rmove continue handling. raise error on unsupported control flow op.

qiskit/transpiler/passes/routing/stochastic_swap.py

@@ -373,7 +373,8 @@ def _transpile_controlflow_op(self, cf_op, current_layout):
             return self._transpile_controlflow_multiblock(cf_op, current_layout)
         elif isinstance(cf_op, (ForLoopOp, WhileLoopOp)):
             return self._transpile_controlflow_looping(cf_op, current_layout)
-        return cf_op, current_layout
+        else:
+            raise TranspilerError(f'unsupported control flow operation: {cf_op}')
 
     def _transpile_controlflow_multiblock(self, cf_op, current_layout):
         # pylint: disable=cyclic-import
@@ -424,32 +425,15 @@ def _transpile_controlflow_looping(self, cf_op, current_layout):
         """
         # pylint: disable=cyclic-import
         from qiskit.transpiler.passes.routing import LayoutTransformation
-
-        def _move_continue_to_end(dag):
-            """Check if continue exists in block. If it does move it to the end of the circuit
-            so layout_xform doesn't get skipped."""
-            continue_nodes = dag.named_nodes("continue_loop")
-            if continue_nodes:
-                if len(continue_nodes) > 1:
-                    raise CircuitError("Multiple 'continue' statements contained in loop")
-                if len(continue_nodes) <= 1:
-                    c_node = continue_nodes[-1]
-                    dag.remove_op_node(c_node)
-                    dag.apply_operation_back(c_node.op, c_node.qargs, c_node.cargs)
-            return dag
-
         new_coupling = layout_transform(self.coupling_map, current_layout)
         dag_block = circuit_to_dag(cf_op.blocks[0])
         _pass = self.__class__(new_coupling, initial_layout=None, seed=self.seed)
         start_qreg = QuantumRegister(len(self._qubit_indices), "q")
         start_layout = Layout.generate_trivial_layout(start_qreg)
         updated_dag_block = _pass.run(dag_block)
         updated_layout = _pass.property_set["final_layout"].copy()
-
         layout_xform = LayoutTransformation(new_coupling, updated_layout, start_layout)
         match_dag = layout_xform.run(updated_dag_block)
-        match_dag = _move_continue_to_end(match_dag)
-
         match_circ = dag_to_circuit(match_dag)
         return cf_op.replace_blocks([match_circ]), current_layout