[SelectionDAG] Rename fextend -> fpextend, fround -> fpround, frnd -> fround

The names of the tablegen defs now match the names of the ISD nodes.
This makes the world a slightly saner place, as previously "fround" matched
ISD::FP_ROUND and not ISD::FROUND.

Differential Revision: https://reviews.llvm.org/D23597

llvm-svn: 279129
diff --git a/llvm/lib/Target/SystemZ/SystemZISelLowering.cpp b/llvm/lib/Target/SystemZ/SystemZISelLowering.cpp
index 9ef03a0..8d8dbfd 100644
--- a/llvm/lib/Target/SystemZ/SystemZISelLowering.cpp
+++ b/llvm/lib/Target/SystemZ/SystemZISelLowering.cpp
@@ -4995,8 +4995,8 @@
 
 SDValue SystemZTargetLowering::combineFP_ROUND(
     SDNode *N, DAGCombinerInfo &DCI) const {
-  // (fround (extract_vector_elt X 0))
-  // (fround (extract_vector_elt X 1)) ->
+  // (fpround (extract_vector_elt X 0))
+  // (fpround (extract_vector_elt X 1)) ->
   // (extract_vector_elt (VROUND X) 0)
   // (extract_vector_elt (VROUND X) 1)
   //