Add some notes
llvm-svn: 38727
diff --git a/clang/README.txt b/clang/README.txt
index af2a375..c3bd824 100644
--- a/clang/README.txt
+++ b/clang/README.txt
@@ -36,6 +36,27 @@
III. Missing Functionality
+File Manager:
+ * We currently do a lot of stat'ing for files that don't exist, particularly
+ when lots of -I paths exist (e.g. see the <iostream> example, check for
+ failures in stat in FileManager::getFile). It would be far better to make
+ the following changes:
+ 1. FileEntry contains a sys::Path instead of a std::string for Name.
+ 2. sys::Path contains timestamp and size, lazily computed. Eliminate from
+ FileEntry.
+ 3. File UIDs are created on request, not when files are opened.
+ These changes make it possible to efficiently have FileEntry objects for
+ files that exist on the file system, but have not been used yet.
+
+ Once this is done:
+ 1. DirectoryEntry gets a boolean value "has read entries". When false, not
+ all entries in the directory are in the file mgr, when true, they are.
+ 2. Instead of stat'ing the file in FileManager::getFile, check to see if
+ the dir has been read. If so, fail immediately, if not, read the dir,
+ then retry.
+ 3. Reading the dir uses the getdirentries syscall, creating an FileEntry
+ for all files found.
+
Lexer:
* Source character mapping. GCC supports ASCII and UTF-8.
See GCC options: -ftarget-charset and -ftarget-wide-charset.
