Add timeout parameter to GreedyPauliSimp (#1664)

* add timeout

* add timeout to serialisation

* Update changelog.rst

* bump library

* Update transform.cpp

* Update test_GreedyPauli.cpp

* update stubs

* fix serialisation

* Update test_GreedyPauli.cpp

* optionally relabel classical expressions when renaming units

* Update predicates_test.py

* update flattenrelabelregisters

* reformat, add false to rename_units again

* bump library

* Update passes_serialisation_test.py

* bump library version

* Update test_GreedyPauli.cpp

* Update test_GreedyPauli.cpp

* Update test_GreedyPauli.cpp

pytket/binders/circuit/Circuit/main.cpp

@@ -322,7 +322,12 @@ void def_circuit(py::class_<Circuit, std::shared_ptr<Circuit>> &pyCircuit) {
       .def(
           "flatten_registers", &Circuit::flatten_registers,
           "Combines all qubits into a single register namespace with "
-          "the default name, and likewise for bits")
+          "the default name, and likewise for bits"
+          "\n\n:param relabel_classical_expression: Determines whether python "
+          "classical expressions held in `ClassicalExpBox` have their "
+          "expression "
+          "relabelled to match relabelled Bit.",
+          py::arg("relabel_classical_expression") = true)
 
       // Circuit composition:
       .def(

pytket/binders/passes.cpp

@@ -752,9 +752,12 @@ PYBIND11_MODULE(passes, m) {
       "FlattenRelabelRegistersPass", &gen_flatten_relabel_registers_pass,
       "Removes empty Quantum wires from the Circuit and relabels all Qubit to "
       "a register from passed name. \n\n:param label: Name to relabel "
-      "remaining Qubit to, default 'q'.\n:return: A pass that removes empty "
+      "remaining Qubit to, default 'q'.\n:param relabel_classical_expressions: "
+      "Whether to relabel arguments of expressions held in `ClassicalExpBox`. "
+      "\n:return: A pass that removes empty "
       "wires and relabels.",
-      py::arg("label") = q_default_reg());
+      py::arg("label") = q_default_reg(),
+      py::arg("relabel_classical_expressions") = true);
 
   m.def(
       "RenameQubitsPass", &gen_rename_qubits_pass,
@@ -957,10 +960,12 @@ PYBIND11_MODULE(passes, m) {
       "\n:param allow_zzphase: If set to True, allows the algorithm to "
       "implement 2-qubit rotations using ZZPhase gates when deemed "
       "optimal. Defaults to False."
+      "\n:param timeout: Sets maximum out of time spent finding solution."
       "\n:return: a pass to perform the simplification",
       py::arg("discount_rate") = 0.7, py::arg("depth_weight") = 0.3,
       py::arg("max_lookahead") = 500, py::arg("max_tqe_candidates") = 500,
-      py::arg("seed") = 0, py::arg("allow_zzphase") = false);
+      py::arg("seed") = 0, py::arg("allow_zzphase") = false,
+      py::arg("timeout") = 100);
   m.def(
       "PauliSquash", &PauliSquash,
       "Applies :py:meth:`PauliSimp` followed by "

pytket/binders/transform.cpp

@@ -440,10 +440,12 @@ PYBIND11_MODULE(transform, m) {
           "\n:param allow_zzphase: If set to True, allows the algorithm to "
           "implement 2-qubit rotations using ZZPhase gates when deemed "
           "optimal. Defaults to False."
+          "\n:param timeout: Sets maximum out of time spent finding solution."
           "\n:return: a pass to perform the simplification",
           py::arg("discount_rate") = 0.7, py::arg("depth_weight") = 0.3,
           py::arg("max_tqe_candidates") = 500, py::arg("max_lookahead") = 500,
-          py::arg("seed") = 0, py::arg("allow_zzphase") = false)
+          py::arg("seed") = 0, py::arg("allow_zzphase") = false,
+          py::arg("timeout") = 100)
       .def_static(
           "ZZPhaseToRz", &Transforms::ZZPhase_to_Rz,
           "Fixes all ZZPhase gate angles to [-1, 1) half turns.")

pytket/conanfile.py

@@ -38,7 +38,7 @@ def requirements(self):
         self.requires("pybind11_json/0.2.14")
         self.requires("symengine/0.12.0")
         self.requires("tkassert/0.3.4@tket/stable")
-        self.requires("tket/1.3.40@tket/stable")
+        self.requires("tket/1.3.42@tket/stable")
         self.requires("tklog/0.3.3@tket/stable")
         self.requires("tkrng/0.3.3@tket/stable")
         self.requires("tktokenswap/0.3.9@tket/stable")

pytket/docs/changelog.rst

@@ -12,6 +12,9 @@ Features:
   conditions.
 * Add `custom_deserialisation` argument to `BasePass` and `SequencePass` 
   `from_dict` method to support construction of `CustomPass` from json.
+* Add `timeout` argument to `GreedyPauliSimp`.
+* Add option to not relabel `ClassicalExpBox` when calling `rename_units`
+  and `flatten_registers`
 
 Fixes:
 

pytket/pytket/_tket/circuit.pyi

@@ -2104,9 +2104,11 @@ class Circuit:
         :param types: the set of operation types of interest
         :return: the circuit depth with respect to operations matching an element of `types`
         """
-    def flatten_registers(self) -> dict[pytket._tket.unit_id.UnitID, pytket._tket.unit_id.UnitID]:
+    def flatten_registers(self, relabel_classical_expression: bool = True) -> dict[pytket._tket.unit_id.UnitID, pytket._tket.unit_id.UnitID]:
         """
         Combines all qubits into a single register namespace with the default name, and likewise for bits
+        
+        :param relabel_classical_expression: Determines whether python classical expressions held in `ClassicalExpBox` have their expression relabelled to match relabelled Bit.
         """
     def free_symbols(self) -> set[sympy.Symbol]:
         """

pytket/pytket/_tket/passes.pyi

@@ -410,11 +410,12 @@ def FlattenRegisters() -> BasePass:
     """
     Merges all quantum and classical registers into their respective default registers with contiguous indexing.
     """
-def FlattenRelabelRegistersPass(label: str = 'q') -> BasePass:
+def FlattenRelabelRegistersPass(label: str = 'q', relabel_classical_expressions: bool = True) -> BasePass:
     """
     Removes empty Quantum wires from the Circuit and relabels all Qubit to a register from passed name. 
     
     :param label: Name to relabel remaining Qubit to, default 'q'.
+    :param relabel_classical_expressions: Whether to relabel arguments of expressions held in `ClassicalExpBox`. 
     :return: A pass that removes empty wires and relabels.
     """
 def FullMappingPass(arc: pytket._tket.architecture.Architecture, placer: pytket._tket.placement.Placement, config: typing.Sequence[pytket._tket.mapping.RoutingMethod]) -> BasePass:
@@ -444,7 +445,7 @@ def GlobalisePhasedX(squash: bool = True) -> BasePass:
     
     It is not recommended to use this pass with symbolic expressions, as in certain cases a blow-up in symbolic expression sizes may occur.
     """
-def GreedyPauliSimp(discount_rate: float = 0.7, depth_weight: float = 0.3, max_lookahead: int = 500, max_tqe_candidates: int = 500, seed: int = 0, allow_zzphase: bool = False) -> BasePass:
+def GreedyPauliSimp(discount_rate: float = 0.7, depth_weight: float = 0.3, max_lookahead: int = 500, max_tqe_candidates: int = 500, seed: int = 0, allow_zzphase: bool = False, timeout: int = 100) -> BasePass:
     """
     Construct a pass that converts a circuit into a graph of Pauli gadgets to account for commutation and phase folding, and resynthesises them using a greedy algorithm adapted from arxiv.org/abs/2103.08602. The method for synthesising the final Clifford operator is adapted from arxiv.org/abs/2305.10966.
     
@@ -454,6 +455,7 @@ def GreedyPauliSimp(discount_rate: float = 0.7, depth_weight: float = 0.3, max_l
     :param max_lookahead:  Maximum lookahead when evaluating each Clifford gate candidate. Default to 500.
     :param seed:  Unsigned integer seed used for sampling candidates and tie breaking. Default to 0.
     :param allow_zzphase: If set to True, allows the algorithm to implement 2-qubit rotations using ZZPhase gates when deemed optimal. Defaults to False.
+    :param timeout: Sets maximum out of time spent finding solution.
     :return: a pass to perform the simplification
     """
 def GuidedPauliSimp(strat: pytket._tket.transform.PauliSynthStrat = pytket._tket.transform.PauliSynthStrat.Sets, cx_config: pytket._tket.circuit.CXConfigType = pytket._tket.circuit.CXConfigType.Snake) -> BasePass:

pytket/pytket/_tket/transform.pyi

@@ -165,7 +165,7 @@ class Transform:
         It is not recommended to use this transformation with symbolic expressions, as in certain cases a blow-up in symbolic expression sizes may occur.
         """
     @staticmethod
-    def GreedyPauliSimp(discount_rate: float = 0.7, depth_weight: float = 0.3, max_tqe_candidates: int = 500, max_lookahead: int = 500, seed: int = 0, allow_zzphase: bool = False) -> Transform:
+    def GreedyPauliSimp(discount_rate: float = 0.7, depth_weight: float = 0.3, max_tqe_candidates: int = 500, max_lookahead: int = 500, seed: int = 0, allow_zzphase: bool = False, timeout: int = 100) -> Transform:
         """
         Convert a circuit into a graph of Pauli gadgets to account for commutation and phase folding, and resynthesises them using a greedy algorithm adapted from arxiv.org/abs/2103.08602. The method for synthesising the final Clifford operator is adapted from arxiv.org/abs/2305.10966.
         
@@ -175,6 +175,7 @@ class Transform:
         :param max_lookahead:  Maximum lookahead when evaluating each Clifford gate candidate. Default to 500.
         :param seed:  Unsigned integer seed used for sampling candidates and tie breaking. Default to 0.
         :param allow_zzphase: If set to True, allows the algorithm to implement 2-qubit rotations using ZZPhase gates when deemed optimal. Defaults to False.
+        :param timeout: Sets maximum out of time spent finding solution.
         :return: a pass to perform the simplification
         """
     @staticmethod

pytket/tests/passes_serialisation_test.py

@@ -296,6 +296,7 @@ def nonparam_predicate_dict(name: str) -> Dict[str, Any]:
             "max_tqe_candidates": 100,
             "seed": 2,
             "allow_zzphase": True,
+            "timeout": 5000,
         }
     ),
     # lists must be sorted by OpType value

pytket/tests/predicates_test.py

@@ -1036,6 +1036,7 @@ def test_greedy_pauli_synth() -> None:
     ).SWAP(regb[1], rega[0])
     d = circ.copy()
     pss = GreedyPauliSimp(0.5, 0.5)
+    assert not GreedyPauliSimp(0.5, 0.5, timeout=0).apply(d)
     assert pss.apply(d)
     assert np.allclose(circ.get_unitary(), d.get_unitary())
     assert d.name == "test"
@@ -1058,7 +1059,8 @@ def test_greedy_pauli_synth() -> None:
     circ.measure_all()
     circ.Reset(0)
     circ.add_pauliexpbox(pg1, [2, 3])
-    assert GreedyPauliSimp(0.5, 0.5, 100, 100, 0, True).apply(circ)
+    assert not GreedyPauliSimp(0.5, 0.5, 100, 100, 0, True, 0).apply(circ)
+    assert GreedyPauliSimp(0.5, 0.5, 100, 100, 0, True, 100).apply(circ)
     # PauliExpBoxes implemented using ZZPhase
     d = Circuit(4, 4, name="test")
     d.H(0)

schemas/compiler_pass_v1.json

@@ -373,6 +373,10 @@
         "allow_zzphase": {
           "type": "boolean",
           "definition": "parameter controlling the use of ZZPhase gates in \"GreedyPauliSimp\""
+        },
+        "timeout": {
+          "type": "number",
+          "definition": "parameter controlling the maximum runtime of \"GreedyPauliSimp\""
         }
       },
       "required": [
@@ -644,9 +648,10 @@
           },
           "then": {
             "required": [
-              "label"
+              "label",
+              "relabel_classical_registers"
             ],
-            "maxProperties": 2
+            "maxProperties": 3
           }
         },
         {
@@ -903,9 +908,10 @@
               "max_lookahead",
               "max_tqe_candidates",
               "seed",
-              "allow_zzphase"
+              "allow_zzphase",
+              "timeout"
             ],
-            "maxProperties": 7
+            "maxProperties": 8
           }
         },
         {

tket/conanfile.py

@@ -23,7 +23,7 @@
 
 class TketConan(ConanFile):
     name = "tket"
-    version = "1.3.40"
+    version = "1.3.42"
     package_type = "library"
     license = "Apache 2"
     homepage = "https://github.com/CQCL/tket"

tket/include/tket/Circuit/Circuit.hpp

@@ -749,9 +749,12 @@ class Circuit {
   /**
    * Convert all quantum and classical bits to use default registers.
    *
+   * @param relabel_classical_expression Whether expressions in ClassicalExpBox
+   *  have their expr updated to match the input wires
+   *
    * @return mapping from old to new unit IDs
    */
-  unit_map_t flatten_registers();
+  unit_map_t flatten_registers(bool relabel_classical_expression = true);
 
   //_________________________________________________
 
@@ -1044,7 +1047,8 @@ class Circuit {
    * @return true iff circuit was modified
    */
   template <typename UnitA, typename UnitB>
-  bool rename_units(const std::map<UnitA, UnitB> &qm);
+  bool rename_units(
+      const std::map<UnitA, UnitB> &qm, bool relabel_classicalexpbox = true);
 
   /** Automatically rewire holes when removing vertices from the circuit? */
   enum class GraphRewiring { Yes, No };
@@ -1719,7 +1723,8 @@ JSON_DECL(Circuit)
 /** Templated method definitions */
 
 template <typename UnitA, typename UnitB>
-bool Circuit::rename_units(const std::map<UnitA, UnitB> &qm) {
+bool Circuit::rename_units(
+    const std::map<UnitA, UnitB> &qm, bool relabel_classicalexpbox) {
   // Can only work for Unit classes
   static_assert(std::is_base_of<UnitID, UnitA>::value);
   static_assert(std::is_base_of<UnitID, UnitB>::value);
@@ -1768,21 +1773,18 @@ bool Circuit::rename_units(const std::map<UnitA, UnitB> &qm) {
           "Unit already exists in circuit: " + pair.first.repr());
     TKET_ASSERT(modified);
   }
-
   // For every ClassicalExpBox, update its logic expressions
-  if (!bm.empty()) {
+  if (!bm.empty() && relabel_classicalexpbox) {
     BGL_FORALL_VERTICES(v, dag, DAG) {
       Op_ptr op = get_Op_ptr_from_Vertex(v);
       if (op->get_type() == OpType::ClassicalExpBox) {
         const ClassicalExpBoxBase &cbox =
             static_cast<const ClassicalExpBoxBase &>(*op);
         // rename_units is marked as const to get around the Op_ptr
-        // cast, but it can still mutate a python object
         modified |= cbox.rename_units(bm);
       }
     }
   }
-
   return modified;
 }
 

tket/include/tket/Predicates/PassGenerators.hpp

@@ -110,7 +110,8 @@ PassPtr gen_clifford_push_through_pass();
  * Qubits removed from the Circuit are preserved in the bimap, but not updated
  * to a new labelling.
  */
-PassPtr gen_flatten_relabel_registers_pass(const std::string& label);
+PassPtr gen_flatten_relabel_registers_pass(
+    const std::string& label, bool relabel_classical_expressions = true);
 /**
  * Pass to rename some or all qubits according to the given map.
  *
@@ -354,12 +355,13 @@ PassPtr gen_special_UCC_synthesis(
  * @param max_tqe_candidates
  * @param seed
  * @param allow_zzphase
+ * @param timeout
  * @return PassPtr
  */
 PassPtr gen_greedy_pauli_simp(
     double discount_rate = 0.7, double depth_weight = 0.3,
     unsigned max_lookahead = 500, unsigned max_tqe_candidates = 500,
-    unsigned seed = 0, bool allow_zzphase = false);
+    unsigned seed = 0, bool allow_zzphase = false, unsigned timeout = 100);
 
 /**
  * Generate a pass to simplify the circuit where it acts on known basis states.

tket/include/tket/Transformations/GreedyPauliOptimisation.hpp

@@ -643,7 +643,7 @@ Circuit greedy_pauli_set_synthesis(
 Transform greedy_pauli_optimisation(
     double discount_rate = 0.7, double depth_weight = 0.3,
     unsigned max_lookahead = 500, unsigned max_tqe_candidates = 500,
-    unsigned seed = 0, bool allow_zzphase = false);
+    unsigned seed = 0, bool allow_zzphase = false, unsigned timeout = 100);
 
 }  // namespace Transforms
 

tket/src/Circuit/basic_circ_manip.cpp

@@ -422,7 +422,7 @@ void Circuit::remove_edge(const Edge& edge) {
   boost::remove_edge(edge, this->dag);
 }
 
-unit_map_t Circuit::flatten_registers() {
+unit_map_t Circuit::flatten_registers(bool relabel_classical_expression) {
   unit_map_t rename_map;
   unsigned q_index = 0;
   unsigned c_index = 0;
@@ -434,7 +434,7 @@ unit_map_t Circuit::flatten_registers() {
     }
   }
   try {
-    rename_units(rename_map);
+    rename_units(rename_map, relabel_classical_expression);
   } catch (const std::exception& e) {
     std::stringstream ss;
     ss << "Unable to flatten registers: " << e.what();

tket/src/Predicates/CompilerPass.cpp

@@ -469,7 +469,8 @@ PassPtr deserialise(
       pp = gen_euler_pass(q, p, s);
     } else if (passname == "FlattenRelabelRegistersPass") {
       pp = gen_flatten_relabel_registers_pass(
-          content.at("label").get<std::string>());
+          content.at("label").get<std::string>(),
+          content.at("relabel_classical_expressions").get<bool>());
     } else if (passname == "RoutingPass") {
       Architecture arc = content.at("architecture").get<Architecture>();
       std::vector<RoutingMethodPtr> con = content.at("routing_config");
@@ -521,9 +522,10 @@ PassPtr deserialise(
       unsigned max_lookahead = content.at("max_lookahead").get<unsigned>();
       unsigned seed = content.at("seed").get<unsigned>();
       bool allow_zzphase = content.at("allow_zzphase").get<bool>();
+      unsigned timeout = content.at("timeout").get<unsigned>();
       pp = gen_greedy_pauli_simp(
           discount_rate, depth_weight, max_lookahead, max_tqe_candidates, seed,
-          allow_zzphase);
+          allow_zzphase, timeout);
 
     } else if (passname == "PauliSimp") {
       // SEQUENCE PASS - DESERIALIZABLE ONLY

tket/src/Predicates/PassGenerators.cpp

@@ -354,7 +354,8 @@ PassPtr gen_clifford_push_through_pass() {
   return std::make_shared<StandardPass>(precons, t, pc, j);
 }
 
-PassPtr gen_flatten_relabel_registers_pass(const std::string& label) {
+PassPtr gen_flatten_relabel_registers_pass(
+    const std::string& label, bool relabel_classical_expressions) {
   Transform t =
       Transform([=](Circuit& circuit, std::shared_ptr<unit_bimaps_t> maps) {
         unsigned n_qubits = circuit.n_qubits();
@@ -366,7 +367,7 @@ PassPtr gen_flatten_relabel_registers_pass(const std::string& label) {
           relabelling_map.insert({all_qubits[i], Qubit(label, i)});
         }
 
-        circuit.rename_units(relabelling_map);
+        circuit.rename_units(relabelling_map, relabel_classical_expressions);
         changed |= update_maps(maps, relabelling_map, relabelling_map);
         return changed;
       });
@@ -376,6 +377,7 @@ PassPtr gen_flatten_relabel_registers_pass(const std::string& label) {
   nlohmann::json j;
   j["name"] = "FlattenRelabelRegistersPass";
   j["label"] = label;
+  j["relabel_classical_expressions"] = relabel_classical_expressions;
   return std::make_shared<StandardPass>(precons, t, postcons, j);
 }
 
@@ -1015,10 +1017,11 @@ PassPtr gen_synthesise_pauli_graph(
 
 PassPtr gen_greedy_pauli_simp(
     double discount_rate, double depth_weight, unsigned max_lookahead,
-    unsigned max_tqe_candidates, unsigned seed, bool allow_zzphase) {
+    unsigned max_tqe_candidates, unsigned seed, bool allow_zzphase,
+    unsigned timeout) {
   Transform t = Transforms::greedy_pauli_optimisation(
       discount_rate, depth_weight, max_lookahead, max_tqe_candidates, seed,
-      allow_zzphase);
+      allow_zzphase, timeout);
   OpTypeSet ins = {
       OpType::Z,
       OpType::X,
@@ -1067,6 +1070,7 @@ PassPtr gen_greedy_pauli_simp(
   j["max_tqe_candidates"] = max_tqe_candidates;
   j["seed"] = seed;
   j["allow_zzphase"] = allow_zzphase;
+  j["timeout"] = timeout;
 
   return std::make_shared<StandardPass>(precons, t, postcon, j);
 }