Qiskit / qiskit / 6965881508

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Commit Message

Avoid routing 2q barriers in SabreSwap (#11295)

* Avoid routing 2q barriers in SabreSwap

This commit fixes an oversight in the sabre swap pass where a 2 qubit
barrier would have been treated like a 2 qubit gate and swaps could
potentially be inserted if the sabre algorithm thought it didn't have
connectivity for the qargs to the barrier. However as barrier is just
a compiler directive it is valid on all qubit pairs so this swap
insertion was unnecessary, it was still valid but just not an optimal
output. This commit fixes it by adding context to the sabre dag around
whether a given node is a directive (and valid on all qubits) or not.

* Update rust tests too

* Skip directives in extended set generation too

Co-authored-by: Kevin Hartman <kevin@hart.mn>

* Add release note

* Update test layout in test_layout_many_search_trials

This commit updates a layout in the:
`TestSabreLayout.test_layout_many_search_trials` test case which was
recently changed in #10323. The change in test ouput caused by #10323
is what triggered the investigation into this bugfix and now that
barriers are being treated correctly by sabre the layout doesn't change
in the test case anymore and this is reverting the test assertion to use
the original layout before #10323 was merged.

---------

Co-authored-by: Kevin Hartman <kevin@hart.mn>

Run Details

36 of 36 new or added lines in 2 files covered. (100.0%)

14 existing lines in 2 files now uncovered.

66280 of 76683 relevant lines covered (86.43%)

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