[NFC][DwarfDebug] Prefer explicit to auto type deduction

We should use explicit type instead of auto type deduction when
the type is so obvious. In addition, we remove ambiguity, since auto
type deduction sometimes is not that intuitive, so that could lead
us to some unwanted behavior.

This patch fixes that in the collectCallSiteParameters() from
DwarfDebug module.

Differential Revision: https://reviews.llvm.org/D79624

llvm/lib/CodeGen/AsmPrinter/DwarfDebug.cpp

@@ -652,9 +652,9 @@ static void collectCallSiteParameters(const MachineInstr *CallMI,
     return;
 
   auto *MBB = CallMI->getParent();
-  const auto &TRI = MF->getSubtarget().getRegisterInfo();
-  const auto &TII = MF->getSubtarget().getInstrInfo();
-  const auto &TLI = MF->getSubtarget().getTargetLowering();
+  const TargetRegisterInfo &TRI = *MF->getSubtarget().getRegisterInfo();
+  const TargetInstrInfo &TII = *MF->getSubtarget().getInstrInfo();
+  const TargetLowering &TLI = *MF->getSubtarget().getTargetLowering();
 
   // Skip the call instruction.
   auto I = std::next(CallMI->getReverseIterator());
@@ -715,7 +715,7 @@ static void collectCallSiteParameters(const MachineInstr *CallMI,
       if (MO.isReg() && MO.isDef() &&
           Register::isPhysicalRegister(MO.getReg())) {
         for (auto FwdReg : ForwardedRegWorklist)
-          if (TRI->regsOverlap(FwdReg.first, MO.getReg()))
+          if (TRI.regsOverlap(FwdReg.first, MO.getReg()))
             Defs.insert(FwdReg.first);
       }
     }
@@ -743,17 +743,17 @@ static void collectCallSiteParameters(const MachineInstr *CallMI,
       continue;
 
     for (auto ParamFwdReg : FwdRegDefs) {
-      if (auto ParamValue = TII->describeLoadedValue(*I, ParamFwdReg)) {
+      if (auto ParamValue = TII.describeLoadedValue(*I, ParamFwdReg)) {
         if (ParamValue->first.isImm()) {
           int64_t Val = ParamValue->first.getImm();
           finishCallSiteParams(Val, ParamValue->second,
                                ForwardedRegWorklist[ParamFwdReg], Params);
         } else if (ParamValue->first.isReg()) {
           Register RegLoc = ParamValue->first.getReg();
-          unsigned SP = TLI->getStackPointerRegisterToSaveRestore();
-          Register FP = TRI->getFrameRegister(*MF);
+          unsigned SP = TLI.getStackPointerRegisterToSaveRestore();
+          Register FP = TRI.getFrameRegister(*MF);
           bool IsSPorFP = (RegLoc == SP) || (RegLoc == FP);
-          if (TRI->isCalleeSavedPhysReg(RegLoc, *MF) || IsSPorFP) {
+          if (TRI.isCalleeSavedPhysReg(RegLoc, *MF) || IsSPorFP) {
             MachineLocation MLoc(RegLoc, /*IsIndirect=*/IsSPorFP);
             finishCallSiteParams(MLoc, ParamValue->second,
                                  ForwardedRegWorklist[ParamFwdReg], Params);