[MLIR][Presburger] Simplify checkExplicitRepresentation

[arjunp]

Summary

This also gets rid of a clang-tidy warning.

[Groverkss]

LGTM.

mlir/lib/Analysis/Presburger/Utils.cpp

static LogicalResult getDivRepr(const IntegerPolyhedron &cst, unsigned pos,
 
   return success();
 }
 
 // Returns `false` if the constraints depends on a variable for which an
 // explicit representation has not been found yet, otherwise returns `true`.
 static bool checkExplicitRepresentation(const IntegerPolyhedron &cst,
                                         ArrayRef<bool> foundRepr,
-                                        SmallVectorImpl<int64_t> &dividend,
+                                        ArrayRef<int64_t> dividend,
                                         unsigned pos) {
   // Exit to avoid circular dependencies between divisions.
-  unsigned c, f;
-  for (c = 0, f = cst.getNumIds(); c < f; ++c) {
+  for (unsigned c = 0, e = cst.getNumIds(); c < e; ++c) {
     if (c == pos)
       continue;
-    if (!foundRepr[c] && dividend[c] != 0)
-      break;
-  }
 
+    if (!foundRepr[c] && dividend[c] != 0) {
       // Expression can't be constructed as it depends on a yet unknown
       // identifier.
+      //
       // TODO: Visit/compute the identifiers in an order so that this doesn't
       // happen. More complex but much more efficient.
-  if (c < f)
       return false;
+    }
+  }
+
   return true;
 }
 
 /// Check if the pos^th identifier can be expressed as a floordiv of an affine
 /// function of other identifiers (where the divisor is a positive constant).
 /// `foundRepr` contains a boolean for each identifier indicating if the
 /// explicit representation for that identifier has already been computed.
 /// Returns the `MaybeLocalRepr` struct which contains the indices of the