silence warnings.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@31394 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Target/Alpha/AlphaInstrInfo.td b/lib/Target/Alpha/AlphaInstrInfo.td
index 807dd25..c2919b0 100644
--- a/lib/Target/Alpha/AlphaInstrInfo.td
+++ b/lib/Target/Alpha/AlphaInstrInfo.td
@@ -96,6 +96,7 @@
 }]>;
 
 def immFPZ  : PatLeaf<(fpimm), [{ //the only fpconstant nodes are +/- 0.0
+  (void)N; // silence warning.
   return true;
 }]>;