[Serialization] No transitive identifier change

Author: ChuanqiXu9

clang/include/clang/Lex/ExternalPreprocessorSource.h

@@ -36,12 +36,64 @@ class ExternalPreprocessorSource {
   /// Return the identifier associated with the given ID number.
   ///
   /// The ID 0 is associated with the NULL identifier.
-  virtual IdentifierInfo *GetIdentifier(unsigned ID) = 0;
+  virtual IdentifierInfo *GetIdentifier(uint64_t ID) = 0;
 
   /// Map a module ID to a module.
   virtual Module *getModule(unsigned ModuleID) = 0;
 };
 
+// Either a pointer to an IdentifierInfo of the controlling macro or the ID
+// number of the controlling macro.
+class LazyIdentifierInfoPtr {
+  // If the low bit is clear, a pointer to the IdentifierInfo. If the low
+  // bit is set, the upper 63 bits are the ID number.
+  mutable uint64_t Ptr = 0;
+
+public:
+  LazyIdentifierInfoPtr() = default;
+
+  explicit LazyIdentifierInfoPtr(const IdentifierInfo *Ptr)
+      : Ptr(reinterpret_cast<uint64_t>(Ptr)) {}
+
+  explicit LazyIdentifierInfoPtr(uint64_t ID) : Ptr((ID << 1) | 0x01) {
+    assert((ID << 1 >> 1) == ID && "ID must require < 63 bits");
+    if (ID == 0)
+      Ptr = 0;
+  }
+
+  LazyIdentifierInfoPtr &operator=(const IdentifierInfo *Ptr) {
+    this->Ptr = reinterpret_cast<uint64_t>(Ptr);
+    return *this;
+  }
+
+  LazyIdentifierInfoPtr &operator=(uint64_t ID) {
+    assert((ID << 1 >> 1) == ID && "IDs must require < 63 bits");
+    if (ID == 0)
+      Ptr = 0;
+    else
+      Ptr = (ID << 1) | 0x01;
+
+    return *this;
+  }
+
+  /// Whether this pointer is non-NULL.
+  ///
+  /// This operation does not require the AST node to be deserialized.
+  bool isValid() const { return Ptr != 0; }
+
+  /// Whether this pointer is currently stored as ID.
+  bool isID() const { return Ptr & 0x01; }
+
+  IdentifierInfo *getPtr() const {
+    assert(!isID());
+    return reinterpret_cast<IdentifierInfo *>(Ptr);
+  }
+
+  uint64_t getID() const {
+    assert(isID());
+    return Ptr >> 1;
+  }
+};
 }
 
 #endif

clang/include/clang/Lex/HeaderSearch.h

@@ -16,6 +16,7 @@
 #include "clang/Basic/SourceLocation.h"
 #include "clang/Basic/SourceManager.h"
 #include "clang/Lex/DirectoryLookup.h"
+#include "clang/Lex/ExternalPreprocessorSource.h"
 #include "clang/Lex/HeaderMap.h"
 #include "clang/Lex/ModuleMap.h"
 #include "llvm/ADT/ArrayRef.h"
@@ -119,13 +120,6 @@ struct HeaderFileInfo {
   LLVM_PREFERRED_TYPE(bool)
   unsigned IsValid : 1;
 
-  /// The ID number of the controlling macro.
-  ///
-  /// This ID number will be non-zero when there is a controlling
-  /// macro whose IdentifierInfo may not yet have been loaded from
-  /// external storage.
-  unsigned ControllingMacroID = 0;
-
   /// If this file has a \#ifndef XXX (or equivalent) guard that
   /// protects the entire contents of the file, this is the identifier
   /// for the macro that controls whether or not it has any effect.
@@ -134,7 +128,7 @@ struct HeaderFileInfo {
   /// the controlling macro of this header, since
   /// getControllingMacro() is able to load a controlling macro from
   /// external storage.
-  const IdentifierInfo *ControllingMacro = nullptr;
+  LazyIdentifierInfoPtr LazyControllingMacro;
 
   /// If this header came from a framework include, this is the name
   /// of the framework.
@@ -580,7 +574,7 @@ class HeaderSearch {
   /// no-op \#includes.
   void SetFileControllingMacro(FileEntryRef File,
                                const IdentifierInfo *ControllingMacro) {
-    getFileInfo(File).ControllingMacro = ControllingMacro;
+    getFileInfo(File).LazyControllingMacro = ControllingMacro;
   }
 
   /// Determine whether this file is intended to be safe from

clang/include/clang/Serialization/ASTBitCodes.h

@@ -59,7 +59,7 @@ const unsigned VERSION_MINOR = 1;
 ///
 /// The ID numbers of identifiers are consecutive (in order of discovery)
 /// and start at 1. 0 is reserved for NULL.
-using IdentifierID = uint32_t;
+using IdentifierID = uint64_t;
 
 /// The number of predefined identifier IDs.
 const unsigned int NUM_PREDEF_IDENT_IDS = 1;

clang/include/clang/Serialization/ASTReader.h

@@ -660,14 +660,6 @@ class ASTReader
   /// been loaded.
   std::vector<IdentifierInfo *> IdentifiersLoaded;
 
-  using GlobalIdentifierMapType =
-      ContinuousRangeMap<serialization::IdentifierID, ModuleFile *, 4>;
-
-  /// Mapping from global identifier IDs to the module in which the
-  /// identifier resides along with the offset that should be added to the
-  /// global identifier ID to produce a local ID.
-  GlobalIdentifierMapType GlobalIdentifierMap;
-
   /// A vector containing macros that have already been
   /// loaded.
   ///
@@ -1539,6 +1531,11 @@ class ASTReader
   /// Translate a \param GlobalDeclID to the index of DeclsLoaded array.
   unsigned translateGlobalDeclIDToIndex(GlobalDeclID ID) const;
 
+  /// Translate an \param IdentifierID ID to the index of IdentifiersLoaded
+  /// array and the corresponding module file.
+  std::pair<ModuleFile *, unsigned>
+  translateIdentifierIDToIndex(serialization::IdentifierID ID) const;
+
 public:
   /// Load the AST file and validate its contents against the given
   /// Preprocessor.
@@ -2123,7 +2120,7 @@ class ASTReader
   /// Load a selector from disk, registering its ID if it exists.
   void LoadSelector(Selector Sel);
 
-  void SetIdentifierInfo(unsigned ID, IdentifierInfo *II);
+  void SetIdentifierInfo(serialization::IdentifierID ID, IdentifierInfo *II);
   void SetGloballyVisibleDecls(IdentifierInfo *II,
                                const SmallVectorImpl<GlobalDeclID> &DeclIDs,
                                SmallVectorImpl<Decl *> *Decls = nullptr);
@@ -2150,10 +2147,10 @@ class ASTReader
     return DecodeIdentifierInfo(ID);
   }
 
-  IdentifierInfo *getLocalIdentifier(ModuleFile &M, unsigned LocalID);
+  IdentifierInfo *getLocalIdentifier(ModuleFile &M, uint64_t LocalID);
 
   serialization::IdentifierID getGlobalIdentifierID(ModuleFile &M,
-                                                    unsigned LocalID);
+                                                    uint64_t LocalID);
 
   void resolvePendingMacro(IdentifierInfo *II, const PendingMacroInfo &PMInfo);
 

clang/include/clang/Serialization/ModuleFile.h

@@ -310,9 +310,6 @@ class ModuleFile {
   /// Base identifier ID for identifiers local to this module.
   serialization::IdentifierID BaseIdentifierID = 0;
 
-  /// Remapping table for identifier IDs in this module.
-  ContinuousRangeMap<uint32_t, int, 2> IdentifierRemap;
-
   /// Actual data for the on-disk hash table of identifiers.
   ///
   /// This pointer points into a memory buffer, where the on-disk hash

clang/lib/Lex/HeaderSearch.cpp

@@ -60,19 +60,21 @@ ALWAYS_ENABLED_STATISTIC(NumSubFrameworkLookups,
 
 const IdentifierInfo *
 HeaderFileInfo::getControllingMacro(ExternalPreprocessorSource *External) {
-  if (ControllingMacro) {
-    if (ControllingMacro->isOutOfDate()) {
-      assert(External && "We must have an external source if we have a "
-                         "controlling macro that is out of date.");
-      External->updateOutOfDateIdentifier(*ControllingMacro);
-    }
-    return ControllingMacro;
-  }
+  if (LazyControllingMacro.isID()) {
+    if (!External)
+      return nullptr;
 
-  if (!ControllingMacroID || !External)
-    return nullptr;
+    LazyControllingMacro =
+        External->GetIdentifier(LazyControllingMacro.getID());
+    return LazyControllingMacro.getPtr();
+  }
 
-  ControllingMacro = External->GetIdentifier(ControllingMacroID);
+  IdentifierInfo *ControllingMacro = LazyControllingMacro.getPtr();
+  if (ControllingMacro && ControllingMacro->isOutOfDate()) {
+    assert(External && "We must have an external source if we have a "
+                       "controlling macro that is out of date.");
+    External->updateOutOfDateIdentifier(*ControllingMacro);
+  }
   return ControllingMacro;
 }
 
@@ -1341,10 +1343,8 @@ static void mergeHeaderFileInfo(HeaderFileInfo &HFI,
   mergeHeaderFileInfoModuleBits(HFI, OtherHFI.isModuleHeader,
                                 OtherHFI.isTextualModuleHeader);
 
-  if (!HFI.ControllingMacro && !HFI.ControllingMacroID) {
-    HFI.ControllingMacro = OtherHFI.ControllingMacro;
-    HFI.ControllingMacroID = OtherHFI.ControllingMacroID;
-  }
+  if (!HFI.LazyControllingMacro.isValid())
+    HFI.LazyControllingMacro = OtherHFI.LazyControllingMacro;
 
   HFI.DirInfo = OtherHFI.DirInfo;
   HFI.External = (!HFI.IsValid || HFI.External);
@@ -1419,8 +1419,7 @@ bool HeaderSearch::isFileMultipleIncludeGuarded(FileEntryRef File) const {
   // once. Note that we dor't check for #import, because that's not a property
   // of the file itself.
   if (auto *HFI = getExistingFileInfo(File))
-    return HFI->isPragmaOnce || HFI->ControllingMacro ||
-           HFI->ControllingMacroID;
+    return HFI->isPragmaOnce || HFI->LazyControllingMacro.isValid();
   return false;
 }