (auto &P : *this)
-      if (P.second.SummaryList.size())
+      if (P.second.getSummaryList().size())
         if (auto *GVS = dyn_cast<GlobalVarSummary>(
-                P.second.SummaryList[0]->getBaseObject()))
+                P.second.getSummaryList()[0]->getBaseObject()))
           if (isGlobalValueLive(GVS)) {
             if (GVS->maybeReadOnly())
               ReadOnlyLiveGVars++;

diff --git a/llvm/lib/LTO/LTO.cpp b/llvm/lib/LTO/LTO.cpp
@@ -457,7 +457,7 @@ void llvm::thinLTOResolvePrevailingInIndex(
   // when needed.
   DenseSet<GlobalValueSummary *> GlobalInvolvedWithAlias;
   for (auto &I : Index)
-    for (auto &S : I.second.SummaryList)
+    for (auto &S : I.second.getSummaryList())
       if (auto AS = dyn_cast<AliasSummary>(S.get()))
         GlobalInvolvedWithAlias.insert(&AS->getAliasee());
 
@@ -1182,7 +1182,7 @@ Error LTO::checkPartiallySplit() {
   // Otherwise check if there are any recorded in the combined summary from the
   // ThinLTO modules.
   for (auto &P : ThinLTO.CombinedIndex) {
-    for (auto &S : P.second.SummaryList) {
+    for (auto &S : P.second.getSummaryList()) {
       auto *FS = dyn_cast<FunctionSummary>(S.get());
       if (!FS)
         continue;

diff --git a/llvm/lib/LTO/LTOBackend.cpp b/llvm/lib/LTO/LTOBackend.cpp
@@ -770,11 +770,11 @@ bool lto::initImportList(const Module &M,
   // via a WriteIndexesThinBackend.
   for (const auto &GlobalList : CombinedIndex) {
     // Ignore entries for undefined references.
-    if (GlobalList.second.SummaryList.empty())
+    if (GlobalList.second.getSummaryList().empty())
       continue;
 
     auto GUID = GlobalList.first;
-    for (const auto &Summary : GlobalList.second.SummaryList) {
+    for (const auto &Summary : GlobalList.second.getSummaryList()) {
       // Skip the summaries for the importing module. These are included to
       // e.g. record required linkage changes.
       if (Summary->modulePath() == M.getModuleIdentifier())

diff --git a/llvm/lib/LTO/ThinLTOCodeGenerator.cpp b/llvm/lib/LTO/ThinLTOCodeGenerator.cpp
@@ -101,8 +101,8 @@ static void saveTempBitcode(const Module &TheModule, StringRef TempDir,
   WriteBitcodeToFile(TheModule, OS, /* ShouldPreserveUseListOrder */ true);
 }
 
-static const GlobalValueSummary *
-getFirstDefinitionForLinker(const GlobalValueSummaryList &GVSummaryList) {
+static const GlobalValueSummary *getFirstDefinitionForLinker(
+    ArrayRef<std::unique_ptr<GlobalValueSummary>> GVSummaryList) {
   // If there is any strong definition anywhere, get it.
   auto StrongDefForLinker = llvm::find_if(
       GVSummaryList, [](const std::unique_ptr<GlobalValueSummary> &Summary) {
@@ -131,14 +131,15 @@ getFirstDefinitionForLinker(const GlobalValueSummaryList &GVSummaryList) {
 static void computePrevailingCopies(
     const ModuleSummaryIndex &Index,
     DenseMap<GlobalValue::GUID, const GlobalValueSummary *> &PrevailingCopy) {
-  auto HasMultipleCopies = [&](const GlobalValueSummaryList &GVSummaryList) {
-    return GVSummaryList.size() > 1;
-  };
+  auto HasMultipleCopies =
+      [&](ArrayRef<std::unique_ptr<GlobalValueSummary>> GVSummaryList) {
+        return GVSummaryList.size() > 1;
+      };
 
   for (auto &I : Index) {
-    if (HasMultipleCopies(I.second.SummaryList))
+    if (HasMultipleCopies(I.second.getSummaryList()))
       PrevailingCopy[I.first] =
-          getFirstDefinitionForLinker(I.second.SummaryList);
+          getFirstDefinitionForLinker(I.second.getSummaryList());
   }
 }
 

diff --git a/llvm/lib/Transforms/IPO/FunctionImport.cpp b/llvm/lib/Transforms/IPO/FunctionImport.cpp
@@ -1368,13 +1368,13 @@ static void ComputeCrossModuleImportForModuleFromIndexForTest(
     FunctionImporter::ImportMapTy &ImportList) {
   for (const auto &GlobalList : Index) {
     // Ignore entries for undefined references.
-    if (GlobalList.second.SummaryList.empty())
+    if (GlobalList.second.getSummaryList().empty())
       continue;
 
     auto GUID = GlobalList.first;
-    assert(GlobalList.second.SummaryList.size() == 1 &&
+    assert(GlobalList.second.getSummaryList().size() == 1 &&
            "Expected individual combined index to have one summary per GUID");
-    auto &Summary = GlobalList.second.SummaryList[0];
+    auto &Summary = GlobalList.second.getSummaryList()[0];
     // Skip the summaries for the importing module. These are included to
     // e.g. record required linkage changes.
     if (Summary->modulePath() == ModulePath)
@@ -1423,7 +1423,7 @@ void updateValueInfoForIndirectCalls(ModuleSummaryIndex &Index,
 
 void llvm::updateIndirectCalls(ModuleSummaryIndex &Index) {
   for (const auto &Entry : Index) {
-    for (const auto &S : Entry.second.SummaryList) {
+    for (const auto &S : Entry.second.getSummaryList()) {
       if (auto *FS = dyn_cast<FunctionSummary>(S.get()))
         updateValueInfoForIndirectCalls(Index, FS);
     }
@@ -1456,7 +1456,7 @@ void llvm::computeDeadSymbolsAndUpdateIndirectCalls(
   // Add values flagged in the index as live roots to the worklist.
   for (const auto &Entry : Index) {
     auto VI = Index.getValueInfo(Entry);
-    for (const auto &S : Entry.second.SummaryList) {
+    for (const auto &S : Entry.second.getSummaryList()) {
       if (auto *FS = dyn_cast<FunctionSummary>(S.get()))
         updateValueInfoForIndirectCalls(Index, FS);
       if (S->isLive()) {
@@ -2094,7 +2094,7 @@ static bool doImportingForModuleForTest(
   // is only enabled when testing importing via the 'opt' tool, which does
   // not do the ThinLink that would normally determine what values to promote.
   for (auto &I : *Index) {
-    for (auto &S : I.second.SummaryList) {
+    for (auto &S : I.second.getSummaryList()) {
       if (GlobalValue::isLocalLinkage(S->linkage()))
         S->setLinkage(GlobalValue::ExternalLinkage);
     }

diff --git a/llvm/lib/Transforms/IPO/LowerTypeTests.cpp b/llvm/lib/Transforms/IPO/LowerTypeTests.cpp
@@ -2130,7 +2130,7 @@ bool LowerTypeTestsModule::lower() {
       // A set of all functions that are address taken by a live global object.
       DenseSet<GlobalValue::GUID> AddressTaken;
       for (auto &I : *ExportSummary)
-        for (auto &GVS : I.second.SummaryList)
+        for (auto &GVS : I.second.getSummaryList())
           if (GVS->isLive())
             for (const auto &Ref : GVS->refs()) {
               AddressTaken.insert(Ref.getGUID());
@@ -2409,7 +2409,7 @@ bool LowerTypeTestsModule::lower() {
     }
 
     for (auto &P : *ExportSummary) {
-      for (auto &S : P.second.SummaryList) {
+      for (auto &S : P.second.getSummaryList()) {
         if (!ExportSummary->isGlobalValueLive(S.get()))
           continue;
         if (auto *FS = dyn_cast<FunctionSummary>(S->getBaseObject()))

diff --git a/llvm/lib/Transforms/IPO/WholeProgramDevirt.cpp b/llvm/lib/Transforms/IPO/WholeProgramDevirt.cpp
@@ -928,7 +928,7 @@ void llvm::updateVCallVisibilityInIndex(
     // linker, as we have no information on their eventual use.
     if (DynamicExportSymbols.count(P.first))
       continue;
-    for (auto &S : P.second.SummaryList) {
+    for (auto &S : P.second.getSummaryList()) {
       auto *GVar = dyn_cast<GlobalVarSummary>(S.get());
       if (!GVar ||
           GVar->getVCallVisibility() != GlobalObject::VCallVisibilityPublic)
@@ -2413,7 +2413,7 @@ bool DevirtModule::run() {
     }
 
     for (auto &P : *ExportSummary) {
-      for (auto &S : P.second.SummaryList) {
+      for (auto &S : P.second.getSummaryList()) {
         auto *FS = dyn_cast<FunctionSummary>(S.get());
         if (!FS)
           continue;
@@ -2564,7 +2564,7 @@ void DevirtIndex::run() {
 
   // Collect information from summary about which calls to try to devirtualize.
   for (auto &P : ExportSummary) {
-    for (auto &S : P.second.SummaryList) {
+    for (auto &S : P.second.getSummaryList()) {
       auto *FS = dyn_cast<FunctionSummary>(S.get());
       if (!FS)
         continue;

diff --git a/llvm/tools/llvm-link/llvm-link.cpp b/llvm/tools/llvm-link/llvm-link.cpp
@@ -420,7 +420,7 @@ static bool linkFiles(const char *argv0, LLVMContext &Context, Linker &L,
       // does not do the ThinLink that would normally determine what values to
       // promote.
       for (auto &I : *Index) {
-        for (auto &S : I.second.SummaryList) {
+        for (auto &S : I.second.getSummaryList()) {
           if (GlobalValue::isLocalLinkage(S->linkage()))
             S->setLinkage(GlobalValue::ExternalLinkage);
         }

diff --git a/llvm/tools/llvm-lto/llvm-lto.cpp b/llvm/tools/llvm-lto/llvm-lto.cpp
@@ -379,7 +379,7 @@ static void printIndexStats() {
 
     unsigned Calls = 0, Refs = 0, Functions = 0, Alias = 0, Globals = 0;
     for (auto &Summaries : *Index) {
-      for (auto &Summary : Summaries.second.SummaryList) {
+      for (auto &Summary : Summaries.second.getSummaryList()) {
         Refs += Summary->refs().size();
         if (auto *FuncSummary = dyn_cast<FunctionSummary>(Summary.get())) {
           Functions++;