Introduce a constant for the number of predefined declarations in an

AST file, along with an enumeration naming those predefined
declarations. No functionality change, but this will make it easier to
introduce new predefined declarations, when/if we need them.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@136781 91177308-0d34-0410-b5e6-96231b3b80d8

diff --git a/include/clang/Serialization/ASTBitCodes.h b/include/clang/Serialization/ASTBitCodes.h
index 761de497c7307c8b8f13d1111e4ad5f2ca31bad5..70a323a5c3740a88414cae679e11889df27679f9 100644 (file)
--- a/include/clang/Serialization/ASTBitCodes.h
+++ b/include/clang/Serialization/ASTBitCodes.h
@@ -56,8 +56,9 @@ namespace clang {
     /// \brief An ID number that refers to a declaration in an AST file.
     ///
     /// The ID numbers of declarations are consecutive (in order of
-    /// discovery) and start at 2. 0 is reserved for NULL, and 1 is
-    /// reserved for the translation unit declaration.
+    /// discovery), with values below NUM_PREDEF_DECL_IDS being reserved. 
+    /// At the start of a chain of precompiled headers, declaration ID 1 is 
+    /// used for the translation unit declaration.
     typedef uint32_t DeclID;
 
     /// \brief a Decl::Kind/DeclID pair.
@@ -661,6 +662,23 @@ namespace clang {
       SPECIAL_TYPE_AUTO_RREF_DEDUCT            = 18
     };
 
+    /// \brief Predefined declaration IDs.
+    ///
+    /// These declaration IDs correspond to predefined declarations in the AST
+    /// context, such as the NULL declaration ID. Such declarations are never
+    /// actually serialized, since they will be built by the AST context when 
+    /// it is created.
+    enum PredefinedDeclIDs {
+      /// \brief The NULL declaration.
+      PREDEF_DECL_NULL_ID       = 0,
+    };
+
+    /// \brief The number of declaration IDs that are predefined.
+    ///
+    /// For more information about predefined declarations, see the
+    /// \c PredefinedDeclIDs type and the PREDEF_DECL_*_ID constants.
+    const unsigned int NUM_PREDEF_DECL_IDS = 1;
+    
     /// \brief Record codes for each kind of declaration.
     ///
     /// These constants describe the declaration records that can occur within

diff --git a/lib/Serialization/ASTReader.cpp b/lib/Serialization/ASTReader.cpp
index 95bc60260c521ac1c63403e39a6e573f05983f55..14094febe50f43b2a0363a9ee1efc437f7826eaa 100644 (file)
--- a/lib/Serialization/ASTReader.cpp
+++ b/lib/Serialization/ASTReader.cpp
@@ -4119,26 +4119,32 @@ TranslationUnitDecl *ASTReader::GetTranslationUnitDecl() {
 
 serialization::DeclID 
 ASTReader::getGlobalDeclID(Module &F, unsigned LocalID) const {
-  if (LocalID == 0)
+  if (LocalID < NUM_PREDEF_DECL_IDS)
     return LocalID;
 
   ContinuousRangeMap<uint32_t, int, 2>::iterator I
-    = F.DeclRemap.find(LocalID - 1);
+    = F.DeclRemap.find(LocalID - NUM_PREDEF_DECL_IDS);
   assert(I != F.DeclRemap.end() && "Invalid index into decl index remap");
   
   return LocalID + I->second;
 }
 
 Decl *ASTReader::GetDecl(DeclID ID) {
-  if (ID == 0)
+  if (ID < NUM_PREDEF_DECL_IDS) {    
+    switch ((PredefinedDeclIDs)ID) {
+    case serialization::PREDEF_DECL_NULL_ID:
+      return 0;
+    }
+    
     return 0;
-
+  }
+  
   if (ID > DeclsLoaded.size()) {
     Error("declaration ID out-of-range for AST file");
     return 0;
   }
 
-  unsigned Index = ID - 1;
+  unsigned Index = ID - NUM_PREDEF_DECL_IDS;
   if (!DeclsLoaded[Index]) {
     ReadDeclRecord(ID);
     if (DeserializationListener)

diff --git a/lib/Serialization/ASTWriter.cpp b/lib/Serialization/ASTWriter.cpp
index c3bbecdb0e7f8f9204101429d5e3ab1e8cd0cd77..fe152b119468b7da5c0c754dda2de19eff6988ce 100644 (file)
--- a/lib/Serialization/ASTWriter.cpp
+++ b/lib/Serialization/ASTWriter.cpp
@@ -2039,7 +2039,7 @@ void ASTWriter::WriteTypeDeclOffsets() {
   Record.clear();
   Record.push_back(DECL_OFFSET);
   Record.push_back(DeclOffsets.size());
-  Record.push_back(FirstDeclID - 1);
+  Record.push_back(FirstDeclID - NUM_PREDEF_DECL_IDS);
   Stream.EmitRecordWithBlob(DeclOffsetAbbrev, Record, data(DeclOffsets));
 }
 
@@ -2740,7 +2740,7 @@ void ASTWriter::SetSelectorOffset(Selector Sel, uint32_t Offset) {
 
 ASTWriter::ASTWriter(llvm::BitstreamWriter &Stream)
   : Stream(Stream), Chain(0), SerializationListener(0), 
-    FirstDeclID(1), NextDeclID(FirstDeclID),
+    FirstDeclID(NUM_PREDEF_DECL_IDS), NextDeclID(FirstDeclID),
     FirstTypeID(NUM_PREDEF_TYPE_IDS), NextTypeID(FirstTypeID),
     FirstIdentID(1), NextIdentID(FirstIdentID), FirstSelectorID(1),
     NextSelectorID(FirstSelectorID), FirstMacroID(1), NextMacroID(FirstMacroID),