[X86] Remove unreachable code in X86TargetTransformInfo.cpp

[XinWang10]

Summary

In Function getVectorInstrCost, situation Opcode == Instruction::ExtractElement
and Opcode == Instruction::InsertElement are all handled in the first 2 if-statements,
So we have no chance for the code in line 4401.

[RKSimon]

LGTM - was originally added in D20601 when we had much a weaker cost model

[XinWang10]

Thanks for review~

llvm/lib/Target/X86/X86TargetTransformInfo.cpp

if (Opcode == Instruction::InsertElement) {
         SubTy = FixedVectorType::get(ScalarType, SubNumElts);
       ShuffleCost = getShuffleCost(TTI::SK_PermuteTwoSrc, SubTy, std::nullopt,
                                    CostKind, 0, SubTy);
     }
     int IntOrFpCost = ScalarType->isFloatingPointTy() ? 0 : 1;
     return ShuffleCost + IntOrFpCost + RegisterFileMoveCost;
   }
 
-  // Add to the base cost if we know that the extracted element of a vector is
-  // destined to be moved to and used in the integer register file.
-  if (Opcode == Instruction::ExtractElement && ScalarType->isPointerTy())
-    RegisterFileMoveCost += 1;
-
   return BaseT::getVectorInstrCost(Opcode, Val, CostKind, Index, Op0, Op1) +
          RegisterFileMoveCost;
 }
 
 InstructionCost
 X86TTIImpl::getScalarizationOverhead(VectorType *Ty, const APInt &DemandedElts,
                                      bool Insert, bool Extract,
                                      TTI::TargetCostKind CostKind) {