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Fix flakiness in pulse-optimal UnitarySynthesis test (#11307)
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The previous iteration of this test asserted that the `sx` count for
non-optimal synthesis was higher than a certain particular value.  This
value did not have any fundamental properties, it was just the value
that happened to be returned for some time.  Recent OpenBLAS support
for x86_64 instructions from the AVX512 SkylakeX set meant that
supporting processors can now return slightly fewer `sx` gates in the
non-optimal path, despite the pulse-optimal synthesis still not being in
use.  This caused flaky CI, when we were allocated an Azure VM that had
access to the new instructions.
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jakelishman authored Nov 23, 2023
1 parent 920fa57 commit c7ecb5f
Showing 1 changed file with 27 additions and 16 deletions.
43 changes: 27 additions & 16 deletions test/python/transpiler/test_unitary_synthesis.py
Original file line number Diff line number Diff line change
Expand Up @@ -344,25 +344,36 @@ def test_two_qubit_synthesis_not_pulse_optimal(self):
backend = FakeVigo()
conf = backend.configuration()
qr = QuantumRegister(2)
coupling_map = CouplingMap([[0, 1], [1, 2], [1, 3], [3, 4]])
triv_layout_pass = TrivialLayout(coupling_map)
qc = QuantumCircuit(qr)
qc.unitary(random_unitary(4, seed=12), [0, 1])
unisynth_pass = UnitarySynthesis(
basis_gates=conf.basis_gates,
coupling_map=coupling_map,
backend_props=backend.properties(),
pulse_optimize=False,
natural_direction=True,
coupling_map = CouplingMap([[0, 1]])
pm_nonoptimal = PassManager(
[
TrivialLayout(coupling_map),
UnitarySynthesis(
basis_gates=conf.basis_gates,
coupling_map=coupling_map,
backend_props=backend.properties(),
pulse_optimize=False,
natural_direction=True,
),
]
)
pm = PassManager([triv_layout_pass, unisynth_pass])
qc_out = pm.run(qc)
if isinstance(qc_out, QuantumCircuit):
num_ops = qc_out.count_ops()
else:
num_ops = qc_out[0].count_ops()
self.assertIn("sx", num_ops)
self.assertGreaterEqual(num_ops["sx"], 16)
pm_optimal = PassManager(
[
TrivialLayout(coupling_map),
UnitarySynthesis(
basis_gates=conf.basis_gates,
coupling_map=coupling_map,
backend_props=backend.properties(),
pulse_optimize=True,
natural_direction=True,
),
]
)
qc_nonoptimal = pm_nonoptimal.run(qc)
qc_optimal = pm_optimal.run(qc)
self.assertGreater(qc_nonoptimal.count_ops()["sx"], qc_optimal.count_ops()["sx"])

def test_two_qubit_pulse_optimal_true_raises(self):
"""Verify raises if pulse optimal==True but cx is not in the backend basis."""
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