[TKET-1598] fix ConnectivityPredicate fails after FullPeepholeOptimis…

…e and AASRouting (#194) * add bugfix * Update tket/src/Predicates/include/Predicates/PassGenerators.hpp Co-authored-by: Alexander Cowtan <[email protected]> * remove bool add break Co-authored-by: Alexander Cowtan <[email protected]>
CQCL · Feb 3, 2022 · d3ab84b · d3ab84b
1 parent a2d2963
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Showing 5 changed files with 104 additions and 6 deletions.
diff --git a/tket/src/Predicates/PassGenerators.cpp b/tket/src/Predicates/PassGenerators.cpp
@@ -268,13 +268,18 @@ PassPtr gen_placement_pass_phase_poly(const Architecture& arc) {
   };
   Transform t = Transform(trans);
 
-  PredicatePtrMap precons{};
+  PredicatePtr no_wire_swap = std::make_shared<NoWireSwapsPredicate>();
+  PredicatePtrMap precons{CompilationUnit::make_type_pair(no_wire_swap)};
+
   PredicatePtr placement_pred = std::make_shared<PlacementPredicate>(arc);
   PredicatePtr n_qubit_pred =
       std::make_shared<MaxNQubitsPredicate>(arc.n_nodes());
+
   PredicatePtrMap s_postcons{
       CompilationUnit::make_type_pair(placement_pred),
-      CompilationUnit::make_type_pair(n_qubit_pred)};
+      CompilationUnit::make_type_pair(n_qubit_pred),
+      CompilationUnit::make_type_pair(no_wire_swap)};
+
   PostConditions pc{s_postcons, {}, Guarantee::Preserve};
   // record pass config
   nlohmann::json j;
@@ -297,6 +302,10 @@ PassPtr aas_routing_pass(
           "Circuit has more qubits than the architecture has nodes.");
     }
 
+    // this pass is not able to handle implicit wire swaps
+    // this is additionally assured by a precondition of this pass
+    TKET_ASSERT(!circ.has_implicit_wireswaps());
+
     qubit_vector_t all_qu = circ.all_qubits();
 
     Circuit input_circ = circ;
@@ -379,9 +388,12 @@ PassPtr aas_routing_pass(
   PredicatePtr placedpred = std::make_shared<PlacementPredicate>(arc);
   PredicatePtr n_qubit_pred =
       std::make_shared<MaxNQubitsPredicate>(arc.n_nodes());
+  PredicatePtr no_wire_swap = std::make_shared<NoWireSwapsPredicate>();
+
   PredicatePtrMap precons{
       CompilationUnit::make_type_pair(placedpred),
-      CompilationUnit::make_type_pair(n_qubit_pred)};
+      CompilationUnit::make_type_pair(n_qubit_pred),
+      CompilationUnit::make_type_pair(no_wire_swap)};
 
   PredicatePtr postcon1 = std::make_shared<ConnectivityPredicate>(arc);
   std::pair<const std::type_index, PredicatePtr> pair1 =

diff --git a/tket/src/Predicates/PassLibrary.cpp b/tket/src/Predicates/PassLibrary.cpp
@@ -285,6 +285,8 @@ const PassPtr &ComposePhasePolyBoxes() {
    * converts a circuit containing all possible gates to a circuit
    * containing only phase poly boxes + H gates (and measure + reset + collapse
    * + barrier)
+   * this pass will replace all wire swaps in the given circuit and they will be
+   * included in the last or an additional phase poly boxes
    */
   static const PassPtr pp([]() {
     Transform t =
@@ -293,7 +295,13 @@ const PassPtr &ComposePhasePolyBoxes() {
 
     PredicatePtrMap precons{CompilationUnit::make_type_pair(noclas)};
 
-    PostConditions postcon = {precons, {}, Guarantee::Clear};
+    PredicatePtr no_wire_swap = std::make_shared<NoWireSwapsPredicate>();
+
+    PredicatePtrMap s_postcons{
+        CompilationUnit::make_type_pair(noclas),
+        CompilationUnit::make_type_pair(no_wire_swap)};
+    PostConditions postcon{s_postcons, {}, Guarantee::Preserve};
+
     nlohmann::json j;
     j["name"] = "ComposePhasePolyBoxes";
     return std::make_shared<StandardPass>(precons, t, postcon, j);

diff --git a/tket/src/Predicates/include/Predicates/PassGenerators.hpp b/tket/src/Predicates/include/Predicates/PassGenerators.hpp
@@ -61,6 +61,7 @@ PassPtr gen_directed_cx_routing_pass(
 /**
  * execute architecture aware synthesis on a given architecture for an allready
  * place circuit, only for circuit which contains Cx+Rz+H gates
+ * this pass is not able to handle implicit wire swaps
  * @param arc architecture to route on
  * @param lookahead parameter for the recursion depth in the algorithm, the
  * value should be > 0

diff --git a/tket/src/Transformations/Decomposition.cpp b/tket/src/Transformations/Decomposition.cpp
@@ -746,6 +746,17 @@ Transform decomp_boxes() {
 
 Transform compose_phase_poly_boxes() {
   return Transform([](Circuit &circ) {
+    // replace wireswaps with three CX
+    while (circ.has_implicit_wireswaps()) {
+      qubit_map_t perm = circ.implicit_qubit_permutation();
+      for (const std::pair<const Qubit, Qubit> &pair : perm) {
+        if (pair.first != pair.second) {
+          circ.replace_implicit_wire_swap(pair.first, pair.second);
+          break;
+        }
+      }
+    }
+
     CircToPhasePolyConversion conv = CircToPhasePolyConversion(circ);
     conv.convert();
     circ = conv.get_circuit();

diff --git a/tket/tests/test_CompilerPass.cpp b/tket/tests/test_CompilerPass.cpp
@@ -797,7 +797,7 @@ SCENARIO("rebase and decompose PhasePolyBox test") {
     Circuit result = cu.get_circ_ref();
 
     REQUIRE(test_unitary_comparison(result, circ));
-    REQUIRE(!NoWireSwapsPredicate().verify(result));
+    REQUIRE(NoWireSwapsPredicate().verify(result));
   }
   GIVEN("NoWireSwapsPredicate for ComposePhasePolyBoxes II") {
     Circuit circ(5);
@@ -817,7 +817,73 @@ SCENARIO("rebase and decompose PhasePolyBox test") {
     Circuit result = cu.get_circ_ref();
 
     REQUIRE(test_unitary_comparison(result, circ));
-    REQUIRE(!NoWireSwapsPredicate().verify(result));
+    REQUIRE(NoWireSwapsPredicate().verify(result));
+  }
+  GIVEN("NoWireSwapsPredicate for ComposePhasePolyBoxes III") {
+    Circuit circ(5);
+    add_2qb_gates(circ, OpType::CX, {{0, 3}, {1, 4}});
+    circ.add_op<unsigned>(OpType::SWAP, {3, 4});
+    circ.add_op<unsigned>(OpType::CX, {2, 3});
+    circ.add_op<unsigned>(OpType::Z, {3});
+    circ.add_op<unsigned>(OpType::CX, {2, 3});
+    circ.add_op<unsigned>(OpType::SWAP, {0, 1});
+    circ.add_op<unsigned>(OpType::CX, {1, 4});
+    circ.add_op<unsigned>(OpType::Z, {4});
+    circ.add_op<unsigned>(OpType::CX, {1, 4});
+    circ.add_op<unsigned>(OpType::SWAP, {1, 2});
+    circ.add_op<unsigned>(OpType::SWAP, {2, 3});
+    circ.add_op<unsigned>(OpType::CX, {0, 1});
+    circ.add_op<unsigned>(OpType::CX, {1, 2});
+    circ.add_op<unsigned>(OpType::CX, {2, 3});
+
+    REQUIRE(NoWireSwapsPredicate().verify(circ));
+    circ.replace_SWAPs();
+    REQUIRE(!NoWireSwapsPredicate().verify(circ));
+
+    CompilationUnit cu(circ);
+    REQUIRE(ComposePhasePolyBoxes()->apply(cu));
+    Circuit result = cu.get_circ_ref();
+
+    REQUIRE(test_unitary_comparison(result, circ));
+    REQUIRE(NoWireSwapsPredicate().verify(result));
+  }
+  GIVEN("NoWireSwapsPredicate for aas I") {
+    std::vector<Node> nodes = {Node(0), Node(1), Node(2), Node(3), Node(4)};
+    Architecture architecture(
+        {{nodes[0], nodes[1]},
+         {nodes[1], nodes[2]},
+         {nodes[2], nodes[3]},
+         {nodes[3], nodes[4]}});
+
+    Circuit circ(5);
+    add_2qb_gates(circ, OpType::CX, {{0, 3}, {1, 4}});
+    circ.add_op<unsigned>(OpType::SWAP, {3, 4});
+    circ.add_op<unsigned>(OpType::CX, {2, 3});
+    circ.add_op<unsigned>(OpType::Z, {3});
+    circ.add_op<unsigned>(OpType::CX, {2, 3});
+    circ.add_op<unsigned>(OpType::SWAP, {0, 1});
+    circ.add_op<unsigned>(OpType::CX, {1, 4});
+    circ.add_op<unsigned>(OpType::Z, {4});
+    circ.add_op<unsigned>(OpType::CX, {1, 4});
+    circ.add_op<unsigned>(OpType::SWAP, {1, 2});
+    circ.add_op<unsigned>(OpType::SWAP, {2, 3});
+    circ.add_op<unsigned>(OpType::CX, {0, 1});
+    circ.add_op<unsigned>(OpType::CX, {1, 2});
+    circ.add_op<unsigned>(OpType::CX, {2, 3});
+
+    REQUIRE(NoWireSwapsPredicate().verify(circ));
+    circ.replace_SWAPs();
+    REQUIRE(!NoWireSwapsPredicate().verify(circ));
+
+    CompilationUnit cu(circ);
+
+    REQUIRE(gen_full_mapping_pass_phase_poly(
+                architecture, 1, aas::CNotSynthType::Rec)
+                ->apply(cu));
+    Circuit result = cu.get_circ_ref();
+
+    REQUIRE(test_unitary_comparison(result, circ));
+    REQUIRE(NoWireSwapsPredicate().verify(result));
   }
 }