Implement register allocator for floating point registers.

Also:
- Fix misuses of emitting the rex prefix in the x86_64 assembler.
- Fix movaps code generation in the x86_64 assembler.

Change-Id: Ib6dcf6e7c4a9c43368cfc46b02ba50f69ae69cbe
diff --git a/compiler/optimizing/ssa_builder.h b/compiler/optimizing/ssa_builder.h
index 9d8c072..24f5ac5 100644
--- a/compiler/optimizing/ssa_builder.h
+++ b/compiler/optimizing/ssa_builder.h
@@ -52,6 +52,10 @@
   void VisitStoreLocal(HStoreLocal* store);
   void VisitInstruction(HInstruction* instruction);
 
+  static HInstruction* GetFloatOrDoubleEquivalent(HInstruction* user,
+                                                  HInstruction* instruction,
+                                                  Primitive::Type type);
+
  private:
   // Locals for the current block being visited.
   GrowableArray<HInstruction*>* current_locals_;