|
| 1 | +# Copyright 2024 Google LLC |
| 2 | +# |
| 3 | +# Licensed under the Apache License, Version 2.0 (the "License"); |
| 4 | +# you may not use this file except in compliance with the License. |
| 5 | +# You may obtain a copy of the License at |
| 6 | +# |
| 7 | +# https://www.apache.org/licenses/LICENSE-2.0 |
| 8 | +# |
| 9 | +# Unless required by applicable law or agreed to in writing, software |
| 10 | +# distributed under the License is distributed on an "AS IS" BASIS, |
| 11 | +# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
| 12 | +# See the License for the specific language governing permissions and |
| 13 | +# limitations under the License. |
| 14 | +import logging |
| 15 | +from collections import defaultdict |
| 16 | +from typing import Callable, Dict, Sequence, Tuple, TYPE_CHECKING |
| 17 | + |
| 18 | +import attrs |
| 19 | +import networkx as nx |
| 20 | +from attrs import field, frozen |
| 21 | + |
| 22 | +from ._call_graph import get_bloq_callee_counts |
| 23 | +from ._costing import CostKey |
| 24 | +from .classify_bloqs import bloq_is_clifford |
| 25 | + |
| 26 | +if TYPE_CHECKING: |
| 27 | + from qualtran import Bloq |
| 28 | + |
| 29 | +logger = logging.getLogger(__name__) |
| 30 | + |
| 31 | +BloqCountDict = Dict['Bloq', int] |
| 32 | + |
| 33 | + |
| 34 | +def _gateset_bloqs_to_tuple(bloqs: Sequence['Bloq']) -> Tuple['Bloq', ...]: |
| 35 | + return tuple(bloqs) |
| 36 | + |
| 37 | + |
| 38 | +@frozen |
| 39 | +class BloqCount(CostKey[BloqCountDict]): |
| 40 | + """A cost which is the count of a specific set of bloqs forming a gateset. |
| 41 | +
|
| 42 | + Often, we wish to know the number of specific gates in our algorithm. This is a generic |
| 43 | + CostKey that can count any gate (bloq) of interest. |
| 44 | +
|
| 45 | + The cost value type for this cost is a mapping from bloq to its count. |
| 46 | +
|
| 47 | + Args: |
| 48 | + gateset_bloqs: A sequence of bloqs which we will count. Bloqs are counted according |
| 49 | + to their equality operator. |
| 50 | + gateset_name: A string name of the gateset. Used for display and debugging purposes. |
| 51 | + """ |
| 52 | + |
| 53 | + gateset_bloqs: Sequence['Bloq'] = field(converter=_gateset_bloqs_to_tuple) |
| 54 | + gateset_name: str |
| 55 | + |
| 56 | + @classmethod |
| 57 | + def for_gateset(cls, gateset_name: str): |
| 58 | + """Helper constructor to configure this cost for some common gatesets. |
| 59 | +
|
| 60 | + Args: |
| 61 | + gateset_name: One of 't', 't+tof', 't+tof+cswap'. This will construct a |
| 62 | + `BloqCount` cost with the indicated gates as the `gateset_bloqs`. In all |
| 63 | + cases, both TGate and its adjoint are included. |
| 64 | + """ |
| 65 | + from qualtran.bloqs.basic_gates import TGate, Toffoli, TwoBitCSwap |
| 66 | + |
| 67 | + bloqs: Tuple['Bloq', ...] |
| 68 | + if gateset_name == 't': |
| 69 | + bloqs = (TGate(), TGate(is_adjoint=True)) |
| 70 | + elif gateset_name == 't+tof': |
| 71 | + bloqs = (TGate(), TGate(is_adjoint=True), Toffoli()) |
| 72 | + elif gateset_name == 't+tof+cswap': |
| 73 | + bloqs = (TGate(), TGate(is_adjoint=True), Toffoli(), TwoBitCSwap()) |
| 74 | + else: |
| 75 | + raise ValueError(f"Unknown gateset name {gateset_name}") |
| 76 | + |
| 77 | + return cls(bloqs, gateset_name=gateset_name) |
| 78 | + |
| 79 | + @classmethod |
| 80 | + def for_call_graph_leaf_bloqs(cls, g: nx.DiGraph): |
| 81 | + """Helper constructor to configure this cost for 'leaf' bloqs in a given call graph. |
| 82 | +
|
| 83 | + Args: |
| 84 | + g: The call graph. Its leaves will be used for `gateset_bloqs`. This call graph |
| 85 | + can be generated from `Bloq.call_graph()` |
| 86 | + """ |
| 87 | + leaf_bloqs = {node for node in g.nodes if not g.succ[node]} |
| 88 | + return cls(tuple(leaf_bloqs), gateset_name='leaf') |
| 89 | + |
| 90 | + def compute( |
| 91 | + self, bloq: 'Bloq', get_callee_cost: Callable[['Bloq'], BloqCountDict] |
| 92 | + ) -> BloqCountDict: |
| 93 | + if bloq in self.gateset_bloqs: |
| 94 | + logger.info("Computing %s: %s is in the target gateset.", self, bloq) |
| 95 | + return {bloq: 1} |
| 96 | + |
| 97 | + totals: BloqCountDict = defaultdict(lambda: 0) |
| 98 | + callees = get_bloq_callee_counts(bloq) |
| 99 | + logger.info("Computing %s for %s from %d callee(s)", self, bloq, len(callees)) |
| 100 | + for callee, n_times_called in callees: |
| 101 | + callee_cost = get_callee_cost(callee) |
| 102 | + for gateset_bloq, count in callee_cost.items(): |
| 103 | + totals[gateset_bloq] += n_times_called * count |
| 104 | + |
| 105 | + return dict(totals) |
| 106 | + |
| 107 | + def zero(self) -> BloqCountDict: |
| 108 | + # The additive identity of the bloq counts dictionary is an empty dictionary. |
| 109 | + return {} |
| 110 | + |
| 111 | + def __str__(self): |
| 112 | + return f'{self.gateset_name} counts' |
| 113 | + |
| 114 | + |
| 115 | +@frozen(kw_only=True) |
| 116 | +class GateCounts: |
| 117 | + """A data class of counts of the typical target gates in a compilation. |
| 118 | +
|
| 119 | + Specifically, this class holds counts for the number of `TGate` (and adjoint), `Toffoli`, |
| 120 | + `TwoBitCSwap`, `And`, and clifford bloqs. |
| 121 | + """ |
| 122 | + |
| 123 | + t: int = 0 |
| 124 | + toffoli: int = 0 |
| 125 | + cswap: int = 0 |
| 126 | + and_bloq: int = 0 |
| 127 | + clifford: int = 0 |
| 128 | + |
| 129 | + def __add__(self, other): |
| 130 | + if not isinstance(other, GateCounts): |
| 131 | + raise TypeError(f"Can only add other `GateCounts` objects, not {self}") |
| 132 | + |
| 133 | + return GateCounts( |
| 134 | + t=self.t + other.t, |
| 135 | + toffoli=self.toffoli + other.toffoli, |
| 136 | + cswap=self.cswap + other.cswap, |
| 137 | + and_bloq=self.and_bloq + other.and_bloq, |
| 138 | + clifford=self.clifford + other.clifford, |
| 139 | + ) |
| 140 | + |
| 141 | + def __mul__(self, other): |
| 142 | + return GateCounts( |
| 143 | + t=other * self.t, |
| 144 | + toffoli=other * self.toffoli, |
| 145 | + cswap=other * self.cswap, |
| 146 | + and_bloq=other * self.and_bloq, |
| 147 | + clifford=other * self.clifford, |
| 148 | + ) |
| 149 | + |
| 150 | + def __rmul__(self, other): |
| 151 | + return self.__mul__(other) |
| 152 | + |
| 153 | + def __str__(self): |
| 154 | + strs = [] |
| 155 | + for f in attrs.fields(self.__class__): |
| 156 | + val = getattr(self, f.name) |
| 157 | + if val != 0: |
| 158 | + strs.append(f'{f.name}: {val}') |
| 159 | + |
| 160 | + if strs: |
| 161 | + return ', '.join(strs) |
| 162 | + return '-' |
| 163 | + |
| 164 | + def total_t_count( |
| 165 | + self, ts_per_toffoli: int = 4, ts_per_cswap: int = 7, ts_per_and_bloq: int = 4 |
| 166 | + ) -> int: |
| 167 | + """Get the total number of T Gates for the `GateCounts` object. |
| 168 | +
|
| 169 | + This simply multiplies each gate type by its cost in terms of T gates, which is configurable |
| 170 | + via the arguments to this method. |
| 171 | + """ |
| 172 | + return ( |
| 173 | + self.t |
| 174 | + + ts_per_toffoli * self.toffoli |
| 175 | + + ts_per_cswap * self.cswap |
| 176 | + + ts_per_and_bloq * self.and_bloq |
| 177 | + ) |
| 178 | + |
| 179 | + |
| 180 | +@frozen |
| 181 | +class QECGatesCost(CostKey[GateCounts]): |
| 182 | + """Counts specifically for 'expensive' gates in a surface code error correction scheme. |
| 183 | +
|
| 184 | + The cost value type for this CostKey is `GateCounts`. |
| 185 | + """ |
| 186 | + |
| 187 | + def compute(self, bloq: 'Bloq', get_callee_cost: Callable[['Bloq'], GateCounts]) -> GateCounts: |
| 188 | + from qualtran.bloqs.basic_gates import TGate, Toffoli, TwoBitCSwap |
| 189 | + from qualtran.bloqs.mcmt.and_bloq import And |
| 190 | + |
| 191 | + # T gates |
| 192 | + if isinstance(bloq, TGate): |
| 193 | + return GateCounts(t=1) |
| 194 | + |
| 195 | + # Toffolis |
| 196 | + if isinstance(bloq, Toffoli): |
| 197 | + return GateCounts(toffoli=1) |
| 198 | + |
| 199 | + # 'And' bloqs |
| 200 | + if isinstance(bloq, And) and not bloq.uncompute: |
| 201 | + return GateCounts(and_bloq=1) |
| 202 | + |
| 203 | + # CSwaps aka Fredkin |
| 204 | + if isinstance(bloq, TwoBitCSwap): |
| 205 | + return GateCounts(cswap=1) |
| 206 | + |
| 207 | + # Cliffords |
| 208 | + if bloq_is_clifford(bloq): |
| 209 | + return GateCounts(clifford=1) |
| 210 | + |
| 211 | + # Recursive case |
| 212 | + totals = GateCounts() |
| 213 | + callees = get_bloq_callee_counts(bloq) |
| 214 | + logger.info("Computing %s for %s from %d callee(s)", self, bloq, len(callees)) |
| 215 | + for callee, n_times_called in callees: |
| 216 | + callee_cost = get_callee_cost(callee) |
| 217 | + totals += n_times_called * callee_cost |
| 218 | + return totals |
| 219 | + |
| 220 | + def zero(self) -> GateCounts: |
| 221 | + return GateCounts() |
| 222 | + |
| 223 | + def validate_val(self, val: GateCounts): |
| 224 | + if not isinstance(val, GateCounts): |
| 225 | + raise TypeError(f"{self} values should be `GateCounts`, got {val}") |
| 226 | + |
| 227 | + def __str__(self): |
| 228 | + return 'gate counts' |
0 commit comments