Implement serialization and lazy deserialization of the preprocessing

record (which includes all macro instantiations and definitions). As
with all lay deserialization, this introduces a new external source
(here, an external preprocessing record source) that loads all of the
preprocessed entities prior to iterating over the entities.

The preprocessing record is an optional part of the precompiled header
that is disabled by default (enabled with
-detailed-preprocessing-record). When the preprocessor given to the
PCH writer has a preprocessing record, that record is written into the
PCH file. When the PCH reader is given a PCH file that contains a
preprocessing record, it will be lazily loaded (which, effectively,
implicitly adds -detailed-preprocessing-record). This is the first
case where we have sections of the precompiled header that are
added/removed based on a compilation flag, which is
unfortunate. However, this data consumes ~550k in the PCH file for
Cocoa.h (out of ~9.9MB), and there is a non-trivial cost to gathering
this detailed preprocessing information, so it's too expensive to turn
on by default. In the future, we should investigate a better encoding
of this information.



git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@99002 91177308-0d34-0410-b5e6-96231b3b80d8

3 files changed, 46 insertions, 5 deletions

diff --git a/include/clang/Frontend/PCHBitCodes.h b/include/clang/Frontend/PCHBitCodes.h
index e2c27e6ddf..de7888e797 100644
--- a/include/clang/Frontend/PCHBitCodes.h
+++ b/include/clang/Frontend/PCHBitCodes.h
@@ -224,8 +224,11 @@ namespace clang {
       VERSION_CONTROL_BRANCH_REVISION = 21,
       
       /// \brief Record code for the array of unused static functions.
-      UNUSED_STATIC_FUNCS = 22
+      UNUSED_STATIC_FUNCS = 22,
       
+      /// \brief Record code for the table of offsets to macro definition
+      /// entries in the preprocessing record.
+      MACRO_DEFINITION_OFFSETS = 23
     };
 
     /// \brief Record types used within a source manager block.
@@ -264,7 +267,14 @@ namespace clang {
 
       /// \brief Describes one token.
       /// [PP_TOKEN, SLoc, Length, IdentInfoID, Kind, Flags]
-      PP_TOKEN = 3
+      PP_TOKEN = 3,
+
+      /// \brief Describes a macro instantiation within the preprocessing 
+      /// record.
+      PP_MACRO_INSTANTIATION = 4,
+      
+      /// \brief Describes a macro definition within the preprocessing record.
+      PP_MACRO_DEFINITION = 5
     };
 
     /// \defgroup PCHAST Precompiled header AST constants
diff --git a/include/clang/Frontend/PCHReader.h b/include/clang/Frontend/PCHReader.h
index e4fd1a2b15..9ccd382dba 100644
--- a/include/clang/Frontend/PCHReader.h
+++ b/include/clang/Frontend/PCHReader.h
@@ -21,6 +21,7 @@
 #include "clang/AST/Type.h"
 #include "clang/AST/TemplateBase.h"
 #include "clang/Lex/ExternalPreprocessorSource.h"
+#include "clang/Lex/PreprocessingRecord.h"
 #include "clang/Basic/Diagnostic.h"
 #include "clang/Basic/IdentifierTable.h"
 #include "clang/Basic/SourceManager.h"
@@ -53,6 +54,7 @@ class Decl;
 class DeclContext;
 class GotoStmt;
 class LabelStmt;
+class MacroDefinition;
 class NamedDecl;
 class Preprocessor;
 class Sema;
@@ -151,6 +153,7 @@ private:
 /// actually required will be de-serialized.
 class PCHReader
   : public ExternalPreprocessorSource,
+    public ExternalPreprocessingRecordSource,
     public ExternalSemaSource,
     public IdentifierInfoLookup,
     public ExternalIdentifierLookup,
@@ -296,6 +299,17 @@ private:
   /// been loaded.
   llvm::SmallVector<Selector, 16> SelectorsLoaded;
 
+  /// \brief Offsets of all of the macro definitions in the preprocessing
+  /// record in the PCH file.
+  const uint32_t *MacroDefinitionOffsets;
+      
+  /// \brief The macro definitions we have already loaded.
+  llvm::SmallVector<MacroDefinition *, 16> MacroDefinitionsLoaded;
+      
+  /// \brief The number of preallocated preprocessing entities in the
+  /// preprocessing record.
+  unsigned NumPreallocatedPreprocessingEntities;
+      
   /// \brief A sorted array of source ranges containing comments.
   SourceRange *Comments;
 
@@ -527,9 +541,7 @@ public:
   }
 
   /// \brief Set the Preprocessor to use.
-  void setPreprocessor(Preprocessor &pp) {
-    PP = &pp;
-  }
+  void setPreprocessor(Preprocessor &pp);
 
   /// \brief Sets and initializes the given Context.
   void InitializeContext(ASTContext &Context);
@@ -550,6 +562,9 @@ public:
   /// which contains a (typically-empty) subset of the predefines
   /// build prior to including the precompiled header.
   const std::string &getSuggestedPredefines() { return SuggestedPredefines; }
+      
+  /// \brief Read preprocessed entities into the 
+  virtual void ReadPreprocessedEntities();
 
   /// \brief Reads the source ranges that correspond to comments from
   /// an external AST source.
@@ -727,6 +742,9 @@ public:
   /// \brief Read the set of macros defined by this external macro source.
   virtual void ReadDefinedMacros();
 
+  /// \brief Retrieve the macro definition with the given ID.
+  MacroDefinition *getMacroDefinition(pch::IdentID ID);
+      
   /// \brief Retrieve the AST context that this PCH reader
   /// supplements.
   ASTContext *getContext() { return Context; }
diff --git a/include/clang/Frontend/PCHWriter.h b/include/clang/Frontend/PCHWriter.h
index c05e2436bc..df733b6cae 100644
--- a/include/clang/Frontend/PCHWriter.h
+++ b/include/clang/Frontend/PCHWriter.h
@@ -33,6 +33,7 @@ namespace clang {
 
 class ASTContext;
 class LabelStmt;
+class MacroDefinition;
 class MemorizeStatCalls;
 class Preprocessor;
 class Sema;
@@ -160,6 +161,14 @@ private:
   /// defined.
   llvm::DenseMap<const IdentifierInfo *, uint64_t> MacroOffsets;
 
+  /// \brief Mapping from macro definitions (as they occur in the preprocessing
+  /// record) to the index into the macro definitions table.
+  llvm::DenseMap<const MacroDefinition *, pch::IdentID> MacroDefinitions;
+  
+  /// \brief Mapping from the macro definition indices in \c MacroDefinitions
+  /// to the corresponding offsets within the preprocessor block.
+  std::vector<uint32_t> MacroDefinitionOffsets;
+  
   /// \brief Declarations encountered that might be external
   /// definitions.
   ///
@@ -272,6 +281,10 @@ public:
     return MacroOffsets[II];
   }
 
+  /// \brief Retrieve the ID number corresponding to the given macro 
+  /// definition.
+  pch::IdentID getMacroDefinitionID(MacroDefinition *MD);
+  
   /// \brief Emit a reference to a type.
   void AddTypeRef(QualType T, RecordData &Record);