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

1 files changed, 13 insertions, 0 deletions

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);