[ARM] Remove unnecessary casts (NFC) (#148391)

getRegisterInfo() already returns const ARMBaseRegisterInfo *.

Likewise, getInstrInfo() already returns const ARMBaseInstrInfo *.

Author: kazutakahirata

llvm/lib/Target/ARM/ARMFastISel.cpp

@@ -2562,8 +2562,7 @@ bool ARMFastISel::SelectIntrinsicCall(const IntrinsicInst &I) {
     const TargetRegisterClass *RC = isThumb2 ? &ARM::tGPRRegClass
                                              : &ARM::GPRRegClass;
 
-    const ARMBaseRegisterInfo *RegInfo =
-        static_cast<const ARMBaseRegisterInfo *>(Subtarget->getRegisterInfo());
+    const ARMBaseRegisterInfo *RegInfo = Subtarget->getRegisterInfo();
     Register FramePtr = RegInfo->getFrameRegister(*(FuncInfo.MF));
     Register SrcReg = FramePtr;
 

llvm/lib/Target/ARM/ARMLowOverheadLoops.cpp

@@ -1293,7 +1293,7 @@ bool ARMLowOverheadLoops::runOnMachineFunction(MachineFunction &mf) {
   RDA = &getAnalysis<ReachingDefAnalysis>();
   MF->getProperties().setTracksLiveness();
   MRI = &MF->getRegInfo();
-  TII = static_cast<const ARMBaseInstrInfo*>(ST.getInstrInfo());
+  TII = ST.getInstrInfo();
   TRI = ST.getRegisterInfo();
   BBUtils = std::make_unique<ARMBasicBlockUtils>(*MF);
   BBUtils->computeAllBlockSizes();