Better CopyToMap (#1675)

By default the transformation uses some linearization followed by a
delinearization approach, while this is needed to copy certain shapes,
it is unnecessarily complicated for memlets such as `a[0:10, 20:30] ->
40:50, 60:70`.
This PR adds special cases where the source and destination subset has
the same size and transforms it to a simple copy.
It also supports the case where some dimensions are one, i.e. memlets
such as `a[0:10, 0:10] -> 0:10, 1, 0:20`.

For all cases tests were added.
Most importantly the transformation now applies if the strides are the
same.
Before this case was blocked.

This PR helps to _avoid_ errors that are related to
[Issue#1674](#1674), but it is not a
fix or a solution to it.

dace/transformation/dataflow/copy_to_map.py

@@ -1,19 +1,24 @@
 # Copyright 2019-2022 ETH Zurich and the DaCe authors. All rights reserved.
 
-from dace import dtypes, symbolic, data, subsets, Memlet
+from dace import dtypes, symbolic, data, subsets, Memlet, properties
 from dace.sdfg.scope import is_devicelevel_gpu
 from dace.transformation import transformation as xf
 from dace.sdfg import SDFGState, SDFG, nodes, utils as sdutil
 from typing import Tuple
+import itertools
 
-
+@properties.make_properties
 class CopyToMap(xf.SingleStateTransformation):
     """
     Converts an access node -> access node copy into a map. Useful for generating manual code and
     controlling schedules for N-dimensional strided copies.
     """
     a = xf.PatternNode(nodes.AccessNode)
     b = xf.PatternNode(nodes.AccessNode)
+    ignore_strides = properties.Property(
+            default=False,
+            desc='Ignore the stride of the data container; Defaults to `False`.',
+    )
 
     @classmethod
     def expressions(cls):
@@ -31,7 +36,10 @@ def can_be_applied(self, graph: SDFGState, expr_index: int, sdfg: SDFG, permissi
         if isinstance(self.b.desc(sdfg), data.View):
             if sdutil.get_view_node(graph, self.b) == self.a:
                 return False
-        if self.a.desc(sdfg).strides == self.b.desc(sdfg).strides:
+        if (not self.ignore_strides) and self.a.desc(sdfg).strides == self.b.desc(sdfg).strides:
+            return False
+        # Ensures that the edge goes from `a` -> `b`.
+        if not any(edge.dst is self.b for edge in graph.out_edges(self.a)):
             return False
 
         return True
@@ -62,31 +70,69 @@ def delinearize_linearize(self, desc: data.Array, copy_shape: Tuple[symbolic.Sym
         return subsets.Range([(ind, ind, 1) for ind in cur_index])
 
     def apply(self, state: SDFGState, sdfg: SDFG):
-        adesc = self.a.desc(sdfg)
-        bdesc = self.b.desc(sdfg)
-        edge = state.edges_between(self.a, self.b)[0]
+        avnode = self.a
+        av = avnode.data
+        adesc = avnode.desc(sdfg)
+        bvnode = self.b
+        bv = bvnode.data
+        bdesc = bvnode.desc(sdfg)
+
+        edge = state.edges_between(avnode, bvnode)[0]
+        src_subset = edge.data.get_src_subset(edge, state)
+        if src_subset is None:
+            src_subset = subsets.Range.from_array(adesc)
+        src_subset_size = src_subset.size()
+        red_src_subset_size = tuple(s for s in src_subset_size if s != 1)
+
+        dst_subset = edge.data.get_dst_subset(edge, state)
+        if dst_subset is None:
+            dst_subset = subsets.Range.from_array(bdesc)
+        dst_subset_size = dst_subset.size()
+        red_dst_subset_size = tuple(s for s in dst_subset_size if s != 1)
 
         if len(adesc.shape) >= len(bdesc.shape):
-            copy_shape = edge.data.get_src_subset(edge, state).size()
+            copy_shape = src_subset_size
             copy_a = True
         else:
-            copy_shape = edge.data.get_dst_subset(edge, state).size()
+            copy_shape = dst_subset_size
             copy_a = False
 
-        maprange = {f'__i{i}': (0, s - 1, 1) for i, s in enumerate(copy_shape)}
-
-        av = self.a.data
-        bv = self.b.data
-        avnode = self.a
-        bvnode = self.b
-
-        # Linearize and delinearize to get index expression for other side
-        if copy_a:
-            a_index = [symbolic.pystr_to_symbolic(f'__i{i}') for i in range(len(copy_shape))]
-            b_index = self.delinearize_linearize(bdesc, copy_shape, edge.data.get_dst_subset(edge, state))
+        if tuple(src_subset_size) == tuple(dst_subset_size):
+            # The two subsets have exactly the same shape, so we can just copying with an offset.
+            #  We use another index variables for the tests only.
+            maprange = {f'__j{i}': (0, s - 1, 1) for i, s in enumerate(copy_shape)}
+            a_index = [symbolic.pystr_to_symbolic(f'__j{i} + ({src_subset[i][0]})') for i in range(len(copy_shape))]
+            b_index = [symbolic.pystr_to_symbolic(f'__j{i} + ({dst_subset[i][0]})') for i in range(len(copy_shape))]
+        elif red_src_subset_size == red_dst_subset_size and (len(red_dst_subset_size) > 0):
+            # If we remove all size 1 dimensions that the two subsets have the same size.
+            #  This is essentially the memlet `a[0:10, 2, 0:10] -> 0:10, 10:20`
+            #  We use another index variable only for the tests but we would have to
+            #  recreate the index anyways.
+            maprange = {f'__j{i}': (0, s - 1, 1) for i, s in enumerate(red_src_subset_size)}
+            cnt = itertools.count(0)
+            a_index = [
+                symbolic.pystr_to_symbolic(f'{src_subset[i][0]}')
+                if s == 1
+                else symbolic.pystr_to_symbolic(f'__j{next(cnt)} + ({src_subset[i][0]})')
+                for i, s in enumerate(src_subset_size)
+            ]
+            cnt = itertools.count(0)
+            b_index = [
+                symbolic.pystr_to_symbolic(f'{dst_subset[i][0]}')
+                if s == 1
+                else symbolic.pystr_to_symbolic(f'__j{next(cnt)} + ({dst_subset[i][0]})')
+                for i, s in enumerate(dst_subset_size)
+            ]
         else:
-            a_index = self.delinearize_linearize(adesc, copy_shape, edge.data.get_src_subset(edge, state))
-            b_index = [symbolic.pystr_to_symbolic(f'__i{i}') for i in range(len(copy_shape))]
+            # We have to delinearize and linearize
+            #  We use another index variable for the tests.
+            maprange = {f'__i{i}': (0, s - 1, 1) for i, s in enumerate(copy_shape)}
+            if copy_a:
+                a_index = [symbolic.pystr_to_symbolic(f'__i{i}') for i in range(len(copy_shape))]
+                b_index = self.delinearize_linearize(bdesc, copy_shape, edge.data.get_dst_subset(edge, state))
+            else:
+                a_index = self.delinearize_linearize(adesc, copy_shape, edge.data.get_src_subset(edge, state))
+                b_index = [symbolic.pystr_to_symbolic(f'__i{i}') for i in range(len(copy_shape))]
 
         a_subset = subsets.Range([(ind, ind, 1) for ind in a_index])
         b_subset = subsets.Range([(ind, ind, 1) for ind in b_index])
@@ -101,7 +147,7 @@ def apply(self, state: SDFGState, sdfg: SDFG):
                 schedule = dtypes.ScheduleType.GPU_Device
 
         # Add copy map
-        t, _, _ = state.add_mapped_tasklet('copy',
+        t, _, _ = state.add_mapped_tasklet(f'copy_{av}_{bv}',
                                            maprange,
                                            dict(__inp=Memlet(data=av, subset=a_subset)),
                                            '__out = __inp',

tests/transformations/copy_to_map_test.py

@@ -4,6 +4,8 @@
 import copy
 import pytest
 import numpy as np
+import re
+from typing import Tuple, Optional
 
 
 def _copy_to_map(storage: dace.StorageType):
@@ -102,9 +104,165 @@ def test_preprocess():
     assert np.allclose(out, inp)
 
 
+def _perform_non_lin_delin_test(
+        sdfg: dace.SDFG,
+) -> bool:
+    """Performs test for the special case CopyToMap that bypasses linearizing and delinearaziong.
+    """
+    assert sdfg.number_of_nodes() == 1
+    state: dace.SDFGState = sdfg.states()[0]
+    assert state.number_of_nodes() == 2
+    assert state.number_of_edges() == 1
+    assert all(isinstance(node, dace.nodes.AccessNode) for node in state.nodes())
+    sdfg.validate()
+
+    a = np.random.rand(*sdfg.arrays["a"].shape)
+    b_unopt = np.random.rand(*sdfg.arrays["b"].shape)
+    b_opt = b_unopt.copy()
+    sdfg(a=a, b=b_unopt)
+
+    nb_runs = sdfg.apply_transformations_repeated(CopyToMap, validate=True, options={"ignore_strides": True})
+    assert nb_runs == 1, f"Expected 1 application, but {nb_runs} were performed."
+
+    # Now looking for the tasklet and checking if the memlets follows the expected
+    #  simple pattern.
+    tasklet: dace.nodes.Tasklet = next(iter([node for node in state.nodes() if isinstance(node, dace.nodes.Tasklet)]))
+    pattern: re.Pattern = re.compile(r"(__j[0-9])|(__j[0-9]+\s*\+\s*[0-9]+)|([0-9]+)")
+
+    assert state.in_degree(tasklet) == 1
+    assert state.out_degree(tasklet) == 1
+    in_edge = next(iter(state.in_edges(tasklet)))
+    out_edge = next(iter(state.out_edges(tasklet)))
+
+    assert all(pattern.fullmatch(str(idxs[0]).strip()) for idxs in in_edge.data.src_subset), f"IN: {in_edge.data.src_subset}"
+    assert all(pattern.fullmatch(str(idxs[0]).strip()) for idxs in out_edge.data.dst_subset), f"OUT: {out_edge.data.dst_subset}"
+
+    # Now call it again after the optimization.
+    sdfg(a=a, b=b_opt)
+    assert np.allclose(b_unopt, b_opt)
+
+    return True
+
+def _make_non_lin_delin_sdfg(
+        shape_a: Tuple[int, ...],
+        shape_b: Optional[Tuple[int, ...]] = None
+) -> Tuple[dace.SDFG, dace.SDFGState, dace.nodes.AccessNode, dace.nodes.AccessNode]:
+
+    if shape_b is None:
+        shape_b = shape_a
+
+    sdfg = dace.SDFG("bypass1")
+    state = sdfg.add_state(is_start_block=True)
+
+    ac = []
+    for name, shape in [('a', shape_a), ('b', shape_b)]:
+        sdfg.add_array(
+                name=name,
+                shape=shape,
+                dtype=dace.float64,
+                transient=False,
+        )
+        ac.append(state.add_access(name))
+
+    return sdfg, state, ac[0], ac[1]
+
+
+def test_non_lin_delin_1():
+    sdfg, state, a, b = _make_non_lin_delin_sdfg((10, 10))
+    state.add_nedge(
+            a,
+            b,
+            dace.Memlet("a[0:10, 0:10] -> [0:10, 0:10]"),
+    )
+    _perform_non_lin_delin_test(sdfg)
+
+def test_non_lin_delin_2():
+    sdfg, state, a, b = _make_non_lin_delin_sdfg((10, 10), (100, 100))
+    state.add_nedge(
+            a,
+            b,
+            dace.Memlet("a[0:10, 0:10] -> [50:60, 40:50]"),
+    )
+    _perform_non_lin_delin_test(sdfg)
+
+
+def test_non_lin_delin_3():
+    sdfg, state, a, b = _make_non_lin_delin_sdfg((100, 100), (100, 100))
+    state.add_nedge(
+            a,
+            b,
+            dace.Memlet("a[1:11, 20:30] -> [50:60, 40:50]"),
+    )
+    _perform_non_lin_delin_test(sdfg)
+
+
+def test_non_lin_delin_4():
+    sdfg, state, a, b = _make_non_lin_delin_sdfg((100, 4, 100), (100, 100))
+    state.add_nedge(
+            a,
+            b,
+            dace.Memlet("a[1:11, 2, 20:30] -> [50:60, 40:50]"),
+    )
+    _perform_non_lin_delin_test(sdfg)
+
+
+def test_non_lin_delin_5():
+    sdfg, state, a, b = _make_non_lin_delin_sdfg((100, 4, 100), (100, 10, 100))
+    state.add_nedge(
+            a,
+            b,
+            dace.Memlet("a[1:11, 2, 20:30] -> [50:60, 4, 40:50]"),
+    )
+    _perform_non_lin_delin_test(sdfg)
+
+
+def test_non_lin_delin_6():
+    sdfg, state, a, b = _make_non_lin_delin_sdfg((100, 100), (100, 10, 100))
+    state.add_nedge(
+            a,
+            b,
+            dace.Memlet("a[1:11, 20:30] -> [50:60, 4, 40:50]"),
+    )
+    _perform_non_lin_delin_test(sdfg)
+
+
+def test_non_lin_delin_7():
+    sdfg, state, a, b = _make_non_lin_delin_sdfg((10, 10), (20, 20))
+    state.add_nedge(
+            a,
+            b,
+            dace.Memlet("b[5:15, 6:16]"),
+    )
+    _perform_non_lin_delin_test(sdfg)
+
+
+def test_non_lin_delin_8():
+    sdfg, state, a, b = _make_non_lin_delin_sdfg((20, 20), (10, 10))
+    state.add_nedge(
+            a,
+            b,
+            dace.Memlet("a[5:15, 6:16]"),
+    )
+    _perform_non_lin_delin_test(sdfg)
+
+
 if __name__ == '__main__':
+    test_non_lin_delin_1()
+    test_non_lin_delin_2()
+    test_non_lin_delin_3()
+    test_non_lin_delin_4()
+    test_non_lin_delin_5()
+    test_non_lin_delin_6()
+    test_non_lin_delin_7()
+    test_non_lin_delin_8()
+
     test_copy_to_map()
-    test_copy_to_map_gpu()
     test_flatten_to_map()
-    test_flatten_to_map_gpu()
-    test_preprocess()
+    try:
+        import cupy
+        test_copy_to_map_gpu()
+        test_flatten_to_map_gpu()
+        test_preprocess()
+    except ModuleNotFoundError as E:
+        if "'cupy'" not in str(E):
+            raise