StagedPassManager

class StagedPassManager(stages=None, **kwargs)

Bases: qiskit.transpiler.passmanager.PassManager

A Pass manager pipeline built up of 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 programmtic 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:

1. init - any initial passes that are run before we start embedding the circuit to the backend

2. layout - This stage runs layout and maps the virtual qubits in the circuit to the physical qubits on a backend

3. routing - This stage runs after a layout has been run and will insert any necessary gates to move the qubit states around until it can be run on backend’s compuling map.

4. translation - Perform the basis gate translation, in other words translate the gates in the circuit to the target backend’s basis set

5. optimization - The main optimization loop, this will typically run in a loop trying to optimize the circuit until a condtion (such as fixed depth) is reached.

6. scheduling - Any hardware aware scheduling passes

Note

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 in stages. If a argument is not defined the stages will default to None 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.

Methods

append	Append a Pass Set to the schedule of passes.
draw	Draw the pass manager.
passes	Return a list structure of the appended passes and its options.
remove	Removes a particular pass in the scheduler.
replace	Replace a particular pass in the scheduler.
run	Run all the passes on the specified circuits.
to_flow_controller	Linearize this manager into a single FlowController, so that it can be nested inside another PassManager.

Attributes

expanded_stages

Expanded Pass manager stages including pre_ and post_ phases.

Return type

Tuple[str, ...]

invalid_stage_regex = re.compile('\\s|\\+|\\-|\\*|\\/|\\\\|\\%|\\<|\\>|\\@|\\!|\\~|\\^|\\&|\\:|\\[|\\]|\\{|\\}|\\(|\\)')

stages

Pass manager stages

Return type

Tuple[str, ...]