Avoid operator creation in transpiler (backport #12826)

crates/circuit/src/circuit_instruction.rs

@@ -22,7 +22,9 @@ use pyo3::{intern, IntoPy, PyObject, PyResult};
 
 use smallvec::SmallVec;
 
-use crate::imports::{GATE, INSTRUCTION, OPERATION, WARNINGS_WARN};
+use crate::imports::{
+    CONTROLLED_GATE, CONTROL_FLOW_OP, GATE, INSTRUCTION, OPERATION, WARNINGS_WARN,
+};
 use crate::operations::{
     Operation, OperationRef, Param, PyGate, PyInstruction, PyOperation, StandardGate,
 };
@@ -266,11 +268,36 @@ impl CircuitInstruction {
             .and_then(|attrs| attrs.unit.as_deref())
     }
 
-    #[getter]
+    /// Is the :class:`.Operation` contained in this instruction a Qiskit standard gate?
     pub fn is_standard_gate(&self) -> bool {
         self.operation.try_standard_gate().is_some()
     }
 
+    /// Is the :class:`.Operation` contained in this instruction a subclass of
+    /// :class:`.ControlledGate`?
+    pub fn is_controlled_gate(&self, py: Python) -> PyResult<bool> {
+        match self.operation.view() {
+            OperationRef::Standard(standard) => Ok(standard.num_ctrl_qubits() != 0),
+            OperationRef::Gate(gate) => gate
+                .gate
+                .bind(py)
+                .is_instance(CONTROLLED_GATE.get_bound(py)),
+            _ => Ok(false),
+        }
+    }
+
+    /// Is the :class:`.Operation` contained in this node a directive?
+    pub fn is_directive(&self) -> bool {
+        self.op().directive()
+    }
+
+    /// Is the :class:`.Operation` contained in this instruction a control-flow operation (i.e. an
+    /// instance of :class:`.ControlFlowOp`)?
+    pub fn is_control_flow(&self) -> bool {
+        self.op().control_flow()
+    }
+
+    /// Does this instruction contain any :class:`.ParameterExpression` parameters?
     pub fn is_parameterized(&self) -> bool {
         self.params
             .iter()
@@ -557,6 +584,7 @@ impl<'py> FromPyObject<'py> for OperationFromPython {
                 clbits: ob.getattr(intern!(py, "num_clbits"))?.extract()?,
                 params: params.len() as u32,
                 op_name: ob.getattr(intern!(py, "name"))?.extract()?,
+                control_flow: ob.is_instance(CONTROL_FLOW_OP.get_bound(py))?,
                 instruction: ob.into_py(py),
             });
             return Ok(OperationFromPython {

crates/circuit/src/dag_node.rs

@@ -291,10 +291,6 @@ impl DAGOpNode {
         self.instruction.params = val;
     }
 
-    pub fn is_parameterized(&self) -> bool {
-        self.instruction.is_parameterized()
-    }
-
     #[getter]
     fn matrix(&self, py: Python) -> Option<PyObject> {
         let matrix = self.instruction.op().matrix(&self.instruction.params);
@@ -333,11 +329,32 @@ impl DAGOpNode {
             .and_then(|attrs| attrs.unit.as_deref())
     }
 
-    #[getter]
+    /// Is the :class:`.Operation` contained in this node a Qiskit standard gate?
     pub fn is_standard_gate(&self) -> bool {
         self.instruction.is_standard_gate()
     }
 
+    /// Is the :class:`.Operation` contained in this node a subclass of :class:`.ControlledGate`?
+    pub fn is_controlled_gate(&self, py: Python) -> PyResult<bool> {
+        self.instruction.is_controlled_gate(py)
+    }
+
+    /// Is the :class:`.Operation` contained in this node a directive?
+    pub fn is_directive(&self) -> bool {
+        self.instruction.is_directive()
+    }
+
+    /// Is the :class:`.Operation` contained in this node a control-flow operation (i.e. an instance
+    /// of :class:`.ControlFlowOp`)?
+    pub fn is_control_flow(&self) -> bool {
+        self.instruction.is_control_flow()
+    }
+
+    /// Does this node contain any :class:`.ParameterExpression` parameters?
+    pub fn is_parameterized(&self) -> bool {
+        self.instruction.is_parameterized()
+    }
+
     #[setter]
     fn set_label(&mut self, val: Option<String>) {
         match self.instruction.extra_attrs.as_mut() {

crates/circuit/src/imports.rs

@@ -61,6 +61,8 @@ pub static OPERATION: ImportOnceCell = ImportOnceCell::new("qiskit.circuit.opera
 pub static INSTRUCTION: ImportOnceCell =
     ImportOnceCell::new("qiskit.circuit.instruction", "Instruction");
 pub static GATE: ImportOnceCell = ImportOnceCell::new("qiskit.circuit.gate", "Gate");
+pub static CONTROL_FLOW_OP: ImportOnceCell =
+    ImportOnceCell::new("qiskit.circuit.controlflow", "ControlFlowOp");
 pub static QUBIT: ImportOnceCell = ImportOnceCell::new("qiskit.circuit.quantumregister", "Qubit");
 pub static CLBIT: ImportOnceCell = ImportOnceCell::new("qiskit.circuit.classicalregister", "Clbit");
 pub static PARAMETER_EXPRESSION: ImportOnceCell =

crates/circuit/src/operations.rs

@@ -2016,6 +2016,7 @@ pub struct PyInstruction {
     pub clbits: u32,
     pub params: u32,
     pub op_name: String,
+    pub control_flow: bool,
     pub instruction: PyObject,
 }
 
@@ -2033,7 +2034,7 @@ impl Operation for PyInstruction {
         self.params
     }
     fn control_flow(&self) -> bool {
-        false
+        self.control_flow
     }
     fn matrix(&self, _params: &[Param]) -> Option<Array2<Complex64>> {
         None

crates/circuit/src/packed_instruction.rs

@@ -283,6 +283,7 @@ impl PackedOperation {
                 qubits: instruction.qubits,
                 clbits: instruction.clbits,
                 params: instruction.params,
+                control_flow: instruction.control_flow,
                 op_name: instruction.op_name.clone(),
             }
             .into()),
@@ -316,6 +317,7 @@ impl PackedOperation {
                 qubits: instruction.qubits,
                 clbits: instruction.clbits,
                 params: instruction.params,
+                control_flow: instruction.control_flow,
                 op_name: instruction.op_name.clone(),
             })
             .into()),

qiskit/circuit/commutation_checker.py

@@ -66,11 +66,11 @@ def commute_nodes(
         """Checks if two DAGOpNodes commute."""
         qargs1 = op1.qargs
         cargs1 = op2.cargs
-        if not op1.is_standard_gate:
+        if not op1.is_standard_gate():
             op1 = op1.op
         qargs2 = op2.qargs
         cargs2 = op2.cargs
-        if not op2.is_standard_gate:
+        if not op2.is_standard_gate():
             op2 = op2.op
         return self.commute(op1, qargs1, cargs1, op2, qargs2, cargs2, max_num_qubits)
 

qiskit/dagcircuit/dagcircuit.py

@@ -974,15 +974,26 @@ def _reject_new_register(reg):
             elif isinstance(nd, DAGOpNode):
                 m_qargs = [edge_map.get(x, x) for x in nd.qargs]
                 m_cargs = [edge_map.get(x, x) for x in nd.cargs]
-                op = nd.op.copy()
-                if (condition := getattr(op, "condition", None)) is not None:
-                    if not isinstance(op, ControlFlowOp):
-                        op = op.c_if(*variable_mapper.map_condition(condition, allow_reorder=True))
+                inst = nd._to_circuit_instruction(deepcopy=True)
+                m_op = None
+                if inst.condition is not None:
+                    if inst.is_control_flow():
+                        m_op = inst.operation
+                        m_op.condition = variable_mapper.map_condition(
+                            inst.condition, allow_reorder=True
+                        )
                     else:
-                        op.condition = variable_mapper.map_condition(condition, allow_reorder=True)
-                elif isinstance(op, SwitchCaseOp):
-                    op.target = variable_mapper.map_target(op.target)
-                dag.apply_operation_back(op, m_qargs, m_cargs, check=False)
+                        m_op = inst.operation.c_if(
+                            *variable_mapper.map_condition(inst.condition, allow_reorder=True)
+                        )
+                elif inst.is_control_flow() and isinstance(inst.operation, SwitchCaseOp):
+                    m_op = inst.operation
+                    m_op.target = variable_mapper.map_target(m_op.target)
+                if m_op is None:
+                    inst = inst.replace(qubits=m_qargs, clbits=m_cargs)
+                else:
+                    inst = inst.replace(operation=m_op, qubits=m_qargs, clbits=m_cargs)
+                dag._apply_op_node_back(DAGOpNode.from_instruction(inst), check=False)
             else:
                 raise DAGCircuitError(f"bad node type {type(nd)}")
 
@@ -1460,11 +1471,7 @@ def substitute_node_with_dag(self, node, input_dag, wires=None, propagate_condit
         reverse_wire_map = {b: a for a, b in wire_map.items()}
         # It doesn't make sense to try and propagate a condition from a control-flow op; a
         # replacement for the control-flow op should implement the operation completely.
-        if (
-            propagate_condition
-            and not isinstance(node.op, ControlFlowOp)
-            and (op_condition := getattr(node.op, "condition", None)) is not None
-        ):
+        if propagate_condition and not node.is_control_flow() and node.condition is not None:
             in_dag = input_dag.copy_empty_like()
             # The remapping of `condition` below is still using the old code that assumes a 2-tuple.
             # This is because this remapping code only makes sense in the case of non-control-flow
@@ -1473,7 +1480,7 @@ def substitute_node_with_dag(self, node, input_dag, wires=None, propagate_condit
             # in favour of the new-style conditional blocks.  The extra logic in here to add
             # additional wires into the map as necessary would hugely complicate matters if we tried
             # to abstract it out into the `VariableMapper` used elsewhere.
-            target, value = op_condition
+            target, value = node.condition
             if isinstance(target, Clbit):
                 new_target = reverse_wire_map.get(target, Clbit())
                 if new_target not in wire_map:
@@ -1593,25 +1600,31 @@ def edge_weight_map(wire):
         for old_node_index, new_node_index in node_map.items():
             # update node attributes
             old_node = in_dag._multi_graph[old_node_index]
-            if isinstance(old_node.op, SwitchCaseOp):
+            m_op = None
+            if not old_node.is_standard_gate() and isinstance(old_node.op, SwitchCaseOp):
                 m_op = SwitchCaseOp(
                     variable_mapper.map_target(old_node.op.target),
                     old_node.op.cases_specifier(),
                     label=old_node.op.label,
                 )
-            elif getattr(old_node.op, "condition", None) is not None:
+            elif old_node.condition is not None:
                 m_op = old_node.op
-                if not isinstance(old_node.op, ControlFlowOp):
+                if old_node.is_control_flow():
+                    m_op.condition = variable_mapper.map_condition(m_op.condition)
+                else:
                     new_condition = variable_mapper.map_condition(m_op.condition)
                     if new_condition is not None:
                         m_op = m_op.c_if(*new_condition)
-                else:
-                    m_op.condition = variable_mapper.map_condition(m_op.condition)
-            else:
-                m_op = old_node.op
             m_qargs = [wire_map[x] for x in old_node.qargs]
             m_cargs = [wire_map[x] for x in old_node.cargs]
-            new_node = DAGOpNode(m_op, qargs=m_qargs, cargs=m_cargs, dag=self)
+            old_instruction = old_node._to_circuit_instruction()
+            if m_op is None:
+                new_instruction = old_instruction.replace(qubits=m_qargs, clbits=m_cargs)
+            else:
+                new_instruction = old_instruction.replace(
+                    operation=m_op, qubits=m_qargs, clbits=m_cargs
+                )
+            new_node = DAGOpNode.from_instruction(new_instruction)
             new_node._node_id = new_node_index
             self._multi_graph[new_node_index] = new_node
             self._increment_op(new_node.name)
@@ -1840,11 +1853,18 @@ def op_nodes(self, op=None, include_directives=True):
             list[DAGOpNode]: the list of node ids containing the given op.
         """
         nodes = []
+        filter_is_nonstandard = getattr(op, "_standard_gate", None) is None
         for node in self._multi_graph.nodes():
             if isinstance(node, DAGOpNode):
-                if not include_directives and getattr(node.op, "_directive", False):
+                if not include_directives and node.is_directive():
                     continue
-                if op is None or isinstance(node.op, op):
+                if op is None or (
+                    # This middle catch is to avoid Python-space operation creation for most uses of
+                    # `op`; we're usually just looking for control-flow ops, and standard gates
+                    # aren't control-flow ops.
+                    not (filter_is_nonstandard and node.is_standard_gate())
+                    and isinstance(node.op, op)
+                ):
                     nodes.append(node)
         return nodes
 
@@ -1864,7 +1884,7 @@ def named_nodes(self, *names):
         """Get the set of "op" nodes with the given name."""
         named_nodes = []
         for node in self._multi_graph.nodes():
-            if isinstance(node, DAGOpNode) and node.op.name in names:
+            if isinstance(node, DAGOpNode) and node.name in names:
                 named_nodes.append(node)
         return named_nodes
 
@@ -2070,14 +2090,11 @@ def layers(self, *, vars_mode: _VarsMode = "captures"):
             new_layer = self.copy_empty_like(vars_mode=vars_mode)
 
             for node in op_nodes:
-                # this creates new DAGOpNodes in the new_layer
-                new_layer.apply_operation_back(node.op, node.qargs, node.cargs, check=False)
+                new_layer._apply_op_node_back(node, check=False)
 
             # The quantum registers that have an operation in this layer.
             support_list = [
-                op_node.qargs
-                for op_node in new_layer.op_nodes()
-                if not getattr(op_node.op, "_directive", False)
+                op_node.qargs for op_node in new_layer.op_nodes() if not op_node.is_directive()
             ]
 
             yield {"graph": new_layer, "partition": support_list}
@@ -2129,11 +2146,7 @@ def collect_runs(self, namelist):
         """
 
         def filter_fn(node):
-            return (
-                isinstance(node, DAGOpNode)
-                and node.op.name in namelist
-                and getattr(node.op, "condition", None) is None
-            )
+            return isinstance(node, DAGOpNode) and node.name in namelist and node.condition is None
 
         group_list = rx.collect_runs(self._multi_graph, filter_fn)
         return {tuple(x) for x in group_list}
@@ -2366,7 +2379,7 @@ def _may_have_additional_wires(node) -> bool:
     #
     # If updating this, you most likely also need to update `_additional_wires`.
     return node.condition is not None or (
-        not node.is_standard_gate and isinstance(node.op, (ControlFlowOp, Store))
+        not node.is_standard_gate() and isinstance(node.op, (ControlFlowOp, Store))
     )
 
 

qiskit/transpiler/passes/basis/basis_translator.py

@@ -323,7 +323,7 @@ def _replace_node(self, dag, node, instr_map):
                     node.cargs[target_dag.find_bit(x).index] for x in inner_node.cargs
                 )
 
-                if not new_node.is_standard_gate:
+                if not new_node.is_standard_gate():
                     new_node.op = new_node.op.copy()
                 if any(isinstance(x, ParameterExpression) for x in inner_node.params):
                     new_params = []
@@ -342,7 +342,7 @@ def _replace_node(self, dag, node, instr_map):
                                 new_value = new_value.numeric()
                             new_params.append(new_value)
                     new_node.params = new_params
-                    if not new_node.is_standard_gate:
+                    if not new_node.is_standard_gate():
                         new_node.op.params = new_params
                 dag._apply_op_node_back(new_node)
 
@@ -533,7 +533,7 @@ def edge_cost(self, edge_data):
 
         cost_tot = 0
         for instruction in edge_data.rule.circuit:
-            key = Key(name=instruction.operation.name, num_qubits=len(instruction.qubits))
+            key = Key(name=instruction.name, num_qubits=len(instruction.qubits))
             cost_tot += self._opt_cost_map[key]
 
         return cost_tot - self._opt_cost_map[edge_data.source]

qiskit/transpiler/passes/layout/apply_layout.py

@@ -13,7 +13,7 @@
 """Transform a circuit with virtual qubits into a circuit with physical qubits."""
 
 from qiskit.circuit import QuantumRegister
-from qiskit.dagcircuit import DAGCircuit
+from qiskit.dagcircuit import DAGCircuit, DAGOpNode
 from qiskit.transpiler.basepasses import TransformationPass
 from qiskit.transpiler.exceptions import TranspilerError
 from qiskit.transpiler.layout import Layout
@@ -79,7 +79,12 @@ def run(self, dag):
             virtual_physical_map = layout.get_virtual_bits()
             for node in dag.topological_op_nodes():
                 qargs = [q[virtual_physical_map[qarg]] for qarg in node.qargs]
-                new_dag.apply_operation_back(node.op, qargs, node.cargs, check=False)
+                new_dag._apply_op_node_back(
+                    DAGOpNode.from_instruction(
+                        node._to_circuit_instruction().replace(qubits=qargs)
+                    ),
+                    check=False,
+                )
         else:
             # First build a new layout object going from:
             # old virtual -> old physical -> new virtual -> new physical
@@ -99,7 +104,12 @@ def run(self, dag):
             # Apply new layout to the circuit
             for node in dag.topological_op_nodes():
                 qargs = [q[new_virtual_to_physical[qarg]] for qarg in node.qargs]
-                new_dag.apply_operation_back(node.op, qargs, node.cargs, check=False)
+                new_dag._apply_op_node_back(
+                    DAGOpNode.from_instruction(
+                        node._to_circuit_instruction().replace(qubits=qargs)
+                    ),
+                    check=False,
+                )
             self.property_set["layout"] = full_layout
             if (final_layout := self.property_set["final_layout"]) is not None:
                 final_layout_mapping = {