Load the selector table lazily from the PCH file.

This results in a 10% speedup on the Cocoa-prefixed "Hello, World!",
all of which is (not surprisingly) user time. There was a tiny
reduction in the size of the PCH file for Cocoa.h, because certain
selectors aren't being written twice.

I'm using two new tricks here that I'd like to replicate elsewhere:
  (1) The selectors not used in the global method pool are packed into
  the blob after the global method pool's on-disk hash table and
  stored as keys, so that all selectors are in the same blob.
  (2) We record the offsets of each selector key when we write it into
  the global method pool (or after it, in the same blob). The offset
  table is written as a blob, so that we don't need to pack/unpack a
  SmallVector with its contents.




git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@70055 91177308-0d34-0410-b5e6-96231b3b80d8

1 files changed, 4 insertions, 6 deletions

diff --git a/include/clang/Frontend/PCHBitCodes.h b/include/clang/Frontend/PCHBitCodes.h
index ba9d3e4c9d..26e2c1744c 100644
--- a/include/clang/Frontend/PCHBitCodes.h
+++ b/include/clang/Frontend/PCHBitCodes.h
@@ -68,10 +68,7 @@ namespace clang {
 
       /// \brief The block containing the definitions of all of the
       /// declarations stored in the PCH file.
-      DECLS_BLOCK_ID,
-
-      /// \brief The block containing ObjC selectors stored in the PCH file.   
-      SELECTOR_BLOCK_ID
+      DECLS_BLOCK_ID
     };
 
     /// \brief Record types that occur within the PCH block itself.
@@ -167,8 +164,9 @@ namespace clang {
       /// declarations.
       LOCALLY_SCOPED_EXTERNAL_DECLS = 11,
       
-      /// \brief Record code for the Objective-C Selector Table.
-      SELECTOR_TABLE = 12,
+      /// \brief Record code for the table of offsets into the
+      /// Objective-C method pool.
+      SELECTOR_OFFSETS = 12,
 
       /// \brief Record code for the Objective-C method pool,
       METHOD_POOL = 13