Do not use register pair in a parallel move.

The ParallelMoveResolver does not work with pairs. Instead,
decompose the pair into two individual moves.

Change-Id: Ie9d3f0b078cef8dc20640c98b20bb20cc4971a7f
diff --git a/compiler/optimizing/parallel_move_resolver.cc b/compiler/optimizing/parallel_move_resolver.cc
index b8f5070..debe466 100644
--- a/compiler/optimizing/parallel_move_resolver.cc
+++ b/compiler/optimizing/parallel_move_resolver.cc
@@ -57,6 +57,9 @@
   // unallocated, or the move was already eliminated).
   for (size_t i = 0; i < parallel_move->NumMoves(); ++i) {
     MoveOperands* move = parallel_move->MoveOperandsAt(i);
+    // The parallel move resolver algorithm does not work with register pairs.
+    DCHECK(!move->GetSource().IsPair());
+    DCHECK(!move->GetDestination().IsPair());
     if (!move->IsRedundant()) {
       moves_.Add(move);
     }