kartik comments

.gitignore

@@ -75,6 +75,9 @@ docs/_build/
 .pybuilder/
 target/
 
+# vscode
+.vscode/
+
 # Jupyter Notebook
 .ipynb_checkpoints
 

pytket/phir/pandr.py → pytket/phir/place_and_route.py

@@ -12,7 +12,7 @@
 
 
 @typing.no_type_check
-def place_and_route(machine: Machine, qasm: Circuit):  # give type hint for return
+def place_and_route(machine: Machine, qasm: Circuit):
     """Get all the routing info needed for PHIR generation."""
     circuit = get_qasm_as_circuit(qasm)
     sharder = Sharder(circuit)

pytket/phir/placement.py

@@ -172,7 +172,7 @@ def place(  # noqa: PLR0912
         raise PlacementCheckError
 
 
-def optimized_place(
+def optimized_place(  # noqa: PLR0912
     ops: list[list[int]],
     tq_options: set[int],
     sq_options: set[int],
@@ -209,7 +209,18 @@ def optimized_place(
 
     # place the tq ops
     order = place_tq_ops(tq_ops_sorted, placed_qubits, order, tq_zones, sq_zones)
-
+    # run a check to avoid unnecessary swaps
+    for zone in tq_zones:
+        # this condition will be true if there was a swap due to the order of qubits_used  # noqa: E501
+        # in the shard creating the TQ op, even if those two qubits were already in a TQ zone  # noqa: E501
+        # example: ops = [[0,1]] prev_state = [0,1,2,3] new order = [1,0,2,3]
+        # this check s to prevent the above situation
+        if (order[zone] == prev_state[zone + 1]) & (
+            order[zone + 1] == prev_state[zone]
+        ):
+            swapped = order[zone + 1]
+            order[zone + 1] = order[zone]
+            order[zone] = swapped
     # place the sq ops
     for op in sq_ops:
         q1 = op[0]

tests/data/qasm/eztest.qasm

@@ -4,7 +4,7 @@ include "hqslib1.inc";
 qreg q[3];
 creg c[3];
 
-CX q[2], q[0];
+CX q[0], q[2];
 h q[0];
 h q[1];
 h q[2];

tests/e2e_test.py

@@ -1,5 +1,5 @@
 from pytket.phir.machine_class import Machine
-from pytket.phir.pandr import place_and_route
+from pytket.phir.place_and_route import place_and_route
 from pytket.phir.placement import placement_check
 from tests.sample_data import QasmFiles
 
@@ -11,10 +11,13 @@
         1.0,
         2.0,
     )
-    # force machine options for this test, machines normally don't like odd numbers of qubits  # noqa: E501
+    # force machine options for this test
+    # machines normally don't like odd numbers of qubits
     machine.sq_options = {0, 1, 2}
+    # The type: ignores in this file are because mypy doesn't like the return type of place and route,  # noqa: E501
+    # list[triple(list[int], list[Shard], float)]
     output = place_and_route(machine, QasmFiles.eztest)  # type: ignore [misc]
-
+    # print(output)
     ez_ops_0 = [[0, 2], [1]]
     ez_ops_1 = [[0], [2]]
     state_0 = output[0][0]  # type: ignore [misc]