Add comment for load folding

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@169880 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/CodeGen/PeepholeOptimizer.cpp b/lib/CodeGen/PeepholeOptimizer.cpp
index cc07d47..0900ba3 100644
--- a/lib/CodeGen/PeepholeOptimizer.cpp
+++ b/lib/CodeGen/PeepholeOptimizer.cpp
@@ -49,6 +49,11 @@
 //     v1 = bitcast v0
 //        = v0
 //
+// - Optimize Loads:
+//
+//     Loads that can be folded into a later instruction. A load is foldable
+//     if it loads to virtual registers and the virtual register defined has 
+//     a single use.
 //===----------------------------------------------------------------------===//
 
 #define DEBUG_TYPE "peephole-opt"