use register scavenger to spill the register

Author: tangaac

llvm/lib/Target/LoongArch/LoongArchRegisterInfo.cpp

@@ -29,7 +29,6 @@ using namespace llvm;
 
 #define GET_REGINFO_TARGET_DESC
 #include "LoongArchGenRegisterInfo.inc"
-
 LoongArchRegisterInfo::LoongArchRegisterInfo(unsigned HwMode)
     : LoongArchGenRegisterInfo(LoongArch::R1, /*DwarfFlavour*/ 0,
                                /*EHFlavor*/ 0,
@@ -254,3 +253,15 @@ bool LoongArchRegisterInfo::canRealignStack(const MachineFunction &MF) const {
   // reserve it.
   return MRI->canReserveReg(LoongArchABI::getBPReg());
 }
+
+bool LoongArchRegisterInfo::saveScavengerRegister(
+    MachineBasicBlock &MBB, MachineBasicBlock::iterator I,
+    MachineBasicBlock::iterator &UseMI, const TargetRegisterClass *RC,
+    Register Reg) const {
+
+  DebugLoc DL;
+  const TargetInstrInfo &TII = *MBB.getParent()->getSubtarget().getInstrInfo();
+  TII.copyPhysReg(MBB, I, DL, LoongArch::R12, Reg, true);
+  TII.copyPhysReg(MBB, UseMI, DL, Reg, LoongArch::R12, true);
+  return true;
+}

llvm/lib/Target/LoongArch/LoongArchRegisterInfo.h

@@ -52,6 +52,11 @@ struct LoongArchRegisterInfo : public LoongArchGenRegisterInfo {
     return true;
   }
   bool canRealignStack(const MachineFunction &MF) const override;
+  bool saveScavengerRegister(MachineBasicBlock &MBB,
+                             MachineBasicBlock::iterator I,
+                             MachineBasicBlock::iterator &UseMI,
+                             const TargetRegisterClass *RC,
+                             Register Reg) const override;
 };
 } // end namespace llvm