[clang] 4f70c5e - Revert "[serialization] no transitive decl change (#92083)"

Chuanqi Xu via cfe-commits cfe-commits at lists.llvm.org
Thu Jun 6 20:29:52 PDT 2024


Author: Chuanqi Xu
Date: 2024-06-07T11:29:09+08:00
New Revision: 4f70c5ec4a57e84642fa0772536f120cd9c75edb

URL: https://github.com/llvm/llvm-project/commit/4f70c5ec4a57e84642fa0772536f120cd9c75edb
DIFF: https://github.com/llvm/llvm-project/commit/4f70c5ec4a57e84642fa0772536f120cd9c75edb.diff

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

This reverts commit 5c104879c1a98eeb845c03e7c45206bd48e88f0c.

The ArmV7 bot is complaining the change breaks the alignment.

Added: 
    

Modified: 
    clang/include/clang/AST/ASTUnresolvedSet.h
    clang/include/clang/AST/DeclAccessPair.h
    clang/include/clang/AST/DeclBase.h
    clang/include/clang/AST/DeclID.h
    clang/include/clang/AST/UnresolvedSet.h
    clang/include/clang/Serialization/ASTBitCodes.h
    clang/include/clang/Serialization/ASTReader.h
    clang/include/clang/Serialization/ModuleFile.h
    clang/include/clang/Serialization/ModuleManager.h
    clang/lib/AST/DeclBase.cpp
    clang/lib/AST/DeclCXX.cpp
    clang/lib/Serialization/ASTReader.cpp
    clang/lib/Serialization/ASTReaderDecl.cpp
    clang/lib/Serialization/ASTWriter.cpp
    clang/lib/Serialization/ModuleFile.cpp

Removed: 
    clang/test/Modules/no-transitive-decls-change.cppm


################################################################################
diff  --git a/clang/include/clang/AST/ASTUnresolvedSet.h b/clang/include/clang/AST/ASTUnresolvedSet.h
index dcce3bc63df25..398ffb188c95b 100644
--- a/clang/include/clang/AST/ASTUnresolvedSet.h
+++ b/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);
   }
 };
 

diff  --git a/clang/include/clang/AST/DeclAccessPair.h b/clang/include/clang/AST/DeclAccessPair.h
index 17f29c3e97cea..805342c2910a7 100644
--- a/clang/include/clang/AST/DeclAccessPair.h
+++ b/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(); }

diff  --git a/clang/include/clang/AST/DeclBase.h b/clang/include/clang/AST/DeclBase.h
index 5f19af1891b74..600ce73c7f019 100644
--- a/clang/include/clang/AST/DeclBase.h
+++ b/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;

diff  --git a/clang/include/clang/AST/DeclID.h b/clang/include/clang/AST/DeclID.h
index 32d2ed41a374a..614ba06b63860 100644
--- a/clang/include/clang/AST/DeclID.h
+++ b/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); }

diff  --git a/clang/include/clang/AST/UnresolvedSet.h b/clang/include/clang/AST/UnresolvedSet.h
index 1369725ab4e96..ee31be969b6e3 100644
--- a/clang/include/clang/AST/UnresolvedSet.h
+++ b/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(); }

diff  --git a/clang/include/clang/Serialization/ASTBitCodes.h b/clang/include/clang/Serialization/ASTBitCodes.h
index 52a6c5e10f802..f59ff6af4c764 100644
--- a/clang/include/clang/Serialization/ASTBitCodes.h
+++ b/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 
diff erent keys, but the

diff  --git a/clang/include/clang/Serialization/ASTReader.h b/clang/include/clang/Serialization/ASTReader.h
index 0a9006223dcbd..bea58d60d36c4 100644
--- a/clang/include/clang/Serialization/ASTReader.h
+++ b/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>>
@@ -1480,11 +1489,10 @@ 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 *, ptr
diff _t,
-            const Decl *, const Decl *> {
+  class ModuleDeclIterator : public llvm::iterator_adaptor_base<
+                                 ModuleDeclIterator, const LocalDeclID *,
+                                 std::random_access_iterator_tag, const Decl *,
+                                 ptr
diff _t, const Decl *, const Decl *> {
     ASTReader *Reader = nullptr;
     ModuleFile *Mod = nullptr;
 
@@ -1492,11 +1500,11 @@ class ASTReader
     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);

diff  --git a/clang/include/clang/Serialization/ModuleFile.h b/clang/include/clang/Serialization/ModuleFile.h
index 56193d44dd6f3..992d26a8b88c1 100644
--- a/clang/include/clang/Serialization/ModuleFile.h
+++ b/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

diff  --git a/clang/include/clang/Serialization/ModuleManager.h b/clang/include/clang/Serialization/ModuleManager.h
index f898dab39f06d..d770bc52eaf4f 100644
--- a/clang/include/clang/Serialization/ModuleManager.h
+++ b/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

diff  --git a/clang/lib/AST/DeclBase.cpp b/clang/lib/AST/DeclBase.cpp
index 7f1ed9c691e98..1e9c879e371bc 100644
--- a/clang/lib/AST/DeclBase.cpp
+++ b/clang/lib/AST/DeclBase.cpp
@@ -74,17 +74,18 @@ void *Decl::operator new(std::size_t Size, const ASTContext &Context,
                          GlobalDeclID ID, std::size_t Extra) {
   // Allocate an extra 8 bytes worth of storage, which ensures that the
   // resulting pointer will still be 8-byte aligned.
-  static_assert(sizeof(uint64_t) >= alignof(Decl), "Decl won't be misaligned");
+  static_assert(sizeof(unsigned) * 2 >= alignof(Decl),
+                "Decl won't be misaligned");
   void *Start = Context.Allocate(Size + Extra + 8);
   void *Result = (char*)Start + 8;
 
-  uint64_t *PrefixPtr = (uint64_t *)Result - 1;
+  unsigned *PrefixPtr = (unsigned *)Result - 2;
 
-  *PrefixPtr = ID.get();
+  // Zero out the first 4 bytes; this is used to store the owning module ID.
+  PrefixPtr[0] = 0;
 
-  // We leave the upper 16 bits to store the module IDs. 48 bits should be
-  // sufficient to store a declaration ID.
-  assert(*PrefixPtr < llvm::maskTrailingOnes<uint64_t>(48));
+  // Store the global declaration ID in the second 4 bytes.
+  PrefixPtr[1] = ID.get();
 
   return Result;
 }
@@ -110,29 +111,6 @@ void *Decl::operator new(std::size_t Size, const ASTContext &Ctx,
   return ::operator new(Size + Extra, Ctx);
 }
 
-GlobalDeclID Decl::getGlobalID() const {
-  if (!isFromASTFile())
-    return GlobalDeclID();
-  // See the comments in `Decl::operator new` for details.
-  uint64_t ID = *((const uint64_t *)this - 1);
-  return GlobalDeclID(ID & llvm::maskTrailingOnes<uint64_t>(48));
-}
-
-unsigned Decl::getOwningModuleID() const {
-  if (!isFromASTFile())
-    return 0;
-
-  uint64_t ID = *((const uint64_t *)this - 1);
-  return ID >> 48;
-}
-
-void Decl::setOwningModuleID(unsigned ID) {
-  assert(isFromASTFile() && "Only works on a deserialized declaration");
-  uint64_t *IDAddress = (uint64_t *)this - 1;
-  *IDAddress &= llvm::maskTrailingOnes<uint64_t>(48);
-  *IDAddress |= (uint64_t)ID << 48;
-}
-
 Module *Decl::getOwningModuleSlow() const {
   assert(isFromASTFile() && "Not from AST file?");
   return getASTContext().getExternalSource()->getModule(getOwningModuleID());
@@ -2185,7 +2163,3 @@ DependentDiagnostic *DependentDiagnostic::Create(ASTContext &C,
 
   return DD;
 }
-
-unsigned DeclIDBase::getLocalDeclIndex() const {
-  return ID & llvm::maskTrailingOnes<DeclID>(32);
-}

diff  --git a/clang/lib/AST/DeclCXX.cpp b/clang/lib/AST/DeclCXX.cpp
index 7f2c786547b9b..75c441293d62e 100644
--- a/clang/lib/AST/DeclCXX.cpp
+++ b/clang/lib/AST/DeclCXX.cpp
@@ -68,8 +68,8 @@ void LazyASTUnresolvedSet::getFromExternalSource(ASTContext &C) const {
   assert(Source && "getFromExternalSource with no external source");
 
   for (ASTUnresolvedSet::iterator I = Impl.begin(); I != Impl.end(); ++I)
-    I.setDecl(
-        cast<NamedDecl>(Source->GetExternalDecl(GlobalDeclID(I.getDeclID()))));
+    I.setDecl(cast<NamedDecl>(Source->GetExternalDecl(
+        GlobalDeclID(reinterpret_cast<uintptr_t>(I.getDecl()) >> 2))));
   Impl.Decls.setLazy(false);
 }
 

diff  --git a/clang/lib/Serialization/ASTReader.cpp b/clang/lib/Serialization/ASTReader.cpp
index 59338b44db32f..33cea32c3be61 100644
--- a/clang/lib/Serialization/ASTReader.cpp
+++ b/clang/lib/Serialization/ASTReader.cpp
@@ -1658,7 +1658,7 @@ bool ASTReader::ReadSLocEntry(int ID) {
 
     unsigned NumFileDecls = Record[7];
     if (NumFileDecls && ContextObj) {
-      const unaligned_decl_id_t *FirstDecl = F->FileSortedDecls + Record[6];
+      const LocalDeclID *FirstDecl = F->FileSortedDecls + Record[6];
       assert(F->FileSortedDecls && "FILE_SORTED_DECLS not encountered yet ?");
       FileDeclIDs[FID] =
           FileDeclsInfo(F, llvm::ArrayRef(FirstDecl, NumFileDecls));
@@ -3377,11 +3377,26 @@ llvm::Error ASTReader::ReadASTBlock(ModuleFile &F,
             "duplicate DECL_OFFSET record in AST file");
       F.DeclOffsets = (const DeclOffset *)Blob.data();
       F.LocalNumDecls = Record[0];
-      F.BaseDeclIndex = getTotalNumDecls();
+      unsigned LocalBaseDeclID = Record[1];
+      F.BaseDeclID = getTotalNumDecls();
 
-      if (F.LocalNumDecls > 0)
-        DeclsLoaded.resize(DeclsLoaded.size() + F.LocalNumDecls);
+      if (F.LocalNumDecls > 0) {
+        // Introduce the global -> local mapping for declarations within this
+        // module.
+        GlobalDeclMap.insert(std::make_pair(
+            GlobalDeclID(getTotalNumDecls() + NUM_PREDEF_DECL_IDS), &F));
+
+        // Introduce the local -> global mapping for declarations within this
+        // module.
+        F.DeclRemap.insertOrReplace(
+          std::make_pair(LocalBaseDeclID, F.BaseDeclID - LocalBaseDeclID));
+
+        // Introduce the global -> local mapping for declarations within this
+        // module.
+        F.GlobalToLocalDeclIDs[&F] = LocalBaseDeclID;
 
+        DeclsLoaded.resize(DeclsLoaded.size() + F.LocalNumDecls);
+      }
       break;
     }
 
@@ -3616,7 +3631,7 @@ llvm::Error ASTReader::ReadASTBlock(ModuleFile &F,
       break;
 
     case FILE_SORTED_DECLS:
-      F.FileSortedDecls = (const unaligned_decl_id_t *)Blob.data();
+      F.FileSortedDecls = (const LocalDeclID *)Blob.data();
       F.NumFileSortedDecls = Record[0];
       break;
 
@@ -4043,6 +4058,7 @@ void ASTReader::ReadModuleOffsetMap(ModuleFile &F) const {
   RemapBuilder PreprocessedEntityRemap(F.PreprocessedEntityRemap);
   RemapBuilder SubmoduleRemap(F.SubmoduleRemap);
   RemapBuilder SelectorRemap(F.SelectorRemap);
+  RemapBuilder DeclRemap(F.DeclRemap);
   RemapBuilder TypeRemap(F.TypeRemap);
 
   auto &ImportedModuleVector = F.TransitiveImports;
@@ -4081,6 +4097,8 @@ void ASTReader::ReadModuleOffsetMap(ModuleFile &F) const {
         endian::readNext<uint32_t, llvm::endianness::little>(Data);
     uint32_t SelectorIDOffset =
         endian::readNext<uint32_t, llvm::endianness::little>(Data);
+    uint32_t DeclIDOffset =
+        endian::readNext<uint32_t, llvm::endianness::little>(Data);
     uint32_t TypeIndexOffset =
         endian::readNext<uint32_t, llvm::endianness::little>(Data);
 
@@ -4098,7 +4116,11 @@ void ASTReader::ReadModuleOffsetMap(ModuleFile &F) const {
               PreprocessedEntityRemap);
     mapOffset(SubmoduleIDOffset, OM->BaseSubmoduleID, SubmoduleRemap);
     mapOffset(SelectorIDOffset, OM->BaseSelectorID, SelectorRemap);
+    mapOffset(DeclIDOffset, OM->BaseDeclID, DeclRemap);
     mapOffset(TypeIndexOffset, OM->BaseTypeIndex, TypeRemap);
+
+    // Global -> local mappings.
+    F.GlobalToLocalDeclIDs[OM] = DeclIDOffset;
   }
 }
 
@@ -4623,7 +4645,7 @@ ASTReader::ASTReadResult ASTReader::ReadAST(StringRef FileName, ModuleKind Type,
   // that we load any additional categories.
   if (ContextObj) {
     for (unsigned I = 0, N = ObjCClassesLoaded.size(); I != N; ++I) {
-      loadObjCCategories(ObjCClassesLoaded[I]->getGlobalID(),
+      loadObjCCategories(GlobalDeclID(ObjCClassesLoaded[I]->getGlobalID()),
                          ObjCClassesLoaded[I], PreviousGeneration);
     }
   }
@@ -7622,25 +7644,18 @@ CXXBaseSpecifier *ASTReader::GetExternalCXXBaseSpecifiers(uint64_t Offset) {
 
 GlobalDeclID ASTReader::getGlobalDeclID(ModuleFile &F,
                                         LocalDeclID LocalID) const {
-  if (LocalID.get() < NUM_PREDEF_DECL_IDS)
-    return GlobalDeclID(LocalID.get());
-
-  unsigned OwningModuleFileIndex = LocalID.getModuleFileIndex();
-  DeclID ID = LocalID.getLocalDeclIndex();
+  DeclID ID = LocalID.get();
+  if (ID < NUM_PREDEF_DECL_IDS)
+    return GlobalDeclID(ID);
 
   if (!F.ModuleOffsetMap.empty())
     ReadModuleOffsetMap(F);
 
-  ModuleFile *OwningModuleFile =
-      OwningModuleFileIndex == 0
-          ? &F
-          : F.TransitiveImports[OwningModuleFileIndex - 1];
-
-  if (OwningModuleFileIndex == 0)
-    ID -= NUM_PREDEF_DECL_IDS;
+  ContinuousRangeMap<DeclID, int, 2>::iterator I =
+      F.DeclRemap.find(ID - NUM_PREDEF_DECL_IDS);
+  assert(I != F.DeclRemap.end() && "Invalid index into decl index remap");
 
-  uint64_t NewModuleFileIndex = OwningModuleFile->Index + 1;
-  return GlobalDeclID(ID, NewModuleFileIndex);
+  return GlobalDeclID(ID + I->second);
 }
 
 bool ASTReader::isDeclIDFromModule(GlobalDeclID ID, ModuleFile &M) const {
@@ -7648,33 +7663,31 @@ bool ASTReader::isDeclIDFromModule(GlobalDeclID ID, ModuleFile &M) const {
   if (ID.get() < NUM_PREDEF_DECL_IDS)
     return false;
 
-  unsigned ModuleFileIndex = ID.getModuleFileIndex();
-  return M.Index == ModuleFileIndex - 1;
-}
-
-ModuleFile *ASTReader::getOwningModuleFile(GlobalDeclID ID) const {
-  // Predefined decls aren't from any module.
-  if (ID.get() < NUM_PREDEF_DECL_IDS)
-    return nullptr;
-
-  uint64_t ModuleFileIndex = ID.getModuleFileIndex();
-  assert(ModuleFileIndex && "Untranslated Local Decl?");
-
-  return &getModuleManager()[ModuleFileIndex - 1];
+  return ID.get() - NUM_PREDEF_DECL_IDS >= M.BaseDeclID &&
+         ID.get() - NUM_PREDEF_DECL_IDS < M.BaseDeclID + M.LocalNumDecls;
 }
 
-ModuleFile *ASTReader::getOwningModuleFile(const Decl *D) const {
+ModuleFile *ASTReader::getOwningModuleFile(const Decl *D) {
   if (!D->isFromASTFile())
     return nullptr;
-
-  return getOwningModuleFile(D->getGlobalID());
+  GlobalDeclMapType::const_iterator I =
+      GlobalDeclMap.find(GlobalDeclID(D->getGlobalID()));
+  assert(I != GlobalDeclMap.end() && "Corrupted global declaration map");
+  return I->second;
 }
 
 SourceLocation ASTReader::getSourceLocationForDeclID(GlobalDeclID ID) {
   if (ID.get() < NUM_PREDEF_DECL_IDS)
     return SourceLocation();
 
-  if (Decl *D = GetExistingDecl(ID))
+  unsigned Index = ID.get() - NUM_PREDEF_DECL_IDS;
+
+  if (Index > DeclsLoaded.size()) {
+    Error("declaration ID out-of-range for AST file");
+    return SourceLocation();
+  }
+
+  if (Decl *D = DeclsLoaded[Index])
     return D->getLocation();
 
   SourceLocation Loc;
@@ -7741,19 +7754,8 @@ static Decl *getPredefinedDecl(ASTContext &Context, PredefinedDeclIDs ID) {
   llvm_unreachable("PredefinedDeclIDs unknown enum value");
 }
 
-unsigned ASTReader::translateGlobalDeclIDToIndex(GlobalDeclID GlobalID) const {
-  ModuleFile *OwningModuleFile = getOwningModuleFile(GlobalID);
-  if (!OwningModuleFile) {
-    assert(GlobalID.get() < NUM_PREDEF_DECL_IDS && "Untransalted Global ID?");
-    return GlobalID.get();
-  }
-
-  return OwningModuleFile->BaseDeclIndex + GlobalID.getLocalDeclIndex();
-}
-
 Decl *ASTReader::GetExistingDecl(GlobalDeclID ID) {
   assert(ContextObj && "reading decl with no AST context");
-
   if (ID.get() < NUM_PREDEF_DECL_IDS) {
     Decl *D = getPredefinedDecl(*ContextObj, (PredefinedDeclIDs)ID);
     if (D) {
@@ -7766,7 +7768,7 @@ Decl *ASTReader::GetExistingDecl(GlobalDeclID ID) {
     return D;
   }
 
-  unsigned Index = translateGlobalDeclIDToIndex(ID);
+  unsigned Index = ID.get() - NUM_PREDEF_DECL_IDS;
 
   if (Index >= DeclsLoaded.size()) {
     assert(0 && "declaration ID out-of-range for AST file");
@@ -7781,7 +7783,7 @@ Decl *ASTReader::GetDecl(GlobalDeclID ID) {
   if (ID.get() < NUM_PREDEF_DECL_IDS)
     return GetExistingDecl(ID);
 
-  unsigned Index = translateGlobalDeclIDToIndex(ID);
+  unsigned Index = ID.get() - NUM_PREDEF_DECL_IDS;
 
   if (Index >= DeclsLoaded.size()) {
     assert(0 && "declaration ID out-of-range for AST file");
@@ -7800,31 +7802,20 @@ Decl *ASTReader::GetDecl(GlobalDeclID ID) {
 
 LocalDeclID ASTReader::mapGlobalIDToModuleFileGlobalID(ModuleFile &M,
                                                        GlobalDeclID GlobalID) {
-  if (GlobalID.get() < NUM_PREDEF_DECL_IDS)
-    return LocalDeclID(GlobalID.get());
-
-  if (!M.ModuleOffsetMap.empty())
-    ReadModuleOffsetMap(M);
-
-  ModuleFile *Owner = getOwningModuleFile(GlobalID);
-  DeclID ID = GlobalID.getLocalDeclIndex();
-
-  if (Owner == &M) {
-    ID += NUM_PREDEF_DECL_IDS;
+  DeclID ID = GlobalID.get();
+  if (ID < NUM_PREDEF_DECL_IDS)
     return LocalDeclID(ID);
-  }
 
-  uint64_t OrignalModuleFileIndex = 0;
-  for (unsigned I = 0; I < M.TransitiveImports.size(); I++)
-    if (M.TransitiveImports[I] == Owner) {
-      OrignalModuleFileIndex = I + 1;
-      break;
-    }
+  GlobalDeclMapType::const_iterator I = GlobalDeclMap.find(GlobalID);
+  assert(I != GlobalDeclMap.end() && "Corrupted global declaration map");
+  ModuleFile *Owner = I->second;
 
-  if (!OrignalModuleFileIndex)
+  llvm::DenseMap<ModuleFile *, DeclID>::iterator Pos =
+      M.GlobalToLocalDeclIDs.find(Owner);
+  if (Pos == M.GlobalToLocalDeclIDs.end())
     return LocalDeclID();
 
-  return LocalDeclID(ID, OrignalModuleFileIndex);
+  return LocalDeclID(ID - Owner->BaseDeclID + Pos->second);
 }
 
 GlobalDeclID ASTReader::ReadDeclID(ModuleFile &F, const RecordData &Record,
@@ -7903,34 +7894,32 @@ void ASTReader::FindExternalLexicalDecls(
 
 namespace {
 
-class UnalignedDeclIDComp {
+class DeclIDComp {
   ASTReader &Reader;
   ModuleFile &Mod;
 
 public:
-  UnalignedDeclIDComp(ASTReader &Reader, ModuleFile &M)
-      : Reader(Reader), Mod(M) {}
+  DeclIDComp(ASTReader &Reader, ModuleFile &M) : Reader(Reader), Mod(M) {}
 
-  bool operator()(unaligned_decl_id_t L, unaligned_decl_id_t R) const {
+  bool operator()(LocalDeclID L, LocalDeclID R) const {
     SourceLocation LHS = getLocation(L);
     SourceLocation RHS = getLocation(R);
     return Reader.getSourceManager().isBeforeInTranslationUnit(LHS, RHS);
   }
 
-  bool operator()(SourceLocation LHS, unaligned_decl_id_t R) const {
+  bool operator()(SourceLocation LHS, LocalDeclID R) const {
     SourceLocation RHS = getLocation(R);
     return Reader.getSourceManager().isBeforeInTranslationUnit(LHS, RHS);
   }
 
-  bool operator()(unaligned_decl_id_t L, SourceLocation RHS) const {
+  bool operator()(LocalDeclID L, SourceLocation RHS) const {
     SourceLocation LHS = getLocation(L);
     return Reader.getSourceManager().isBeforeInTranslationUnit(LHS, RHS);
   }
 
-  SourceLocation getLocation(unaligned_decl_id_t ID) const {
+  SourceLocation getLocation(LocalDeclID ID) const {
     return Reader.getSourceManager().getFileLoc(
-        Reader.getSourceLocationForDeclID(
-            Reader.getGlobalDeclID(Mod, (LocalDeclID)ID)));
+            Reader.getSourceLocationForDeclID(Reader.getGlobalDeclID(Mod, ID)));
   }
 };
 
@@ -7953,8 +7942,8 @@ void ASTReader::FindFileRegionDecls(FileID File,
     BeginLoc = SM.getLocForStartOfFile(File).getLocWithOffset(Offset);
   SourceLocation EndLoc = BeginLoc.getLocWithOffset(Length);
 
-  UnalignedDeclIDComp DIDComp(*this, *DInfo.Mod);
-  ArrayRef<unaligned_decl_id_t>::iterator BeginIt =
+  DeclIDComp DIDComp(*this, *DInfo.Mod);
+  ArrayRef<LocalDeclID>::iterator BeginIt =
       llvm::lower_bound(DInfo.Decls, BeginLoc, DIDComp);
   if (BeginIt != DInfo.Decls.begin())
     --BeginIt;
@@ -7963,18 +7952,17 @@ void ASTReader::FindFileRegionDecls(FileID File,
   // to backtrack until we find it otherwise we will fail to report that the
   // region overlaps with an objc container.
   while (BeginIt != DInfo.Decls.begin() &&
-         GetDecl(getGlobalDeclID(*DInfo.Mod, (LocalDeclID)(*BeginIt)))
+         GetDecl(getGlobalDeclID(*DInfo.Mod, *BeginIt))
              ->isTopLevelDeclInObjCContainer())
     --BeginIt;
 
-  ArrayRef<unaligned_decl_id_t>::iterator EndIt =
+  ArrayRef<LocalDeclID>::iterator EndIt =
       llvm::upper_bound(DInfo.Decls, EndLoc, DIDComp);
   if (EndIt != DInfo.Decls.end())
     ++EndIt;
 
-  for (ArrayRef<unaligned_decl_id_t>::iterator DIt = BeginIt; DIt != EndIt;
-       ++DIt)
-    Decls.push_back(GetDecl(getGlobalDeclID(*DInfo.Mod, (LocalDeclID)(*DIt))));
+  for (ArrayRef<LocalDeclID>::iterator DIt = BeginIt; DIt != EndIt; ++DIt)
+    Decls.push_back(GetDecl(getGlobalDeclID(*DInfo.Mod, *DIt)));
 }
 
 bool
@@ -8181,6 +8169,7 @@ LLVM_DUMP_METHOD void ASTReader::dump() {
   dumpModuleIDMap("Global bit offset map", GlobalBitOffsetsMap);
   dumpModuleIDMap("Global source location entry map", GlobalSLocEntryMap);
   dumpModuleIDMap("Global type map", GlobalTypeMap);
+  dumpModuleIDMap("Global declaration map", GlobalDeclMap);
   dumpModuleIDMap("Global identifier map", GlobalIdentifierMap);
   dumpModuleIDMap("Global macro map", GlobalMacroMap);
   dumpModuleIDMap("Global submodule map", GlobalSubmoduleMap);
@@ -9196,7 +9185,7 @@ void ASTRecordReader::readUnresolvedSet(LazyASTUnresolvedSet &Set) {
   while (NumDecls--) {
     GlobalDeclID ID = readDeclID();
     AccessSpecifier AS = (AccessSpecifier) readInt();
-    Set.addLazyDecl(getContext(), ID, AS);
+    Set.addLazyDecl(getContext(), ID.get(), AS);
   }
 }
 

diff  --git a/clang/lib/Serialization/ASTReaderDecl.cpp b/clang/lib/Serialization/ASTReaderDecl.cpp
index cf2dc32e30b91..765c083ce8df8 100644
--- a/clang/lib/Serialization/ASTReaderDecl.cpp
+++ b/clang/lib/Serialization/ASTReaderDecl.cpp
@@ -2924,7 +2924,7 @@ void ASTDeclReader::mergeTemplatePattern(RedeclarableTemplateDecl *D,
   auto *ExistingPattern = Existing->getTemplatedDecl();
   RedeclarableResult Result(
       /*MergeWith*/ ExistingPattern,
-      DPattern->getCanonicalDecl()->getGlobalID(), IsKeyDecl);
+      GlobalDeclID(DPattern->getCanonicalDecl()->getGlobalID()), IsKeyDecl);
 
   if (auto *DClass = dyn_cast<CXXRecordDecl>(DPattern)) {
     // Merge with any existing definition.
@@ -3245,10 +3245,11 @@ bool ASTReader::isConsumerInterestedIn(Decl *D) {
 /// Get the correct cursor and offset for loading a declaration.
 ASTReader::RecordLocation ASTReader::DeclCursorForID(GlobalDeclID ID,
                                                      SourceLocation &Loc) {
-  ModuleFile *M = getOwningModuleFile(ID);
-  assert(M);
-  unsigned LocalDeclIndex = ID.getLocalDeclIndex();
-  const DeclOffset &DOffs = M->DeclOffsets[LocalDeclIndex];
+  GlobalDeclMapType::iterator I = GlobalDeclMap.find(ID);
+  assert(I != GlobalDeclMap.end() && "Corrupted global declaration map");
+  ModuleFile *M = I->second;
+  const DeclOffset &DOffs =
+      M->DeclOffsets[ID.get() - M->BaseDeclID - NUM_PREDEF_DECL_IDS];
   Loc = ReadSourceLocation(*M, DOffs.getRawLoc());
   return RecordLocation(M, DOffs.getBitOffset(M->DeclsBlockStartOffset));
 }
@@ -3791,6 +3792,7 @@ void ASTReader::markIncompleteDeclChain(Decl *D) {
 
 /// Read the declaration at the given offset from the AST file.
 Decl *ASTReader::ReadDeclRecord(GlobalDeclID ID) {
+  unsigned Index = ID.get() - NUM_PREDEF_DECL_IDS;
   SourceLocation DeclLoc;
   RecordLocation Loc = DeclCursorForID(ID, DeclLoc);
   llvm::BitstreamCursor &DeclsCursor = Loc.F->DeclsCursor;
@@ -4121,7 +4123,7 @@ Decl *ASTReader::ReadDeclRecord(GlobalDeclID ID) {
   }
 
   assert(D && "Unknown declaration reading AST file");
-  LoadedDecl(translateGlobalDeclIDToIndex(ID), D);
+  LoadedDecl(Index, D);
   // Set the DeclContext before doing any deserialization, to make sure internal
   // calls to Decl::getASTContext() by Decl's methods will find the
   // TranslationUnitDecl without crashing.
@@ -4447,7 +4449,7 @@ namespace {
                            M.ObjCCategoriesMap + M.LocalNumObjCCategoriesInMap,
                            Compare);
       if (Result == M.ObjCCategoriesMap + M.LocalNumObjCCategoriesInMap ||
-          Result->getDefinitionID() != LocalID) {
+          Result->DefinitionID != LocalID) {
         // We didn't find anything. If the class definition is in this module
         // file, then the module files it depends on cannot have any categories,
         // so suppress further lookup.

diff  --git a/clang/lib/Serialization/ASTWriter.cpp b/clang/lib/Serialization/ASTWriter.cpp
index ee3e687636e6a..953990a4aca6d 100644
--- a/clang/lib/Serialization/ASTWriter.cpp
+++ b/clang/lib/Serialization/ASTWriter.cpp
@@ -3357,10 +3357,12 @@ void ASTWriter::WriteTypeDeclOffsets() {
   Abbrev = std::make_shared<BitCodeAbbrev>();
   Abbrev->Add(BitCodeAbbrevOp(DECL_OFFSET));
   Abbrev->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 32)); // # of declarations
+  Abbrev->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 32)); // base decl ID
   Abbrev->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Blob)); // declarations block
   unsigned DeclOffsetAbbrev = Stream.EmitAbbrev(std::move(Abbrev));
   {
-    RecordData::value_type Record[] = {DECL_OFFSET, DeclOffsets.size()};
+    RecordData::value_type Record[] = {DECL_OFFSET, DeclOffsets.size(),
+                                       FirstDeclID.get() - NUM_PREDEF_DECL_IDS};
     Stream.EmitRecordWithBlob(DeclOffsetAbbrev, Record, bytes(DeclOffsets));
   }
 }
@@ -5421,6 +5423,7 @@ ASTFileSignature ASTWriter::WriteASTCore(Sema &SemaRef, StringRef isysroot,
                           M.NumPreprocessedEntities);
         writeBaseIDOrNone(M.BaseSubmoduleID, M.LocalNumSubmodules);
         writeBaseIDOrNone(M.BaseSelectorID, M.LocalNumSelectors);
+        writeBaseIDOrNone(M.BaseDeclID, M.LocalNumDecls);
         writeBaseIDOrNone(M.BaseTypeIndex, M.LocalNumTypes);
       }
     }
@@ -6615,11 +6618,13 @@ void ASTWriter::ReaderInitialized(ASTReader *Reader) {
 
   // Note, this will get called multiple times, once one the reader starts up
   // and again each time it's done reading a PCH or module.
+  FirstDeclID = LocalDeclID(NUM_PREDEF_DECL_IDS + Chain->getTotalNumDecls());
   FirstTypeID = NUM_PREDEF_TYPE_IDS + Chain->getTotalNumTypes();
   FirstIdentID = NUM_PREDEF_IDENT_IDS + Chain->getTotalNumIdentifiers();
   FirstMacroID = NUM_PREDEF_MACRO_IDS + Chain->getTotalNumMacros();
   FirstSubmoduleID = NUM_PREDEF_SUBMODULE_IDS + Chain->getTotalNumSubmodules();
   FirstSelectorID = NUM_PREDEF_SELECTOR_IDS + Chain->getTotalNumSelectors();
+  NextDeclID = FirstDeclID;
   NextTypeID = FirstTypeID;
   NextIdentID = FirstIdentID;
   NextMacroID = FirstMacroID;

diff  --git a/clang/lib/Serialization/ModuleFile.cpp b/clang/lib/Serialization/ModuleFile.cpp
index f64a59bd94891..2c42d33a8f5dd 100644
--- a/clang/lib/Serialization/ModuleFile.cpp
+++ b/clang/lib/Serialization/ModuleFile.cpp
@@ -87,6 +87,7 @@ LLVM_DUMP_METHOD void ModuleFile::dump() {
                << "  Number of types: " << LocalNumTypes << '\n';
   dumpLocalRemap("Type index local -> global map", TypeRemap);
 
-  llvm::errs() << "  Base decl index: " << BaseDeclIndex << '\n'
+  llvm::errs() << "  Base decl ID: " << BaseDeclID << '\n'
                << "  Number of decls: " << LocalNumDecls << '\n';
+  dumpLocalRemap("Decl ID local -> global map", DeclRemap);
 }

diff  --git a/clang/test/Modules/no-transitive-decls-change.cppm b/clang/test/Modules/no-transitive-decls-change.cppm
deleted file mode 100644
index 42ac061bc90b3..0000000000000
--- a/clang/test/Modules/no-transitive-decls-change.cppm
+++ /dev/null
@@ -1,112 +0,0 @@
-// Testing that changing a declaration in an unused module file won't change 
-// the BMI of the current module file.
-//
-// RUN: rm -rf %t
-// RUN: split-file %s %t
-//
-// RUN: %clang_cc1 -std=c++20 %t/m-partA.cppm -emit-reduced-module-interface -o %t/m-partA.pcm
-// RUN: %clang_cc1 -std=c++20 %t/m-partA.v1.cppm -emit-reduced-module-interface -o \
-// RUN:     %t/m-partA.v1.pcm
-// RUN: %clang_cc1 -std=c++20 %t/m-partB.cppm -emit-reduced-module-interface -o %t/m-partB.pcm
-// RUN: %clang_cc1 -std=c++20 %t/m.cppm -emit-reduced-module-interface -o %t/m.pcm \
-// RUN:     -fmodule-file=m:partA=%t/m-partA.pcm -fmodule-file=m:partB=%t/m-partB.pcm
-// RUN: %clang_cc1 -std=c++20 %t/m.cppm -emit-reduced-module-interface -o %t/m.v1.pcm \
-// RUN:     -fmodule-file=m:partA=%t/m-partA.v1.pcm -fmodule-file=m:partB=%t/m-partB.pcm
-//
-// RUN: %clang_cc1 -std=c++20 %t/useBOnly.cppm -emit-reduced-module-interface -o %t/useBOnly.pcm \
-// RUN:     -fmodule-file=m=%t/m.pcm -fmodule-file=m:partA=%t/m-partA.pcm \
-// RUN:     -fmodule-file=m:partB=%t/m-partB.pcm
-// RUN: %clang_cc1 -std=c++20 %t/useBOnly.cppm -emit-reduced-module-interface -o %t/useBOnly.v1.pcm \
-// RUN:     -fmodule-file=m=%t/m.v1.pcm -fmodule-file=m:partA=%t/m-partA.v1.pcm \
-// RUN:     -fmodule-file=m:partB=%t/m-partB.pcm
-// Since useBOnly only uses partB from module M, the change in partA shouldn't affect
-// useBOnly.
-// RUN: 
diff  %t/useBOnly.pcm %t/useBOnly.v1.pcm &> /dev/null
-
-//--- m-partA.cppm
-export module m:partA;
-
-namespace A_Impl {
-    inline int getAImpl() {
-        return 43;
-    }
-
-    inline int getA2Impl() {
-        return 43;
-    }
-}
-
-namespace A {
-    using A_Impl::getAImpl;
-}
-
-export inline int getA() {
-    return 43;
-}
-
-export inline int getA2(int) {
-    return 88;
-}
-
-//--- m-partA.v1.cppm
-export module m:partA;
-
-namespace A_Impl {
-    inline int getAImpl() {
-        return 43;
-    }
-
-    inline int getA2Impl() {
-        return 43;
-    }
-}
-
-namespace A {
-    using A_Impl::getAImpl;
-    // Adding a new declaration without introducing a new declaration name.
-    using A_Impl::getA2Impl;
-}
-
-inline int getA() {
-    return 43;
-}
-
-inline int getA2(int) {
-    return 88;
-}
-
-// Now we add a new declaration without introducing new identifier and new types.
-// The consuming module which didn't use m:partA completely is expected to be
-// not changed.
-inline int getA(int) {
-    return 88;
-}
-
-//--- m-partB.cppm
-export module m:partB;
-
-export inline int getB() {
-    return 430;
-}
-
-//--- m.cppm
-export module m;
-export import :partA;
-export import :partB;
-
-//--- useBOnly.cppm
-export module useBOnly;
-import m;
-
-export inline int get() {
-    return getB();
-}
-
-//--- useAOnly.cppm
-export module useAOnly;
-import m;
-
-export inline int get() {
-    A<int> a;
-    return a.getValue();
-}


        


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