StagedPassManager
class qiskit.transpiler.StagedPassManager(stages=None, **kwargs)
Bases: PassManager
A pass manager pipeline built from individual stages.
This class enables building a compilation pipeline out of fixed stages. Each StagedPassManager
defines a list of stages which are executed in a fixed order, and each stage is defined as a standalone PassManager
instance. There are also pre_
and post_
stages for each defined stage. This enables easily composing and replacing different stages and also adding hook points to enable programmatic modifications to a pipeline. When using a staged pass manager you are not able to modify the individual passes and are only able to modify stages.
By default, instances of StagedPassManager
define a typical full compilation pipeline from an abstract virtual circuit to one that is optimized and capable of running on the specified backend. The default pre-defined stages are:
init
- Initial passes to run before embedding the circuit to the backend.layout
- Maps the virtual qubits in the circuit to the physical qubits on the backend.routing
- Inserts gates as needed to move the qubit states around until the circuit can be run with the chosen layout on the backend’s coupling map.translation
- Translates the gates in the circuit to the target backend’s basis gate set.optimization
- Optimizes the circuit to reduce the cost of executing it. These passes will typically run in a loop until a convergence criteria is met. For example, the convergence criteria might be that the circuit depth does not decrease in successive iterations.scheduling
- Hardware-aware passes that schedule the operations in the circuit.
For backwards compatibility the relative positioning of these default stages will remain stable moving forward. However, new stages may be added to the default stage list in between current stages. For example, in a future release a new phase, something like logical_optimization
, could be added immediately after the existing init
stage in the default stage list. This would preserve compatibility for pre-existing StagedPassManager
users as the relative positions of the stage are preserved so the behavior will not change between releases.
These stages will be executed in order and any stage set to None
will be skipped. If a stage is provided multiple times (i.e. at diferent relative positions), the associated passes, including pre and post, will run once per declaration. If a PassManager
input is being used for more than 1 stage here (for example in the case of a Pass
that covers both Layout and Routing) you will want to set that to the earliest stage in sequence that it covers.
Initialize a new StagedPassManager object
Parameters
- stages (Iterable[str]) – An optional list of stages to use for this instance. If this is not specified the default stages list
['init', 'layout', 'routing', 'translation', 'optimization', 'scheduling']
is used. After instantiation, the final list will be immutable and stored as tuple. If a stage is provided multiple times (i.e. at diferent relative positions), the associated passes, including pre and post, will run once per declaration. - kwargs – The initial
PassManager
values for any stages defined instages
. If a argument is not defined the stages will default toNone
indicating an empty/undefined stage.
Raises
- AttributeError – If a stage in the input keyword arguments is not defined.
- ValueError – If an invalid stage name is specified.
Attributes
expanded_stages
Expanded Pass manager stages including pre_
and post_
phases.
invalid_stage_regex
Default value: re.compile('\\s|\\+|\\-|\\*|\\/|\\\\|\\%|\\<|\\>|\\@|\\!|\\~|\\^|\\&|\\:|\\[|\\]|\\{|\\}|\\(|\\)')
stages
Pass manager stages
Methods
append
append(passes)
Append a Pass Set to the schedule of passes.
Parameters
passes (Task | list[Task]) – A set of transpiler passes to be added to schedule.
Raises
TranspilerError – if a pass in passes is not a proper pass.
draw
remove
remove(index)
Removes a particular pass in the scheduler.
Parameters
index (int) – Pass index to remove, based on the position in passes()
.
Raises
PassManagerError – If the index is not found.
replace
run
run(circuits, output_name=None, callback=None, num_processes=None)
Run all the passes on the specified circuits
.
Parameters
-
circuits (_CircuitsT) – Circuit(s) to transform via all the registered passes.
-
output_name (str | None) – The output circuit name. If
None
, it will be set to the same as the input circuit name. -
callback (Callable | None) –
A callback function that will be called after each pass execution. The function will be called with 5 keyword arguments:
pass_ (Pass): the pass being run dag (DAGCircuit): the dag output of the pass time (float): the time to execute the pass property_set (PropertySet): the property set count (int): the index for the pass execution
NoteBeware that the keyword arguments here are different to those used by the generic
BasePassManager
. This pass manager will translate those arguments into the form described above.The exact arguments pass expose the internals of the pass manager and are subject to change as the pass manager internals change. If you intend to reuse a callback function over multiple releases be sure to check that the arguments being passed are the same.
To use the callback feature you define a function that will take in kwargs dict and access the variables. For example:
def callback_func(**kwargs): pass_ = kwargs['pass_'] dag = kwargs['dag'] time = kwargs['time'] property_set = kwargs['property_set'] count = kwargs['count'] ...
-
num_processes (int) – The maximum number of parallel processes to launch if parallel execution is enabled. This argument overrides
num_processes
in the user configuration file, and theQISKIT_NUM_PROCS
environment variable. If set toNone
the system default or local user configuration will be used.
Returns
The transformed circuit(s).
Return type
_CircuitsT
to_flow_controller
to_flow_controller()
Linearize this manager into a single FlowControllerLinear
, so that it can be nested inside another pass manager.
Returns
A linearized pass manager.
Return type