Update AnalysisGroup documentation to document restriction that allows
only one ImmutablePass in a group.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@37675 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/docs/WritingAnLLVMPass.html b/docs/WritingAnLLVMPass.html
index 3d896cf..09e5f53 100644
--- a/docs/WritingAnLLVMPass.html
+++ b/docs/WritingAnLLVMPass.html
@@ -1308,8 +1308,9 @@
<p>Here we show how the default implementation is specified (using the extra
argument to the <tt>RegisterAnalysisGroup</tt> template). There must be exactly
one default implementation available at all times for an Analysis Group to be
-used. Here we declare that the <tt><a
-href="http://llvm.org/doxygen/structBasicAliasAnalysis.html">BasicAliasAnalysis</a></tt>
+used. Only default implementation can derive from <tt>ImmutablePass</tt>.
+Here we declare that the
+ <tt><a href="http://llvm.org/doxygen/structBasicAliasAnalysis.html">BasicAliasAnalysis</a></tt>
pass is the default implementation for the interface.</p>
</div>