Copy the documentation of -fstandalone-debug from the man page to the user

manual.

rdar://problem/17307006

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@210936 91177308-0d34-0410-b5e6-96231b3b80d8

diff --git a/docs/UsersManual.rst b/docs/UsersManual.rst
index b716c0a982e7392a749aeb8fc9fbde041746843d..1f1b99a4bf9cd857505705ec385fd40fc7145a16 100644 (file)
--- a/docs/UsersManual.rst
+++ b/docs/UsersManual.rst
@@ -1298,6 +1298,22 @@ below. If multiple flags are present, the last one is used.
   doesn't contain any other data (e.g. description of local variables or
   function parameters).
 
+.. option:: -fstandalone-debug -fno-standalone-debug
+
+  Clang supports a number of optimizations to reduce the size of debug
+  information in the binary. They work based on the assumption that
+  the debug type information can be spread out over multiple
+  compilation units.  For instance, Clang will not emit type
+  definitions for types that are not needed by a module and could be
+  replaced with a forward declaration.  Further, Clang will only emit
+  type info for a dynamic C++ class in the module that contains the
+  vtable for the class.
+
+  The ``-fstandalone-debug`` option turns off these optimizations.
+  This is useful when working with 3rd-party libraries that don't come
+  with debug information.  Note that Clang will never emit type
+  information for types that are not referenced at all by the program.
+
 .. option:: -g
 
   Generate complete debug info.