Revert rG57ee0435bd47f23f3939f402914c231b4f65ca5e - [TII] Use optional destination and source pair as a return value; NFC

This is breaking MSVC builds: http://lab.llvm.org:8011/builders/llvm-clang-x86_64-expensive-checks-win/builds/20375
diff --git a/llvm/lib/CodeGen/LiveDebugValues.cpp b/llvm/lib/CodeGen/LiveDebugValues.cpp
index d38840b..b15c594 100644
--- a/llvm/lib/CodeGen/LiveDebugValues.cpp
+++ b/llvm/lib/CodeGen/LiveDebugValues.cpp
@@ -997,14 +997,10 @@
                                            OpenRangesSet &OpenRanges,
                                            VarLocMap &VarLocIDs,
                                            TransferMap &Transfers) {
+  const MachineOperand *SrcRegOp, *DestRegOp;
 
-  auto DestSrc = TII->isCopyInstr(MI);
-  if (!DestSrc)
-    return;
-
-  const MachineOperand &DestRegOp = DestSrc->Destination;
-  const MachineOperand &SrcRegOp = DestSrc->Source;
-  if (!SrcRegOp.isKill() || !DestRegOp.isDef())
+  if (!TII->isCopyInstr(MI, SrcRegOp, DestRegOp) || !SrcRegOp->isKill() ||
+      !DestRegOp->isDef())
     return;
 
   auto isCalleeSavedReg = [&](unsigned Reg) {
@@ -1014,8 +1010,8 @@
     return false;
   };
 
-  Register SrcReg = SrcRegOp.getReg();
-  Register DestReg = DestRegOp.getReg();
+  Register SrcReg = SrcRegOp->getReg();
+  Register DestReg = DestRegOp->getReg();
 
   // We want to recognize instructions where destination register is callee
   // saved register. If register that could be clobbered by the call is
diff --git a/llvm/lib/CodeGen/TargetInstrInfo.cpp b/llvm/lib/CodeGen/TargetInstrInfo.cpp
index f5f53b5..88fbfcb 100644
--- a/llvm/lib/CodeGen/TargetInstrInfo.cpp
+++ b/llvm/lib/CodeGen/TargetInstrInfo.cpp
@@ -1124,13 +1124,14 @@
 TargetInstrInfo::describeLoadedValue(const MachineInstr &MI) const {
   const MachineFunction *MF = MI.getMF();
   DIExpression *Expr = DIExpression::get(MF->getFunction().getContext(), {});
+  const MachineOperand *SrcRegOp, *DestRegOp;
   int64_t Offset;
 
-  if (auto DestSrc = isCopyInstr(MI)) {
-    return ParamLoadedValue(DestSrc->Source, Expr);
-  } else if (auto DestSrc = isAddImmediate(MI, Offset)) {
+  if (isCopyInstr(MI, SrcRegOp, DestRegOp)) {
+    return ParamLoadedValue(*SrcRegOp, Expr);
+  } else if (isAddImmediate(MI, DestRegOp, SrcRegOp, Offset)) {
     Expr = DIExpression::prepend(Expr, DIExpression::ApplyOffset, Offset);
-    return ParamLoadedValue(DestSrc->Source, Expr);
+    return ParamLoadedValue(*SrcRegOp, Expr);
   }
 
   return None;