From 14ad03b6f4350f062256757efc4149a7df94bdf9 Mon Sep 17 00:00:00 2001
From: Douglas Gregor <dgregor@apple.com>
Date: Wed, 20 Jul 2011 01:29:15 +0000
Subject: [PATCH] Use a ContinuousRangeMap to map from the global macro
 definition ID in the AST reader down to the AST file + local ID, rather than
 walking the PCH chain. More cleanup/generalization, although there is more
 work to do for preprocessed entities. In particular, the "preallocation"
 scheme for preprocessed entities is not going to work well with late loading
 of PCH files, and it's likely we'll have to do something akin to the
 SourceManager's negative/positive loading.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@135556 91177308-0d34-0410-b5e6-96231b3b80d8
---
 include/clang/Serialization/ASTReader.h |  9 +++++++
 lib/Serialization/ASTReader.cpp         | 35 ++++++++++++++-----------
 2 files changed, 28 insertions(+), 16 deletions(-)

diff --git a/include/clang/Serialization/ASTReader.h b/include/clang/Serialization/ASTReader.h
index 72bfb0f8a4..c7bded06ad 100644
--- a/include/clang/Serialization/ASTReader.h
+++ b/include/clang/Serialization/ASTReader.h
@@ -582,6 +582,15 @@ private:
   /// \brief The macro definitions we have already loaded.
   llvm::SmallVector<MacroDefinition *, 16> MacroDefinitionsLoaded;
 
+  typedef ContinuousRangeMap<serialization::MacroID, 
+                             std::pair<PerFileData *, int32_t>, 4> 
+    GlobalMacroDefinitionMapType;
+  
+  /// \brief Mapping from global macro definition IDs to the module in which the
+  /// selector resides along with the offset that should be added to the
+  /// global selector ID to produce a local ID.
+  GlobalMacroDefinitionMapType GlobalMacroDefinitionMap;
+
   /// \brief Mapping from identifiers that represent macros whose definitions
   /// have not yet been deserialized to the global offset where the macro
   /// record resides.
diff --git a/lib/Serialization/ASTReader.cpp b/lib/Serialization/ASTReader.cpp
index 3bb9177011..f31fb751ab 100644
--- a/lib/Serialization/ASTReader.cpp
+++ b/lib/Serialization/ASTReader.cpp
@@ -1833,18 +1833,14 @@ MacroDefinition *ASTReader::getMacroDefinition(MacroID ID) {
     return 0;
 
   if (!MacroDefinitionsLoaded[ID - 1]) {
-    unsigned Index = ID - 1;
-    for (unsigned I = 0, N = Chain.size(); I != N; ++I) {
-      PerFileData &F = *Chain[N - I - 1];
-      if (Index < F.LocalNumMacroDefinitions) {
-        SavedStreamPosition SavedPosition(F.PreprocessorDetailCursor);  
-        F.PreprocessorDetailCursor.JumpToBit(F.MacroDefinitionOffsets[Index]);
-        LoadPreprocessedEntity(F);
-        break;
-      }
-      Index -= F.LocalNumMacroDefinitions;
-    }
-    assert(MacroDefinitionsLoaded[ID - 1] && "Broken chain");
+    GlobalMacroDefinitionMapType::iterator I =GlobalMacroDefinitionMap.find(ID);
+    assert(I != GlobalMacroDefinitionMap.end() && 
+           "Corrupted global macro definition map");
+    PerFileData &F = *I->second.first;
+    unsigned Index = ID - 1 + I->second.second;
+    SavedStreamPosition SavedPosition(F.PreprocessorDetailCursor);  
+    F.PreprocessorDetailCursor.JumpToBit(F.MacroDefinitionOffsets[Index]);
+    LoadPreprocessedEntity(F);
   }
 
   return MacroDefinitionsLoaded[ID - 1];
@@ -2357,6 +2353,16 @@ ASTReader::ReadASTBlock(PerFileData &F) {
       F.MacroDefinitionOffsets = (const uint32_t *)BlobStart;
       F.NumPreallocatedPreprocessingEntities = Record[0];
       F.LocalNumMacroDefinitions = Record[1];
+        
+      // Introduce the global -> local mapping for identifiers within this AST
+      // file
+      GlobalMacroDefinitionMap.insert(
+               std::make_pair(getTotalNumMacroDefinitions() + 1, 
+                              std::make_pair(&F, 
+                                             -getTotalNumMacroDefinitions())));
+      MacroDefinitionsLoaded.resize(
+                    MacroDefinitionsLoaded.size() + F.LocalNumMacroDefinitions);
+
       break;
 
     case DECL_UPDATE_OFFSETS: {
@@ -2545,17 +2551,14 @@ ASTReader::ASTReadResult ASTReader::ReadAST(const std::string &FileName,
   }
 
   // Allocate space for loaded slocentries, identifiers, decls and types.
-  unsigned TotalNumTypes = 0, 
-           TotalNumPreallocatedPreprocessingEntities = 0, TotalNumMacroDefs = 0;
+  unsigned TotalNumTypes = 0, TotalNumPreallocatedPreprocessingEntities = 0;
   for (unsigned I = 0, N = Chain.size(); I != N; ++I) {
     TotalNumSLocEntries += Chain[I]->LocalNumSLocEntries;
     TotalNumTypes += Chain[I]->LocalNumTypes;
     TotalNumPreallocatedPreprocessingEntities +=
         Chain[I]->NumPreallocatedPreprocessingEntities;
-    TotalNumMacroDefs += Chain[I]->LocalNumMacroDefinitions;
   }
   TypesLoaded.resize(TotalNumTypes);
-  MacroDefinitionsLoaded.resize(TotalNumMacroDefs);
   if (PP) {
     PP->getHeaderSearchInfo().SetExternalLookup(this);
     if (TotalNumPreallocatedPreprocessingEntities > 0) {
-- 
2.40.0