[PowerPC] Generate VSX version of splat word

This patch corresponds to review:
http://reviews.llvm.org/D18592

It allows the PPC back end to generate the xxspltw instruction where we
previously only emitted vspltw.

llvm-svn: 268516
diff --git a/llvm/lib/Target/PowerPC/PPCISelLowering.h b/llvm/lib/Target/PowerPC/PPCISelLowering.h
index c097a62..b60fa53 100644
--- a/llvm/lib/Target/PowerPC/PPCISelLowering.h
+++ b/llvm/lib/Target/PowerPC/PPCISelLowering.h
@@ -61,6 +61,10 @@
       ///
       VPERM,
 
+      /// XXSPLT - The PPC VSX splat instructions
+      ///
+      XXSPLT,
+
       /// The CMPB instruction (takes two operands of i32 or i64).
       CMPB,