[Analysis] Remove unused fields in MemorySSA.cpp (NFC)

The last uses of AR were removed on July 28, 2022 in commit
f96ea53e89.

Differential Revision: https://reviews.llvm.org/D138730

llvm/lib/Analysis/MemorySSA.cpp

@@ -359,7 +359,6 @@ struct UpwardsMemoryQuery {
   const Instruction *Inst = nullptr;
   // The MemoryAccess we actually got called with, used to test local domination
   const MemoryAccess *OriginalAccess = nullptr;
-  Optional<AliasResult> AR = AliasResult(AliasResult::MayAlias);
   bool SkipSelfAccess = false;
 
   UpwardsMemoryQuery() = default;
@@ -1306,7 +1305,6 @@ private:
     // This is where the last walk for this memory location ended.
     unsigned long LastKill;
     bool LastKillValid;
-    Optional<AliasResult> AR;
   };
 
   void optimizeUsesInBlock(const BasicBlock *, unsigned long &, unsigned long &,
@@ -1460,8 +1458,6 @@ void MemorySSA::OptimizeUses::optimizeUsesInBlock(
       --UpperBound;
     }
 
-    // Note: Phis always have AliasResult AR set to MayAlias ATM.
-
     // At the end of this loop, UpperBound is either a clobber, or lower bound
     // PHI walking may cause it to be < LowerBound, and in fact, < LastKill.
     if (FoundClobberResult || UpperBound < LocInfo.LastKill) {