replace CXCancellation with InverseCancellation (#11937)

qiskit/transpiler/passes/optimization/cx_cancellation.py

@@ -14,11 +14,21 @@
 
 from qiskit.transpiler.basepasses import TransformationPass
 from qiskit.transpiler.passes.utils import control_flow
+from qiskit.utils.deprecation import deprecate_func
 
 
 class CXCancellation(TransformationPass):
     """Cancel back-to-back ``cx`` gates in dag."""
 
+    @deprecate_func(
+        additional_msg=(
+            "Instead, use :class:`~.InverseCancellation`, which is a more generic pass."
+        ),
+        since="1.1.0",
+    )
+    def __init__(self, *args, **kwargs):
+        super().__init__(*args, **kwargs)
+
     @control_flow.trivial_recurse
     def run(self, dag):
         """Run the CXCancellation pass on `dag`.

releasenotes/notes/fixes_11212-d6de3c007ce6d697.yaml

@@ -0,0 +1,6 @@
+---
+deprecations_transpiler:
+  - |
+    The pass ``qiskit.transpiler.passes.CXCancellation`` was deprecated in favor of
+    class:`.InverseCancellation`, which is more generic.
+    ``CXCancellation`` is fully semantically equivalent to ``InverseCancellation([CXGate()])``.

test/benchmarks/passes.py

@@ -18,6 +18,7 @@
 from qiskit.circuit.equivalence_library import SessionEquivalenceLibrary as SEL
 from qiskit.transpiler.passes import *
 from qiskit.converters import circuit_to_dag
+from qiskit.circuit.library import CXGate
 
 from .utils import random_circuit
 
@@ -128,7 +129,7 @@ def time_resource_optimization(self, _, __):
         ResourceEstimation().run(self.dag)
 
     def time_cx_cancellation(self, _, __):
-        CXCancellation().run(self.dag)
+        InverseCancellation([CXGate()]).run(self.dag)
 
     def time_dag_longest_path(self, _, __):
         DAGLongestPath().run(self.dag)

test/python/circuit/test_unitary.py

@@ -17,13 +17,13 @@
 from numpy.testing import assert_allclose
 
 import qiskit
-from qiskit.circuit.library import UnitaryGate
+from qiskit.circuit.library import UnitaryGate, CXGate
 from qiskit import QuantumRegister, ClassicalRegister, QuantumCircuit
 from qiskit.transpiler import PassManager
 from qiskit.converters import circuit_to_dag, dag_to_circuit
 from qiskit.quantum_info.random import random_unitary
 from qiskit.quantum_info.operators import Operator
-from qiskit.transpiler.passes import CXCancellation
+from qiskit.transpiler.passes import InverseCancellation
 from qiskit.qasm2 import dumps
 from test import QiskitTestCase  # pylint: disable=wrong-import-order
 
@@ -103,7 +103,7 @@ def test_2q_unitary(self):
         uni2q = UnitaryGate(matrix)
         qc.append(uni2q, [qr[0], qr[1]])
         passman = PassManager()
-        passman.append(CXCancellation())
+        passman.append(InverseCancellation([CXGate()]))
         qc2 = passman.run(qc)
         # test of qasm output
         self.log.info(dumps(qc2))

test/python/transpiler/test_cx_cancellation.py

@@ -39,7 +39,8 @@ def test_pass_cx_cancellation(self):
         circuit.cx(qr[1], qr[0])
 
         pass_manager = PassManager()
-        pass_manager.append(CXCancellation())
+        with self.assertWarns(DeprecationWarning):
+            pass_manager.append(CXCancellation())
         out_circuit = pass_manager.run(circuit)
 
         expected = QuantumCircuit(qr)
@@ -60,7 +61,8 @@ def test_pass_cx_cancellation_intermixed_ops(self):
         circuit.cx(qr[2], qr[3])
 
         pass_manager = PassManager()
-        pass_manager.append(CXCancellation())
+        with self.assertWarns(DeprecationWarning):
+            pass_manager.append(CXCancellation())
         out_circuit = pass_manager.run(circuit)
 
         expected = QuantumCircuit(qr)
@@ -92,7 +94,8 @@ def test_pass_cx_cancellation_chained_cx(self):
         circuit.cx(qr[2], qr[3])
 
         pass_manager = PassManager()
-        pass_manager.append(CXCancellation())
+        with self.assertWarns(DeprecationWarning):
+            pass_manager.append(CXCancellation())
         out_circuit = pass_manager.run(circuit)
 
         #       ┌───┐
@@ -121,7 +124,8 @@ def test_swapped_cx(self):
         circuit.cx(qr[1], qr[0])
 
         pass_manager = PassManager()
-        pass_manager.append(CXCancellation())
+        with self.assertWarns(DeprecationWarning):
+            pass_manager.append(CXCancellation())
         out_circuit = pass_manager.run(circuit)
         self.assertEqual(out_circuit, circuit)
 
@@ -134,13 +138,15 @@ def test_inverted_cx(self):
         circuit.cx(qr[0], qr[1])
 
         pass_manager = PassManager()
-        pass_manager.append(CXCancellation())
+        with self.assertWarns(DeprecationWarning):
+            pass_manager.append(CXCancellation())
         out_circuit = pass_manager.run(circuit)
         self.assertEqual(out_circuit, circuit)
 
     def test_if_else(self):
         """Test that the pass recurses in a simple if-else."""
-        pass_ = CXCancellation()
+        with self.assertWarns(DeprecationWarning):
+            pass_ = CXCancellation()
 
         inner_test = QuantumCircuit(4, 1)
         inner_test.cx(0, 1)
@@ -164,7 +170,8 @@ def test_if_else(self):
 
     def test_nested_control_flow(self):
         """Test that collection recurses into nested control flow."""
-        pass_ = CXCancellation()
+        with self.assertWarns(DeprecationWarning):
+            pass_ = CXCancellation()
         qubits = [Qubit() for _ in [None] * 4]
         clbit = Clbit()
 

test/python/transpiler/test_swap_strategy_router.py

@@ -16,7 +16,7 @@
 
 from qiskit.circuit import QuantumCircuit, Qubit, QuantumRegister
 from qiskit.transpiler import PassManager, CouplingMap, Layout, TranspilerError
-from qiskit.circuit.library import PauliEvolutionGate
+from qiskit.circuit.library import PauliEvolutionGate, CXGate
 from qiskit.circuit.library.n_local import QAOAAnsatz
 from qiskit.converters import circuit_to_dag
 from qiskit.exceptions import QiskitError
@@ -25,7 +25,7 @@
 from qiskit.transpiler.passes import EnlargeWithAncilla
 from qiskit.transpiler.passes import ApplyLayout
 from qiskit.transpiler.passes import SetLayout
-from qiskit.transpiler.passes import CXCancellation
+from qiskit.transpiler.passes import InverseCancellation
 from qiskit.transpiler.passes import Decompose
 from qiskit.transpiler.passes.routing.commuting_2q_gate_routing.commuting_2q_block import (
     Commuting2qBlock,
@@ -524,7 +524,7 @@ def test_edge_coloring(self, edge_coloring):
                 Commuting2qGateRouter(swap_strat, edge_coloring=edge_coloring),
                 Decompose(),  # double decompose gets to CX
                 Decompose(),
-                CXCancellation(),
+                InverseCancellation([CXGate()]),
             ]
         )