Passthrough params (#708)

Pass objects to local kernels without packing and unpacking.

---------

Co-authored-by: Connor Ward <[email protected]>

pyop2/codegen/builder.py

@@ -4,9 +4,8 @@
 from functools import reduce
 
 import numpy
-from loopy.types import OpaqueType
 from pyop2.global_kernel import (GlobalKernelArg, DatKernelArg, MixedDatKernelArg,
-                                 MatKernelArg, MixedMatKernelArg, PermutedMapKernelArg, ComposedMapKernelArg)
+                                 MatKernelArg, MixedMatKernelArg, PermutedMapKernelArg, ComposedMapKernelArg, PassthroughKernelArg)
 from pyop2.codegen.representation import (Accumulate, Argument, Comparison, Conditional,
                                           DummyInstruction, Extent, FixedIndex,
                                           FunctionCall, Index, Indexed,
@@ -16,16 +15,13 @@
                                           PreUnpackInst, Product, RuntimeIndex,
                                           Sum, Symbol, UnpackInst, Variable,
                                           When, Zero)
-from pyop2.datatypes import IntType
+from pyop2.datatypes import IntType, OpaqueType
 from pyop2.op2 import (ALL, INC, MAX, MIN, ON_BOTTOM, ON_INTERIOR_FACETS,
                        ON_TOP, READ, RW, WRITE)
 from pyop2.utils import cached_property
 
 
-class PetscMat(OpaqueType):
-
-    def __init__(self):
-        super().__init__(name="Mat")
+MatType = OpaqueType("Mat")
 
 
 def _Remainder(a, b):
@@ -226,6 +222,23 @@ def emit_unpack_instruction(self, *, loop_indices=None):
         """Either yield an instruction, or else return an empty tuple (to indicate no instruction)"""
 
 
+class PassthroughPack(Pack):
+    def __init__(self, outer):
+        self.outer = outer
+
+    def kernel_arg(self, loop_indices=None):
+        return self.outer
+
+    def pack(self, loop_indices=None):
+        pass
+
+    def emit_pack_instruction(self, **kwargs):
+        return ()
+
+    def emit_unpack_instruction(self, **kwargs):
+        return ()
+
+
 class GlobalPack(Pack):
 
     def __init__(self, outer, access, init_with_zero=False):
@@ -813,7 +826,12 @@ def add_argument(self, arg):
         dtype = local_arg.dtype
         interior_horizontal = self.iteration_region == ON_INTERIOR_FACETS
 
-        if isinstance(arg, GlobalKernelArg):
+        if isinstance(arg, PassthroughKernelArg):
+            argument = Argument((), dtype, pfx="arg")
+            pack = PassthroughPack(argument)
+            self.arguments.append(argument)
+
+        elif isinstance(arg, GlobalKernelArg):
             argument = Argument(arg.dim, dtype, pfx="glob")
 
             pack = GlobalPack(argument, access,
@@ -856,7 +874,7 @@ def add_argument(self, arg):
             pack = MixedDatPack(packs, access, dtype,
                                 interior_horizontal=interior_horizontal)
         elif isinstance(arg, MatKernelArg):
-            argument = Argument((), PetscMat(), pfx="mat")
+            argument = Argument((), MatType, pfx="mat")
             maps = tuple(self._add_map(m, arg.unroll)
                          for m in arg.maps)
             pack = arg.pack(argument, access, maps,
@@ -866,7 +884,7 @@ def add_argument(self, arg):
         elif isinstance(arg, MixedMatKernelArg):
             packs = []
             for a in arg:
-                argument = Argument((), PetscMat(), pfx="mat")
+                argument = Argument((), MatType, pfx="mat")
                 maps = tuple(self._add_map(m, a.unroll)
                              for m in a.maps)
 
@@ -949,7 +967,7 @@ def kernel_call(self):
         args = self.kernel_args
         access = tuple(self.loopy_argument_accesses)
         # assuming every index is free index
-        free_indices = set(itertools.chain.from_iterable(arg.multiindex for arg in args))
+        free_indices = set(itertools.chain.from_iterable(arg.multiindex for arg in args if isinstance(arg, Indexed)))
         # remove runtime index
         free_indices = tuple(i for i in free_indices if isinstance(i, Index))
         if self.pass_layer_to_kernel:

pyop2/codegen/representation.py

@@ -352,8 +352,6 @@ def __new__(cls, aggregate, multiindex):
         for index, extent in zip(multiindex, aggregate.shape):
             if isinstance(index, Index):
                 index.set_extent(extent)
-        if not multiindex:
-            return aggregate
 
         self = super().__new__(cls)
         self.children = (aggregate, multiindex)

pyop2/datatypes.py

@@ -69,3 +69,11 @@ def dtype_limits(dtype):
         except ValueError as e:
             raise ValueError("Unable to determine numeric limits from %s" % dtype) from e
     return info.min, info.max
+
+
+class OpaqueType(lp.types.OpaqueType):
+    def __init__(self, name):
+        super().__init__(name=name)
+
+    def __repr__(self):
+        return self.name

pyop2/global_kernel.py

@@ -206,6 +206,16 @@ def pack(self):
         return DatPack
 
 
+class PassthroughKernelArg:
+    @property
+    def cache_key(self):
+        return type(self)
+
+    @property
+    def maps(self):
+        return ()
+
+
 @dataclass(frozen=True)
 class MixedMatKernelArg:
     """Class representing a :class:`pyop2.types.MixedDat` being passed to the kernel.

pyop2/op2.py

@@ -36,6 +36,7 @@
 import atexit
 
 from pyop2.configuration import configuration
+from pyop2.datatypes import OpaqueType  # noqa: F401
 from pyop2.logger import debug, info, warning, error, critical, set_log_level
 from pyop2.mpi import MPI, COMM_WORLD, collective
 
@@ -52,7 +53,7 @@
 from pyop2.global_kernel import (GlobalKernelArg, DatKernelArg, MixedDatKernelArg,  # noqa: F401
                                  MatKernelArg, MixedMatKernelArg, MapKernelArg, GlobalKernel)
 from pyop2.parloop import (GlobalParloopArg, DatParloopArg, MixedDatParloopArg,  # noqa: F401
-                           MatParloopArg, MixedMatParloopArg, Parloop, parloop, par_loop)
+                           MatParloopArg, MixedMatParloopArg, PassthroughArg, Parloop, parloop, par_loop)
 from pyop2.parloop import (GlobalLegacyArg, DatLegacyArg, MixedDatLegacyArg,  # noqa: F401
                            MatLegacyArg, MixedMatLegacyArg, LegacyParloop, ParLoop)
 

pyop2/parloop.py

@@ -13,7 +13,7 @@
 from pyop2.datatypes import as_numpy_dtype
 from pyop2.exceptions import KernelTypeError, MapValueError, SetTypeError
 from pyop2.global_kernel import (GlobalKernelArg, DatKernelArg, MixedDatKernelArg,
-                                 MatKernelArg, MixedMatKernelArg, GlobalKernel)
+                                 MatKernelArg, MixedMatKernelArg, PassthroughKernelArg, GlobalKernel)
 from pyop2.local_kernel import LocalKernel, CStringLocalKernel, LoopyLocalKernel
 from pyop2.types import (Access, Global, AbstractDat, Dat, DatView, MixedDat, Mat, Set,
                          MixedSet, ExtrudedSet, Subset, Map, ComposedMap, MixedMap)
@@ -39,6 +39,10 @@ class GlobalParloopArg(ParloopArg):
 
     data: Global
 
+    @property
+    def _kernel_args_(self):
+        return self.data._kernel_args_
+
     @property
     def map_kernel_args(self):
         return ()
@@ -59,6 +63,10 @@ def __post_init__(self):
         if self.map_ is not None:
             self.check_map(self.map_)
 
+    @property
+    def _kernel_args_(self):
+        return self.data._kernel_args_
+
     @property
     def map_kernel_args(self):
         return self.map_._kernel_args_ if self.map_ else ()
@@ -81,6 +89,10 @@ class MixedDatParloopArg(ParloopArg):
     def __post_init__(self):
         self.check_map(self.map_)
 
+    @property
+    def _kernel_args_(self):
+        return self.data._kernel_args_
+
     @property
     def map_kernel_args(self):
         return self.map_._kernel_args_ if self.map_ else ()
@@ -102,6 +114,10 @@ def __post_init__(self):
         for m in self.maps:
             self.check_map(m)
 
+    @property
+    def _kernel_args_(self):
+        return self.data._kernel_args_
+
     @property
     def map_kernel_args(self):
         rmap, cmap = self.maps
@@ -120,12 +136,34 @@ def __post_init__(self):
         for m in self.maps:
             self.check_map(m)
 
+    @property
+    def _kernel_args_(self):
+        return self.data._kernel_args_
+
     @property
     def map_kernel_args(self):
         rmap, cmap = self.maps
         return tuple(itertools.chain(*itertools.product(rmap._kernel_args_, cmap._kernel_args_)))
 
 
+@dataclass
+class PassthroughParloopArg(ParloopArg):
+    # a pointer
+    data: int
+
+    @property
+    def _kernel_args_(self):
+        return (self.data,)
+
+    @property
+    def map_kernel_args(self):
+        return ()
+
+    @property
+    def maps(self):
+        return ()
+
+
 class Parloop:
     """A parallel loop invocation.
 
@@ -167,7 +205,7 @@ def arglist(self):
         """Prepare the argument list for calling generated code."""
         arglist = self.iterset._kernel_args_
         for d in self.arguments:
-            arglist += d.data._kernel_args_
+            arglist += d._kernel_args_
 
         # Collect an ordered set of maps (ignore duplicates)
         maps = {m: None for d in self.arguments for m in d.map_kernel_args}
@@ -224,6 +262,8 @@ def __call__(self):
     def increment_dat_version(self):
         """Increment dat versions of :class:`DataCarrier`s in the arguments."""
         for lk_arg, gk_arg, pl_arg in self.zipped_arguments:
+            if isinstance(pl_arg, PassthroughParloopArg):
+                continue
             assert isinstance(pl_arg.data, DataCarrier)
             if lk_arg.access is not Access.READ:
                 if pl_arg.data in self.reduced_globals:
@@ -520,6 +560,10 @@ class GlobalLegacyArg(LegacyArg):
     data: Global
     access: Access
 
+    @property
+    def dtype(self):
+        return self.data.dtype
+
     @property
     def global_kernel_arg(self):
         return GlobalKernelArg(self.data.dim)
@@ -537,6 +581,10 @@ class DatLegacyArg(LegacyArg):
     map_: Optional[Map]
     access: Access
 
+    @property
+    def dtype(self):
+        return self.data.dtype
+
     @property
     def global_kernel_arg(self):
         map_arg = self.map_._global_kernel_arg if self.map_ is not None else None
@@ -556,6 +604,10 @@ class MixedDatLegacyArg(LegacyArg):
     map_: MixedMap
     access: Access
 
+    @property
+    def dtype(self):
+        return self.data.dtype
+
     @property
     def global_kernel_arg(self):
         args = []
@@ -579,6 +631,10 @@ class MatLegacyArg(LegacyArg):
     lgmaps: Optional[Tuple[Any, Any]] = None
     needs_unrolling: Optional[bool] = False
 
+    @property
+    def dtype(self):
+        return self.data.dtype
+
     @property
     def global_kernel_arg(self):
         map_args = [m._global_kernel_arg for m in self.maps]
@@ -599,6 +655,10 @@ class MixedMatLegacyArg(LegacyArg):
     lgmaps: Tuple[Any] = None
     needs_unrolling: Optional[bool] = False
 
+    @property
+    def dtype(self):
+        return self.data.dtype
+
     @property
     def global_kernel_arg(self):
         nrows, ncols = self.data.sparsity.shape
@@ -618,6 +678,28 @@ def parloop_arg(self):
         return MixedMatParloopArg(self.data, tuple(self.maps), self.lgmaps)
 
 
+@dataclass
+class PassthroughArg(LegacyArg):
+    """Argument that is simply passed to the local kernel without packing.
+
+    :param dtype: The datatype of the argument. This is needed for code generation.
+    :param data: A pointer to the data.
+    """
+    # We don't know what the local kernel is doing with this argument
+    access = Access.RW
+
+    dtype: Any
+    data: int
+
+    @property
+    def global_kernel_arg(self):
+        return PassthroughKernelArg()
+
+    @property
+    def parloop_arg(self):
+        return PassthroughParloopArg(self.data)
+
+
 def ParLoop(*args, **kwargs):
     return LegacyParloop(*args, **kwargs)
 
@@ -641,7 +723,7 @@ def LegacyParloop(local_knl, iterset, *args, **kwargs):
     # finish building the local kernel
     local_knl.accesses = tuple(a.access for a in args)
     if isinstance(local_knl, CStringLocalKernel):
-        local_knl.dtypes = tuple(a.data.dtype for a in args)
+        local_knl.dtypes = tuple(a.dtype for a in args)
 
     global_knl_args = tuple(a.global_kernel_arg for a in args)
     extruded = iterset._extruded

test/unit/test_direct_loop.py

@@ -34,6 +34,7 @@
 
 import pytest
 import numpy as np
+from petsc4py import PETSc
 
 from pyop2 import op2
 from pyop2.exceptions import MapValueError
@@ -249,6 +250,41 @@ def test_kernel_cplusplus(self, delems):
 
         assert (y.data == 10.5).all()
 
+    def test_passthrough_mat(self):
+        niters = 10
+        iterset = op2.Set(niters)
+
+        c_kernel = """
+static void mat_inc(Mat mat) {
+    PetscScalar values[] = {1, 2, 3, 4, 5, 6, 7, 8, 9};
+    PetscInt idxs[] = {0, 2, 4};
+    MatSetValues(mat, 3, idxs, 3, idxs, values, ADD_VALUES);
+}
+        """
+        kernel = op2.Kernel(c_kernel, "mat_inc")
+
+        # create a tiny 5x5 sparse matrix
+        petsc_mat = PETSc.Mat().create()
+        petsc_mat.setSizes(5)
+        petsc_mat.setUp()
+        petsc_mat.setValues([0, 2, 4], [0, 2, 4], np.zeros((3, 3), dtype=PETSc.ScalarType))
+        petsc_mat.assemble()
+
+        arg = op2.PassthroughArg(op2.OpaqueType("Mat"), petsc_mat.handle)
+        op2.par_loop(kernel, iterset, arg)
+        petsc_mat.assemble()
+
+        assert np.allclose(
+            petsc_mat.getValues(range(5), range(5)),
+            [
+                [10, 0, 20, 0, 30],
+                [0]*5,
+                [40, 0, 50, 0, 60],
+                [0]*5,
+                [70, 0, 80, 0, 90],
+            ]
+        )
+
 
 if __name__ == '__main__':
     import os