[serialization] No transitive type change

clang/include/clang/Serialization/ASTBitCodes.h

@@ -26,6 +26,7 @@
 #include "clang/Serialization/SourceLocationEncoding.h"
 #include "llvm/ADT/DenseMapInfo.h"
 #include "llvm/Bitstream/BitCodes.h"
+#include "llvm/Support/MathExtras.h"
 #include <cassert>
 #include <cstdint>
 
@@ -70,41 +71,64 @@ using DeclID = DeclIDBase::DeclID;
 
 /// An ID number that refers to a type in an AST file.
 ///
-/// The ID of a type is partitioned into two parts: the lower
-/// three bits are used to store the const/volatile/restrict
-/// qualifiers (as with QualType) and the upper bits provide a
-/// type index. The type index values are partitioned into two
+/// The ID of a type is partitioned into three parts:
+/// - the lower three bits are used to store the const/volatile/restrict
+///   qualifiers (as with QualType).
+/// - the next 29 bits provide a type index in the corresponding
+///   module file.
+/// - the upper 32 bits provide a module file index.
+///
+/// The type index values are partitioned into two
 /// sets. The values below NUM_PREDEF_TYPE_IDs are predefined type
 /// IDs (based on the PREDEF_TYPE_*_ID constants), with 0 as a
-/// placeholder for "no type". Values from NUM_PREDEF_TYPE_IDs are
-/// other types that have serialized representations.
-using TypeID = uint32_t;
+/// placeholder for "no type". The module file index for predefined
+/// types are always 0 since they don't belong to any modules.
+/// Values from NUM_PREDEF_TYPE_IDs are other types that have
+/// serialized representations.
+using TypeID = uint64_t;
+/// Same with TypeID except that the LocalTypeID is only meaningful
+/// with the corresponding ModuleFile.
+///
+/// FIXME: Make TypeID and LocalTypeID a class to improve the type
+/// safety.
+using LocalTypeID = TypeID;
 
 /// A type index; the type ID with the qualifier bits removed.
+/// Keep structure alignment 32-bit since the blob is assumed as 32-bit
+/// aligned.
 class TypeIdx {
+  uint32_t ModuleFileIndex = 0;
   uint32_t Idx = 0;
 
 public:
   TypeIdx() = default;
-  explicit TypeIdx(uint32_t index) : Idx(index) {}
 
-  uint32_t getIndex() const { return Idx; }
+  explicit TypeIdx(uint32_t ModuleFileIdx, uint32_t Idx)
+      : ModuleFileIndex(ModuleFileIdx), Idx(Idx) {}
+
+  uint32_t getModuleFileIndex() const { return ModuleFileIndex; }
+
+  uint64_t getValue() const { return ((uint64_t)ModuleFileIndex << 32) | Idx; }
 
   TypeID asTypeID(unsigned FastQuals) const {
     if (Idx == uint32_t(-1))
       return TypeID(-1);
 
-    return (Idx << Qualifiers::FastWidth) | FastQuals;
+    unsigned Index = (Idx << Qualifiers::FastWidth) | FastQuals;
+    return ((uint64_t)ModuleFileIndex << 32) | Index;
   }
 
   static TypeIdx fromTypeID(TypeID ID) {
     if (ID == TypeID(-1))
-      return TypeIdx(-1);
+      return TypeIdx(0, -1);
 
-    return TypeIdx(ID >> Qualifiers::FastWidth);
+    return TypeIdx(ID >> 32, (ID & llvm::maskTrailingOnes<TypeID>(32)) >>
+                                 Qualifiers::FastWidth);
   }
 };
 
+static_assert(alignof(TypeIdx) == 4);
+
 /// A structure for putting "fast"-unqualified QualTypes into a
 /// DenseMap.  This uses the standard pointer hash function.
 struct UnsafeQualTypeDenseMapInfo {

clang/include/clang/Serialization/ASTReader.h

@@ -491,14 +491,6 @@ class ASTReader
   /// ID = (I + 1) << FastQual::Width has already been loaded
   llvm::PagedVector<QualType> TypesLoaded;
 
-  using GlobalTypeMapType =
-      ContinuousRangeMap<serialization::TypeID, ModuleFile *, 4>;
-
-  /// Mapping from global type IDs to the module in which the
-  /// type resides along with the offset that should be added to the
-  /// global type ID to produce a local ID.
-  GlobalTypeMapType GlobalTypeMap;
-
   /// Declarations that have already been loaded from the chain.
   ///
   /// When the pointer at index I is non-NULL, the declaration with ID
@@ -1429,8 +1421,8 @@ class ASTReader
     RecordLocation(ModuleFile *M, uint64_t O) : F(M), Offset(O) {}
   };
 
-  QualType readTypeRecord(unsigned Index);
-  RecordLocation TypeCursorForIndex(unsigned Index);
+  QualType readTypeRecord(serialization::TypeID ID);
+  RecordLocation TypeCursorForIndex(serialization::TypeID ID);
   void LoadedDecl(unsigned Index, Decl *D);
   Decl *ReadDeclRecord(GlobalDeclID ID);
   void markIncompleteDeclChain(Decl *D);
@@ -1544,6 +1536,11 @@ class ASTReader
   std::pair<ModuleFile *, unsigned>
   translateIdentifierIDToIndex(serialization::IdentifierID ID) const;
 
+  /// Translate an \param TypeID ID to the index of TypesLoaded
+  /// array and the corresponding module file.
+  std::pair<ModuleFile *, unsigned>
+  translateTypeIDToIndex(serialization::TypeID ID) const;
+
 public:
   /// Load the AST file and validate its contents against the given
   /// Preprocessor.
@@ -1892,10 +1889,11 @@ class ASTReader
   QualType GetType(serialization::TypeID ID);
 
   /// Resolve a local type ID within a given AST file into a type.
-  QualType getLocalType(ModuleFile &F, unsigned LocalID);
+  QualType getLocalType(ModuleFile &F, serialization::LocalTypeID LocalID);
 
   /// Map a local type ID within a given AST file into a global type ID.
-  serialization::TypeID getGlobalTypeID(ModuleFile &F, unsigned LocalID) const;
+  serialization::TypeID
+  getGlobalTypeID(ModuleFile &F, serialization::LocalTypeID LocalID) const;
 
   /// Read a type from the current position in the given record, which
   /// was read from the given AST file.

clang/include/clang/Serialization/ASTRecordReader.h

@@ -163,7 +163,7 @@ class ASTRecordReader
   void readTypeLoc(TypeLoc TL, LocSeq *Seq = nullptr);
 
   /// Map a local type ID within a given AST file to a global type ID.
-  serialization::TypeID getGlobalTypeID(unsigned LocalID) const {
+  serialization::TypeID getGlobalTypeID(serialization::TypeID LocalID) const {
     return Reader->getGlobalTypeID(*F, LocalID);
   }
 

clang/include/clang/Serialization/ModuleFile.h

@@ -482,9 +482,6 @@ class ModuleFile {
   /// the global type ID space.
   serialization::TypeID BaseTypeIndex = 0;
 
-  /// Remapping table for type IDs in this module.
-  ContinuousRangeMap<uint32_t, int, 2> TypeRemap;
-
   // === Miscellaneous ===
 
   /// Diagnostic IDs and their mappings that the user changed.

clang/lib/Serialization/ASTCommon.cpp

@@ -283,7 +283,7 @@ serialization::TypeIdxFromBuiltin(const BuiltinType *BT) {
     break;
   }
 
-  return TypeIdx(ID);
+  return TypeIdx(0, ID);
 }
 
 unsigned serialization::ComputeHash(Selector Sel) {