From e9b76c11a88d0af98f32d11a6668d03d45be3123 Mon Sep 17 00:00:00 2001
From: "Jonathan D. Turner" <jonathan.d.turner@gmail.com>
Date: Wed, 20 Jul 2011 21:31:32 +0000
Subject: [PATCH] Continuing to improve and generalize how IDs are handled in
 ASTReader.  This patch cleans up and generalizes TypeID loading and uses a
 similar table-lookup to Doug's previous Decl patch.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@135622 91177308-0d34-0410-b5e6-96231b3b80d8
---
 include/clang/Serialization/ASTReader.h |  9 +++++++++
 lib/Serialization/ASTReader.cpp         | 24 ++++++++++++------------
 2 files changed, 21 insertions(+), 12 deletions(-)

diff --git a/include/clang/Serialization/ASTReader.h b/include/clang/Serialization/ASTReader.h
index 5bce761a55..a024cb88a4 100644
--- a/include/clang/Serialization/ASTReader.h
+++ b/include/clang/Serialization/ASTReader.h
@@ -457,6 +457,15 @@ private:
   /// ID = (I + 1) << FastQual::Width has already been loaded
   std::vector<QualType> TypesLoaded;
 
+  typedef ContinuousRangeMap<serialization::TypeID,
+      std::pair<PerFileData *, int32_t>, 4>
+    GlobalTypeMapType;
+
+  /// \brief 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;
+
   /// \brief Map that provides the ID numbers of each type within the
   /// output stream, plus those deserialized from a chained PCH.
   ///
diff --git a/lib/Serialization/ASTReader.cpp b/lib/Serialization/ASTReader.cpp
index f31fb751ab..884cc1556b 100644
--- a/lib/Serialization/ASTReader.cpp
+++ b/lib/Serialization/ASTReader.cpp
@@ -2033,6 +2033,13 @@ ASTReader::ReadASTBlock(PerFileData &F) {
       }
       F.TypeOffsets = (const uint32_t *)BlobStart;
       F.LocalNumTypes = Record[0];
+
+      // Introduce the global -> local mapping for types within this
+      // AST file.
+      GlobalTypeMap.insert(std::make_pair(getTotalNumTypes() + 1,
+                                          std::make_pair(&F,
+                                                         -getTotalNumTypes())));
+      TypesLoaded.resize(TypesLoaded.size() + F.LocalNumTypes);
       break;
 
     case DECL_OFFSET:
@@ -2551,14 +2558,12 @@ ASTReader::ASTReadResult ASTReader::ReadAST(const std::string &FileName,
   }
 
   // Allocate space for loaded slocentries, identifiers, decls and types.
-  unsigned TotalNumTypes = 0, TotalNumPreallocatedPreprocessingEntities = 0;
+  unsigned TotalNumPreallocatedPreprocessingEntities = 0;
   for (unsigned I = 0, N = Chain.size(); I != N; ++I) {
     TotalNumSLocEntries += Chain[I]->LocalNumSLocEntries;
-    TotalNumTypes += Chain[I]->LocalNumTypes;
     TotalNumPreallocatedPreprocessingEntities +=
         Chain[I]->NumPreallocatedPreprocessingEntities;
   }
-  TypesLoaded.resize(TotalNumTypes);
   if (PP) {
     PP->getHeaderSearchInfo().SetExternalLookup(this);
     if (TotalNumPreallocatedPreprocessingEntities > 0) {
@@ -3157,15 +3162,10 @@ void ASTReader::ReadPragmaDiagnosticMappings(Diagnostic &Diag) {
 
 /// \brief Get the correct cursor and offset for loading a type.
 ASTReader::RecordLocation ASTReader::TypeCursorForIndex(unsigned Index) {
-  PerFileData *F = 0;
-  for (unsigned I = 0, N = Chain.size(); I != N; ++I) {
-    F = Chain[N - I - 1];
-    if (Index < F->LocalNumTypes)
-      break;
-    Index -= F->LocalNumTypes;
-  }
-  assert(F && F->LocalNumTypes > Index && "Broken chain");
-  return RecordLocation(F, F->TypeOffsets[Index]);
+  GlobalTypeMapType::iterator I = GlobalTypeMap.find(Index+1);
+  assert(I != GlobalTypeMap.end() && "Corrupted global type map");
+  return RecordLocation(I->second.first,
+      I->second.first->TypeOffsets[Index + I->second.second]);
 }
 
 /// \brief Read and return the type with the given index..
-- 
2.50.1