Mention invariant.group in ReleaseNotes

[hans]

lgtm

[Prazek]

Where should I commit it? Are there any ReleaseNotes-4.0 in repo?

[hans]

In D28605#644548, @Prazek wrote:

Where should I commit it? Are there any ReleaseNotes-4.0 in repo?

Sorry, bad timing.

They are in the release_40 branch. Something like this should do it:

svn checkout https://llvm.org/svn/llvm-project/llvm/branches/release_40/docs llvm_40_docs
cd llvm_40_docs
(edit ReleaseNotes.rst)
svn commit

[Prazek]

Oh right, I will try it tomorrow. I hope there will be no problems with git-svn

[Prazek]

Commited to 4.0 branch

docs/ReleaseNotes.rst

* The definition and uses of LLVM_ATRIBUTE_UNUSED_RESULT in the LLVM source
   semantics rather than gcc's __attribute__((warn_unused_result)).
 
 * Minimum compiler version to build has been raised to GCC 4.8 and VS 2015.
 
 * The Timer related APIs now expect a Name and Description. When upgrading code
   the previously used names should become descriptions and a short name in the
   style of a programming language identifier should be added.
 
+* LLVM now handles invariant.group across different basic blocks, which makes
+  it possible to devirtualize virtual calls inside loops.
+
 * ... next change ...
 
 .. NOTE
    If you would like to document a larger change, then you can add a
    subsection about it right here. You can copy the following boilerplate
    and un-indent it (the indentation causes it to be inside this comment).
 
    Special New Feature