TargetRegisterInfo: Provide a way to check assigned registers in getRegAllocationHints()

Pass a const reference to LiveRegMatrix to getRegAllocationHints()
because some targets can prodive better hints if they can test whether a
physreg has been used for register allocation yet.

llvm-svn: 242340
diff --git a/llvm/lib/CodeGen/AllocationOrder.cpp b/llvm/lib/CodeGen/AllocationOrder.cpp
index dc9bcff..40451c0 100644
--- a/llvm/lib/CodeGen/AllocationOrder.cpp
+++ b/llvm/lib/CodeGen/AllocationOrder.cpp
@@ -29,12 +29,13 @@
 // Compare VirtRegMap::getRegAllocPref().
 AllocationOrder::AllocationOrder(unsigned VirtReg,
                                  const VirtRegMap &VRM,
-                                 const RegisterClassInfo &RegClassInfo)
+                                 const RegisterClassInfo &RegClassInfo,
+                                 const LiveRegMatrix *Matrix)
   : Pos(0) {
   const MachineFunction &MF = VRM.getMachineFunction();
   const TargetRegisterInfo *TRI = &VRM.getTargetRegInfo();
   Order = RegClassInfo.getOrder(MF.getRegInfo().getRegClass(VirtReg));
-  TRI->getRegAllocationHints(VirtReg, Order, Hints, MF, &VRM);
+  TRI->getRegAllocationHints(VirtReg, Order, Hints, MF, &VRM, Matrix);
   rewind();
 
   DEBUG({