[AArch64] Delete an unused parameter for isExtPartOfAvgExpr, NFC

[Allen]

Summary

Depend on D157628

[kmclaughlin]

Thank you @Allen, this change LGTM

llvm/lib/Target/AArch64/AArch64TargetTransformInfo.h

InstructionCost getMaskedMemoryOpCost(unsigned Opcode, Type *Src,
                                         TTI::TargetCostKind CostKind);
 
   InstructionCost getGatherScatterOpCost(unsigned Opcode, Type *DataTy,
                                          const Value *Ptr, bool VariableMask,
                                          Align Alignment,
                                          TTI::TargetCostKind CostKind,
                                          const Instruction *I = nullptr);
 
-  bool isExtPartOfAvgExpr(const Instruction *ExtUser, const CastInst *Ext,
-                          Type *Dst, Type *Src);
+  bool isExtPartOfAvgExpr(const Instruction *ExtUser, Type *Dst, Type *Src);
 
   InstructionCost getCastInstrCost(unsigned Opcode, Type *Dst, Type *Src,
                                    TTI::CastContextHint CCH,
                                    TTI::TargetCostKind CostKind,
                                    const Instruction *I = nullptr);
 
   InstructionCost getExtractWithExtendCost(unsigned Opcode, Type *Dst,
                                            VectorType *VecTy, unsigned Index);

llvm/lib/Target/AArch64/AArch64TargetTransformInfo.cpp

 }
 
 // s/urhadd instructions implement the following pattern, making the
 // extends free:
 //   %x = add ((zext i8 -> i16), 1)
 //   %y = (zext i8 -> i16)
 //   trunc i16 (lshr (add %x, %y), 1) -> i8
 //
-bool AArch64TTIImpl::isExtPartOfAvgExpr(const Instruction *ExtUser,
-                                        const CastInst *Ext, Type *Dst,
+bool AArch64TTIImpl::isExtPartOfAvgExpr(const Instruction *ExtUser, Type *Dst,
                                         Type *Src) {
-
   // The source should be a legal vector type.
   if (!Src->isVectorTy() || !TLI->isTypeLegal(TLI->getValueType(DL, Src)) ||
       (Src->isScalableTy() && !ST->hasSVE2()))
     return false;
 
   if (ExtUser->getOpcode() != Instruction::Add || !ExtUser->hasOneUse())
     return false;
 
if (isWideningInstruction(Dst, SingleUser->getOpcode(), Operands, Src)) {
              cast<CastInst>(SingleUser->getOperand(1))->getOpcode() == Opcode))
           return 0;
       } else // Others are free so long as isWideningInstruction returned true.
         return 0;
     }
 
     // The cast will be free for the s/urhadd instructions
     if ((isa<ZExtInst>(I) || isa<SExtInst>(I)) &&
-        isExtPartOfAvgExpr(SingleUser, cast<CastInst>(I), Dst, Src))
+        isExtPartOfAvgExpr(SingleUser, Dst, Src))
       return 0;
   }
 
   // TODO: Allow non-throughput costs that aren't binary.
   auto AdjustCost = [&CostKind](InstructionCost Cost) -> InstructionCost {
     if (CostKind != TTI::TCK_RecipThroughput)
       return Cost == 0 ? 0 : 1;
     return Cost;