libcpp: preprocessor speedup patches from mainline.

* lex.c (_cpp_clean_line): Add uses of __builtin_expect.  Don't
look backward at the end of the line unless we saw a backslash.

* internal.h (struct cpp_reader): Add new fields:
nonexistent_file_hash and nonexistent_file_ob.
* files.c: Include "obstack.h".
(find_file_in_dir): Before trying to open the file, look up the
path name in the hash table of nonexistent files.  After failing
to open the file, add the path name to the hash table.
(_cpp_find_file): Cache the results of looking up the file name
starting with the quote and bracket chain heads, if we can.
(nonexistent_file_hash_eq): New static function.
(_cpp_init_files): Initialize pfile->nonexistent_file_hash and
pfile->nonexistent_file_ob.
(_cpp_cleanup_files): Free pfile->nonexistent_file_hash and
pfile->nonexistent_file_ob.

Obtained from:	gcc 4.3 (rev. 120263, 124929 ; GPLv2)
MFC after:	3 weeks

1 files changed, 4 insertions, 0 deletions

diff --git a/contrib/gcclibs/libcpp/internal.h b/contrib/gcclibs/libcpp/internal.h
index addff61..1661f7a 100644
--- a/contrib/gcclibs/libcpp/internal.h
+++ b/contrib/gcclibs/libcpp/internal.h
@@ -355,6 +355,10 @@ struct cpp_reader
   struct file_hash_entry *file_hash_entries;
   unsigned int file_hash_entries_allocated, file_hash_entries_used;
 
+  /* Negative path lookup hash table.  */
+  struct htab *nonexistent_file_hash;
+  struct obstack nonexistent_file_ob;
+
   /* Nonzero means don't look for #include "foo" the source-file
      directory.  */
   bool quote_ignores_source_dir;