Update comments and documentation to reflect that GCSE and ValueNumbering are
deprecated by the GVN and GVNPRE passes.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@51983 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Analysis/ValueNumbering.cpp b/lib/Analysis/ValueNumbering.cpp
index 98f04bd..55323ea 100644
--- a/lib/Analysis/ValueNumbering.cpp
+++ b/lib/Analysis/ValueNumbering.cpp
@@ -10,6 +10,10 @@
 // This file implements the non-abstract Value Numbering methods as well as a
 // default implementation for the analysis group.
 //
+// The ValueNumbering analysis pass is mostly deprecated. It is only used by the
+// Global Common Subexpression Elimination pass, which is deprecated by the
+// Global Value Numbering pass (which does its value numbering on its own).
+//
 //===----------------------------------------------------------------------===//
 
 #include "llvm/Analysis/Passes.h"