Remember the VR64 register class

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@107920 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Target/X86/X86InstrInfo.cpp b/lib/Target/X86/X86InstrInfo.cpp
index 1be64589..6a6e861 100644
--- a/lib/Target/X86/X86InstrInfo.cpp
+++ b/lib/Target/X86/X86InstrInfo.cpp
@@ -2080,6 +2080,8 @@
       Opc = X86::MOV8rr;
   } else if (X86::VR128RegClass.contains(DestReg, SrcReg))
     Opc = X86::MOVAPSrr;
+  else if (X86::VR64RegClass.contains(DestReg, SrcReg))
+    Opc = X86::MMX_MOVQ64rr;
 
   if (Opc) {
     BuildMI(MBB, MI, DL, get(Opc), DestReg)