Revert "[serialization] no transitive decl change (#92083)"

This reverts commit 5c10487.

The ArmV7 bot is complaining the change breaks the alignment.

Author: ChuanqiXu9

clang/include/clang/AST/ASTUnresolvedSet.h

@@ -16,7 +16,6 @@
 
 #include "clang/AST/ASTVector.h"
 #include "clang/AST/DeclAccessPair.h"
-#include "clang/AST/DeclID.h"
 #include "clang/AST/UnresolvedSet.h"
 #include "clang/Basic/Specifiers.h"
 #include <cassert>
@@ -57,10 +56,6 @@ class ASTUnresolvedSet {
     Decls.push_back(DeclAccessPair::make(D, AS), C);
   }
 
-  void addLazyDecl(ASTContext &C, GlobalDeclID ID, AccessSpecifier AS) {
-    Decls.push_back(DeclAccessPair::makeLazy(ID.get(), AS), C);
-  }
-
   /// Replaces the given declaration with the new one, once.
   ///
   /// \return true if the set changed
@@ -114,10 +109,10 @@ class LazyASTUnresolvedSet {
 
   void reserve(ASTContext &C, unsigned N) { Impl.reserve(C, N); }
 
-  void addLazyDecl(ASTContext &C, GlobalDeclID ID, AccessSpecifier AS) {
+  void addLazyDecl(ASTContext &C, uintptr_t ID, AccessSpecifier AS) {
     assert(Impl.empty() || Impl.Decls.isLazy());
     Impl.Decls.setLazy(true);
-    Impl.addLazyDecl(C, ID, AS);
+    Impl.addDecl(C, reinterpret_cast<NamedDecl *>(ID << 2), AS);
   }
 };
 

clang/include/clang/AST/DeclAccessPair.h

@@ -27,17 +27,9 @@ class NamedDecl;
 /// A POD class for pairing a NamedDecl* with an access specifier.
 /// Can be put into unions.
 class DeclAccessPair {
-  /// Use the lower 2 bit to store AccessSpecifier. Use the higher
-  /// 61 bit to store the pointer to a NamedDecl or the DeclID to
-  /// a NamedDecl. If the 3rd bit is set, storing the DeclID, otherwise
-  /// storing the pointer.
-  //
-  // we'd use llvm::PointerUnion, but it isn't trivial
-  uint64_t Ptr;
+  uintptr_t Ptr; // we'd use llvm::PointerUnion, but it isn't trivial
 
-  enum { ASMask = 0x3, Mask = 0x7 };
-
-  bool isDeclID() const { return (Ptr >> 2) & 0x1; }
+  enum { Mask = 0x3 };
 
 public:
   static DeclAccessPair make(NamedDecl *D, AccessSpecifier AS) {
@@ -46,22 +38,12 @@ class DeclAccessPair {
     return p;
   }
 
-  static DeclAccessPair makeLazy(uint64_t ID, AccessSpecifier AS) {
-    DeclAccessPair p;
-    p.Ptr = (ID << 3) | (0x1 << 2) | uint64_t(AS);
-    return p;
-  }
-
-  uint64_t getDeclID() const {
-    assert(isDeclID());
-    return (~Mask & Ptr) >> 3;
-  }
-
   NamedDecl *getDecl() const {
-    assert(!isDeclID());
     return reinterpret_cast<NamedDecl*>(~Mask & Ptr);
   }
-  AccessSpecifier getAccess() const { return AccessSpecifier(ASMask & Ptr); }
+  AccessSpecifier getAccess() const {
+    return AccessSpecifier(Mask & Ptr);
+  }
 
   void setDecl(NamedDecl *D) {
     set(D, getAccess());
@@ -70,7 +52,7 @@ class DeclAccessPair {
     set(getDecl(), AS);
   }
   void set(NamedDecl *D, AccessSpecifier AS) {
-    Ptr = uint64_t(AS) | reinterpret_cast<uint64_t>(D);
+    Ptr = uintptr_t(AS) | reinterpret_cast<uintptr_t>(D);
   }
 
   operator NamedDecl*() const { return getDecl(); }

clang/include/clang/AST/DeclBase.h

@@ -708,7 +708,10 @@ class alignas(8) Decl {
 
   /// Set the owning module ID.  This may only be called for
   /// deserialized Decls.
-  void setOwningModuleID(unsigned ID);
+  void setOwningModuleID(unsigned ID) {
+    assert(isFromASTFile() && "Only works on a deserialized declaration");
+    *((unsigned*)this - 2) = ID;
+  }
 
 public:
   /// Determine the availability of the given declaration.
@@ -781,11 +784,19 @@ class alignas(8) Decl {
 
   /// Retrieve the global declaration ID associated with this
   /// declaration, which specifies where this Decl was loaded from.
-  GlobalDeclID getGlobalID() const;
+  GlobalDeclID getGlobalID() const {
+    if (isFromASTFile())
+      return (*((const GlobalDeclID *)this - 1));
+    return GlobalDeclID();
+  }
 
   /// Retrieve the global ID of the module that owns this particular
   /// declaration.
-  unsigned getOwningModuleID() const;
+  unsigned getOwningModuleID() const {
+    if (isFromASTFile())
+      return *((const unsigned*)this - 2);
+    return 0;
+  }
 
 private:
   Module *getOwningModuleSlow() const;

clang/include/clang/AST/DeclID.h

@@ -19,8 +19,6 @@
 #include "llvm/ADT/DenseMapInfo.h"
 #include "llvm/ADT/iterator.h"
 
-#include <climits>
-
 namespace clang {
 
 /// Predefined declaration IDs.
@@ -109,16 +107,12 @@ class DeclIDBase {
   ///
   /// DeclID should only be used directly in serialization. All other users
   /// should use LocalDeclID or GlobalDeclID.
-  using DeclID = uint64_t;
+  using DeclID = uint32_t;
 
 protected:
   DeclIDBase() : ID(PREDEF_DECL_NULL_ID) {}
   explicit DeclIDBase(DeclID ID) : ID(ID) {}
 
-  explicit DeclIDBase(unsigned LocalID, unsigned ModuleFileIndex) {
-    ID = (DeclID)LocalID | ((DeclID)ModuleFileIndex << 32);
-  }
-
 public:
   DeclID get() const { return ID; }
 
@@ -130,10 +124,6 @@ class DeclIDBase {
 
   bool isInvalid() const { return ID == PREDEF_DECL_NULL_ID; }
 
-  unsigned getModuleFileIndex() const { return ID >> 32; }
-
-  unsigned getLocalDeclIndex() const;
-
   friend bool operator==(const DeclIDBase &LHS, const DeclIDBase &RHS) {
     return LHS.ID == RHS.ID;
   }
@@ -166,9 +156,6 @@ class LocalDeclID : public DeclIDBase {
   LocalDeclID(PredefinedDeclIDs ID) : Base(ID) {}
   explicit LocalDeclID(DeclID ID) : Base(ID) {}
 
-  explicit LocalDeclID(unsigned LocalID, unsigned ModuleFileIndex)
-      : Base(LocalID, ModuleFileIndex) {}
-
   LocalDeclID &operator++() {
     ++ID;
     return *this;
@@ -188,9 +175,6 @@ class GlobalDeclID : public DeclIDBase {
   GlobalDeclID() : Base() {}
   explicit GlobalDeclID(DeclID ID) : Base(ID) {}
 
-  explicit GlobalDeclID(unsigned LocalID, unsigned ModuleFileIndex)
-      : Base(LocalID, ModuleFileIndex) {}
-
   // For DeclIDIterator<GlobalDeclID> to be able to convert a GlobalDeclID
   // to a LocalDeclID.
   explicit operator LocalDeclID() const { return LocalDeclID(this->ID); }

clang/include/clang/AST/UnresolvedSet.h

@@ -47,7 +47,6 @@ class UnresolvedSetIterator : public llvm::iterator_adaptor_base<
   // temporaries with defaulted ctors are not zero initialized.
   UnresolvedSetIterator() : iterator_adaptor_base(nullptr) {}
 
-  uint64_t getDeclID() const { return I->getDeclID(); }
   NamedDecl *getDecl() const { return I->getDecl(); }
   void setDecl(NamedDecl *ND) const { return I->setDecl(ND); }
   AccessSpecifier getAccess() const { return I->getAccess(); }

clang/include/clang/Serialization/ASTBitCodes.h

@@ -255,12 +255,6 @@ class DeclOffset {
   }
 };
 
-// The unaligned decl ID used in the Blobs of bistreams.
-using unaligned_decl_id_t =
-    llvm::support::detail::packed_endian_specific_integral<
-        serialization::DeclID, llvm::endianness::native,
-        llvm::support::unaligned>;
-
 /// The number of predefined preprocessed entity IDs.
 const unsigned int NUM_PREDEF_PP_ENTITY_IDS = 1;
 
@@ -1986,44 +1980,33 @@ enum CleanupObjectKind { COK_Block, COK_CompoundLiteral };
 
 /// Describes the categories of an Objective-C class.
 struct ObjCCategoriesInfo {
-  // The ID of the definition. Use unaligned_decl_id_t to keep
-  // ObjCCategoriesInfo 32-bit aligned.
-  unaligned_decl_id_t DefinitionID;
+  // The ID of the definition
+  LocalDeclID DefinitionID;
 
   // Offset into the array of category lists.
   unsigned Offset;
 
-  ObjCCategoriesInfo() = default;
-  ObjCCategoriesInfo(LocalDeclID ID, unsigned Offset)
-      : DefinitionID(ID.get()), Offset(Offset) {}
-
-  LocalDeclID getDefinitionID() const { return LocalDeclID(DefinitionID); }
-
   friend bool operator<(const ObjCCategoriesInfo &X,
                         const ObjCCategoriesInfo &Y) {
-    return X.getDefinitionID() < Y.getDefinitionID();
+    return X.DefinitionID < Y.DefinitionID;
   }
 
   friend bool operator>(const ObjCCategoriesInfo &X,
                         const ObjCCategoriesInfo &Y) {
-    return X.getDefinitionID() > Y.getDefinitionID();
+    return X.DefinitionID > Y.DefinitionID;
   }
 
   friend bool operator<=(const ObjCCategoriesInfo &X,
                          const ObjCCategoriesInfo &Y) {
-    return X.getDefinitionID() <= Y.getDefinitionID();
+    return X.DefinitionID <= Y.DefinitionID;
   }
 
   friend bool operator>=(const ObjCCategoriesInfo &X,
                          const ObjCCategoriesInfo &Y) {
-    return X.getDefinitionID() >= Y.getDefinitionID();
+    return X.DefinitionID >= Y.DefinitionID;
   }
 };
 
-static_assert(alignof(ObjCCategoriesInfo) <= 4);
-static_assert(std::is_standard_layout_v<ObjCCategoriesInfo> &&
-              std::is_trivial_v<ObjCCategoriesInfo>);
-
 /// A key used when looking up entities by \ref DeclarationName.
 ///
 /// Different \ref DeclarationNames are mapped to different keys, but the

clang/include/clang/Serialization/ASTReader.h

@@ -504,6 +504,12 @@ class ASTReader
   /// = I + 1 has already been loaded.
   llvm::PagedVector<Decl *> DeclsLoaded;
 
+  using GlobalDeclMapType = ContinuousRangeMap<GlobalDeclID, ModuleFile *, 4>;
+
+  /// Mapping from global declaration IDs to the module in which the
+  /// declaration resides.
+  GlobalDeclMapType GlobalDeclMap;
+
   using FileOffset = std::pair<ModuleFile *, uint64_t>;
   using FileOffsetsTy = SmallVector<FileOffset, 2>;
   using DeclUpdateOffsetsMap = llvm::DenseMap<GlobalDeclID, FileOffsetsTy>;
@@ -586,11 +592,10 @@ class ASTReader
 
   struct FileDeclsInfo {
     ModuleFile *Mod = nullptr;
-    ArrayRef<serialization::unaligned_decl_id_t> Decls;
+    ArrayRef<LocalDeclID> Decls;
 
     FileDeclsInfo() = default;
-    FileDeclsInfo(ModuleFile *Mod,
-                  ArrayRef<serialization::unaligned_decl_id_t> Decls)
+    FileDeclsInfo(ModuleFile *Mod, ArrayRef<LocalDeclID> Decls)
         : Mod(Mod), Decls(Decls) {}
   };
 
@@ -599,7 +604,11 @@ class ASTReader
 
   /// An array of lexical contents of a declaration context, as a sequence of
   /// Decl::Kind, DeclID pairs.
-  using LexicalContents = ArrayRef<serialization::unaligned_decl_id_t>;
+  using unaligned_decl_id_t =
+      llvm::support::detail::packed_endian_specific_integral<
+          serialization::DeclID, llvm::endianness::native,
+          llvm::support::unaligned>;
+  using LexicalContents = ArrayRef<unaligned_decl_id_t>;
 
   /// Map from a DeclContext to its lexical contents.
   llvm::DenseMap<const DeclContext*, std::pair<ModuleFile*, LexicalContents>>
@@ -1480,23 +1489,22 @@ class ASTReader
                                unsigned ClientLoadCapabilities);
 
 public:
-  class ModuleDeclIterator
-      : public llvm::iterator_adaptor_base<
-            ModuleDeclIterator, const serialization::unaligned_decl_id_t *,
-            std::random_access_iterator_tag, const Decl *, ptrdiff_t,
-            const Decl *, const Decl *> {
+  class ModuleDeclIterator : public llvm::iterator_adaptor_base<
+                                 ModuleDeclIterator, const LocalDeclID *,
+                                 std::random_access_iterator_tag, const Decl *,
+                                 ptrdiff_t, const Decl *, const Decl *> {
     ASTReader *Reader = nullptr;
     ModuleFile *Mod = nullptr;
 
   public:
     ModuleDeclIterator() : iterator_adaptor_base(nullptr) {}
 
     ModuleDeclIterator(ASTReader *Reader, ModuleFile *Mod,
-                       const serialization::unaligned_decl_id_t *Pos)
+                       const LocalDeclID *Pos)
         : iterator_adaptor_base(Pos), Reader(Reader), Mod(Mod) {}
 
     value_type operator*() const {
-      return Reader->GetDecl(Reader->getGlobalDeclID(*Mod, (LocalDeclID)*I));
+      return Reader->GetDecl(Reader->getGlobalDeclID(*Mod, *I));
     }
 
     value_type operator->() const { return **this; }
@@ -1536,9 +1544,6 @@ class ASTReader
              StringRef Arg2 = StringRef(), StringRef Arg3 = StringRef()) const;
   void Error(llvm::Error &&Err) const;
 
-  /// Translate a \param GlobalDeclID to the index of DeclsLoaded array.
-  unsigned translateGlobalDeclIDToIndex(GlobalDeclID ID) const;
-
 public:
   /// Load the AST file and validate its contents against the given
   /// Preprocessor.
@@ -1910,8 +1915,7 @@ class ASTReader
 
   /// Retrieve the module file that owns the given declaration, or NULL
   /// if the declaration is not from a module file.
-  ModuleFile *getOwningModuleFile(const Decl *D) const;
-  ModuleFile *getOwningModuleFile(GlobalDeclID ID) const;
+  ModuleFile *getOwningModuleFile(const Decl *D);
 
   /// Returns the source location for the decl \p ID.
   SourceLocation getSourceLocationForDeclID(GlobalDeclID ID);

clang/include/clang/Serialization/ModuleFile.h

@@ -454,11 +454,23 @@ class ModuleFile {
   /// by the declaration ID (-1).
   const DeclOffset *DeclOffsets = nullptr;
 
-  /// Base declaration index in ASTReader for declarations local to this module.
-  unsigned BaseDeclIndex = 0;
+  /// Base declaration ID for declarations local to this module.
+  serialization::DeclID BaseDeclID = 0;
+
+  /// Remapping table for declaration IDs in this module.
+  ContinuousRangeMap<serialization::DeclID, int, 2> DeclRemap;
+
+  /// Mapping from the module files that this module file depends on
+  /// to the base declaration ID for that module as it is understood within this
+  /// module.
+  ///
+  /// This is effectively a reverse global-to-local mapping for declaration
+  /// IDs, so that we can interpret a true global ID (for this translation unit)
+  /// as a local ID (for this module file).
+  llvm::DenseMap<ModuleFile *, serialization::DeclID> GlobalToLocalDeclIDs;
 
   /// Array of file-level DeclIDs sorted by file.
-  const serialization::unaligned_decl_id_t *FileSortedDecls = nullptr;
+  const LocalDeclID *FileSortedDecls = nullptr;
   unsigned NumFileSortedDecls = 0;
 
   /// Array of category list location information within this

clang/include/clang/Serialization/ModuleManager.h

@@ -45,7 +45,7 @@ namespace serialization {
 /// Manages the set of modules loaded by an AST reader.
 class ModuleManager {
   /// The chain of AST files, in the order in which we started to load
-  /// them.
+  /// them (this order isn't really useful for anything).
   SmallVector<std::unique_ptr<ModuleFile>, 2> Chain;
 
   /// The chain of non-module PCH files. The first entry is the one named