Mention devirtualization in release notes

llvm-svn: 290675

clang/docs/ReleaseNotes.rst

@@ -47,6 +47,24 @@ sections with improvements to Clang's support for those languages.
 Major New Features
 ------------------
 
+- Enhanced devirtualization with `-fstrict-vtable-pointers`. Clang devirtualizes
+across different basic blocks, like loops:
+
+.. code-block:: c++
+   struct A {
+       virtual void foo() {}
+   };
+   void indirect(A &a, int n) {
+       for (int i = 0 ; i < n; i++)
+           a.foo();
+
+   }
+   void test(int n) {
+       A a;
+       indirect(a);
+   }
+
+
 -  ...
 
 Improvements to Clang's diagnostics