GridDevice gateset, gate_duration, and compilation_target_gateset sup…

…port (quantumlib#5315)

* GridDevice gateset, gate_duration, and compilation_target_gateset support

* Displays a warning about old Cirq version if DeviceSpecification contains gates not recognized by the client.
* Added compilation target gateset example in GridDevice docstring

* Addresses Tanuj's comments

* Added GridDevice docstring comment about WaitGates.

I avoided mentioning the alternative of inserting no_compile tags because transforming a circuit which contains WaitGates is the wrong approach as all delays would be scrambled by the transformation.

* Set gate_duration to None if the spec doesn't have duration info

* Addressed Doug's comments

* Addressed Tanuj's 2nd round of comments

* Break FSimGateFamily into one for each 2q gate type

cirq-google/cirq_google/devices/grid_device.py

@@ -16,9 +16,14 @@
 
 import re
 
-from typing import Any, Set, Tuple, cast
+from typing import Any, Dict, List, Sequence, Set, Tuple, Type, Union, cast
+import warnings
+
 import cirq
+from cirq_google import ops
+from cirq_google import transformers
 from cirq_google.api import v2
+from cirq_google.experimental import ops as experimental_ops
 
 
 def _validate_device_specification(proto: v2.device_pb2.DeviceSpecification) -> None:
@@ -67,6 +72,94 @@ def _validate_device_specification(proto: v2.device_pb2.DeviceSpecification) ->
             raise ValueError("Invalid DeviceSpecification: target_ordering cannot be ASYMMETRIC.")
 
 
+def _build_gateset_and_gate_durations(
+    proto: v2.device_pb2.DeviceSpecification,
+) -> Tuple[cirq.Gateset, Dict[cirq.GateFamily, cirq.Duration]]:
+    """Extracts gate set and gate duration information from the given DeviceSpecification proto."""
+
+    gates_list: List[Union[Type[cirq.Gate], cirq.Gate, cirq.GateFamily]] = []
+    gate_durations: Dict[cirq.GateFamily, cirq.Duration] = {}
+
+    # TODO(#5050) Describe how to add/remove gates.
+
+    for gate_spec in proto.valid_gates:
+        gate_name = gate_spec.WhichOneof('gate')
+        cirq_gates: List[Union[Type[cirq.Gate], cirq.Gate, cirq.GateFamily]] = []
+
+        if gate_name == 'syc':
+            cirq_gates = [ops.FSimGateFamily(gates_to_accept=[ops.SYC])]
+        elif gate_name == 'sqrt_iswap':
+            cirq_gates = [ops.FSimGateFamily(gates_to_accept=[cirq.SQRT_ISWAP])]
+        elif gate_name == 'sqrt_iswap_inv':
+            cirq_gates = [ops.FSimGateFamily(gates_to_accept=[cirq.SQRT_ISWAP_INV])]
+        elif gate_name == 'cz':
+            cirq_gates = [ops.FSimGateFamily(gates_to_accept=[cirq.CZ])]
+        elif gate_name == 'phased_xz':
+            cirq_gates = [cirq.PhasedXZGate, cirq.XPowGate, cirq.YPowGate, cirq.PhasedXPowGate]
+        elif gate_name == 'virtual_zpow':
+            cirq_gates = [cirq.GateFamily(cirq.ZPowGate, tags_to_ignore=[ops.PhysicalZTag()])]
+        elif gate_name == 'physical_zpow':
+            cirq_gates = [cirq.GateFamily(cirq.ZPowGate, tags_to_accept=[ops.PhysicalZTag()])]
+        elif gate_name == 'coupler_pulse':
+            cirq_gates = [experimental_ops.CouplerPulse]
+        elif gate_name == 'meas':
+            cirq_gates = [cirq.MeasurementGate]
+        elif gate_name == 'wait':
+            cirq_gates = [cirq.WaitGate]
+        else:
+            # coverage: ignore
+            warnings.warn(
+                f"The DeviceSpecification contains the gate '{gate_name}' which is not recognized"
+                " by Cirq and will be ignored. This may be due to an out-of-date Cirq version.",
+                UserWarning,
+            )
+            continue
+
+        gates_list.extend(cirq_gates)
+
+        # TODO(#5050) Allow different gate representations of the same gate to be looked up in
+        # gate_durations.
+        for g in cirq_gates:
+            if not isinstance(g, cirq.GateFamily):
+                g = cirq.GateFamily(g)
+            gate_durations[g] = cirq.Duration(picos=gate_spec.gate_duration_picos)
+
+    # TODO(#4833) Add identity gate support
+    # TODO(#5050) Add GlobalPhaseGate support
+
+    return cirq.Gateset(*gates_list), gate_durations
+
+
+def _build_compilation_target_gatesets(
+    gateset: cirq.Gateset,
+) -> Sequence[cirq.CompilationTargetGateset]:
+    """Detects compilation target gatesets based on what gates are inside the gateset.
+
+    If a device contains gates which yield multiple compilation target gatesets, the user can only
+    choose one target gateset to compile to. For example, a device may contain both SYC and
+    SQRT_ISWAP gates which yield two separate target gatesets, but a circuit can only be compiled to
+    either SYC or SQRT_ISWAP for its two-qubit gates, not both.
+
+    TODO(#5050) when cirq-google CompilationTargetGateset subclasses are implemented, mention that
+    gates which are part of the gateset but not the compilation target gateset are untouched when
+    compiled.
+    """
+
+    # TODO(#5050) Subclass core CompilationTargetGatesets in cirq-google.
+
+    target_gatesets: List[cirq.CompilationTargetGateset] = []
+    if cirq.CZ in gateset:
+        target_gatesets.append(cirq.CZTargetGateset())
+    if ops.SYC in gateset:
+        target_gatesets.append(transformers.SycamoreTargetGateset())
+    if cirq.SQRT_ISWAP in gateset:
+        target_gatesets.append(
+            cirq.SqrtIswapTargetGateset(use_sqrt_iswap_inv=cirq.SQRT_ISWAP_INV in gateset)
+        )
+
+    return tuple(target_gatesets)
+
+
 @cirq.value_equality
 class GridDevice(cirq.Device):
     """Device object representing Google devices with a grid qubit layout.
@@ -112,7 +205,24 @@ class GridDevice(cirq.Device):
         * Get a collection of approximate gate durations for every gate supported by the device.
         >>> device.metadata.gate_durations
 
-        TODO(#5050) Add compilation_target_gatesets example.
+        * Get a collection of valid CompilationTargetGatesets for the device, which can be used to
+          transform a circuit to one which only contains gates from a native target gateset
+          supported by the device.
+        >>> device.metadata.compilation_target_gatesets
+
+        * Assuming valid CompilationTargetGatesets exist for the device, select the first one and
+          use it to transform a circuit to one which only contains gates from a native target
+          gateset supported by the device.
+        >>> cirq.optimize_for_target_gateset(
+                circuit,
+                gateset=device.metadata.compilation_target_gatesets[0]
+            )
+
+    A note about CompilationTargetGatesets:
+
+    A circuit which contains `cirq.WaitGate`s will be dropped if it is transformed using
+    CompilationTargetGatesets generated by GridDevice. To better control circuit timing, insert
+    WaitGates after the circuit has been transformed.
 
     Notes for cirq_google internal implementation:
 
@@ -162,12 +272,15 @@ def from_proto(cls, proto: v2.device_pb2.DeviceSpecification) -> 'GridDevice':
             if len(target.ids) == 2 and ts.target_ordering == v2.device_pb2.TargetSet.SYMMETRIC
         ]
 
-        # TODO(#5050) implement gate durations
+        gateset, gate_durations = _build_gateset_and_gate_durations(proto)
+
         try:
             metadata = cirq.GridDeviceMetadata(
                 qubit_pairs=qubit_pairs,
-                gateset=cirq.Gateset(),  # TODO(#5050) implement
+                gateset=gateset,
+                gate_durations=gate_durations if len(gate_durations) > 0 else None,
                 all_qubits=all_qubits,
+                compilation_target_gatesets=_build_compilation_target_gatesets(gateset),
             )
         except ValueError as ve:  # coverage: ignore
             # Spec errors should have been caught in validation above.
@@ -194,19 +307,19 @@ def validate_operation(self, operation: cirq.Operation) -> None:
         Raises:
             ValueError: The operation isn't valid for this device.
         """
-        # TODO(#5050) uncomment once gateset logic is implemented
-        # if operation not in self._metadata.gateset:
-        #     raise ValueError(f'Operation {operation} is not a supported gate')
+
+        if operation not in self._metadata.gateset:
+            raise ValueError(f'Operation {operation} contains a gate which is not supported.')
 
         for q in operation.qubits:
             if q not in self._metadata.qubit_set:
-                raise ValueError(f'Qubit not on device: {q!r}')
+                raise ValueError(f'Qubit not on device: {q!r}.')
 
         if (
             len(operation.qubits) == 2
             and frozenset(operation.qubits) not in self._metadata.qubit_pairs
         ):
-            raise ValueError(f'Qubit pair is not valid on device: {operation.qubits!r}')
+            raise ValueError(f'Qubit pair is not valid on device: {operation.qubits!r}.')
 
     def __str__(self) -> str:
         diagram = cirq.TextDiagramDrawer()

cirq-google/cirq_google/devices/grid_device_test.py

@@ -47,9 +47,23 @@ def _create_device_spec_with_horizontal_couplings():
         # to verify GridDevice properly handles pair symmetry.
         new_target = grid_targets.targets.add()
         new_target.ids.extend([v2.qubit_to_proto_id(cirq.GridQubit(row, 1 - j)) for j in range(2)])
-    gate = spec.valid_gates.add()
-    gate.syc.SetInParent()
-    gate.gate_duration_picos = 12000
+
+    gate_names = [
+        'syc',
+        'sqrt_iswap',
+        'sqrt_iswap_inv',
+        'cz',
+        'phased_xz',
+        'virtual_zpow',
+        'physical_zpow',
+        'coupler_pulse',
+        'meas',
+        'wait',
+    ]
+    for i, g in enumerate(gate_names):
+        gate = spec.valid_gates.add()
+        getattr(gate, g).SetInParent()
+        gate.gate_duration_picos = i * 1000
 
     return grid_qubits, spec
 
@@ -153,6 +167,53 @@ def test_grid_device_from_proto():
         frozenset((cirq.GridQubit(row, 0), cirq.GridQubit(row, 1))) in device.metadata.qubit_pairs
         for row in range(GRID_HEIGHT)
     )
+    assert device.metadata.gateset == cirq.Gateset(
+        cirq_google.FSimGateFamily(gates_to_accept=[cirq_google.SYC]),
+        cirq_google.FSimGateFamily(gates_to_accept=[cirq.SQRT_ISWAP]),
+        cirq_google.FSimGateFamily(gates_to_accept=[cirq.SQRT_ISWAP_INV]),
+        cirq_google.FSimGateFamily(gates_to_accept=[cirq.CZ]),
+        cirq.ops.phased_x_z_gate.PhasedXZGate,
+        cirq.ops.common_gates.XPowGate,
+        cirq.ops.common_gates.YPowGate,
+        cirq.ops.phased_x_gate.PhasedXPowGate,
+        cirq.GateFamily(
+            cirq.ops.common_gates.ZPowGate, tags_to_ignore=[cirq_google.PhysicalZTag()]
+        ),
+        cirq.GateFamily(
+            cirq.ops.common_gates.ZPowGate, tags_to_accept=[cirq_google.PhysicalZTag()]
+        ),
+        cirq_google.experimental.ops.coupler_pulse.CouplerPulse,
+        cirq.ops.measurement_gate.MeasurementGate,
+        cirq.ops.wait_gate.WaitGate,
+    )
+    assert tuple(device.metadata.compilation_target_gatesets) == (
+        cirq.CZTargetGateset(),
+        cirq_google.SycamoreTargetGateset(),
+        cirq.SqrtIswapTargetGateset(use_sqrt_iswap_inv=True),
+    )
+
+    base_duration = cirq.Duration(picos=1_000)
+    assert device.metadata.gate_durations == {
+        cirq_google.FSimGateFamily(gates_to_accept=[cirq_google.SYC]): base_duration * 0,
+        cirq_google.FSimGateFamily(gates_to_accept=[cirq.SQRT_ISWAP]): base_duration * 1,
+        cirq_google.FSimGateFamily(gates_to_accept=[cirq.SQRT_ISWAP_INV]): base_duration * 2,
+        cirq_google.FSimGateFamily(gates_to_accept=[cirq.CZ]): base_duration * 3,
+        cirq.GateFamily(cirq.ops.phased_x_z_gate.PhasedXZGate): base_duration * 4,
+        cirq.GateFamily(cirq.ops.common_gates.XPowGate): base_duration * 4,
+        cirq.GateFamily(cirq.ops.common_gates.YPowGate): base_duration * 4,
+        cirq.GateFamily(cirq.ops.phased_x_gate.PhasedXPowGate): base_duration * 4,
+        cirq.GateFamily(
+            cirq.ops.common_gates.ZPowGate, tags_to_ignore=[cirq_google.PhysicalZTag()]
+        ): base_duration
+        * 5,
+        cirq.GateFamily(
+            cirq.ops.common_gates.ZPowGate, tags_to_accept=[cirq_google.PhysicalZTag()]
+        ): base_duration
+        * 6,
+        cirq.GateFamily(cirq_google.experimental.ops.coupler_pulse.CouplerPulse): base_duration * 7,
+        cirq.GateFamily(cirq.ops.measurement_gate.MeasurementGate): base_duration * 8,
+        cirq.GateFamily(cirq.ops.wait_gate.WaitGate): base_duration * 9,
+    }
 
 
 def test_grid_device_validate_operations_positive():
@@ -166,23 +227,22 @@ def test_grid_device_validate_operations_positive():
     for i in range(GRID_HEIGHT):
         device.validate_operation(cirq.CZ(grid_qubits[2 * i], grid_qubits[2 * i + 1]))
 
-    # TODO(#5050) verify validate_operations gateset support
-
 
 def test_grid_device_validate_operations_negative():
     grid_qubits, spec = _create_device_spec_with_horizontal_couplings()
     device = cirq_google.GridDevice.from_proto(spec)
 
-    q = cirq.GridQubit(10, 10)
+    bad_qubit = cirq.GridQubit(10, 10)
     with pytest.raises(ValueError, match='Qubit not on device'):
-        device.validate_operation(cirq.X(q))
+        device.validate_operation(cirq.X(bad_qubit))
 
     # vertical qubit pair
     q00, q10 = grid_qubits[0], grid_qubits[2]  # (0, 0), (1, 0)
     with pytest.raises(ValueError, match='Qubit pair is not valid'):
         device.validate_operation(cirq.CZ(q00, q10))
 
-    # TODO(#5050) verify validate_operations gateset errors
+    with pytest.raises(ValueError, match='gate which is not supported'):
+        device.validate_operation(cirq.H(grid_qubits[0]))
 
 
 @pytest.mark.parametrize(