Moved isLiveIn check logic to a utility function

Author: vg0204

llvm/lib/Target/AMDGPU/SILowerSGPRSpills.cpp

@@ -101,6 +101,16 @@ INITIALIZE_PASS_END(SILowerSGPRSpillsLegacy, DEBUG_TYPE,
 
 char &llvm::SILowerSGPRSpillsLegacyID = SILowerSGPRSpillsLegacy::ID;
 
+static bool isLiveInIntoMBB(MCRegister Reg, MachineBasicBlock &MBB,
+                            const TargetRegisterInfo *TRI) {
+  for (MCRegAliasIterator R(Reg, TRI, true); R.isValid(); ++R) {
+    if (MBB.isLiveIn(*R)) {
+      return true;
+    }
+  }
+  return false;
+}
+
 /// Insert spill code for the callee-saved registers used in the function.
 static void insertCSRSaves(MachineBasicBlock &SaveBlock,
                            ArrayRef<CalleeSavedInfo> CSI, SlotIndexes *Indexes,
@@ -126,13 +136,7 @@ static void insertCSRSaves(MachineBasicBlock &SaveBlock,
       // incoming register value, so don't kill at the spill point. This happens
       // since we pass some special inputs (workgroup IDs) in the callee saved
       // range.
-      bool IsLiveIn = false;
-      for (MCRegAliasIterator R(Reg, TRI, true); R.isValid(); ++R) {
-        if (SaveBlock.isLiveIn(*R)) {
-          IsLiveIn = true;
-          break;
-        }
-      }
+      bool IsLiveIn = isLiveInIntoMBB(Reg, SaveBlock, TRI);
       TII.storeRegToStackSlot(SaveBlock, I, Reg, !IsLiveIn, CS.getFrameIdx(),
                               RC, TRI, Register());