D41416: [modules] [pch] Do not deserialize all lazy template specializations when looking for one.

Fix test mismatch failure

fmt

[Serialization] Introduce OnDiskHashTable for specializations

Following up for llvm#83108

This follows the suggestion literally from
llvm#76774 (comment)

which introduces OnDiskHashTable for specializations based on D41416.

Note that I didn't polish this patch to reduce the diff from D41416 to
it easier to review. I'll make the polishing patch later. So that we can
focus what we're doing in this patch and focus on the style in the next
patch.

[Serialization] Code cleanups and polish 83233

Author: vgvassilev

clang/include/clang/AST/DeclTemplate.h

@@ -256,6 +256,9 @@ class TemplateArgumentList final
   TemplateArgumentList(const TemplateArgumentList &) = delete;
   TemplateArgumentList &operator=(const TemplateArgumentList &) = delete;
 
+  /// 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.
   static TemplateArgumentList *CreateCopy(ASTContext &Context,
@@ -730,6 +733,7 @@ class RedeclarableTemplateDecl : public TemplateDecl,
   }
 
   void anchor() override;
+
 protected:
   template <typename EntryType> struct SpecEntryTraits {
     using DeclType = EntryType;
@@ -770,13 +774,22 @@ class RedeclarableTemplateDecl : public TemplateDecl,
     return SpecIterator<EntryType>(isEnd ? Specs.end() : Specs.begin());
   }
 
-  void loadLazySpecializationsImpl() const;
+  void loadLazySpecializationsImpl(bool OnlyPartial = false) const;
+
+  bool loadLazySpecializationsImpl(llvm::ArrayRef<TemplateArgument> Args,
+                                   TemplateParameterList *TPL = nullptr) const;
 
   template <class EntryType, typename ...ProfileArguments>
   typename SpecEntryTraits<EntryType>::DeclType*
   findSpecializationImpl(llvm::FoldingSetVector<EntryType> &Specs,
                          void *&InsertPos, ProfileArguments &&...ProfileArgs);
 
+  template <class EntryType, typename... ProfileArguments>
+  typename SpecEntryTraits<EntryType>::DeclType *
+  findSpecializationLocally(llvm::FoldingSetVector<EntryType> &Specs,
+                            void *&InsertPos,
+                            ProfileArguments &&...ProfileArgs);
+
   template <class Derived, class EntryType>
   void addSpecializationImpl(llvm::FoldingSetVector<EntryType> &Specs,
                              EntryType *Entry, void *InsertPos);
@@ -792,13 +805,6 @@ 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.
-    uint32_t *LazySpecializations = nullptr;
-
     /// The set of "injected" template arguments used within this
     /// template.
     ///
@@ -2268,7 +2274,7 @@ class ClassTemplateDecl : public RedeclarableTemplateDecl {
   friend class TemplateDeclInstantiator;
 
   /// Load any lazily-loaded specializations from the external source.
-  void LoadLazySpecializations() const;
+  void LoadLazySpecializations(bool OnlyPartial = false) const;
 
   /// Get the underlying class declarations of the template.
   CXXRecordDecl *getTemplatedDecl() const {
@@ -3039,7 +3045,7 @@ class VarTemplateDecl : public RedeclarableTemplateDecl {
   friend class ASTDeclWriter;
 
   /// Load any lazily-loaded specializations from the external source.
-  void LoadLazySpecializations() const;
+  void LoadLazySpecializations(bool OnlyPartial = false) const;
 
   /// Get the underlying variable declarations of the template.
   VarDecl *getTemplatedDecl() const {

clang/include/clang/AST/ExternalASTSource.h

@@ -150,6 +150,19 @@ class ExternalASTSource : public RefCountedBase<ExternalASTSource> {
   virtual bool
   FindExternalVisibleDeclsByName(const DeclContext *DC, DeclarationName Name);
 
+  /// Load all the external specializations for the Decl \param D if \param
+  /// OnlyPartial is false. Otherwise, load all the external **partial**
+  /// specializations for the \param D.
+  virtual void LoadExternalSpecializations(const Decl *D, bool OnlyPartial);
+
+  /// Load all the specializations for the Decl \param D with the same template
+  /// args specified by \param TemplateArgs.
+  ///
+  /// Return true if any new specializations get loaded. Return false otherwise.
+  virtual bool
+  LoadExternalSpecializations(const Decl *D,
+                              ArrayRef<TemplateArgument> TemplateArgs);
+
   /// Ensures that the table of all visible declarations inside this
   /// context is up to date.
   ///

clang/include/clang/Sema/MultiplexExternalSemaSource.h

@@ -97,6 +97,12 @@ class MultiplexExternalSemaSource : public ExternalSemaSource {
   bool FindExternalVisibleDeclsByName(const DeclContext *DC,
                                       DeclarationName Name) override;
 
+  void LoadExternalSpecializations(const Decl *D, bool OnlyPartial) override;
+
+  bool
+  LoadExternalSpecializations(const Decl *D,
+                              ArrayRef<TemplateArgument> TemplateArgs) override;
+
   /// Ensures that the table of all visible declarations inside this
   /// context is up to date.
   void completeVisibleDeclsMap(const DeclContext *DC) override;

clang/include/clang/Serialization/ASTBitCodes.h

@@ -698,6 +698,8 @@ enum ASTRecordTypes {
   /// Record code for an unterminated \#pragma clang assume_nonnull begin
   /// recorded in a preamble.
   PP_ASSUME_NONNULL_LOC = 67,
+
+  CXX_ADDED_TEMPLATE_SPECIALIZATION = 68,
 };
 
 /// Record types used within a source manager block.
@@ -1523,6 +1525,9 @@ enum DeclCode {
   /// A HLSLBufferDecl record.
   DECL_HLSL_BUFFER,
 
+  // A decls specilization record.
+  DECL_SPECIALIZATIONS,
+
   /// An ImplicitConceptSpecializationDecl record.
   DECL_IMPLICIT_CONCEPT_SPECIALIZATION,
 

clang/include/clang/Serialization/ASTReader.h

@@ -340,6 +340,9 @@ class ASTIdentifierLookupTrait;
 /// The on-disk hash table(s) used for DeclContext name lookup.
 struct DeclContextLookupTable;
 
+/// The on-disk hash table(s) used for specialization decls.
+struct LazySpecializationInfoLookupTable;
+
 } // namespace reader
 
 } // namespace serialization
@@ -603,21 +606,30 @@ class ASTReader
   llvm::DenseMap<const DeclContext *,
                  serialization::reader::DeclContextLookupTable> Lookups;
 
+  /// Map from decls to specialized decls.
+  llvm::DenseMap<const Decl *,
+                 serialization::reader::LazySpecializationInfoLookupTable>
+      SpecializationsLookups;
+
   // Updates for visible decls can occur for other contexts than just the
   // TU, and when we read those update records, the actual context may not
   // be available yet, so have this pending map using the ID as a key. It
-  // will be realized when the context is actually loaded.
-  struct PendingVisibleUpdate {
+  // will be realized when the data is actually loaded.
+  struct UpdateData {
     ModuleFile *Mod;
     const unsigned char *Data;
   };
-  using DeclContextVisibleUpdates = SmallVector<PendingVisibleUpdate, 1>;
+  using DeclContextVisibleUpdates = SmallVector<UpdateData, 1>;
 
   /// Updates to the visible declarations of declaration contexts that
   /// haven't been loaded yet.
   llvm::DenseMap<serialization::DeclID, DeclContextVisibleUpdates>
       PendingVisibleUpdates;
 
+  using SpecializationsUpdate = SmallVector<UpdateData, 1>;
+  llvm::DenseMap<serialization::DeclID, SpecializationsUpdate>
+      PendingSpecializationsUpdates;
+
   /// The set of C++ or Objective-C classes that have forward
   /// declarations that have not yet been linked to their definitions.
   llvm::SmallPtrSet<Decl *, 4> PendingDefinitions;
@@ -644,6 +656,11 @@ class ASTReader
                                      llvm::BitstreamCursor &Cursor,
                                      uint64_t Offset, serialization::DeclID ID);
 
+  bool ReadSpecializations(ModuleFile &M, llvm::BitstreamCursor &Cursor,
+                           uint64_t Offset, Decl *D);
+  void AddSpecializations(const Decl *D, const unsigned char *Data,
+                          ModuleFile &M);
+
   /// A vector containing identifiers that have already been
   /// loaded.
   ///
@@ -1348,6 +1365,11 @@ class ASTReader
   const serialization::reader::DeclContextLookupTable *
   getLoadedLookupTables(DeclContext *Primary) const;
 
+  /// Get the loaded specializations lookup tables for \p D,
+  /// if any.
+  serialization::reader::LazySpecializationInfoLookupTable *
+  getLoadedSpecializationsLookupTables(const Decl *D);
+
 private:
   struct ImportedModule {
     ModuleFile *Mod;
@@ -1982,6 +2004,12 @@ class ASTReader
                                       unsigned BlockID,
                                       uint64_t *StartOfBlockOffset = nullptr);
 
+  void LoadExternalSpecializations(const Decl *D, bool OnlyPartial) override;
+
+  bool
+  LoadExternalSpecializations(const Decl *D,
+                              ArrayRef<TemplateArgument> TemplateArgs) override;
+
   /// Finds all the visible declarations with a given name.
   /// The current implementation of this method just loads the entire
   /// lookup table as unmaterialized references.

clang/include/clang/Serialization/ASTWriter.h

@@ -389,6 +389,10 @@ class ASTWriter : public ASTDeserializationListener,
   /// record containing modifications to them.
   DeclUpdateMap DeclUpdates;
 
+  using SpecializationUpdateMap =
+      llvm::MapVector<const NamedDecl *, SmallVector<const Decl *>>;
+  SpecializationUpdateMap SpecializationsUpdates;
+
   using FirstLatestDeclMap = llvm::DenseMap<Decl *, Decl *>;
 
   /// Map of first declarations from a chained PCH that point to the
@@ -531,6 +535,12 @@ class ASTWriter : public ASTDeserializationListener,
   bool isLookupResultExternal(StoredDeclsList &Result, DeclContext *DC);
   bool isLookupResultEntirelyExternal(StoredDeclsList &Result, DeclContext *DC);
 
+  void GenerateSpecializationInfoLookupTable(
+      const NamedDecl *D, llvm::SmallVectorImpl<const Decl *> &Specializations,
+      llvm::SmallVectorImpl<char> &LookupTable);
+  uint64_t WriteSpecializationInfoLookupTable(
+      const NamedDecl *D, llvm::SmallVectorImpl<const Decl *> &Specializations);
+
   void GenerateNameLookupTable(const DeclContext *DC,
                                llvm::SmallVectorImpl<char> &LookupTable);
   uint64_t WriteDeclContextLexicalBlock(ASTContext &Context, DeclContext *DC);
@@ -542,6 +552,7 @@ class ASTWriter : public ASTDeserializationListener,
   void WriteReferencedSelectorsPool(Sema &SemaRef);
   void WriteIdentifierTable(Preprocessor &PP, IdentifierResolver &IdResolver,
                             bool IsModule);
+  void WriteSpecializationsUpdates();
   void WriteDeclUpdatesBlocks(RecordDataImpl &OffsetsRecord);
   void WriteDeclContextVisibleUpdate(const DeclContext *DC);
   void WriteFPPragmaOptions(const FPOptionsOverride &Opts);
@@ -568,6 +579,8 @@ class ASTWriter : public ASTDeserializationListener,
   unsigned DeclEnumAbbrev = 0;
   unsigned DeclObjCIvarAbbrev = 0;
   unsigned DeclCXXMethodAbbrev = 0;
+  unsigned DeclSpecializationsAbbrev = 0;
+
   unsigned DeclDependentNonTemplateCXXMethodAbbrev = 0;
   unsigned DeclTemplateCXXMethodAbbrev = 0;
   unsigned DeclMemberSpecializedCXXMethodAbbrev = 0;