[ValueLattice] Use getters instead of direct accesses (NFC).

[davide]

LGTM

llvm/trunk/include/llvm/Analysis/ValueLattice.h

bool mergeIn(const ValueLatticeElement &RHS, const DataLayout &DL) {
     }
 
     if (isUndefined()) {
       *this = RHS;
       return !RHS.isUndefined();
     }
 
     if (isConstant()) {
-      if (RHS.isConstant() && Val == RHS.Val)
+      if (RHS.isConstant() && getConstant() == RHS.getConstant())
         return false;
       markOverdefined();
       return true;
     }
 
     if (isNotConstant()) {
-      if (RHS.isNotConstant() && Val == RHS.Val)
+      if (RHS.isNotConstant() && getNotConstant() == RHS.getNotConstant())
         return false;
       markOverdefined();
       return true;
     }
 
     assert(isConstantRange() && "New ValueLattice type?");
     if (!RHS.isConstantRange()) {
       // We can get here if we've encountered a constantexpr of integer type
       // and merge it with a constantrange.
       markOverdefined();
       return true;
     }
-    ConstantRange NewR = Range.unionWith(RHS.getConstantRange());
+    ConstantRange NewR = getConstantRange().unionWith(RHS.getConstantRange());
     if (NewR.isFullSet())
       markOverdefined();
     else
       markConstantRange(std::move(NewR));
     return true;
   }
 
   ConstantInt *getConstantInt() const {