Use Subscript.index_tuple in more places

loopy/expression.py

@@ -323,9 +323,7 @@ class VectorizabilityChecker(RecursiveMapper):
         if not isinstance(var, ArrayBase):
             raise LoopyError("non-array subscript '%s'" % expr)
 
-        index = expr.index
-        if not isinstance(index, tuple):
-            index = (index,)
+        index = expr.index_tuple
 
         from loopy.symbolic import get_dependencies
         from loopy.kernel.array import VectorArrayDimTag

loopy/kernel/data.py

@@ -703,11 +703,7 @@ def _get_assignee_and_index(expr):
         agg = expr.aggregate
         assert isinstance(agg, Variable)
 
-        idx = expr.index
-        if not isinstance(idx, tuple):
-            idx = (idx,)
-
-        return (agg.name, idx)
+        return (agg.name, expr.index_tuple)
     else:
         raise RuntimeError("invalid lvalue '%s'" % expr)
 

loopy/symbolic.py

@@ -1159,9 +1159,7 @@ class AccessRangeMapper(WalkMapper):
         if expr.aggregate.name != self.arg_name:
             return
 
-        subscript = expr.index
-        if not isinstance(subscript, tuple):
-            subscript = (subscript,)
+        subscript = expr.index_tuple
 
         if not get_dependencies(subscript) <= set(domain.get_var_dict()):
             self.bad_subscripts.append(expr)