[CodeGen] Use MCRegister for ignoreCSRForAllocationOrder.

llvm/include/llvm/CodeGen/TargetSubtargetInfo.h

@@ -324,7 +324,7 @@ class TargetSubtargetInfo : public MCSubtargetInfo {
   /// written in the tablegen descriptions, false if it should allocate
   /// the specified physical register later if is it callee-saved.
   virtual bool ignoreCSRForAllocationOrder(const MachineFunction &MF,
-                                           unsigned PhysReg) const {
+                                           MCRegister PhysReg) const {
     return false;
   }
 

llvm/lib/Target/ARM/ARMSubtarget.cpp

@@ -478,7 +478,7 @@ unsigned ARMSubtarget::getGPRAllocationOrder(const MachineFunction &MF) const {
 }
 
 bool ARMSubtarget::ignoreCSRForAllocationOrder(const MachineFunction &MF,
-                                               unsigned PhysReg) const {
+                                               MCRegister PhysReg) const {
   // To minimize code size in Thumb2, we prefer the usage of low regs (lower
   // cost per use) so we can  use narrow encoding. By default, caller-saved
   // registers (e.g. lr, r12) are always  allocated first, regardless of

llvm/lib/Target/ARM/ARMSubtarget.h

@@ -523,7 +523,7 @@ class ARMSubtarget : public ARMGenSubtargetInfo {
   }
 
   bool ignoreCSRForAllocationOrder(const MachineFunction &MF,
-                                   unsigned PhysReg) const override;
+                                   MCRegister PhysReg) const override;
   unsigned getGPRAllocationOrder(const MachineFunction &MF) const;
 };