Add support for XMM registers in SSA code generation pipeline.

runtime/vm/compiler.cc

Index: runtime/vm/compiler.cc
diff --git a/runtime/vm/compiler.cc b/runtime/vm/compiler.cc
index b3f9ad3e80ee5f329a8e474fbd31e7f1851fd8be..10183565a9362c01cb6335fa0c489dd0f55e180c 100644
--- a/runtime/vm/compiler.cc
+++ b/runtime/vm/compiler.cc
@@ -177,7 +177,13 @@ static bool CompileParsedFunctionHelper(const ParsedFunction& parsed_function,
       }
 
       if (optimized) {
-        FlowGraphOptimizer optimizer(*flow_graph);
+        // TODO(vegorov): we need to compute uses for the
+        // purposes of unboxing. Move unboxing to a later
+        // stage.
+        // Compute the use lists.
+        flow_graph->ComputeUseLists();
+
+        FlowGraphOptimizer optimizer(flow_graph);
         optimizer.ApplyICData();
 
         // Compute the use lists.