Completely re-implement (de-)serialization of declaration

chains. The previous implementation relied heavily on the declaration
chain being stored as a (circular) linked list on disk, as it is in
memory. However, when deserializing from multiple modules, the
different chains could get mixed up, leading to broken declaration chains.

The new solution keeps track of the first and last declarations in the
chain for each module file. When we load a declaration, we search all
of the module files for redeclarations of that declaration, then
splice together all of the lists into a coherent whole (along with any
redeclarations that were actually parsed). 

As a drive-by fix, (de-)serialize the redeclaration chains of
TypedefNameDecls, which had somehow gotten missed previously. Add a
test of this serialization.

This new scheme creates a redeclaration table that is fairly large in
the PCH file (on the order of 400k for Cocoa.h's 12MB PCH file). The
table is mmap'd in and searched via a binary search, but it's still
quite large. A future tweak will eliminate entries for declarations
that have no redeclarations anywhere, and should
drastically reduce the size of this table.



git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@146841 91177308-0d34-0410-b5e6-96231b3b80d8

1 files changed, 32 insertions, 1 deletions

diff --git a/include/clang/Serialization/ASTBitCodes.h b/include/clang/Serialization/ASTBitCodes.h
index 41ef74ee0a..cce6916b4e 100644
--- a/include/clang/Serialization/ASTBitCodes.h
+++ b/include/clang/Serialization/ASTBitCodes.h
@@ -452,7 +452,11 @@ namespace clang {
       
       /// \brief Record code for an array of all of the (sub)modules that were
       /// imported by the AST file.
-      IMPORTED_MODULES
+      IMPORTED_MODULES,
+      
+      /// \brief Record code for the array describing the first/last local
+      /// redeclarations of each entity.
+      LOCAL_REDECLARATIONS
     };
 
     /// \brief Record types used within a source manager block.
@@ -1190,6 +1194,33 @@ namespace clang {
       CTOR_INITIALIZER_INDIRECT_MEMBER
     };
 
+    /// \brief Describes the redeclarations of a declaration.
+    struct LocalRedeclarationsInfo {
+      DeclID FirstID;      // The ID of the first declaration
+      DeclID FirstLocalID; // The ID of the first local declaration
+      DeclID LastLocalID;  // The ID of the last local declaration
+      
+      friend bool operator<(const LocalRedeclarationsInfo &X,
+                            const LocalRedeclarationsInfo &Y) {
+        return X.FirstID < Y.FirstID;
+      }
+      
+      friend bool operator>(const LocalRedeclarationsInfo &X,
+                            const LocalRedeclarationsInfo &Y) {
+        return X.FirstID > Y.FirstID;
+      }
+      
+      friend bool operator<=(const LocalRedeclarationsInfo &X,
+                             const LocalRedeclarationsInfo &Y) {
+        return X.FirstID <= Y.FirstID;
+      }
+      
+      friend bool operator>=(const LocalRedeclarationsInfo &X,
+                             const LocalRedeclarationsInfo &Y) {
+        return X.FirstID >= Y.FirstID;
+      }
+    };
+
     /// @}
   }
 } // end namespace clang