Address review comments

Author: CarolineConcatto

llvm/lib/Target/AArch64/AArch64FrameLowering.cpp

@@ -2762,7 +2762,7 @@ struct RegPairInfo {
   unsigned Reg2 = AArch64::NoRegister;
   int FrameIdx;
   int Offset;
-  enum RegType { GPR, FPR64, FPR128, ZPR, PPR } Type;
+  enum RegType { GPR, FPR64, FPR128, PPR, ZPR } Type;
 
   RegPairInfo() = default;
 
@@ -2787,22 +2787,6 @@ struct RegPairInfo {
 
 } // end anonymous namespace
 
-static unsigned findFreePredicateAsCounterReg(MachineBasicBlock *MBB) {
-  MachineFunction *MF = MBB->getParent();
-
-  const AArch64Subtarget &Subtarget = MF->getSubtarget<AArch64Subtarget>();
-  const AArch64RegisterInfo &TRI = *Subtarget.getRegisterInfo();
-  LivePhysRegs LiveRegs(TRI);
-  getLiveRegsForEntryMBB(LiveRegs, *MBB);
-
-  for (MCRegister PReg :
-       {AArch64::PN8, AArch64::PN9, AArch64::PN10, AArch64::PN11, AArch64::PN12,
-        AArch64::PN13, AArch64::PN14, AArch64::PN15}){
-      return PReg;
-  }
-  llvm_unreachable("No predicated register free");
-}
-
 static void computeCalleeSaveRegisterPairs(
     MachineFunction &MF, ArrayRef<CalleeSavedInfo> CSI,
     const TargetRegisterInfo *TRI, SmallVectorImpl<RegPairInfo> &RegPairs,
@@ -3097,7 +3081,9 @@ bool AArch64FrameLowering::spillCalleeSavedRegisters(
       PairRegs = AArch64::Z0_Z1 + (RPI.Reg1 - AArch64::Z0);
       if (!PtrueCreated) {
         PtrueCreated = true;
-        PnReg = findFreePredicateAsCounterReg(&MBB);
+        // Any one of predicate-as-count will be free to use
+        // This can be replaced in the future if needed
+        PnReg = AArch64::PN8;
         BuildMI(MBB, MI, DL, TII.get(AArch64::PTRUE_C_B), PnReg)
             .setMIFlags(MachineInstr::FrameSetup);
       }
@@ -3220,7 +3206,9 @@ bool AArch64FrameLowering::restoreCalleeSavedRegisters(
       PairRegs = AArch64::Z0_Z1 + (RPI.Reg1 - AArch64::Z0);
       if (!PtrueCreated) {
         PtrueCreated = true;
-        PnReg = findFreePredicateAsCounterReg(&MBB);
+        // Any one of predicate-as-count will be free to use
+        // This can be replaced in the future if needed
+        PnReg = AArch64::PN8;
         BuildMI(MBB, MBBI, DL, TII.get(AArch64::PTRUE_C_B), PnReg)
             .setMIFlags(MachineInstr::FrameDestroy);
       }