Revamp the SourceManager to separate the representation of parsed

source locations from source locations loaded from an AST/PCH file.

Previously, loading an AST/PCH file involved carefully pre-allocating
space at the beginning of the source manager for the source locations
and FileIDs that correspond to the prefix, and then appending the
source locations/FileIDs used for parsing the remaining translation
unit. This design forced us into loading PCH files early, as a prefix,
whic has become a rather significant limitation.

This patch splits the SourceManager space into two parts: for source
location "addresses", the lower values (growing upward) are used to
describe parsed code, while upper values (growing downward) are used
for source locations loaded from AST/PCH files. Similarly, positive
FileIDs are used to describe parsed code while negative FileIDs are
used to file/macro locations loaded from AST/PCH files. As a result,
we can load PCH/AST files even during parsing, making various
improvemnts in the future possible, e.g., teaching #include <foo.h> to
look for and load <foo.h.gch> if it happens to be already available.

This patch was originally written by Sebastian Redl, then brought
forward to the modern age by Jonathan Turner, and finally
polished/finished by me to be committed.




git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@135484 91177308-0d34-0410-b5e6-96231b3b80d8

1 files changed, 8 insertions, 5 deletions

diff --git a/include/clang/Serialization/ASTBitCodes.h b/include/clang/Serialization/ASTBitCodes.h
index 11b8bed903..a01bf6235a 100644
--- a/include/clang/Serialization/ASTBitCodes.h
+++ b/include/clang/Serialization/ASTBitCodes.h
@@ -375,8 +375,14 @@ namespace clang {
       
       /// \brief Record code for the set of known namespaces, which are used
       /// for typo correction.
-      KNOWN_NAMESPACES = 46
+      KNOWN_NAMESPACES = 46,
 
+      /// \brief Record code for the source location remapping information.
+      SOURCE_LOCATION_MAP = 47,
+
+      /// \brief Record code for the source manager line table information,
+      /// which stores information about #line directives.
+      SOURCE_MANAGER_LINE_TABLE = 48
     };
 
     /// \brief Record types used within a source manager block.
@@ -393,10 +399,7 @@ namespace clang {
       SM_SLOC_BUFFER_BLOB = 3,
       /// \brief Describes a source location entry (SLocEntry) for a
       /// macro expansion.
-      SM_SLOC_EXPANSION_ENTRY = 4,
-      /// \brief Describes the SourceManager's line table, with
-      /// information about #line directives.
-      SM_LINE_TABLE = 5
+      SM_SLOC_EXPANSION_ENTRY = 4
     };
 
     /// \brief Record types used within a preprocessor block.