schedule() considers instruction map

[MozammilQ]

Summary

In issue #10837 , I discovered that the schedule of qiskit.compiler works fine for BackendV1 but doesn't work for BackendV2. See this comment for details.

Details and comments

Details:
On inspection I discovered that measure function in macros.py requires backend, It uses backend to decide which of the two private methods _measure_v1 or _measure_v2 to call.
So, I decided to pass in this backend from the user to measure of macros.py
I did this as follows:
1>> I changed the definition of schedule_circuit in qiskit/qiskit/scheduler/schedule_circuit.py and added backend as Optional here.
2>> I used this backend and passed it to as_soon_as_possible and as_late_as_possible of qiskit/qiskit/scheduler/methods/basic.py, I also changed the definition of these two methods as_soon_as_possible and as_late_as_possible.
3>> I passed this backend to lower_gates by changing the definition of lower_gates in qiskit/qiskit/scheduler/lowering.py
4>> I also changed the definition of the nested function get_measure_schedule of lowering.py.
5>> Finally I passed in the backend to measure of macros.py

I have made backend in the definition of these changed methods Optional because I do not want the tests to fail, complaining the methods require backend as an additional argument.
I have reformatted the files that I changed and made sure that all the tests have passed! :) 

Comments:
qiskit/qiskit/compile/scheduler.py in the definition of schedule one cannot omit the backend because, how the inst_map is processed depends on it.Furthermore, there is no need to ask for inst_map and meas_map separately if you already have the backend with you!So, backend should not be Optional here! I think inst_map, meas_map and dt are redundant here, please correct me if I am wrong :)

Final result after issue fixed:

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• @nkanazawa1989

[MozammilQ]

sir, please see if my efforts a good enough :), please let me know if any additional changes are required :)

[nkanazawa1989]

@to24toro Could you please review the PR first? I'll merge if this looks good.

[to24toro]

Thank you @MozammilQ .
It almost is good for me and will help solving the issue of scheduling with backendV2.

I have two additional requests for improvement.

• Add an argument of backend for the sequence in

  qiskit/qiskit/scheduler/sequence.py

  Line 28 in 947e175

  def sequence(scheduled_circuit: QuantumCircuit, schedule_config: ScheduleConfig) -> Schedule:

  and lower_gates in this sequence.
• Include explanations for added arguments to pass tests lint.

[MozammilQ]

Thank you @to24toro for your suggestions.

I have done some improvements.

* Add an argument of `backend` for the `sequence` in https://github.com/Qiskit/qiskit/blob/947e175edca77900cf1b0b266c55361bca0a7add/qiskit/scheduler/sequence.py#L28

DONE

   and `lower_gates` in this `sequence`. 

DONE

* Include explanations for added arguments to pass tests lint.

I do not understand what I am supposed to do here, anyways I have added relevant docstring in the changed methods which I forgot to add, am I supposed to do anything else? adding explanations for added arguments in which file? and I have run all tests with tox and all tests have passed.

[to24toro]

Thank you @MozammilQ . I will confirm it.
Anyway, you need to pass all the test to merge it (see :https://dev.azure.com/qiskit-ci/qiskit/_build/results?buildId=50336&view=logs&jobId=86d13450-b8b4-5d9a-22f1-9f7e71062a71&j=86d13450-b8b4-5d9a-22f1-9f7e71062a71&t=a7f62dd9-9d78-5db3-3068-aed07887bd76). Could you please run tox -eblack and tox -elint in your PC and add the modification, referring to it?

[MozammilQ]

@to24toro , :)
Aaah!! Now, I got it! thanks for the kind words, you explained it very well.
I ran tox -eblack and tox -elint, and did the required modifications in the last commit. Is it good this time? :)
just for the information I have run tox -eblack/tox -elint on fedora 38.

[to24toro]

Thank you @MozammilQ .
I think we are almost done. The left thing is to write test codes for backendV2 because the existing test codes related with your modification use backendV1.

Especially, it's better to add the backendV2 version of

qiskit/test/python/scheduler/test_basic_scheduler.py

Line 37 in 65e8c1a

class TestBasicSchedule(QiskitTestCase):

. These tests don't include handling the case that backend is backendV2.
However, this requires some knowledges and it might be tough.

[MozammilQ]

@TsafrirA , I have added many tests that uses BackendV2, there are a few tests that I am yet to add in, I am in talks with @to24toro , regarding that :)

[MozammilQ]

Thank you @MozammilQ . I think we are almost done. The left thing is to write test codes for backendV2 because the existing test codes related with your modification use backendV1.

Especially, it's better to add the backendV2 version of

qiskit/test/python/scheduler/test_basic_scheduler.py

Line 37 in 65e8c1a

class TestBasicSchedule(QiskitTestCase):

. These tests don't include handling the case that backend is backendV2.
However, this requires some knowledges and it might be tough.

@to24toro , please see if this is ok :)

[to24toro]

Thank you @MozammilQ for adding tests. Your comments about the pulse durations is very clear and helps me understand it. I suggested the minor changes.

I would like you to add the release note about the bugfix (see: https://github.com/Qiskit/qiskit/blob/main/CONTRIBUTING.md#release-notes)

[to24toro]

Suggested change

	def test_unavailable_defaults(self):
	"""Test backend with unavailable defaults."""
	qr = QuantumRegister(1)
	qc = QuantumCircuit(qr)
	backend = FakeBackend(None)
	backend.defaults = backend.configuration
	self.assertRaises(QiskitError, lambda: schedule(qc, backend))

This test is not related with the backend version and you can remove it.

[to24toro]

I don't understand that you change the number of gates from backendV1?
Isn't it enough to replace U2 gates with sx gates?

[to24toro]

Suggested change

	prelude: >
	Added support for BackendV2 in schedule of qiskit.compiler.scheduler.
	Test methods in test/python/scheduler/test_basic_scheduler.py have been replicated with backend
	being BackenV2.
	features:
	- |
	Adds support for BackendV2 in schedule of qiskit.compiler.scheduler.
	Example usage::
	#import a fake backend which is a sub-class of BackendV2.
	from qiskit.providers.fake_provider import FakePerth
	from qiskit.compiler.scheduler import schedule
	from qiskit.circuit import QuantumCircuit
	qc=QuantumCircuit(1, 1)
	qc.x(0)
	qc.measure(0,0)
	sched=schedule(circuits=qc, backend=FakePerth())
	- |
	Adds tests with backend being a sub-class of BackendV2.
	In test file:: test/python/scheduler/test_basic_scheduler.py
	All the test methods that used BackendV1 has been replicated to use BackendV2.

Thank you for adding the release notes and sorry for my poor explanation. It would be sufficient to just add an item for "fixes". Also, please describe what was fixed in the fixes section. It would be good to briefly mention what was fixed, such as enabling scheduling using backendV2.

[MozammilQ]

@to24toro , is everything good now? :)

[to24toro]

Thank you @MozammilQ . This Bugfix definitely helps users.

[TsafrirA]

It's a little nitpicky, but all these unions could be replaced with Backend.

[nkanazawa1989]

Thanks @MozammilQ for contribution and @to24toro for review. I just added suggestion of the release note cleanup. You can push commit button if you like it. I'll approve the PR as is so that we can safely add this PR to merge queue before the release date.

[MozammilQ]

@nkanazawa1989 , does this look good now? :)

[nkanazawa1989]

Thanks @MozammilQ this looks good to me. I'll add this to merge queue.

[coveralls]

Pull Request Test Coverage Report for Build 6568856424

• 17 of 17 (100.0%) changed or added relevant lines in 5 files are covered.
• 15 unchanged lines in 2 files lost coverage.
• Overall coverage decreased (-0.009%) to 86.954%

---

Files with Coverage Reduction	New Missed Lines	%
crates/qasm2/src/lex.rs	3	90.91%
crates/qasm2/src/parse.rs	12	97.13%

Totals
Change from base Build 6568317014:	-0.009%
Covered Lines:	73738
Relevant Lines:	84801

---

💛 - Coveralls