Timeout GreedyPauliSimp

pytket/binders/passes.cpp

@@ -970,14 +970,19 @@ 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:param thread_timeout: Sets maximum out of time spent finding a "
+      "single solution in one thread."
       "\n:param only_reduce: Only returns modified circuit if it has "
       "fewer two-qubit gates."
+      "\n:param trials: Sets maximum number of found solutions. The "
+      "smallest circuit is returned, prioritising the number of 2qb-gates, "
+      "then the number of gates, then the depth."
       "\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("timeout") = 100, py::arg("only_reduce") = false);
+      py::arg("thread_timeout") = 100, py::arg("only_reduce") = false,
+      py::arg("trials") = 1);
   m.def(
       "PauliSquash", &PauliSquash,
       "Applies :py:meth:`PauliSimp` followed by "

pytket/binders/transform.cpp

@@ -451,12 +451,16 @@ 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:param thread_timeout: Sets maximum out of time spent finding a "
+          "single solution in one thread."
+          "\n:param trials: Sets maximum number of found solutions. The "
+          "smallest circuit is returned, prioritising the number of 2qb-gates, "
+          "then the number of gates, then the depth."
           "\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("timeout") = 100)
+          py::arg("thread_timeout") = 100, py::arg("trials") = 1)
       .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/0.13.0")
         self.requires("tkassert/0.3.4@tket/stable")
-        self.requires("tket/1.3.47@tket/stable")
+        self.requires("tket/1.3.48@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

@@ -12,8 +12,8 @@ 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 `only_reduce` argument to `GreedyPauliSimp`.
+* Add `thread_timeout`, `only_reduce`, and `trials` arguments 
+  to `GreedyPauliSimp`.
 * Add option to not relabel `ClassicalExpBox` when calling `rename_units`
   and `flatten_registers`
 * Implement `dagger()` and `transpose()` for `CustomGate`.

pytket/pytket/_tket/passes.pyi

@@ -447,7 +447,7 @@ 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, timeout: int = 100, only_reduce: 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, thread_timeout: int = 100, only_reduce: bool = False, trials: int = 1) -> 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.
 
@@ -457,8 +457,9 @@ 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.
+    :param thread_timeout: Sets maximum out of time spent finding a single solution in one thread.
     :param only_reduce: Only returns modified circuit if it has fewer two-qubit gates.
+    :param trials: Sets maximum number of found solutions. The smallest circuit is returned, prioritising the number of 2qb-gates, then the number of gates, then the depth.
     :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

@@ -167,7 +167,7 @@ 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, timeout: int = 100) -> 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, thread_timeout: int = 100, trials: int = 1) -> 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.
 
@@ -177,7 +177,8 @@ 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.
+        :param thread_timeout: Sets maximum out of time spent finding a single solution in one thread.
+        :param trials: Sets maximum number of found solutions. The smallest circuit is returned, prioritising the number of 2qb-gates, then the number of gates, then the depth.
         :return: a pass to perform the simplification
         """
     @staticmethod

pytket/tests/passes_serialisation_test.py

@@ -296,8 +296,9 @@ def nonparam_predicate_dict(name: str) -> Dict[str, Any]:
             "max_tqe_candidates": 100,
             "seed": 2,
             "allow_zzphase": True,
-            "timeout": 5000,
+            "thread_timeout": 5000,
             "only_reduce": False,
+            "trials": 1,
         }
     ),
     # lists must be sorted by OpType value

pytket/tests/predicates_test.py

@@ -1035,9 +1035,8 @@ def test_greedy_pauli_synth() -> None:
         rega[0], regb[0]
     ).SWAP(regb[1], rega[0])
     d = circ.copy()
-    pss = GreedyPauliSimp(0.5, 0.5)
-    assert not GreedyPauliSimp(0.5, 0.5, timeout=0, only_reduce=False).apply(d)
-    assert pss.apply(d)
+    assert GreedyPauliSimp(0.5, 0.5, thread_timeout=10, trials=5).apply(d)
+
     assert np.allclose(circ.get_unitary(), d.get_unitary())
     assert d.name == "test"
     # test gateset
@@ -1059,7 +1058,6 @@ def test_greedy_pauli_synth() -> None:
     circ.measure_all()
     circ.Reset(0)
     circ.add_pauliexpbox(pg1, [2, 3])
-    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")
@@ -1084,6 +1082,16 @@ def test_greedy_pauli_synth() -> None:
         GreedyPauliSimp().apply(circ)
     err_msg = "Predicate requirements are not satisfied"
     assert err_msg in str(e.value)
+    # large circuit that doesn't complete within thread_timeout argument
+    c = Circuit(13)
+    for _ in range(20):
+        for i in range(13):
+            for j in range(i + 1, 13):
+                c.CX(i, j)
+                c.Rz(0.23, j)
+            c.H(i)
+    assert not GreedyPauliSimp(thread_timeout=1).apply(c)
+    assert GreedyPauliSimp().apply(c)
 
 
 def test_auto_rebase_deprecation(recwarn: Any) -> None:

schemas/compiler_pass_v1.json

@@ -374,13 +374,17 @@
           "type": "boolean",
           "definition": "parameter controlling the use of ZZPhase gates in \"GreedyPauliSimp\""
         },
-        "timeout": {
+        "thread_timeout": {
           "type": "number",
-          "definition": "parameter controlling the maximum runtime of \"GreedyPauliSimp\""
+          "definition": "parameter controlling the maximum runtime of a single thread in \"GreedyPauliSimp\""
         },
         "only_reduce": {
           "type": "boolean",
           "definition": "parameter controlling whether \"GreedyPauliSimp\" can return circuits with more two qubit gates"
+        },
+        "trials": {
+          "type": "number",
+          "definition": "parameter controlling the number of random solutions found when calling \"GreedyPauliSimp\""
         }
       },
       "required": [
@@ -913,10 +917,11 @@
               "max_tqe_candidates",
               "seed",
               "allow_zzphase",
-              "timeout",
-              "only_reduce"
+              "thread_timeout",
+              "only_reduce",
+              "trials"
             ],
-            "maxProperties": 9
+            "maxProperties": 10
           }
         },
         {

tket/conanfile.py

@@ -23,7 +23,7 @@
 
 class TketConan(ConanFile):
     name = "tket"
-    version = "1.3.47"
+    version = "1.3.48"
     package_type = "library"
     license = "Apache 2"
     homepage = "https://github.com/CQCL/tket"

tket/include/tket/Predicates/PassGenerators.hpp

@@ -355,15 +355,17 @@ PassPtr gen_special_UCC_synthesis(
  * @param max_tqe_candidates
  * @param seed
  * @param allow_zzphase
- * @param timeout
+ * @param thread_timeout
  * @param only_reduce
+ * @param trials
  * @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 timeout = 100,
-    bool only_reduce = false);
+    unsigned seed = 0, bool allow_zzphase = false,
+    unsigned thread_timeout = 100, bool only_reduce = false,
+    unsigned trials = 1);
 
 /**
  * Generate a pass to simplify the circuit where it acts on known basis states.

tket/include/tket/Transformations/GreedyPauliOptimisation.hpp

@@ -14,6 +14,8 @@
 
 #pragma once
 
+#include <atomic>
+
 #include "Transform.hpp"
 #include "tket/Circuit/Circuit.hpp"
 #include "tket/Clifford/UnitaryTableau.hpp"
@@ -600,6 +602,29 @@ class GPGraph {
 std::tuple<std::vector<PauliNode_ptr>, std::vector<PauliNode_ptr>>
 gpg_from_unordered_set(const std::vector<SymPauliTensor>& unordered_set);
 
+/**
+ * @brief Converts the given circuit into a GPGraph and conjugates each node
+ * by greedily applying 2-qubit Clifford gates until the node can be realised
+ * as a single-qubit gate, a measurement, or a reset. The final Clifford
+ * operator is synthesized in a similar fashion. Allows early termination
+ * from a thread via a stop_flag.
+ *
+ * @param circ
+ * @param stop_flag
+ * @param discount_rate
+ * @param depth_weight
+ * @param max_lookahead
+ * @param max_tqe_candidates
+ * @param seed
+ * @param allow_zzphase
+ * @return Circuit
+ */
+Circuit greedy_pauli_graph_synthesis_flag(
+    Circuit circ, std::atomic<bool>& stop_flag, 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);
+
 /**
  * @brief Converts the given circuit into a GPGraph and conjugates each node
  * by greedily applying 2-qubit Clifford gates until the node can be realised
@@ -643,7 +668,8 @@ 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 timeout = 100);
+    unsigned seed = 0, bool allow_zzphase = false,
+    unsigned thread_timeout = 100, unsigned trials = 1);
 
 }  // namespace Transforms
 

tket/src/Predicates/CompilerPass.cpp

@@ -522,11 +522,12 @@ 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>();
+      unsigned timeout = content.at("thread_timeout").get<unsigned>();
       bool only_reduce = content.at("only_reduce").get<bool>();
+      unsigned trials = content.at("trials").get<unsigned>();
       pp = gen_greedy_pauli_simp(
           discount_rate, depth_weight, max_lookahead, max_tqe_candidates, seed,
-          allow_zzphase, timeout, only_reduce);
+          allow_zzphase, timeout, only_reduce, trials);
 
     } else if (passname == "PauliSimp") {
       // SEQUENCE PASS - DESERIALIZABLE ONLY

tket/src/Predicates/PassGenerators.cpp

@@ -1017,24 +1017,33 @@ 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 timeout, bool only_reduce) {
-  Transform t =
-      Transform([discount_rate, depth_weight, max_lookahead, max_tqe_candidates,
-                 seed, allow_zzphase, timeout, only_reduce](Circuit& circ) {
-        Transform gpo = Transforms::greedy_pauli_optimisation(
-            discount_rate, depth_weight, max_lookahead, max_tqe_candidates,
-            seed, allow_zzphase, timeout);
-        if (only_reduce) {
-          Circuit gpo_circ = circ;
-          if (gpo.apply(gpo_circ) &&
-              gpo_circ.count_n_qubit_gates(2) < circ.count_n_qubit_gates(2)) {
-            circ = gpo_circ;
-            return true;
-          }
-          return false;
-        }
-        return gpo.apply(circ);
-      });
+    unsigned thread_timeout, bool only_reduce, unsigned trials) {
+  Transform t = Transform([discount_rate, depth_weight, max_lookahead,
+                           max_tqe_candidates, seed, allow_zzphase,
+                           thread_timeout, only_reduce, trials](Circuit& circ) {
+    Transform gpo = Transforms::greedy_pauli_optimisation(
+        discount_rate, depth_weight, max_lookahead, max_tqe_candidates, seed,
+        allow_zzphase, thread_timeout, trials);
+    if (only_reduce) {
+      Circuit gpo_circ = circ;
+      // comparison will be inaccurate if circuit has PauliExpBox
+      gpo_circ.decompose_boxes_recursively();
+      unsigned original_n_2qb_gates = gpo_circ.count_n_qubit_gates(2);
+      unsigned original_n_gates = gpo_circ.n_gates();
+      unsigned original_depth = gpo_circ.depth();
+      if (gpo.apply(gpo_circ) &&
+          std::make_tuple(
+              gpo_circ.count_n_qubit_gates(2), gpo_circ.n_gates(),
+              gpo_circ.depth()) <
+              std::make_tuple(
+                  original_n_2qb_gates, original_n_gates, original_depth)) {
+        circ = gpo_circ;
+        return true;
+      }
+      return false;
+    }
+    return gpo.apply(circ);
+  });
   OpTypeSet ins = {
       OpType::Z,
       OpType::X,
@@ -1083,8 +1092,9 @@ PassPtr gen_greedy_pauli_simp(
   j["max_tqe_candidates"] = max_tqe_candidates;
   j["seed"] = seed;
   j["allow_zzphase"] = allow_zzphase;
-  j["timeout"] = timeout;
+  j["thread_timeout"] = thread_timeout;
   j["only_reduce"] = only_reduce;
+  j["trials"] = trials;
 
   return std::make_shared<StandardPass>(precons, t, postcon, j);
 }