Make note of the -simplify-libcalls pass.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@22049 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/docs/ReleaseNotes.html b/docs/ReleaseNotes.html
index 0c11255..7c9fb63 100644
--- a/docs/ReleaseNotes.html
+++ b/docs/ReleaseNotes.html
@@ -211,6 +211,12 @@
 <li>The code generator now uses information about takes advantage of commutative
 two-address instructions when performing register allocation.</li>
 
+<li>A new pass has been added to gccas to simplify well-known library calls. The
+pass will short circuit calls to many of the string, memory, and printf type 
+functions or replace the calls with simpler/faster calls, where possible given
+information known statically about the arguments to the call. To use the
+pass, specify <tt>-simplify-libcalls</tt> to the <tt>opt</tt> tool.</li>
+
    
 </ol>
 </div>