Support target and basis gates in Unroll3qOrMore transpiler pass

This commit adds two new constructor arguments to the Unroll3qOrMore
transpiler pass, target and basis_gates, which are used to specify a
backend target and basis gate list respectively. If these are specified
the pass will not decompose any multiqubit operations present in the
circuit if they are in the target or basis_gates list.

Fixes Qiskit#5518
Related to Qiskit#7812
Part of Qiskit#7113

qiskit/transpiler/passes/basis/unroll_3q_or_more.py

@@ -20,6 +20,27 @@
 class Unroll3qOrMore(TransformationPass):
     """Recursively expands 3q+ gates until the circuit only contains 2q or 1q gates."""
 
+    def __init__(self, target=None, basis_gates=None):
+        """Initialize the Unroll3qOrMore pass
+
+        Args:
+            target (Target): The target object reprsenting the compilation
+                target. If specified any multiqubit instructions in the
+                circuit when the pass is run that are supported by the target
+                device will be left in place. If both this and ``basis_gates``
+                are specified only the target will be checked.
+            basis_gates (list): A list of basis gate names that the target
+                device supports. If specified any gate names in the circuit
+                which are present in this list will not be unrolled. If both
+                this and ``target`` are specified only the target will be used
+                for checking which gates are supported.
+        """
+        super().__init__()
+        self.target = target
+        self.basis_gates = None
+        if basis_gates is not None:
+            self.basis_gates = set(basis_gates)
+
     def run(self, dag):
         """Run the Unroll3qOrMore pass on `dag`.
 
@@ -33,6 +54,15 @@ def run(self, dag):
         for node in dag.multi_qubit_ops():
             if dag.has_calibration_for(node):
                 continue
+            if self.target is not None:
+                # Treat target instructions as global since this pass can be run
+                # prior to layout and routing we don't have phsyical qubits from
+                # the circuit yet
+                if node.name in self.target:
+                    continue
+            elif self.basis_gates is not None and node.name in self.basis_gates:
+                continue
+
             # TODO: allow choosing other possible decompositions
             rule = node.op.definition.data
             if not rule:

qiskit/transpiler/preset_passmanagers/level0.py

@@ -108,7 +108,7 @@ def level_0_pass_manager(pass_manager_config: PassManagerConfig) -> PassManager:
             plugin_config=unitary_synthesis_plugin_config,
             target=target,
         ),
-        Unroll3qOrMore(),
+        Unroll3qOrMore(target=target, basis_gates=basis_gates),
     ]
 
     # 2. Choose an initial layout if not set by user (default: trivial layout)
@@ -190,7 +190,7 @@ def _swap_condition(property_set):
                 plugin_config=unitary_synthesis_plugin_config,
                 target=target,
             ),
-            Unroll3qOrMore(),
+            Unroll3qOrMore(target=target, basis_gates=basis_gates),
             Collect2qBlocks(),
             Collect1qRuns(),
             ConsolidateBlocks(basis_gates=basis_gates, target=target),

qiskit/transpiler/preset_passmanagers/level1.py

@@ -173,7 +173,7 @@ def _vf2_match_not_found(property_set):
             plugin_config=unitary_synthesis_plugin_config,
             target=target,
         ),
-        Unroll3qOrMore(),
+        Unroll3qOrMore(target=target, basis_gates=basis_gates),
     ]
 
     # 3. Use a better layout on densely connected qubits, if circuit needs swaps
@@ -253,7 +253,7 @@ def _swap_condition(property_set):
                 min_qubits=3,
                 target=target,
             ),
-            Unroll3qOrMore(),
+            Unroll3qOrMore(target=target, basis_gates=basis_gates),
             Collect2qBlocks(),
             ConsolidateBlocks(basis_gates=basis_gates, target=target),
             UnitarySynthesis(

qiskit/transpiler/preset_passmanagers/level2.py

@@ -122,7 +122,7 @@ def level_2_pass_manager(pass_manager_config: PassManagerConfig) -> PassManager:
             plugin_config=unitary_synthesis_plugin_config,
             target=target,
         ),
-        Unroll3qOrMore(),
+        Unroll3qOrMore(target=target, basis_gates=basis_gates),
     ]
 
     # 2. Search for a perfect layout, or choose a dense layout, if no layout given
@@ -238,7 +238,7 @@ def _swap_condition(property_set):
                 min_qubits=3,
                 target=target,
             ),
-            Unroll3qOrMore(),
+            Unroll3qOrMore(target=target, basis_gates=basis_gates),
             Collect2qBlocks(),
             ConsolidateBlocks(basis_gates=basis_gates, target=target),
             UnitarySynthesis(

qiskit/transpiler/preset_passmanagers/level3.py

@@ -125,7 +125,7 @@ def level_3_pass_manager(pass_manager_config: PassManagerConfig) -> PassManager:
             min_qubits=3,
             target=target,
         ),
-        Unroll3qOrMore(),
+        Unroll3qOrMore(target=target, basis_gates=basis_gates),
     ]
 
     # 2. Layout on good qubits if calibration info available, otherwise on dense links
@@ -236,7 +236,7 @@ def _swap_condition(property_set):
                 min_qubits=3,
                 target=target,
             ),
-            Unroll3qOrMore(),
+            Unroll3qOrMore(target=target, basis_gates=basis_gates),
             Collect2qBlocks(),
             ConsolidateBlocks(basis_gates=basis_gates, target=target),
             UnitarySynthesis(

releasenotes/notes/unroll3q-target-bf57cc4365808862.yaml

@@ -0,0 +1,10 @@
+---
+features:
+  - |
+    The constructor for the :class:`~.Unroll3qOrMore` transpiler pass has
+    two new optional keyword arguments, ``target`` and ``basis`` gates. These
+    options enable you to specify the :class:`~.Target` or supported basis
+    gates respectively to describe the target backend. If any of the operations
+    in the circuit are in the ``target`` or ``basis_gates`` those will not
+    be unrolled by the pass as the target device has native support for the
+    operation.

test/python/transpiler/test_unroll_3q_or_more.py

@@ -12,13 +12,16 @@
 
 """Test the Unroll3qOrMore pass"""
 import numpy as np
+
 from qiskit import QuantumRegister, ClassicalRegister, QuantumCircuit
+from qiskit.circuit.library import CCXGate, RCCXGate
 from qiskit.transpiler.passes import Unroll3qOrMore
 from qiskit.converters import circuit_to_dag, dag_to_circuit
 from qiskit.quantum_info.operators import Operator
 from qiskit.quantum_info.random import random_unitary
 from qiskit.test import QiskitTestCase
 from qiskit.extensions import UnitaryGate
+from qiskit.transpiler import Target
 
 
 class TestUnroll3qOrMore(QiskitTestCase):
@@ -91,3 +94,39 @@ def test_identity(self):
         after_dag = pass_.run(dag)
         after_circ = dag_to_circuit(after_dag)
         self.assertTrue(Operator(circuit).equiv(Operator(after_circ)))
+
+    def test_target(self):
+        """Test target is respected by the unroll 3q or more pass."""
+        target = Target(num_qubits=3)
+        target.add_instruction(CCXGate())
+        qc = QuantumCircuit(3)
+        qc.ccx(0, 1, 2)
+        qc.append(RCCXGate(), [0, 1, 2])
+        unroll_pass = Unroll3qOrMore(target=target)
+        res = unroll_pass(qc)
+        self.assertIn('ccx', res.count_ops())
+        self.assertNotIn('rccx', res.count_ops())
+
+    def test_basis_gates(self):
+        """Test basis_gates are respected by the unroll 3q or more pass."""
+        basis_gates = ["rccx"]
+        qc = QuantumCircuit(3)
+        qc.ccx(0, 1, 2)
+        qc.append(RCCXGate(), [0, 1, 2])
+        unroll_pass = Unroll3qOrMore(basis_gates=basis_gates)
+        res = unroll_pass(qc)
+        self.assertNotIn('ccx', res.count_ops())
+        self.assertIn('rccx', res.count_ops())
+
+    def test_target_over_basis_gates(self):
+        """Test target is respected over basis_gates  by the unroll 3q or more pass."""
+        target = Target(num_qubits=3)
+        basis_gates = ['rccx']
+        target.add_instruction(CCXGate())
+        qc = QuantumCircuit(3)
+        qc.ccx(0, 1, 2)
+        qc.append(RCCXGate(), [0, 1, 2])
+        unroll_pass = Unroll3qOrMore(target=target, basis_gates=basis_gates)
+        res = unroll_pass(qc)
+        self.assertIn('ccx', res.count_ops())
+        self.assertNotIn('rccx', res.count_ops())