diff --git a/lib/CodeGen/MachineFunction.cpp b/lib/CodeGen/MachineFunction.cpp
index b9462db..c1699f0 100644
--- a/lib/CodeGen/MachineFunction.cpp
+++ b/lib/CodeGen/MachineFunction.cpp
@@ -309,6 +309,8 @@
 
 //===----------------------------------------------------------------------===//
 //  MachineFunctionInfo implementation
+//  NOTE: MachineFunctionInfo and its methods are specific to the SparcV9
+//  target - don't use them in other targets.
 //===----------------------------------------------------------------------===//
 
 static unsigned