Avoid need for SLocEntryLoaded BitVector

clang/include/clang/Basic/SourceManager.h

@@ -474,9 +474,10 @@ static_assert(sizeof(FileInfo) <= sizeof(ExpansionInfo),
 /// SourceManager keeps an array of these objects, and they are uniquely
 /// identified by the FileID datatype.
 class SLocEntry {
-  static constexpr int OffsetBits = 8 * sizeof(SourceLocation::UIntTy) - 1;
+  static constexpr int OffsetBits = 8 * sizeof(SourceLocation::UIntTy) - 2;
   SourceLocation::UIntTy Offset : OffsetBits;
   SourceLocation::UIntTy IsExpansion : 1;
+  SourceLocation::UIntTy Loaded : 1;
   union {
     FileInfo File;
     ExpansionInfo Expansion;
@@ -489,6 +490,8 @@ class SLocEntry {
 
   bool isExpansion() const { return IsExpansion; }
   bool isFile() const { return !isExpansion(); }
+  bool isLoaded() const { return Loaded; }
+  void setLoaded(bool Value) { Loaded = Value; }
 
   const FileInfo &getFile() const {
     assert(isFile() && "Not a file SLocEntry!");
@@ -716,13 +719,7 @@ class SourceManager : public RefCountedBase<SourceManager> {
   /// The highest possible offset is 2^31-1 (2^63-1 for 64-bit source
   /// locations), so CurrentLoadedOffset starts at 2^31 (2^63 resp.).
   static const SourceLocation::UIntTy MaxLoadedOffset =
-      1ULL << (8 * sizeof(SourceLocation::UIntTy) - 1);
-
-  /// A bitmap that indicates whether the entries of LoadedSLocEntryTable
-  /// have already been loaded from the external source.
-  ///
-  /// Same indexing as LoadedSLocEntryTable.
-  llvm::BitVector SLocEntryLoaded;
+      1ULL << (8 * sizeof(SourceLocation::UIntTy) - 2);
 
   /// An external source for source location entries.
   ExternalSLocEntrySource *ExternalSLocEntries = nullptr;
@@ -1710,7 +1707,8 @@ class SourceManager : public RefCountedBase<SourceManager> {
   const SrcMgr::SLocEntry &getLoadedSLocEntry(unsigned Index,
                                               bool *Invalid = nullptr) const {
     assert(Index < LoadedSLocEntryTable.size() && "Invalid index");
-    if (SLocEntryLoaded[Index])
+    if (LoadedSLocEntryTable.isMaterialized(Index) &&
+        LoadedSLocEntryTable[Index].isLoaded())
       return LoadedSLocEntryTable[Index];
     return loadSLocEntry(Index, Invalid);
   }

clang/lib/Basic/SourceManager.cpp

@@ -336,7 +336,6 @@ void SourceManager::clearIDTables() {
   MainFileID = FileID();
   LocalSLocEntryTable.clear();
   LoadedSLocEntryTable.clear();
-  SLocEntryLoaded.clear();
   LastLineNoFileIDQuery = FileID();
   LastLineNoContentCache = nullptr;
   LastFileIDLookup = FileID();
@@ -373,7 +372,8 @@ void SourceManager::initializeForReplay(const SourceManager &Old) {
 
   // Ensure all SLocEntries are loaded from the external source.
   for (unsigned I = 0, N = Old.LoadedSLocEntryTable.size(); I != N; ++I)
-    if (!Old.SLocEntryLoaded[I])
+    if (!Old.LoadedSLocEntryTable.isMaterialized(I) ||
+        !Old.LoadedSLocEntryTable[I].isLoaded())
       Old.loadSLocEntry(I, nullptr);
 
   // Inherit any content cache data from the old source manager.
@@ -430,12 +430,14 @@ ContentCache &SourceManager::createMemBufferContentCache(
 
 const SrcMgr::SLocEntry &SourceManager::loadSLocEntry(unsigned Index,
                                                       bool *Invalid) const {
-  assert(!SLocEntryLoaded[Index]);
+  assert(!LoadedSLocEntryTable.isMaterialized(Index) ||
+         !LoadedSLocEntryTable[Index].isLoaded());
   if (ExternalSLocEntries->ReadSLocEntry(-(static_cast<int>(Index) + 2))) {
     if (Invalid)
       *Invalid = true;
     // If the file of the SLocEntry changed we could still have loaded it.
-    if (!SLocEntryLoaded[Index]) {
+    if (!LoadedSLocEntryTable.isMaterialized(Index) ||
+        !LoadedSLocEntryTable[Index].isLoaded()) {
       // Try to recover; create a SLocEntry so the rest of clang can handle it.
       if (!FakeSLocEntryForRecovery)
         FakeSLocEntryForRecovery = std::make_unique<SLocEntry>(SLocEntry::get(
@@ -458,7 +460,6 @@ SourceManager::AllocateLoadedSLocEntries(unsigned NumSLocEntries,
     return std::make_pair(0, 0);
   }
   LoadedSLocEntryTable.resize(LoadedSLocEntryTable.size() + NumSLocEntries);
-  SLocEntryLoaded.resize(LoadedSLocEntryTable.size());
   CurrentLoadedOffset -= TotalSize;
   int ID = LoadedSLocEntryTable.size();
   return std::make_pair(-ID - 1, CurrentLoadedOffset);
@@ -604,10 +605,12 @@ FileID SourceManager::createFileIDImpl(ContentCache &File, StringRef Filename,
     assert(LoadedID != -1 && "Loading sentinel FileID");
     unsigned Index = unsigned(-LoadedID) - 2;
     assert(Index < LoadedSLocEntryTable.size() && "FileID out of range");
-    assert(!SLocEntryLoaded[Index] && "FileID already loaded");
+    assert((!LoadedSLocEntryTable.isMaterialized(Index) ||
+            !LoadedSLocEntryTable[Index].isLoaded()) &&
+           "FileID already loaded");
     LoadedSLocEntryTable[Index] = SLocEntry::get(
         LoadedOffset, FileInfo::get(IncludePos, File, FileCharacter, Filename));
-    SLocEntryLoaded[Index] = true;
+    LoadedSLocEntryTable[Index].setLoaded(true);
     return FileID::get(LoadedID);
   }
   unsigned FileSize = File.getSize();
@@ -665,9 +668,11 @@ SourceManager::createExpansionLocImpl(const ExpansionInfo &Info,
     assert(LoadedID != -1 && "Loading sentinel FileID");
     unsigned Index = unsigned(-LoadedID) - 2;
     assert(Index < LoadedSLocEntryTable.size() && "FileID out of range");
-    assert(!SLocEntryLoaded[Index] && "FileID already loaded");
+    assert((!LoadedSLocEntryTable.isMaterialized(Index) ||
+            !LoadedSLocEntryTable[Index].isLoaded()) &&
+           "FileID already loaded");
     LoadedSLocEntryTable[Index] = SLocEntry::get(LoadedOffset, Info);
-    SLocEntryLoaded[Index] = true;
+    LoadedSLocEntryTable[Index].setLoaded(true);
     return SourceLocation::getMacroLoc(LoadedOffset);
   }
   LocalSLocEntryTable.push_back(SLocEntry::get(NextLocalOffset, Info));
@@ -2223,7 +2228,8 @@ LLVM_DUMP_METHOD void SourceManager::dump() const {
   std::optional<SourceLocation::UIntTy> NextStart;
   for (unsigned Index = 0; Index != LoadedSLocEntryTable.size(); ++Index) {
     int ID = -(int)Index - 2;
-    if (SLocEntryLoaded[Index]) {
+    if (LoadedSLocEntryTable.isMaterialized(Index) &&
+        LoadedSLocEntryTable[Index].isLoaded()) {
       DumpSLocEntry(ID, LoadedSLocEntryTable[Index], NextStart);
       NextStart = LoadedSLocEntryTable[Index].getOffset();
     } else {
@@ -2346,7 +2352,6 @@ size_t SourceManager::getDataStructureSizes() const {
   size_t size = llvm::capacity_in_bytes(MemBufferInfos) +
                 llvm::capacity_in_bytes(LocalSLocEntryTable) +
                 llvm::capacity_in_bytes(LoadedSLocEntryTable) +
-                llvm::capacity_in_bytes(SLocEntryLoaded) +
                 llvm::capacity_in_bytes(FileInfos);
 
   if (OverriddenFilesInfo)

llvm/include/llvm/ADT/PagedVector.h

@@ -103,6 +103,14 @@ template <typename T, size_t PageSize = 1024 / sizeof(T)> class PagedVector {
   /// Return the size of the vector.
   [[nodiscard]] size_t size() const { return Size; }
 
+  /// Return true if the element at `Index` belongs to a page which was already
+  /// materialized, i.e., had at least one element accessed.
+  [[nodiscard]] bool isMaterialized(size_t Index) const {
+    assert(Index < Size);
+    assert(Index / PageSize < PageToDataPtrs.size());
+    return PageToDataPtrs[Index / PageSize];
+  }
+
   /// Resize the vector. Notice that the constructor of the elements will not
   /// be invoked until an element of a given page is accessed, at which point
   /// all the elements of the page will be constructed.

llvm/unittests/ADT/PagedVectorTest.cpp

@@ -180,6 +180,20 @@ TEST(PagedVectorTest, FillNonTrivialConstructor) {
   EXPECT_EQ(std::distance(V.materialized_begin(), V.materialized_end()), 10LL);
 }
 
+// Test that isMaterialized returns true for all the elements
+// of the page, not only the one that was accessed.
+TEST(PagedVectorTest, IsMaterialized) {
+  PagedVector<int, 10> V;
+  V.resize(20);
+  EXPECT_FALSE(V.isMaterialized(0));
+  EXPECT_FALSE(V.isMaterialized(1));
+  EXPECT_FALSE(V.isMaterialized(10));
+  V[0] = 0;
+  EXPECT_TRUE(V.isMaterialized(0));
+  EXPECT_TRUE(V.isMaterialized(1));
+  EXPECT_FALSE(V.isMaterialized(10));
+}
+
 // Elements are constructed, destructed in pages, so we expect
 // the number of constructed / destructed elements to be a multiple of the
 // page size and the constructor is invoked when the page is actually accessed