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[Serialization] Code cleanups and polish 83233 #83237

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This is the following of #83233. This simply removes LazySpecializationInfo from RedeclarableTemplateDecl. I feel it can make the review process much more easier after splitting this.

@llvmbot llvmbot added clang Clang issues not falling into any other category clang:frontend Language frontend issues, e.g. anything involving "Sema" clang:modules C++20 modules and Clang Header Modules labels Feb 28, 2024
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llvmbot commented Feb 28, 2024

@llvm/pr-subscribers-clang-modules

@llvm/pr-subscribers-clang

Author: Chuanqi Xu (ChuanqiXu9)

Changes

This is the following of #83233. This simply removes LazySpecializationInfo from RedeclarableTemplateDecl. I feel it can make the review process much more easier after splitting this.


Patch is 21.06 KiB, truncated to 20.00 KiB below, full version: https://github.com/llvm/llvm-project/pull/83237.diff

8 Files Affected:

  • (modified) clang/include/clang/AST/DeclTemplate.h (+2-30)
  • (modified) clang/include/clang/Serialization/ASTBitCodes.h (+1-1)
  • (modified) clang/lib/AST/DeclTemplate.cpp (+14-35)
  • (modified) clang/lib/Serialization/ASTCommon.h (-1)
  • (modified) clang/lib/Serialization/ASTReader.cpp (+2-2)
  • (modified) clang/lib/Serialization/ASTReaderDecl.cpp (+3-73)
  • (modified) clang/lib/Serialization/ASTWriter.cpp (+4-22)
  • (modified) clang/lib/Serialization/ASTWriterDecl.cpp (+4-48)
diff --git a/clang/include/clang/AST/DeclTemplate.h b/clang/include/clang/AST/DeclTemplate.h
index 51caef54baac26..d25e10adb5453d 100644
--- a/clang/include/clang/AST/DeclTemplate.h
+++ b/clang/include/clang/AST/DeclTemplate.h
@@ -256,8 +256,8 @@ class TemplateArgumentList final
   TemplateArgumentList(const TemplateArgumentList &) = delete;
   TemplateArgumentList &operator=(const TemplateArgumentList &) = delete;
 
-  /// Create hash for the given arguments.
-  static unsigned ComputeODRHash(ArrayRef<TemplateArgument> Args);
+  /// Create stable hash for the given arguments across compiler invocations.
+  static unsigned ComputeStableHash(ArrayRef<TemplateArgument> Args);
 
   /// Create a new template argument list that copies the given set of
   /// template arguments.
@@ -733,25 +733,6 @@ class RedeclarableTemplateDecl : public TemplateDecl,
   }
 
   void anchor() override;
-  struct LazySpecializationInfo {
-    uint32_t DeclID = ~0U;
-    unsigned ODRHash = ~0U;
-    bool IsPartial = false;
-    LazySpecializationInfo(uint32_t ID, unsigned Hash = ~0U,
-                           bool Partial = false)
-        : DeclID(ID), ODRHash(Hash), IsPartial(Partial) {}
-    LazySpecializationInfo() {}
-    bool operator<(const LazySpecializationInfo &Other) const {
-      return DeclID < Other.DeclID;
-    }
-    bool operator==(const LazySpecializationInfo &Other) const {
-      assert((DeclID != Other.DeclID || ODRHash == Other.ODRHash) &&
-             "Hashes differ!");
-      assert((DeclID != Other.DeclID || IsPartial == Other.IsPartial) &&
-             "Both must be the same kinds!");
-      return DeclID == Other.DeclID;
-    }
-  };
 
 protected:
   template <typename EntryType> struct SpecEntryTraits {
@@ -798,8 +779,6 @@ class RedeclarableTemplateDecl : public TemplateDecl,
   void loadLazySpecializationsImpl(llvm::ArrayRef<TemplateArgument> Args,
                                    TemplateParameterList *TPL = nullptr) const;
 
-  Decl *loadLazySpecializationImpl(LazySpecializationInfo &LazySpecInfo) const;
-
   template <class EntryType, typename ...ProfileArguments>
   typename SpecEntryTraits<EntryType>::DeclType*
   findSpecializationImpl(llvm::FoldingSetVector<EntryType> &Specs,
@@ -820,13 +799,6 @@ class RedeclarableTemplateDecl : public TemplateDecl,
     llvm::PointerIntPair<RedeclarableTemplateDecl*, 1, bool>
       InstantiatedFromMember;
 
-    /// If non-null, points to an array of specializations (including
-    /// partial specializations) known only by their external declaration IDs.
-    ///
-    /// The first value in the array is the number of specializations/partial
-    /// specializations that follow.
-    LazySpecializationInfo *LazySpecializations = nullptr;
-
     /// The set of "injected" template arguments used within this
     /// template.
     ///
diff --git a/clang/include/clang/Serialization/ASTBitCodes.h b/clang/include/clang/Serialization/ASTBitCodes.h
index 15e7aef826a52a..827799ec7f0a3b 100644
--- a/clang/include/clang/Serialization/ASTBitCodes.h
+++ b/clang/include/clang/Serialization/ASTBitCodes.h
@@ -699,7 +699,7 @@ enum ASTRecordTypes {
   /// recorded in a preamble.
   PP_ASSUME_NONNULL_LOC = 67,
 
-  UPDATE_SPECIALIZATION = 68,
+  CXX_ADDED_TEMPLATE_SPECIALIZATION = 68,
 };
 
 /// Record types used within a source manager block.
diff --git a/clang/lib/AST/DeclTemplate.cpp b/clang/lib/AST/DeclTemplate.cpp
index 7b98b046d00725..4115f8ae4f0382 100644
--- a/clang/lib/AST/DeclTemplate.cpp
+++ b/clang/lib/AST/DeclTemplate.cpp
@@ -342,32 +342,6 @@ void RedeclarableTemplateDecl::loadLazySpecializationsImpl(
   ExternalSource->LoadExternalSpecializations(this->getCanonicalDecl(),
                                               OnlyPartial);
   return;
-
-  // Grab the most recent declaration to ensure we've loaded any lazy
-  // redeclarations of this template.
-  CommonBase *CommonBasePtr = getMostRecentDecl()->getCommonPtr();
-  if (auto *Specs = CommonBasePtr->LazySpecializations) {
-    if (!OnlyPartial)
-      CommonBasePtr->LazySpecializations = nullptr;
-    for (uint32_t I = 0, N = Specs[0].DeclID; I != N; ++I) {
-      // Skip over already loaded specializations.
-      if (!Specs[I + 1].ODRHash)
-        continue;
-      if (!OnlyPartial || Specs[I + 1].IsPartial)
-        (void)loadLazySpecializationImpl(Specs[I + 1]);
-    }
-  }
-}
-
-Decl *RedeclarableTemplateDecl::loadLazySpecializationImpl(
-    LazySpecializationInfo &LazySpecInfo) const {
-  llvm_unreachable("We don't use LazySpecializationInfo any more");
-
-  uint32_t ID = LazySpecInfo.DeclID;
-  assert(ID && "Loading already loaded specialization!");
-  // Note that we loaded the specialization.
-  LazySpecInfo.DeclID = LazySpecInfo.ODRHash = LazySpecInfo.IsPartial = 0;
-  return getASTContext().getExternalSource()->GetExternalDecl(ID);
 }
 
 void RedeclarableTemplateDecl::loadLazySpecializationsImpl(
@@ -378,14 +352,6 @@ void RedeclarableTemplateDecl::loadLazySpecializationsImpl(
 
   ExternalSource->LoadExternalSpecializations(this->getCanonicalDecl(), Args);
   return;
-
-  CommonBase *CommonBasePtr = getMostRecentDecl()->getCommonPtr();
-  if (auto *Specs = CommonBasePtr->LazySpecializations) {
-    unsigned Hash = TemplateArgumentList::ComputeODRHash(Args);
-    for (uint32_t I = 0, N = Specs[0].DeclID; I != N; ++I)
-      if (Specs[I + 1].ODRHash && Specs[I + 1].ODRHash == Hash)
-        (void)loadLazySpecializationImpl(Specs[I + 1]);
-  }
 }
 
 template<class EntryType, typename... ProfileArguments>
@@ -939,7 +905,20 @@ TemplateArgumentList::CreateCopy(ASTContext &Context,
   return new (Mem) TemplateArgumentList(Args);
 }
 
-unsigned TemplateArgumentList::ComputeODRHash(ArrayRef<TemplateArgument> Args) {
+unsigned
+TemplateArgumentList::ComputeStableHash(ArrayRef<TemplateArgument> Args) {
+  // FIXME: ODR hashing may not be the best mechanism to hash the template
+  // arguments. ODR hashing is (or perhaps, should be) about determining whether
+  // two things are spelled the same way and have the same meaning (as required
+  // by the C++ ODR), whereas what we want here is whether they have the same
+  // meaning regardless of spelling. Maybe we can get away with reusing ODR
+  // hashing anyway, on the basis that any canonical, non-dependent template
+  // argument should have the same (invented) spelling in every translation
+  // unit, but it is not sure that's true in all cases. There may still be cases
+  // where the canonical type includes some aspect of "whatever we saw first",
+  // in which case the ODR hash can differ across translation units for
+  // non-dependent, canonical template arguments that are spelled differently
+  // but have the same meaning. But it is not easy to raise examples.
   ODRHash Hasher;
   for (TemplateArgument TA : Args)
     Hasher.AddTemplateArgument(TA);
diff --git a/clang/lib/Serialization/ASTCommon.h b/clang/lib/Serialization/ASTCommon.h
index 296642e3674a49..485809f234113f 100644
--- a/clang/lib/Serialization/ASTCommon.h
+++ b/clang/lib/Serialization/ASTCommon.h
@@ -23,7 +23,6 @@ namespace serialization {
 
 enum DeclUpdateKind {
   UPD_CXX_ADDED_IMPLICIT_MEMBER,
-  UPD_CXX_ADDED_TEMPLATE_SPECIALIZATION,
   UPD_CXX_ADDED_ANONYMOUS_NAMESPACE,
   UPD_CXX_ADDED_FUNCTION_DEFINITION,
   UPD_CXX_ADDED_VAR_DEFINITION,
diff --git a/clang/lib/Serialization/ASTReader.cpp b/clang/lib/Serialization/ASTReader.cpp
index 0c6c19dfe5f908..94d7b959bcfdcc 100644
--- a/clang/lib/Serialization/ASTReader.cpp
+++ b/clang/lib/Serialization/ASTReader.cpp
@@ -3497,7 +3497,7 @@ llvm::Error ASTReader::ReadASTBlock(ModuleFile &F,
       break;
     }
 
-    case UPDATE_SPECIALIZATION: {
+    case CXX_ADDED_TEMPLATE_SPECIALIZATION: {
       unsigned Idx = 0;
       serialization::DeclID ID = ReadDeclID(F, Record, Idx);
       auto *Data = (const unsigned char *)Blob.data();
@@ -7972,7 +7972,7 @@ void ASTReader::LoadExternalSpecializations(
     return;
 
   Deserializing LookupResults(this);
-  auto HashValue = TemplateArgumentList::ComputeODRHash(TemplateArgs);
+  auto HashValue = TemplateArgumentList::ComputeStableHash(TemplateArgs);
 
   // Get Decl may violate the iterator from SpecializationsLookups
   llvm::SmallVector<serialization::reader::LazySpecializationInfo, 8> Infos;
diff --git a/clang/lib/Serialization/ASTReaderDecl.cpp b/clang/lib/Serialization/ASTReaderDecl.cpp
index 0b42b4c2713162..6236795dcd4156 100644
--- a/clang/lib/Serialization/ASTReaderDecl.cpp
+++ b/clang/lib/Serialization/ASTReaderDecl.cpp
@@ -88,8 +88,6 @@ namespace clang {
     const SourceLocation ThisDeclLoc;
 
     using RecordData = ASTReader::RecordData;
-    using LazySpecializationInfo =
-        RedeclarableTemplateDecl::LazySpecializationInfo;
 
     TypeID DeferredTypeID = 0;
     unsigned AnonymousDeclNumber = 0;
@@ -136,18 +134,6 @@ namespace clang {
       return Record.readString();
     }
 
-    LazySpecializationInfo ReadLazySpecializationInfo() {
-      DeclID ID = readDeclID();
-      unsigned Hash = Record.readInt();
-      bool IsPartial = Record.readInt();
-      return LazySpecializationInfo(ID, Hash, IsPartial);
-    }
-
-    void readDeclIDList(SmallVectorImpl<LazySpecializationInfo> &IDs) {
-      for (unsigned I = 0, Size = Record.readInt(); I != Size; ++I)
-        IDs.push_back(ReadLazySpecializationInfo());
-    }
-
     Decl *readDecl() {
       return Record.readDecl();
     }
@@ -274,29 +260,6 @@ namespace clang {
         : Reader(Reader), Record(Record), Loc(Loc), ThisDeclID(thisDeclID),
           ThisDeclLoc(ThisDeclLoc) {}
 
-    template <typename T>
-    static void
-    AddLazySpecializations(T *D, SmallVectorImpl<LazySpecializationInfo> &IDs) {
-      if (IDs.empty())
-        return;
-
-      // FIXME: We should avoid this pattern of getting the ASTContext.
-      ASTContext &C = D->getASTContext();
-
-      auto *&LazySpecializations = D->getCommonPtr()->LazySpecializations;
-
-      if (auto &Old = LazySpecializations) {
-        IDs.insert(IDs.end(), Old + 1, Old + 1 + Old[0].DeclID);
-        llvm::sort(IDs);
-        IDs.erase(std::unique(IDs.begin(), IDs.end()), IDs.end());
-      }
-      auto *Result = new (C) LazySpecializationInfo[1 + IDs.size()];
-      *Result = IDs.size();
-      std::copy(IDs.begin(), IDs.end(), Result + 1);
-
-      LazySpecializations = Result;
-    }
-
     template <typename DeclT>
     static Decl *getMostRecentDeclImpl(Redeclarable<DeclT> *D);
     static Decl *getMostRecentDeclImpl(...);
@@ -328,7 +291,7 @@ namespace clang {
     void ReadFunctionDefinition(FunctionDecl *FD);
     void Visit(Decl *D);
 
-    void UpdateDecl(Decl *D, llvm::SmallVectorImpl<LazySpecializationInfo> &);
+    void UpdateDecl(Decl *D);
 
     static void setNextObjCCategory(ObjCCategoryDecl *Cat,
                                     ObjCCategoryDecl *Next) {
@@ -2469,9 +2432,6 @@ void ASTDeclReader::VisitClassTemplateDecl(ClassTemplateDecl *D) {
   if (ThisDeclID == Redecl.getFirstID()) {
     // This ClassTemplateDecl owns a CommonPtr; read it to keep track of all of
     // the specializations.
-    SmallVector<LazySpecializationInfo, 32> SpecIDs;
-    readDeclIDList(SpecIDs);
-    ASTDeclReader::AddLazySpecializations(D, SpecIDs);
     ReadSpecializations(*Loc.F, D, Loc.F->DeclsCursor);
   }
 
@@ -2498,9 +2458,6 @@ void ASTDeclReader::VisitVarTemplateDecl(VarTemplateDecl *D) {
   if (ThisDeclID == Redecl.getFirstID()) {
     // This VarTemplateDecl owns a CommonPtr; read it to keep track of all of
     // the specializations.
-    SmallVector<LazySpecializationInfo, 32> SpecIDs;
-    readDeclIDList(SpecIDs);
-    ASTDeclReader::AddLazySpecializations(D, SpecIDs);
     ReadSpecializations(*Loc.F, D, Loc.F->DeclsCursor);
   }
 }
@@ -2601,9 +2558,6 @@ void ASTDeclReader::VisitFunctionTemplateDecl(FunctionTemplateDecl *D) {
 
   if (ThisDeclID == Redecl.getFirstID()) {
     // This FunctionTemplateDecl owns a CommonPtr; read it.
-    SmallVector<LazySpecializationInfo, 32> SpecIDs;
-    readDeclIDList(SpecIDs);
-    ASTDeclReader::AddLazySpecializations(D, SpecIDs);
     ReadSpecializations(*Loc.F, D, Loc.F->DeclsCursor);
   }
 }
@@ -4214,10 +4168,6 @@ void ASTReader::loadDeclUpdateRecords(PendingUpdateRecord &Record) {
   ProcessingUpdatesRAIIObj ProcessingUpdates(*this);
   DeclUpdateOffsetsMap::iterator UpdI = DeclUpdateOffsets.find(ID);
 
-  using LazySpecializationInfo =
-      RedeclarableTemplateDecl::LazySpecializationInfo;
-  llvm::SmallVector<LazySpecializationInfo, 8> PendingLazySpecializationIDs;
-
   if (UpdI != DeclUpdateOffsets.end()) {
     auto UpdateOffsets = std::move(UpdI->second);
     DeclUpdateOffsets.erase(UpdI);
@@ -4255,7 +4205,7 @@ void ASTReader::loadDeclUpdateRecords(PendingUpdateRecord &Record) {
 
       ASTDeclReader Reader(*this, Record, RecordLocation(F, Offset), ID,
                            SourceLocation());
-      Reader.UpdateDecl(D, PendingLazySpecializationIDs);
+      Reader.UpdateDecl(D);
 
       // We might have made this declaration interesting. If so, remember that
       // we need to hand it off to the consumer.
@@ -4267,19 +4217,6 @@ void ASTReader::loadDeclUpdateRecords(PendingUpdateRecord &Record) {
       }
     }
   }
-  // Add the lazy specializations to the template.
-  assert((PendingLazySpecializationIDs.empty() || isa<ClassTemplateDecl>(D) ||
-          isa<FunctionTemplateDecl, VarTemplateDecl>(D)) &&
-         "Must not have pending specializations");
-  /*
-  if (auto *CTD = dyn_cast<ClassTemplateDecl>(D))
-    ASTDeclReader::AddLazySpecializations(CTD, PendingLazySpecializationIDs);
-  else if (auto *FTD = dyn_cast<FunctionTemplateDecl>(D))
-    ASTDeclReader::AddLazySpecializations(FTD, PendingLazySpecializationIDs);
-  else if (auto *VTD = dyn_cast<VarTemplateDecl>(D))
-    ASTDeclReader::AddLazySpecializations(VTD, PendingLazySpecializationIDs);
-  */
-  PendingLazySpecializationIDs.clear();
 
   // Load the pending visible updates for this decl context, if it has any.
   auto I = PendingVisibleUpdates.find(ID);
@@ -4497,9 +4434,7 @@ static void forAllLaterRedecls(DeclT *D, Fn F) {
   }
 }
 
-void ASTDeclReader::UpdateDecl(
-    Decl *D,
-    SmallVectorImpl<LazySpecializationInfo> &PendingLazySpecializationIDs) {
+void ASTDeclReader::UpdateDecl(Decl *D) {
   while (Record.getIdx() < Record.size()) {
     switch ((DeclUpdateKind)Record.readInt()) {
     case UPD_CXX_ADDED_IMPLICIT_MEMBER: {
@@ -4510,11 +4445,6 @@ void ASTDeclReader::UpdateDecl(
       break;
     }
 
-    case UPD_CXX_ADDED_TEMPLATE_SPECIALIZATION:
-      // It will be added to the template's lazy specialization set.
-      PendingLazySpecializationIDs.push_back(ReadLazySpecializationInfo());
-      break;
-
     case UPD_CXX_ADDED_ANONYMOUS_NAMESPACE: {
       auto *Anon = readDeclAs<NamespaceDecl>();
 
diff --git a/clang/lib/Serialization/ASTWriter.cpp b/clang/lib/Serialization/ASTWriter.cpp
index 20d5a357647a75..0f217919ce3993 100644
--- a/clang/lib/Serialization/ASTWriter.cpp
+++ b/clang/lib/Serialization/ASTWriter.cpp
@@ -4044,7 +4044,7 @@ unsigned CalculateODRHashForSpecs(const Decl *Spec) {
   else
     llvm_unreachable("New Specialization Kind?");
 
-  return TemplateArgumentList::ComputeODRHash(Args);
+  return TemplateArgumentList::ComputeStableHash(Args);
 }
 } // namespace
 
@@ -5453,7 +5453,7 @@ ASTFileSignature ASTWriter::WriteASTCore(Sema &SemaRef, StringRef isysroot,
 
 void ASTWriter::WriteSpecializationsUpdates() {
   auto Abv = std::make_shared<llvm::BitCodeAbbrev>();
-  Abv->Add(llvm::BitCodeAbbrevOp(UPDATE_SPECIALIZATION));
+  Abv->Add(llvm::BitCodeAbbrevOp(CXX_ADDED_TEMPLATE_SPECIALIZATION));
   Abv->Add(llvm::BitCodeAbbrevOp(llvm::BitCodeAbbrevOp::VBR, 6));
   Abv->Add(llvm::BitCodeAbbrevOp(llvm::BitCodeAbbrevOp::Blob));
   auto UpdateSpecializationAbbrev = Stream.EmitAbbrev(std::move(Abv));
@@ -5466,7 +5466,8 @@ void ASTWriter::WriteSpecializationsUpdates() {
                                           LookupTable);
 
     // Write the lookup table
-    RecordData::value_type Record[] = {UPDATE_SPECIALIZATION, getDeclID(D)};
+    RecordData::value_type Record[] = {CXX_ADDED_TEMPLATE_SPECIALIZATION,
+                                       getDeclID(D)};
     Stream.EmitRecordWithBlob(UpdateSpecializationAbbrev, Record, LookupTable);
   }
 }
@@ -5503,25 +5504,6 @@ void ASTWriter::WriteDeclUpdatesBlocks(RecordDataImpl &OffsetsRecord) {
         assert(Update.getDecl() && "no decl to add?");
         Record.push_back(GetDeclRef(Update.getDecl()));
         break;
-      case UPD_CXX_ADDED_TEMPLATE_SPECIALIZATION: {
-        const Decl *Spec = Update.getDecl();
-        assert(Spec && "no decl to add?");
-        Record.push_back(GetDeclRef(Spec));
-        ArrayRef<TemplateArgument> Args;
-        if (auto *CTSD = dyn_cast<ClassTemplateSpecializationDecl>(Spec))
-          Args = CTSD->getTemplateArgs().asArray();
-        else if (auto *VTSD = dyn_cast<VarTemplateSpecializationDecl>(Spec))
-          Args = VTSD->getTemplateArgs().asArray();
-        else if (auto *FD = dyn_cast<FunctionDecl>(Spec))
-          Args = FD->getTemplateSpecializationArgs()->asArray();
-        assert(Args.size());
-        Record.push_back(TemplateArgumentList::ComputeODRHash(Args));
-        bool IsPartialSpecialization =
-            isa<ClassTemplatePartialSpecializationDecl>(Spec) ||
-            isa<VarTemplatePartialSpecializationDecl>(Spec);
-        Record.push_back(IsPartialSpecialization);
-        break;
-      }
       case UPD_CXX_ADDED_FUNCTION_DEFINITION:
       case UPD_CXX_ADDED_VAR_DEFINITION:
         break;
diff --git a/clang/lib/Serialization/ASTWriterDecl.cpp b/clang/lib/Serialization/ASTWriterDecl.cpp
index f021d82a6d2409..30c1ef403ecf01 100644
--- a/clang/lib/Serialization/ASTWriterDecl.cpp
+++ b/clang/lib/Serialization/ASTWriterDecl.cpp
@@ -213,24 +213,8 @@ namespace clang {
       llvm::MapVector<ModuleFile *, const Decl *> Firsts;
       CollectFirstDeclFromEachModule(D, /*IncludeLocal*/ true, Firsts);
 
-      for (const auto &F : Firsts) {
+      for (const auto &F : Firsts)
         SpecsInMap.push_back(F.second);
-
-        Record.AddDeclRef(F.second);
-        ArrayRef<TemplateArgument> Args;
-        if (auto *CTSD = dyn_cast<ClassTemplateSpecializationDecl>(D))
-          Args = CTSD->getTemplateArgs().asArray();
-        else if (auto *VTSD = dyn_cast<VarTemplateSpecializationDecl>(D))
-          Args = VTSD->getTemplateArgs().asArray();
-        else if (auto *FD = dyn_cast<FunctionDecl>(D))
-          Args = FD->getTemplateSpecializationArgs()->asArray();
-        assert(Args.size());
-        Record.push_back(TemplateArgumentList::ComputeODRHash(Args));
-        bool IsPartialSpecialization =
-            isa<ClassTemplatePartialSpecializationDecl>(D) ||
-            isa<VarTemplatePartialSpecializationDecl>(D);
-        Record.push_back(IsPartialSpecialization);
-      }
     }
 
     /// Get the specialization decl from an entry in the specialization list.
@@ -257,22 +241,12 @@ namespace clang {
       // If we have any lazy specializations, and the external AST source is
       // our chained AST reader, we can just write out the DeclIDs. Otherwise,
       // we need to resolve them to actual declarations.
-      if (Writer.Chain != Writer.Context->getExternalSource() &&
-          Common->LazySpecializations) {
+      if (Writer.Chain != Writer.Context->getExternalSource() && Writer.Chain &&
+          Writer.Chain->getLoadedSpecializationsLookupTables(D)) {
         D->LoadLazySpecializations();
-        assert(!Common->LazySpecializations);
+        assert(!Writer.Chain->getLoadedSpecializationsLookupTables(D));
       }
 
-      using LazySpecializationInfo =
-          RedeclarableTemplateDecl::LazySpecializationInfo;
-      ArrayRef<LazySpecializationInfo> LazySpecializations;
-      if (auto *LS = Common->LazySpecializations)
-        LazySpecializations = llvm::ArrayRef(LS + 1, LS[0].DeclID);
-
-      // Add a slot to the record for the number of specializations.
-      unsigned I = Record.size();
-      Record.push_back(0);
-
       // AddFirstDeclFromEachModule might trigger deserialization, invalidating
       // *Specializations iterators.
       llvm::SmallVector<const Decl*, 16> Specs;
@@ -288,21 +262,6 @@ namespace clang {
         AddFirstSpecializationDeclFromEachModule(D, SpecsInOnDiskMap);
       }
 
-      // We don't need to insert LazySpecializations to SpecsInOnDiskMap,
-      // since we'll handle that in GenerateSpeciali...
[truncated]

Comment on lines +244 to 251
if (Writer.Chain != Writer.Context->getExternalSource() && Writer.Chain &&
Writer.Chain->getLoadedSpecializationsLookupTables(D)) {
D->LoadLazySpecializations();
assert(!Common->LazySpecializations);
assert(!Writer.Chain->getLoadedSpecializationsLookupTables(D));
}
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During the process of rewriting, I just realized that this may be a significant change between D41416 and my original patch. In my original patch, I feel this is redundant since I think https://github.com/llvm/llvm-project/pull/83233/files#diff-6fe53759e8d797c328c73ada5f3324c6248a8634ef36131c7eb2b9d89192bb64R4082-R4084 can handle the external specialization. But this is not true. The process of loading specializations has a strong side effect that it may trigger more deserialization and probably loading other specializations. However, the process of re-inserting the OnDiskHashTable won't trigger deserialization. It simply moves stored hash value and the DeclID.

I guess this may be the problem why my original patch can't pass the workloads in google and ROOT. If it is the case, it shows that we lack in tree test cases for that.

@ChuanqiXu9
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@vgvassilev this may be ready to test.

@vgvassilev
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@vgvassilev this may be ready to test.

I triggered a test here: root-project/root#14495

I still need to verify if I did not screw up bringing your changes back to our builds but locally it crashes quite early with:

0  rootcling_stage1         0x00000001091d1c9d llvm::sys::PrintStackTrace(llvm::raw_ostream&, int) + 61
1  rootcling_stage1         0x00000001091d221b PrintStackTraceSignalHandler(void*) + 27
2  rootcling_stage1         0x00000001091cff06 llvm::sys::RunSignalHandlers() + 134
3  rootcling_stage1         0x00000001091d480f SignalHandler(int) + 223
4  libsystem_platform.dylib 0x00007ff800ad137d _sigtramp + 29
5  rootcling_stage1         0x0000000100059595 llvm::SmallVectorTemplateCommon<char, void>::assertSafeToReferenceAfterResize(void const*, unsigned long) + 37
6  libsystem_c.dylib        0x00007ff8009c1a49 abort + 126
7  libsystem_c.dylib        0x00007ff8009c0d30 err + 0
8  rootcling_stage1         0x00000001019959f0 llvm::SmallVectorTemplateCommon<unsigned long long, void>::operator[](unsigned long) const + 96
9  rootcling_stage1         0x00000001017d43d9 clang::ASTReader::ReadString(llvm::SmallVector<unsigned long long, 64u> const&, unsigned int&) + 57
10 rootcling_stage1         0x00000001017e0f0b clang::ASTReader::ParseLanguageOptions(llvm::SmallVector<unsigned long long, 64u> const&, bool, clang::ASTReaderListener&, bool) + 27691
11 rootcling_stage1         0x00000001017da096 clang::ASTReader::ReadOptionsBlock(llvm::BitstreamCursor&, unsigned int, bool, clang::ASTReaderListener&, std::__1::basic_string<char, std::__1::char_traits<char>, std::__1::allocator<char>>&) + 758
12 rootcling_stage1         0x00000001017e2537 clang::ASTReader::ReadControlBlock(clang::serialization::ModuleFile&, llvm::SmallVectorImpl<clang::ASTReader::ImportedModule>&, clang::serialization::ModuleFile const*, unsigned int) + 2487
13 rootcling_stage1         0x00000001017e487e clang::ASTReader::ReadASTCore(llvm::StringRef, clang::serialization::ModuleKind, clang::SourceLocation, clang::serialization::ModuleFile*, llvm::SmallVectorImpl<clang::ASTReader::ImportedModule>&, long long, long, clang::ASTFileSignature, unsigned int) + 2110
14 rootcling_stage1         0x00000001017efae3 clang::ASTReader::ReadAST(llvm::StringRef, clang::serialization::ModuleKind, clang::SourceLocation, unsigned int, llvm::SmallVectorImpl<clang::ASTReader::ImportedSubmodule>*) + 627
15 rootcling_stage1         0x0000000101249f53 clang::CompilerInstance::findOrCompileModuleAndReadAST(llvm::StringRef, clang::SourceLocation, clang::SourceLocation, bool) + 1443
16 rootcling_stage1         0x000000010124b4be clang::CompilerInstance::loadModule(clang::SourceLocation, llvm::ArrayRef<std::__1::pair<clang::IdentifierInfo*, clang::SourceLocation>>, clang::Module::NameVisibilityKind, bool) + 1006
17 rootcling_stage1         0x0000000103f6a144 clang::Preprocessor::HandleHeaderIncludeOrImport(clang::SourceLocation, clang::Token&, clang::Token&, clang::SourceLocation, clang::detail::SearchDirIteratorImpl<true>, clang::FileEntry const*) + 3348
18 rootcling_stage1         0x0000000103f648ec clang::Preprocessor::HandleIncludeDirective(clang::SourceLocation, clang::Token&, clang::detail::SearchDirIteratorImpl<true>, clang::FileEntry const*) + 316
19 rootcling_stage1         0x0000000103f65064 clang::Preprocessor::HandleDirective(clang::Token&) + 1412
20 rootcling_stage1         0x0000000103f07de8 clang::Lexer::LexTokenInternal(clang::Token&, bool) + 10120
21 rootcling_stage1         0x0000000103f032ce clang::Lexer::Lex(clang::Token&) + 270
22 rootcling_stage1         0x0000000103fd3cbf clang::Preprocessor::Lex(clang::Token&) + 111
23 rootcling_stage1         0x00000001005e1669 clang::Parser::ConsumeAnnotationToken() + 169
24 rootcling_stage1         0x00000001017ab553 clang::Parser::ParseTopLevelDecl(clang::OpaquePtr<clang::DeclGroupRef>&, clang::Sema::ModuleImportState&) + 1475
25 rootcling_stage1         0x0000000100583b29 clang::Parser::ParseTopLevelDecl() + 57
26 rootcling_stage1         0x00000001016b5d67 clang::Parser::ParseLinkage(clang::ParsingDeclSpec&, clang::DeclaratorContext) + 1303
27 rootcling_stage1         0x00000001017afa70 clang::Parser::ParseDeclOrFunctionDefInternal(clang::ParsedAttributes&, clang::ParsedAttributes&, clang::ParsingDeclSpec&, clang::AccessSpecifier) + 1792
28 rootcling_stage1         0x00000001017aef1a clang::Parser::ParseDeclarationOrFunctionDefinition(clang::ParsedAttributes&, clang::ParsedAttributes&, clang::ParsingDeclSpec*, clang::AccessSpecifier) + 218
29 rootcling_stage1         0x00000001017adeb0 clang::Parser::ParseExternalDeclaration(clang::ParsedAttributes&, clang::ParsedAttributes&, clang::ParsingDeclSpec*) + 3920
30 rootcling_stage1         0x00000001017ab8f3 clang::Parser::ParseTopLevelDecl(clang::OpaquePtr<clang::DeclGroupRef>&, clang::Sema::ModuleImportState&) + 2403
31 rootcling_stage1         0x00000001017aaf00 clang::Parser::ParseFirstTopLevelDecl(clang::OpaquePtr<clang::DeclGroupRef>&, clang::Sema::ModuleImportState&) + 64
32 rootcling_stage1         0x000000010167af3b clang::ParseAST(clang::Sema&, bool, bool) + 459
33 rootcling_stage1         0x000000010135a5cc clang::ASTFrontendAction::ExecuteAction() + 300
34 rootcling_stage1         0x0000000101359dcc clang::FrontendAction::Execute() + 124
35 rootcling_stage1         0x000000010124769d clang::CompilerInstance::ExecuteAction(clang::FrontendAction&) + 957
36 rootcling_stage1         0x000000010126e77d compileModuleImpl(clang::CompilerInstance&, clang::SourceLocation, llvm::StringRef, clang::FrontendInputFile, llvm::StringRef, llvm::StringRef, llvm::function_ref<void (clang::CompilerInstance&)>, llvm::function_ref<void (clang::CompilerInstance&)>)::$_5::operator()() const + 45
37 rootcling_stage1         0x000000010126e745 void llvm::function_ref<void ()>::callback_fn<compileModuleImpl(clang::CompilerInstance&, clang::SourceLocation, llvm::StringRef, clang::FrontendInputFile, llvm::StringRef, llvm::StringRef, llvm::function_ref<void (clang::CompilerInstance&)>, llvm::function_ref<void (clang::CompilerInstance&)>)::$_5>(long) + 21
38 rootcling_stage1         0x0000000108fc98e9 llvm::function_ref<void ()>::operator()() const + 25
39 rootcling_stage1         0x0000000108ff1bfc llvm::CrashRecoveryContext::RunSafely(llvm::function_ref<void ()>) + 236
40 rootcling_stage1         0x0000000108ff1fdf RunSafelyOnThread_Dispatch(void*) + 79
41 rootcling_stage1         0x0000000108ff2335 llvm::thread::thread<void (&)(void*), (anonymous namespace)::RunSafelyOnThreadInfo*>(std::__1::optional<unsigned int>, void (&)(void*), (anonymous namespace)::RunSafelyOnThreadInfo*&&) + 53
42 rootcling_stage1         0x0000000108ff202d llvm::thread::thread<void (&)(void*), (anonymous namespace)::RunSafelyOnThreadInfo*>(std::__1::optional<unsigned int>, void (&)(void*), (anonymous namespace)::RunSafelyOnThreadInfo*&&) + 45
43 rootcling_stage1         0x0000000108ff1ee5 llvm::CrashRecoveryContext::RunSafelyOnThread(llvm::function_ref<void ()>, unsigned int) + 149
44 rootcling_stage1         0x000000010124decb compileModuleImpl(clang::CompilerInstance&, clang::SourceLocation, llvm::StringRef, clang::FrontendInputFile, llvm::StringRef, llvm::StringRef, llvm::function_ref<void (clang::CompilerInstance&)>, llvm::function_ref<void (clang::CompilerInstance&)>) + 2171
45 rootcling_stage1         0x000000010125d719 compileModule(clang::CompilerInstance&, clang::SourceLocation, clang::Module*, llvm::StringRef) + 761
46 rootcling_stage1         0x000000010125d16f compileModuleAndReadASTImpl(clang::CompilerInstance&, clang::SourceLocation, clang::SourceLocation, clang::Module*, llvm::StringRef) + 79
47 rootcling_stage1         0x000000010125cee1 compileModuleAndReadASTBehindLock(clang::CompilerInstance&, clang::SourceLocation, clang::SourceLocation, clang::Module*, llvm::StringRef) + 673
48 rootcling_stage1         0x000000010124afde compileModuleAndReadAST(clang::CompilerInstance&, clang::SourceLocation, clang::SourceLocation, clang::Module*, llvm::StringRef) + 126
49 rootcling_stage1         0x000000010124a7c1 clang::CompilerInstance::findOrCompileModuleAndReadAST(llvm::StringRef, clang::SourceLocation, clang::SourceLocation, bool) + 3601
50 rootcling_stage1         0x000000010124b4be clang::CompilerInstance::loadModule(clang::SourceLocation, llvm::ArrayRef<std::__1::pair<clang::IdentifierInfo*, clang::SourceLocation>>, clang::Module::NameVisibilityKind, bool) + 1006
51 rootcling_stage1         0x0000000103f6a144 clang::Preprocessor::HandleHeaderIncludeOrImport(clang::SourceLocation, clang::Token&, clang::Token&, clang::SourceLocation, clang::detail::SearchDirIteratorImpl<true>, clang::FileEntry const*) + 3348
52 rootcling_stage1         0x0000000103f648ec clang::Preprocessor::HandleIncludeDirective(clang::SourceLocation, clang::Token&, clang::detail::SearchDirIteratorImpl<true>, clang::FileEntry const*) + 316
53 rootcling_stage1         0x0000000103f65064 clang::Preprocessor::HandleDirective(clang::Token&) + 1412
54 rootcling_stage1         0x0000000103f07de8 clang::Lexer::LexTokenInternal(clang::Token&, bool) + 10120
55 rootcling_stage1         0x0000000103f032ce clang::Lexer::Lex(clang::Token&) + 270
56 rootcling_stage1         0x0000000103fd3cbf clang::Preprocessor::Lex(clang::Token&) + 111
57 rootcling_stage1         0x00000001005da570 clang::Parser::ConsumeToken() + 144
58 rootcling_stage1         0x00000001017ab023 clang::Parser::ParseTopLevelDecl(clang::OpaquePtr<clang::DeclGroupRef>&, clang::Sema::ModuleImportState&) + 147
59 rootcling_stage1         0x00000001005843ea cling::IncrementalParser::ParseInternal(llvm::StringRef) + 2218
60 rootcling_stage1         0x0000000100583431 cling::IncrementalParser::Initialize(llvm::SmallVectorImpl<llvm::PointerIntPair<cling::Transaction*, 2u, cling::IncrementalParser::EParseResult, llvm::PointerLikeTypeTraits<cling::Transaction*>, llvm::PointerIntPairInfo<cling::Transaction*, 2u, llvm::PointerLikeTypeTraits<cling::Transaction*>>>>&, bool) + 1121
61 rootcling_stage1         0x00000001005a4233 cling::Interpreter::Interpreter(int, char const* const*, char const*, std::__1::vector<std::__1::shared_ptr<clang::ModuleFileExtension>, std::__1::allocator<std::__1::shared_ptr<clang::ModuleFileExtension>>> const&, void*, bool, cling::Interpreter const*) + 4131
62 rootcling_stage1         0x00000001005a5d80 cling::Interpreter::Interpreter(int, char const* const*, char const*, std::__1::vector<std::__1::shared_ptr<clang::ModuleFileExtension>, std::__1::allocator<std::__1::shared_ptr<clang::ModuleFileExtension>>> const&, void*, bool, cling::Interpreter const*) + 96
63 rootcling_stage1         0x00000001001acb2a cling::Interpreter::Interpreter(int, char const* const*, char const*, std::__1::vector<std::__1::shared_ptr<clang::ModuleFileExtension>, std::__1::allocator<std::__1::shared_ptr<clang::ModuleFileExtension>>> const&, void*, bool) + 90
64 rootcling_stage1         0x00000001001a384e RootClingMain(int, char**, bool) + 15838
65 rootcling_stage1         0x00000001001b390f ROOT_rootcling_Driver + 447
66 rootcling_stage1         0x0000000100003de4 main + 148
67 dyld                     0x000000022286a386 start + 1942

@ChuanqiXu9
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The error message looks odd since the language options shouldn't be involved.

@vgvassilev
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The error message looks odd since the language options shouldn't be involved.

Sorry, I did not push. Now you can take a look.

@ChuanqiXu9
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The error message looks odd since the language options shouldn't be involved.

Sorry, I did not push. Now you can take a look.

I mean your local results.

@ChuanqiXu9 ChuanqiXu9 force-pushed the users/ChuanqiXu9/D41416_on_disk_hash_table branch from 9a88b07 to 03e7d56 Compare March 5, 2024 03:35
@ChuanqiXu9 ChuanqiXu9 force-pushed the users/ChuanqiXu9/D41416_on_disk_hash_table_polishing branch 2 times, most recently from 19617bb to 1d288e7 Compare March 5, 2024 15:28
@ChuanqiXu9
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@ilya-biryukov hi, the functional and performance test on the root side looks good: root-project/root#14495 (comment)

Could you try to test this within google internals?

Also if your projects implements new ExternalASTSource, you need to handle that like I did in root: ChuanqiXu9/root@570fd78

@vgvassilev
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@ilya-biryukov hi, the functional and performance test on the root side looks good: root-project/root#14495 (comment)

Could you try to test this within google internals?

Also if your projects implements new ExternalASTSource, you need to handle that like I did in root: ChuanqiXu9/root@570fd78

@ilya-biryukov, can you test this PR on your side. We'd like to move forward.

cc: @dwblaikie

@ilya-biryukov
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We'll pick this up, I'll get back with the testing results.
(Sorry for the delayed response)

@ilya-biryukov
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Btw, if I don't respond timely to these requests and you need an urgent reaction, feel free to ping me via email at ibiryukov@google.com.
We heavily use Clang header modules internally at Google and we are really interested in helping to discover and prevent the module bugs as early as possible. And we also really appreciate your work on improving and optimizing the modules implementation!

@vgvassilev
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Btw, if I don't respond timely to these requests and you need an urgent reaction, feel free to ping me via email at ibiryukov@google.com. We heavily use Clang header modules internally at Google and we are really interested in helping to discover and prevent the module bugs as early as possible. And we also really appreciate your work on improving and optimizing the modules implementation!

@ilya-biryukov, I was wondering if you have had a chance to test this PR?

@ChuanqiXu9
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@vgvassilev BTW, I found all of pages: #83108, #83233 and #83237 doesn't say here is a conflict. Do we need to rebase in this case?

@ilya-biryukov
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Sorry for the delay, I had an emergency and took a week off.
We have hit some form of OOM (an infinite loop or some exponential computation allocating memory?) on the following small example (ready as a test case, also in this commit):

// RUN: rm -rf %t
// RUN: mkdir -p %t
// RUN: split-file %s %t
//
// RUN: %clang_cc1 -std=c++20 %t/type_traits.cppm -emit-module-interface -o %t/type_traits.pcm
// RUN: %clang_cc1 -std=c++20 %t/test.cpp -fprebuilt-module-path=%t -verify

//--- type_traits.cppm
export module type_traits;

export template <typename T>
constexpr bool is_pod_v = __is_pod(T);

//--- test.cpp
import type_traits;
// Base is either void or wrapper<T>.
template <class Base> struct wrapper : Base {};
template <> struct wrapper<void> {};

// wrap<0>::type<T> is wrapper<T>, wrap<1>::type<T> is wrapper<wrapper<T>>,
// and so on.
template <int N>
struct wrap {
  template <class Base>
  using type = wrapper<typename wrap<N-1>::template type<Base>>;
};

template <>
struct wrap<0> {
  template <class Base>
  using type = wrapper<Base>;
};

inline constexpr int kMaxRank = 40;
template <int N, class Base = void>
using rank = typename wrap<N>::template type<Base>;
using rank_selector_t = rank<40>;

static_assert(is_pod_v<rank_selector_t>, "Must be POD");

There might be more problems as this one has been caught early and blocked further progress.

@ChuanqiXu9 ChuanqiXu9 force-pushed the users/ChuanqiXu9/D41416_on_disk_hash_table branch from 03e7d56 to f87a54e Compare April 7, 2024 06:02
@ChuanqiXu9 ChuanqiXu9 force-pushed the users/ChuanqiXu9/D41416_on_disk_hash_table_polishing branch from 1d288e7 to 859705c Compare April 7, 2024 06:02
@ChuanqiXu9
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Thanks for the reduced test case. It is pretty helpful. I've added it to the current patch.

The root cause of the issue comes from an oversight in https://github.com/llvm/llvm-project/pull/83108/files#diff-dffd10772d07fb8c737cdf812839afa0173447c4812698c0c19618c34d92daddR806-R829. That we calculate the ODR Hash for class template specialization twice. Then for the example you described, the linear recursive computation becomes to somewhat similar to fibonacci computation:

wrap<40> -> wrap<39>  -> wrap<38> -> ...
                  |                        -> wrap<38>
                   -> wrap<39> -> wrap<38>
                                           -> wrap<38>

This test case passes quickly now after I remove the duplicated ODR computation.

@ilya-biryukov
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Thanks for fixing it quickly, we'll try the new patch and get back with the results.

@ilya-biryukov
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We have hit quite a few issues when trying this out. I have spent a day trying to reduce to a small repro that I can share, but haven't not fully succeeded yet, I will continue tomorrow.
Still wanted to share the error descriptions in case that would allow to make progress in the meanwhile.

  • Crash with the following assertion failure:
assert.h assertion failed at third_party/llvm/llvm-project/clang/include/clang/AST/DeclCXX.h:464 in struct DefinitionData &clang::CXXRecordDecl::data() const: DD && "queried property of class with no definition"
*** Check failure stack trace: ***
    @     0x55fb619aaea4  absl::log_internal::LogMessage::SendToLog()
    @     0x55fb619aad04  absl::log_internal::LogMessage::Flush()
    @     0x55fb619ab209  absl::log_internal::LogMessageFatal::~LogMessageFatal()
    @     0x55fb6199a3e4  __assert_fail
    @     0x55fb5bd8d400  clang::CXXRecordDecl::data()
    @     0x55fb5e24de0d  clang::CXXBasePaths::lookupInBases()
    @     0x55fb5e24e388  clang::CXXBasePaths::lookupInBases()
    @     0x55fb5e24d55c  clang::CXXRecordDecl::lookupInBases()
    @     0x55fb5da8bd60  clang::Sema::LookupQualifiedName()
    @     0x55fb5dc747f3  clang::Sema::CheckTypenameType()
    @     0x55fb5de19e72  clang::TreeTransform<>::TransformDependentNameType()
    @     0x55fb5ddee35c  clang::TreeTransform<>::TransformType()
    @     0x55fb5ddedd3f  clang::TreeTransform<>::TransformType()
    @     0x55fb5dded94d  clang::Sema::SubstType()
    @     0x55fb5dc62c9f  SubstDefaultTemplateArgument()
    @     0x55fb5dc58761  clang::Sema::CheckTemplateArgumentList()
    @     0x55fb5dc5720b  clang::Sema::CheckTemplateIdType()
    @     0x55fb5de19086  clang::TreeTransform<>::TransformTemplateSpecializationType()
    @     0x55fb5de2115d  clang::TreeTransform<>::TransformTemplateSpecializationType()
    @     0x55fb5ddee280  clang::TreeTransform<>::TransformType()
    @     0x55fb5de1dc1a  clang::TreeTransform<>::TransformElaboratedType()
    @     0x55fb5ddee3c4  clang::TreeTransform<>::TransformType()
    @     0x55fb5ddedd3f  clang::TreeTransform<>::TransformType()
    @     0x55fb5dded94d  clang::Sema::SubstType()
    @     0x55fb5dc62c9f  SubstDefaultTemplateArgument()
    @     0x55fb5dc62632  clang::Sema::SubstDefaultTemplateArgumentIfAvailable()
    @     0x55fb5dd7056b  clang::Sema::FinishTemplateArgumentDeduction()
    @     0x55fb5dde5796  llvm::function_ref<>::callback_fn<>()
    @     0x55fb5d420dcf  clang::Sema::runWithSufficientStackSpace()
    @     0x55fb5dd729f4  clang::Sema::DeduceTemplateArguments()
    @     0x55fb5dbc00d5  clang::Sema::AddTemplateOverloadCandidate()
    @     0x55fb5da7065d  ResolveConstructorOverload()
    @     0x55fb5da52dd8  TryConstructorInitialization()
    @     0x55fb5da50e7a  TryDefaultInitialization()
    @     0x55fb5da4e6b1  clang::InitializationSequence::InitializeFrom()
    @     0x55fb5d72c3ed  CollectFieldInitializer()
    @     0x55fb5d72a972  clang::Sema::SetCtorInitializers()
    @     0x55fb5d72ef65  clang::Sema::ActOnDefaultCtorInitializers()
    @     0x55fb5d2401b0  clang::Parser::ParseLexedMethodDef()
    @     0x55fb5d23e77a  clang::Parser::ParseLexedMethodDefs()
    @     0x55fb5d1b50e0  clang::Parser::ParseCXXMemberSpecification()
    @     0x55fb5d1b2744  clang::Parser::ParseClassSpecifier()
    @     0x55fb5d1d8ef0  clang::Parser::ParseDeclarationSpecifiers()
    @     0x55fb5d15ea4a  clang::Parser::ParseDeclOrFunctionDefInternal()
    @     0x55fb5d15e5b6  clang::Parser::ParseDeclarationOrFunctionDefinition()
    @     0x55fb5d15d2ea  clang::Parser::ParseExternalDeclaration()
    @     0x55fb5d1a8c73  clang::Parser::ParseInnerNamespace()
    @     0x55fb5d1a7e4f  clang::Parser::ParseNamespace()
    @     0x55fb5d1d2bde  clang::Parser::ParseDeclaration()
    @     0x55fb5d15ceb6  clang::Parser::ParseExternalDeclaration()
    @     0x55fb5d1a8c73  clang::Parser::ParseInnerNamespace()
    @     0x55fb5d1a7e4f  clang::Parser::ParseNamespace()
    @     0x55fb5d1d2bde  clang::Parser::ParseDeclaration()
    @     0x55fb5d15ceb6  clang::Parser::ParseExternalDeclaration()
    @     0x55fb5d15b04b  clang::Parser::ParseTopLevelDecl()
    @     0x55fb5d154d2e  clang::ParseAST()
    @     0x55fb5cea31e3  clang::FrontendAction::Execute()
    @     0x55fb5ce1c62d  clang::CompilerInstance::ExecuteAction()
    @     0x55fb5bd4a20e  clang::ExecuteCompilerInvocation()
    @     0x55fb5bd3e106  cc1_main()
    @     0x55fb5bd3b9a6  ExecuteCC1Tool()
  • Invalid errors about absence or presence of certain members in std::pointer_traits and other types:
third_party/crosstool/v18/stable/toolchain/bin/../include/c++/v1/__memory/pointer_traits.h:161:3: error: 'std::pointer_traits<const proto2::FieldDescriptor **>::pointer_to' from module '/
/third_party/crosstool/v18/stable:stl_cc_library.third_party/stl/cxx17/optional' is not present in definition of 'std::pointer_traits<const proto2::FieldDescriptor **>' provided earlier
  161 |   pointer_to(__conditional_t<is_void<element_type>::value, __nat, element_type>& __r) _NOEXCEPT {
      |   ^
third_party/crosstool/v18/stable/toolchain/bin/../include/c++/v1/__memory/pointer_traits.h:138:29: note: definition has no member 'pointer_to'
  138 | struct _LIBCPP_TEMPLATE_VIS pointer_traits : __pointer_traits_impl<_Ptr> {};
      |                             ^
In module '//third_party/crosstool/v18/stable:stl_cc_library':
third_party/crosstool/v18/stable/toolchain/bin/../include/c++/v1/__memory/pointer_traits.h:161:3: error: multiple overloads of 'pointer_to' instantiate to the same signature 'pointer (__c
onditional_t<is_void<element_type>::value, __nat, element_type> &) noexcept' (aka 'const proto2::FieldDescriptor **(const proto2::FieldDescriptor *&) noexcept')
  161 |   pointer_to(__conditional_t<is_void<element_type>::value, __nat, element_type>& __r) _NOEXCEPT {
      |   ^
third_party/crosstool/v18/stable/toolchain/bin/../include/c++/v1/__memory/allocator_traits.h:68:41: note: in instantiation of template class 'std::pointer_traits<const proto2::FieldDescri
ptor **>' requested here
   68 |   using type _LIBCPP_NODEBUG = typename pointer_traits<_Ptr>::template rebind<const _Tp>;
      |                                         ^
third_party/crosstool/v18/stable/toolchain/bin/../include/c++/v1/__memory/allocator_traits.h:251:39: note: in instantiation of template class 'std::__const_pointer<const proto2::FieldDesc
riptor *, const proto2::FieldDescriptor **, std::allocator<const proto2::FieldDescriptor *>>' requested here
  251 |   using const_pointer      = typename __const_pointer<value_type, pointer, allocator_type>::type;
      |                                       ^
third_party/crosstool/v18/stable/toolchain/bin/../include/c++/v1/vector:399:20: note: in instantiation of template class 'std::allocator_traits<std::allocator<const proto2::FieldDescripto
r *>>' requested here
  399 |   typedef typename __alloc_traits::size_type size_type;
      |                    ^
maps/render/pipeline/signals-side-input-utils.cc:3:47: note: in instantiation of template class 'std::vector<const proto2::FieldDescriptor *>' requested here
    3 |   std::vector<const proto2::FieldDescriptor*> filter_subfield_descriptors_;
      |                                               ^
third_party/crosstool/v18/stable/toolchain/bin/../include/c++/v1/__memory/pointer_traits.h:161:3: note: previous declaration is here
  161 |   pointer_to(__conditional_t<is_void<element_type>::value, __nat, element_type>& __r) _NOEXCEPT {

  • Errors from "different definitions", probably coming from invalid merging or ODR hashing
third_party/absl/functional/any_invocable.h:170:3: error: 'absl::AnyInvocable<void () &&>' has different definitions in different modules; first difference is defined here found constructor with body
  170 |   AnyInvocable() noexcept = default;
      |   ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
third_party/absl/functional/any_invocable.h:170:3: note: but in '//third_party/absl/functional:any_invocable.third_party/absl/functional/any_invocable.h' found constructor with different body
  170 |   AnyInvocable() noexcept = default;
      |   ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
1 error generated.
  • Some significant compile-time regressions (up to 33%).
    Unfortunately that's on internal code, will need further investigation to profile or reduce.

  • Some compilations timed out. This needs more investigation to see if that was a flake, but likely not.

@ilya-biryukov
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Sorry, still struggling to get a small repro. The build graphs we have are quite large, unfortunately.
Did any of the stack traces or error message I posted help to find certain problems? Or is there no hope until we get a smaller repro?

@vgvassilev
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Can you export all files into a standalone reproducer? I might be able to reduce an example.

@ilya-biryukov
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Can you export all files into a standalone reproducer? I might be able to reduce an example.

Not really, this is why it's taking so long. Our infrastructure in that space is lacking, the issue is that the root case is not in one compilation step, but rather in some of the dependencies and the dependency graph for any of those problems is really large.

We will get you a reproducer, please bear with us. Sorry for taking a long time.

@vgvassilev
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Can you export all files into a standalone reproducer? I might be able to reduce an example.

Not really, this is why it's taking so long. Our infrastructure in that space is lacking, the issue is that the root case is not in one compilation step, but rather in some of the dependencies and the dependency graph for any of those problems is really large.

We will get you a reproducer, please bear with us. Sorry for taking a long time.

Back in the day when we were more active developing modules we wrote this tool: https://github.com/Teemperor/hippie It hooks to the system calls and copies all files involved in a crash/miscompilation under a common sysroot preserving the file structure. Maybe that'd help...

@ChuanqiXu9
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Sorry, still struggling to get a small repro. The build graphs we have are quite large, unfortunately. Did any of the stack traces or error message I posted help to find certain problems? Or is there no hope until we get a smaller repro?

I tried to review the patch purely but it looks like not easy to fix the failures without reproducers... for performances, I am wondering if we can improve it by caching the hash results. But it will be helpful if we can have profile data for that.

A lot thanks for testing this.

@ChuanqiXu9 ChuanqiXu9 force-pushed the users/ChuanqiXu9/D41416_on_disk_hash_table_polishing branch from 859705c to d7a7273 Compare April 25, 2024 09:46
@ChuanqiXu9
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Rebased with main

@alexfh
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alexfh commented Apr 29, 2024

Apologies for the delay with the reproducer. @ilya-biryukov is on vacation, but maybe @sam-mccall can help with an isolated test case. Either way it seems to be challenging.

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After endless hours and recompilations, I finally have this to share.
It could probably be smaller, but I decided to share this as soon as it crashed outside of our monorepo.

module.tgz
^^ If you run build.sh with Clang 16, it builds. However, it fails with the current patch.
See out/errors for a list of errors I get on my machine.
This breaks with libstdc++ 13, but also latest libc++ (which is what we use in our monorepo).

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5 participants