[Lexicon] Add GVN

Summary: Add a lexicon entry for global value numbering.

Reviewers: davide, majnemer

Reviewed By: davide

Subscribers: llvm-commits, inouehrs

Differential Revision: https://reviews.llvm.org/D33664

llvm-svn: 305270

1 files changed, 7 insertions, 0 deletions

diff --git a/llvm/docs/Lexicon.rst b/llvm/docs/Lexicon.rst
index ebc3fb772e8..ce7ed318fe4 100644
--- a/llvm/docs/Lexicon.rst
+++ b/llvm/docs/Lexicon.rst
@@ -109,6 +109,13 @@ G
     Garbage Collection. The practice of using reachability analysis instead of
     explicit memory management to reclaim unused memory.
 
+**GVN**
+    Global Value Numbering. GVN is a pass that partitions values computed by a
+    function into congruence classes. Values ending up in the same congruence
+    class are guaranteed to be the same for every execution of the program.
+    In that respect, congruency is a compile-time approximation of equivalence
+    of values at runtime.
+
 H
 -