[DebugInfo] Skip DBG_LABEL in calculateDbgValueHistory().

lib/CodeGen/AsmPrinter/DbgValueHistoryCalculator.cpp

void llvm::calculateDbgValueHistory(const MachineFunction *MF,
   BitVector ChangingRegs(TRI->getNumRegs());
   collectChangingRegs(MF, TRI, ChangingRegs);
 
   const TargetLowering *TLI = MF->getSubtarget().getTargetLowering();
   unsigned SP = TLI->getStackPointerRegisterToSaveRestore();
   RegDescribedVarsMap RegVars;
   for (const auto &MBB : *MF) {
     for (const auto &MI : MBB) {
-      if (!MI.isDebugValue()) {
+      if (!MI.isDebugValue() && !MI.isDebugLabel()) {
         // Not a DBG_VALUE instruction. It may clobber registers which describe
         // some variables.
         for (const MachineOperand &MO : MI.operands()) {
           if (MO.isReg() && MO.isDef() && MO.getReg()) {
             // Ignore call instructions that claim to clobber SP. The AArch64
             // backend does this for aggregate function arguments.
             if (MI.isCall() && MO.getReg() == SP)
               continue;
for (const auto &MI : MBB) {
                 clobberRegisterUses(RegVars, I, Result, MI);
               }
             }
           }
         }
         continue;
       }
 
+      if (MI.isDebugLabel())
+  continue;
+
       assert(MI.getNumOperands() > 1 && "Invalid DBG_VALUE instruction!");
       // Use the base variable (without any DW_OP_piece expressions)
       // as index into History. The full variables including the
       // piece expressions are attached to the MI.
       const DILocalVariable *RawVar = MI.getDebugVariable();
       assert(RawVar->isValidLocationForIntrinsic(MI.getDebugLoc()) &&
              "Expected inlined-at fields to agree");
       InlinedVariable Var(RawVar, MI.getDebugLoc()->getInlinedAt());