diff --git a/include/llvm/Target/TargetLowering.h b/include/llvm/Target/TargetLowering.h
index e3e5737..5d74848 100644
--- a/include/llvm/Target/TargetLowering.h
+++ b/include/llvm/Target/TargetLowering.h
@@ -958,6 +958,13 @@
     RegClassForVT[VT.SimpleTy] = RC;
   }
 
+  /// clearRegisterClasses - remove all register classes
+  void clearRegisterClasses() {
+    for (unsigned i = 0 ; i<array_lengthof(RegClassForVT); i++)
+      RegClassForVT[i] = 0;
+    AvailableRegClasses.clear();
+  }
+
   /// findRepresentativeClass - Return the largest legal super-reg register class
   /// of the register class for the specified type and its associated "cost".
   virtual std::pair<const TargetRegisterClass*, uint8_t>
diff --git a/lib/Target/Mips/Mips16ISelLowering.cpp b/lib/Target/Mips/Mips16ISelLowering.cpp
index 6de62cf..23eb537 100644
--- a/lib/Target/Mips/Mips16ISelLowering.cpp
+++ b/lib/Target/Mips/Mips16ISelLowering.cpp
@@ -39,6 +39,14 @@
 
 Mips16TargetLowering::Mips16TargetLowering(MipsTargetMachine &TM)
   : MipsTargetLowering(TM) {
+  //
+  // set up as if mips32 and then revert so we can test the mechanism
+  // for switching
+  addRegisterClass(MVT::i32, &Mips::CPURegsRegClass);
+  addRegisterClass(MVT::f32, &Mips::FGR32RegClass);
+  computeRegisterProperties();
+  clearRegisterClasses();
+
   // Set up the register classes
   addRegisterClass(MVT::i32, &Mips::CPU16RegsRegClass);