diff --git a/include/llvm/Target/TargetRegisterInfo.h b/include/llvm/Target/TargetRegisterInfo.h
index 390b95fbe2f..e90fc6cccc3 100644
--- a/include/llvm/Target/TargetRegisterInfo.h
+++ b/include/llvm/Target/TargetRegisterInfo.h
@@ -325,7 +325,7 @@ public:
   /// getAllocatableSet - Returns a bitset indexed by register number
   /// indicating if a register is allocatable or not. If a register class is
   /// specified, returns the subset for the class.
-  BitVector getAllocatableSet(MachineFunction &MF,
+  BitVector getAllocatableSet(const MachineFunction &MF,
                               const TargetRegisterClass *RC = NULL) const;
 
   const TargetRegisterDesc &operator[](unsigned RegNo) const {
diff --git a/lib/Target/TargetRegisterInfo.cpp b/lib/Target/TargetRegisterInfo.cpp
index 43123991ea8..fac67e2e1aa 100644
--- a/lib/Target/TargetRegisterInfo.cpp
+++ b/lib/Target/TargetRegisterInfo.cpp
@@ -62,14 +62,14 @@ TargetRegisterInfo::getPhysicalRegisterRegClass(unsigned reg, EVT VT) const {
 
 /// getAllocatableSetForRC - Toggle the bits that represent allocatable
 /// registers for the specific register class.
-static void getAllocatableSetForRC(MachineFunction &MF,
+static void getAllocatableSetForRC(const MachineFunction &MF,
                                    const TargetRegisterClass *RC, BitVector &R){  
   for (TargetRegisterClass::iterator I = RC->allocation_order_begin(MF),
          E = RC->allocation_order_end(MF); I != E; ++I)
     R.set(*I);
 }
 
-BitVector TargetRegisterInfo::getAllocatableSet(MachineFunction &MF,
+BitVector TargetRegisterInfo::getAllocatableSet(const MachineFunction &MF,
                                           const TargetRegisterClass *RC) const {
   BitVector Allocatable(NumRegs);
   if (RC) {