Esempio n. 1
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    def can_be_applied(
        self,
        graph: SDFGState,
        candidate: Dict[str, dace.nodes.Node],
        expr_index: int,
        sdfg: dace.SDFG,
        strict: bool = False,
    ) -> bool:
        left = self.left(sdfg)
        right = self.right(sdfg)
        if expr_index >= 2:
            if nx.has_path(graph.nx, right, left):
                return False
        intermediate_accesses = set(
            n for path in nx.all_simple_paths(graph.nx, left, right)
            for n in path[1:-1])
        if not all(
                isinstance(n, dace.nodes.AccessNode) and
            (graph.edges_between(left, n) and graph.edges_between(n, right))
                for n in intermediate_accesses):
            return False

        protected_intermediate_names = set(n.label
                                           for n in intermediate_accesses
                                           if any(
                                               edge.dst is not right
                                               for edge in graph.out_edges(n)))
        output_names = set(edge.data.data for edge in graph.out_edges(right)
                           if edge.data is not None)
        if len(protected_intermediate_names & output_names) > 0:
            return False

        return offsets_match(left, right) and iteration_space_compatible(
            left, right, self.api_fields)
Esempio n. 2
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    def apply(self, sdfg):
        def gnode(nname):
            return graph.nodes()[self.subgraph[nname]]

        graph = sdfg.nodes()[self.state_id]
        in_array = gnode(RedundantSecondArray._in_array)
        out_array = gnode(RedundantSecondArray._out_array)

        # We assume the following pattern: A -- e1 --> B -- e2 --> others

        # 1. Get edge e1 and extract subsets for arrays A and B
        e1 = graph.edges_between(in_array, out_array)[0]
        a_subset, b1_subset = _validate_subsets(e1, sdfg.arrays)
        # 2. Iterate over the e2 edges and traverse the memlet tree
        for e2 in graph.out_edges(out_array):
            path = graph.memlet_tree(e2)
            for e3 in path:
                # 2-a. Extract subsets for array B and others
                b3_subset, other_subset = _validate_subsets(
                    e3, sdfg.arrays, src_name=out_array.data)
                # 2-b. Modify memlet to match array A. Example:
                # A -- (0, a:b)/(c:c+b) --> B -- (c+d)/None --> others
                # A -- (0, a+d)/None --> others
                e3.data.data = in_array.data
                # (c+d) - (c:c+b) = (d)
                b3_subset.offset(b1_subset, negative=True)
                # (0, a:b)(d) = (0, a+d) (or offset for indices)
                if isinstance(a_subset, subsets.Indices):
                    tmp = copy.deepcopy(a_subset)
                    tmp.offset(b3_subset, negative=False)
                    e3.data.subset = tmp
                else:
                    e3.data.subset = a_subset.compose(b3_subset)
                e3.data.other_subset = other_subset
            # 2-c. Remove edge and add new one
            graph.remove_edge(e2)
            graph.add_edge(in_array, e2.src_conn, e2.dst, e2.dst_conn, e2.data)

        # Finally, remove out_array node
        graph.remove_node(out_array)
        # TODO: Should the array be removed from the SDFG?
        # del sdfg.arrays[out_array]
        if Config.get_bool("debugprint"):
            RedundantSecondArray._arrays_removed += 1
Esempio n. 3
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    def expansion(node: 'Reduce', state: SDFGState, sdfg: SDFG):
        """ Create a map around the BlockReduce node
            with in and out transients in registers
            and an if tasklet that redirects the output
            of thread 0 to a shared memory transient
        """
        ### define some useful vars
        graph = state
        reduce_node = node
        in_edge = graph.in_edges(reduce_node)[0]
        out_edge = graph.out_edges(reduce_node)[0]

        axes = reduce_node.axes
        ### add a map that encloses the reduce node
        (new_entry, new_exit) = graph.add_map(
                      name = 'inner_reduce_block',
                      ndrange = {'i'+str(i): f'{rng[0]}:{rng[1]+1}:{rng[2]}'  \
                                for (i,rng) in enumerate(in_edge.data.subset) \
                                if i in axes},
                      schedule = dtypes.ScheduleType.Default)

        map = new_entry.map
        ExpandReduceCUDABlockAll.redirect_edge(graph,
                                               in_edge,
                                               new_dst=new_entry)
        ExpandReduceCUDABlockAll.redirect_edge(graph,
                                               out_edge,
                                               new_src=new_exit)

        subset_in = subsets.Range([
            in_edge.data.subset[i] if i not in axes else
            (new_entry.map.params[0], new_entry.map.params[0], 1)
            for i in range(len(in_edge.data.subset))
        ])
        memlet_in = dace.Memlet(data=in_edge.data.data,
                                volume=1,
                                subset=subset_in)
        memlet_out = dcpy(out_edge.data)
        graph.add_edge(u=new_entry,
                       u_connector=None,
                       v=reduce_node,
                       v_connector=None,
                       memlet=memlet_in)
        graph.add_edge(u=reduce_node,
                       u_connector=None,
                       v=new_exit,
                       v_connector=None,
                       memlet=memlet_out)

        ### add in and out local storage
        from dace.transformation.dataflow.local_storage import LocalStorage

        in_local_storage_subgraph = {
            LocalStorage._node_a: graph.nodes().index(new_entry),
            LocalStorage._node_b: graph.nodes().index(reduce_node)
        }
        out_local_storage_subgraph = {
            LocalStorage._node_a: graph.nodes().index(reduce_node),
            LocalStorage._node_b: graph.nodes().index(new_exit)
        }

        local_storage = LocalStorage(sdfg.sdfg_id,
                                     sdfg.nodes().index(state),
                                     in_local_storage_subgraph, 0)

        local_storage.array = in_edge.data.data
        local_storage.apply(sdfg)
        in_transient = local_storage._data_node
        sdfg.data(in_transient.data).storage = dtypes.StorageType.Register

        local_storage = LocalStorage(sdfg.sdfg_id,
                                     sdfg.nodes().index(state),
                                     out_local_storage_subgraph, 0)
        local_storage.array = out_edge.data.data
        local_storage.apply(sdfg)
        out_transient = local_storage._data_node
        sdfg.data(out_transient.data).storage = dtypes.StorageType.Register

        # hack: swap edges as local_storage does not work correctly here
        # as subsets and data get assigned wrongly (should be swapped)
        # NOTE: If local_storage ever changes, this will not work any more
        e1 = graph.in_edges(out_transient)[0]
        e2 = graph.out_edges(out_transient)[0]
        e1.data.data = dcpy(e2.data.data)
        e1.data.subset = dcpy(e2.data.subset)

        ### add an if tasket and diverge
        code = 'if '
        for (i, param) in enumerate(new_entry.map.params):
            code += (param + '== 0')
            if i < len(axes) - 1:
                code += ' and '
        code += ':\n'
        code += '\tout=inp'

        tasklet_node = graph.add_tasklet(name='block_reduce_write',
                                         inputs=['inp'],
                                         outputs=['out'],
                                         code=code)

        edge_out_outtrans = graph.out_edges(out_transient)[0]
        edge_out_innerexit = graph.out_edges(new_exit)[0]
        ExpandReduceCUDABlockAll.redirect_edge(graph,
                                               edge_out_outtrans,
                                               new_dst=tasklet_node,
                                               new_dst_conn='inp')
        e = graph.add_edge(u=tasklet_node,
                           u_connector='out',
                           v=new_exit,
                           v_connector=None,
                           memlet=dcpy(edge_out_innerexit.data))
        # set dynamic with volume 0 FORNOW
        e.data.volume = 0
        e.data.dynamic = True

        ### set reduce_node axes to all (needed)
        reduce_node.axes = None

        # fill scope connectors, done.
        sdfg.fill_scope_connectors()

        # finally, change the implementation to cuda (block)
        # itself and expand again.
        reduce_node.implementation = 'CUDA (block)'
        sub_expansion = ExpandReduceCUDABlock(0, 0, {}, 0)
        return sub_expansion.expansion(node=node, state=state, sdfg=sdfg)
Esempio n. 4
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    def can_be_applied(graph, candidate, expr_index, sdfg, strict=False):
        in_array = graph.nodes()[candidate[RedundantSecondArray._in_array]]
        out_array = graph.nodes()[candidate[RedundantSecondArray._out_array]]

        in_desc = in_array.desc(sdfg)
        out_desc = out_array.desc(sdfg)

        # Ensure in degree is one (only one source, which is in_array)
        if graph.in_degree(out_array) != 1:
            return False

        # Make sure that the candidate is a transient variable
        if not out_desc.transient:
            return False

        # Dimensionality must be the same in strict mode
        if strict and len(in_desc.shape) != len(out_desc.shape):
            return False

        # Make sure that both arrays are using the same storage location
        # and are of the same type (e.g., Stream->Stream)
        if in_desc.storage != out_desc.storage:
            return False
        if type(in_desc) != type(out_desc):
            return False

        # Find occurrences in this and other states
        occurrences = []
        for state in sdfg.nodes():
            occurrences.extend([
                n for n in state.nodes()
                if isinstance(n, nodes.AccessNode) and n.desc(sdfg) == out_desc
            ])
        for isedge in sdfg.edges():
            if out_array.data in isedge.data.free_symbols:
                occurrences.append(isedge)

        if len(occurrences) > 1:
            return False

        # Check whether the data copied from the first datanode cover
        # the subsets of all the output edges of the second datanode.
        # We assume the following pattern: A -- e1 --> B -- e2 --> others

        # 1. Get edge e1 and extract/validate subsets for arrays A and B
        e1 = graph.edges_between(in_array, out_array)[0]
        try:
            _, b1_subset = _validate_subsets(e1, sdfg.arrays)
        except NotImplementedError:
            return False
        # 2. Iterate over the e2 edges
        for e2 in graph.out_edges(out_array):
            # 2-a. Extract/validate subsets for array B and others
            try:
                b2_subset, _ = _validate_subsets(e2, sdfg.arrays)
            except NotImplementedError:
                return False
            # 2-b. Check where b1_subset covers b2_subset
            if not b1_subset.covers(b2_subset):
                return False
            # 2-c. Validate subsets in memlet tree
            # (should not be needed for valid SDGs)
            path = graph.memlet_tree(e2)
            for e3 in path:
                if e3 is not e2:
                    try:
                        _validate_subsets(e3,
                                          sdfg.arrays,
                                          src_name=out_array.data)
                    except NotImplementedError:
                        return False

        return True
Esempio n. 5
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    def apply(self, sdfg):
        def gnode(nname):
            return graph.nodes()[self.subgraph[nname]]

        graph = sdfg.nodes()[self.state_id]
        in_array = gnode(RedundantSecondArray._in_array)
        out_array = gnode(RedundantSecondArray._out_array)
        in_desc = sdfg.arrays[in_array.data]
        out_desc = sdfg.arrays[out_array.data]

        # We assume the following pattern: A -- e1 --> B -- e2 --> others

        # 1. Get edge e1 and extract subsets for arrays A and B
        e1 = graph.edges_between(in_array, out_array)[0]
        a_subset, b1_subset = _validate_subsets(e1, sdfg.arrays)

        # Find extraneous A or B subset dimensions
        a_dims_to_pop = []
        b_dims_to_pop = []
        aset = a_subset
        popped = []
        if a_subset and b1_subset and a_subset.dims() != b1_subset.dims():
            a_size = a_subset.size_exact()
            b_size = b1_subset.size_exact()
            if a_subset.dims() > b1_subset.dims():
                a_dims_to_pop = find_dims_to_pop(a_size, b_size)
                aset, popped = pop_dims(a_subset, a_dims_to_pop)
            else:
                b_dims_to_pop = find_dims_to_pop(b_size, a_size)

        # If the src subset does not cover the removed array, create a view.
        if a_subset and any(m != a
                            for m, a in zip(a_subset.size(), out_desc.shape)):
            # NOTE: We do not want to create another view, if the immediate
            # successors of out_array are views as well. We just remove it.
            out_successors_desc = [
                e.dst.desc(sdfg)
                if isinstance(e.dst, nodes.AccessNode) else None
                for e in graph.out_edges(out_array)
            ]
            if all([
                    desc and isinstance(desc, data.View)
                    for desc in out_successors_desc
            ]):
                for e in graph.out_edges(out_array):
                    _, b_subset = _validate_subsets(e, sdfg.arrays)
                    graph.add_edge(
                        in_array, None, e.dst, e.dst_conn,
                        mm.Memlet(in_array.data,
                                  subset=a_subset,
                                  other_subset=b_subset,
                                  wcr=e1.data.wcr,
                                  wcr_nonatomic=e1.data.wcr_nonatomic))
                    graph.remove_edge(e)
                graph.remove_edge(e1)
                graph.remove_node(out_array)
                if out_array.data in sdfg.arrays:
                    del sdfg.arrays[out_array.data]
                return
            view_strides = out_desc.strides
            if (a_dims_to_pop and len(a_dims_to_pop)
                    == len(in_desc.shape) - len(out_desc.shape)):
                view_strides = [
                    s for i, s in enumerate(in_desc.strides)
                    if i not in a_dims_to_pop
                ]
            sdfg.arrays[out_array.data] = data.View(
                out_desc.dtype, out_desc.shape, True, out_desc.allow_conflicts,
                in_desc.storage, in_desc.location, view_strides,
                out_desc.offset, in_desc.may_alias,
                dtypes.AllocationLifetime.Scope, out_desc.alignment,
                out_desc.debuginfo, out_desc.total_size)
            return

        # 2. Iterate over the e2 edges and traverse the memlet tree
        for e2 in graph.out_edges(out_array):
            path = graph.memlet_tree(e2)
            wcr = e1.data.wcr
            wcr_nonatomic = e1.data.wcr_nonatomic
            for e3 in path:
                # 2-a. Extract subsets for array B and others
                b3_subset, other_subset = _validate_subsets(
                    e3, sdfg.arrays, src_name=out_array.data)
                # 2-b. Modify memlet to match array A. Example:
                # A -- (0, a:b)/(c:c+b) --> B -- (c+d)/None --> others
                # A -- (0, a+d)/None --> others
                e3.data.data = in_array.data
                # (c+d) - (c:c+b) = (d)
                b3_subset.offset(b1_subset, negative=True)
                # (0, a:b)(d) = (0, a+d) (or offset for indices)

                if b3_subset and b_dims_to_pop:
                    bset, _ = pop_dims(b3_subset, b_dims_to_pop)
                else:
                    bset = b3_subset

                e3.data.subset = compose_and_push_back(aset, bset,
                                                       a_dims_to_pop, popped)
                # NOTE: This fixes the following case:
                # A ----> A[subset] ----> ... -----> Tasklet
                # Tasklet is not data, so it doesn't have an other subset.
                if isinstance(e3.dst, nodes.AccessNode):
                    e3.data.other_subset = other_subset
                else:
                    e3.data.other_subset = None
                wcr = wcr or e3.data.wcr
                wcr_nonatomic = wcr_nonatomic or e3.data.wcr_nonatomic
                e3.data.wcr = wcr
                e3.data.wcr_nonatomic = wcr_nonatomic

            # 2-c. Remove edge and add new one
            graph.remove_edge(e2)
            e2.data.wcr = wcr
            e2.data.wcr_nonatomic = wcr_nonatomic
            graph.add_edge(in_array, e2.src_conn, e2.dst, e2.dst_conn, e2.data)

        # Finally, remove out_array node
        graph.remove_node(out_array)
        if out_array.data in sdfg.arrays:
            try:
                sdfg.remove_data(out_array.data)
            except ValueError:  # Already in use (e.g., with Views)
                pass
Esempio n. 6
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    def can_be_applied(graph, candidate, expr_index, sdfg, strict=False):
        in_array = graph.nodes()[candidate[RedundantSecondArray._in_array]]
        out_array = graph.nodes()[candidate[RedundantSecondArray._out_array]]

        in_desc = in_array.desc(sdfg)
        out_desc = out_array.desc(sdfg)

        # Ensure in degree is one (only one source, which is in_array)
        if graph.in_degree(out_array) != 1:
            return False

        # Make sure that the candidate is a transient variable
        if not out_desc.transient:
            return False

        # 1. Get edge e1 and extract/validate subsets for arrays A and B
        e1 = graph.edges_between(in_array, out_array)[0]
        a_subset, b1_subset = _validate_subsets(e1, sdfg.arrays)

        if strict:
            # In strict mode, make sure the memlet covers the removed array
            if not b1_subset:
                return False
            subset = copy.deepcopy(b1_subset)
            subset.squeeze()
            shape = [sz for sz in out_desc.shape if sz != 1]
            if any(m != a for m, a in zip(subset.size(), shape)):
                return False

            # NOTE: Library node check
            # The transformation must not apply in strict mode if out_array is
            # not a view, is input to a library node, and an access or a view
            # of in_desc is also output to the same library node.
            # The reason is that the application of the transformation will lead
            # to in_desc being both input and output of the library node.
            # We do not know if this is safe.

            # First find the true in_desc (in case in_array is a view).
            true_in_desc = in_desc
            if isinstance(in_desc, data.View):
                e = sdutil.get_view_edge(graph, in_array)
                if not e:
                    return False
                true_in_desc = sdfg.arrays[e.dst.data]

            if not isinstance(out_desc, data.View):

                edges_to_check = []
                for a in graph.out_edges(out_array):
                    if isinstance(a.dst, nodes.LibraryNode):
                        edges_to_check.append(a)
                    elif (isinstance(a.dst, nodes.AccessNode)
                          and isinstance(sdfg.arrays[a.dst.data], data.View)):
                        for b in graph.out_edges(a.dst):
                            edges_to_check.append(graph.memlet_path(b)[-1])

                for a in edges_to_check:
                    if isinstance(a.dst, nodes.LibraryNode):
                        for b in graph.out_edges(a.dst):
                            if isinstance(b.dst, nodes.AccessNode):
                                desc = sdfg.arrays[b.dst.data]
                                if isinstance(desc, data.View):
                                    e = sdutil.get_view_edge(graph, b.dst)
                                    if not e:
                                        return False
                                    desc = sdfg.arrays[e.dst.data]
                                    if desc is true_in_desc:
                                        return False

            # In strict mode, check if the state has two or more access nodes
            # for in_array and at least one of them is a write access. There
            # might be a RW, WR, or WW dependency.
            accesses = [
                n for n in graph.nodes() if isinstance(n, nodes.AccessNode)
                and n.desc(sdfg) == in_desc and n is not in_array
            ]
            if len(accesses) > 0:
                if (graph.in_degree(in_array) > 0
                        or any(graph.in_degree(a) > 0 for a in accesses)):
                    # We need to ensure that a data race will not happen if we
                    # remove in_array.
                    # First, we simplify the graph
                    G = helpers.simplify_state(graph)
                    # Loop over the accesses
                    for a in accesses:
                        subsets_intersect = False
                        for e in graph.in_edges(a):
                            _, subset = _validate_subsets(e,
                                                          sdfg.arrays,
                                                          dst_name=a.data)
                            res = subsets.intersects(a_subset, subset)
                            if res == True or res is None:
                                subsets_intersect = True
                                break
                        if not subsets_intersect:
                            continue
                        try:
                            has_bward_path = nx.has_path(G, a, in_array)
                        except NodeNotFound:
                            has_bward_path = nx.has_path(graph.nx, a, in_array)
                        try:
                            has_fward_path = nx.has_path(G, in_array, a)
                        except NodeNotFound:
                            has_fward_path = nx.has_path(graph.nx, in_array, a)
                        # If there is no path between the access nodes
                        # (disconnected components), then it is definitely
                        # possible to have data races. Abort.
                        if not (has_bward_path or has_fward_path):
                            return False
                        # If there is a forward path then a must not be a direct
                        # successor of in_array.
                        if has_fward_path and a in G.successors(in_array):
                            for src, _ in G.in_edges(a):
                                if src is in_array:
                                    continue
                                if (nx.has_path(G, in_array, src)
                                        and src != out_array):
                                    continue
                                return False

        # Make sure that both arrays are using the same storage location
        # and are of the same type (e.g., Stream->Stream)
        if in_desc.storage != out_desc.storage:
            return False
        if in_desc.location != out_desc.location:
            return False
        if type(in_desc) != type(out_desc):
            if isinstance(in_desc, data.View):
                # Case View -> Access
                # If the View points to the Access (and has a different shape?)
                # then we should (probably) not remove the Access.
                e = sdutil.get_view_edge(graph, in_array)
                if e and e.dst is out_array and in_desc.shape != out_desc.shape:
                    return False
                # Check that the View's immediate ancestors are Accesses.
                # Otherwise, the application of the transformation will result
                # in an ambiguous View.
                view_ancestors_desc = [
                    e.src.desc(sdfg)
                    if isinstance(e.src, nodes.AccessNode) else None
                    for e in graph.in_edges(in_array)
                ]
                if any([
                        not desc or isinstance(desc, data.View)
                        for desc in view_ancestors_desc
                ]):
                    return False
            elif isinstance(out_desc, data.View):
                # Case Access -> View
                # If the View points to the Access and has the same shape,
                # it can be removed
                e = sdutil.get_view_edge(graph, out_array)
                if e and e.src is in_array and in_desc.shape == out_desc.shape:
                    return True
                return False
            else:
                # Something else, for example, Stream
                return False
        else:
            # Two views connected to each other
            if isinstance(in_desc, data.View):
                return False

        # Find occurrences in this and other states
        occurrences = []
        for state in sdfg.nodes():
            occurrences.extend([
                n for n in state.nodes()
                if isinstance(n, nodes.AccessNode) and n.desc(sdfg) == out_desc
            ])
        for isedge in sdfg.edges():
            if out_array.data in isedge.data.free_symbols:
                occurrences.append(isedge)

        if len(occurrences) > 1:
            return False

        # Check whether the data copied from the first datanode cover
        # the subsets of all the output edges of the second datanode.
        # We assume the following pattern: A -- e1 --> B -- e2 --> others

        # 2. Iterate over the e2 edges
        for e2 in graph.out_edges(out_array):
            # 2-a. Extract/validate subsets for array B and others
            try:
                b2_subset, _ = _validate_subsets(e2, sdfg.arrays)
            except NotImplementedError:
                return False
            # 2-b. Check where b1_subset covers b2_subset
            if not b1_subset.covers(b2_subset):
                return False
            # 2-c. Validate subsets in memlet tree
            # (should not be needed for valid SDGs)
            path = graph.memlet_tree(e2)
            for e3 in path:
                if e3 is not e2:
                    try:
                        _validate_subsets(e3,
                                          sdfg.arrays,
                                          src_name=out_array.data)
                    except NotImplementedError:
                        return False

        return True
Esempio n. 7
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    def expand(self, sdfg: SDFG, graph: SDFGState, reduce_node):
        """ Splits the data dimension into an inner and outer dimension,
            where the inner dimension are the reduction axes and the
            outer axes the complement. Pushes the reduce inside a new
            map consisting of the complement axes.

        """

        # get out storage node, might be hidden behind view node
        out_data = graph.out_edges(reduce_node)[0].data
        out_storage_node = reduce_node
        while not isinstance(out_storage_node, nodes.AccessNode):
            out_storage_node = graph.out_edges(out_storage_node)[0].dst

        if isinstance(sdfg.data(out_storage_node.data), View):
            out_storage_node = graph.out_edges(out_storage_node)[0].dst
            while not isinstance(out_storage_node, nodes.AccessNode):
                out_storage_node = graph.out_edges(out_storage_node)[0].dst

        # get other useful quantities from the original reduce node
        wcr = reduce_node.wcr
        identity = reduce_node.identity
        implementation = reduce_node.implementation

        # remove the reduce identity, will get reassigned after expansion
        reduce_node.identity = None
        # expand the reduce node
        in_edge = graph.in_edges(reduce_node)[0]
        nsdfg = self._expand_reduce(sdfg, graph, reduce_node)
        # find the new nodes in the nested sdfg created
        nstate = nsdfg.sdfg.nodes()[0]
        for node, scope in nstate.scope_dict().items():
            if isinstance(node, nodes.MapEntry):
                if scope is None:
                    outer_entry = node
                else:
                    inner_entry = node
            if isinstance(node, nodes.Tasklet):
                tasklet_node = node

        inner_exit = nstate.exit_node(inner_entry)
        outer_exit = nstate.exit_node(outer_entry)

        # find earliest parent read-write occurrence of array onto which the reduction is performed: BFS

        if self.create_out_transient:
            queue = [nsdfg]
            enqueued = set()
            array_closest_ancestor = None

            while len(queue) > 0:
                current = queue.pop()
                if isinstance(current, nodes.AccessNode):
                    if current.data == out_storage_node.data:
                        # it suffices to find the first node
                        # no matter what access (ReadWrite or Read)
                        array_closest_ancestor = current
                        break
                for in_edge in graph.in_edges(current):
                    if in_edge.src not in enqueued:
                        queue.append(in_edge.src)
                        enqueued.add(in_edge.src)

            if self.debug and array_closest_ancestor:
                print(
                    f"ReduceExpansion::Closest ancestor={array_closest_ancestor}"
                )
            elif self.debug:
                print("ReduceExpansion::No closest ancestor found")

        if self.create_out_transient:
            # create an out transient between inner and outer map exit
            array_out = nstate.out_edges(outer_exit)[0].data.data

            from dace.transformation.dataflow.local_storage import LocalStorage, OutLocalStorage
            local_storage_subgraph = {
                LocalStorage.node_a:
                nsdfg.sdfg.nodes()[0].nodes().index(inner_exit),
                LocalStorage.node_b:
                nsdfg.sdfg.nodes()[0].nodes().index(outer_exit)
            }
            nsdfg_id = nsdfg.sdfg.sdfg_list.index(nsdfg.sdfg)
            nstate_id = 0
            local_storage = OutLocalStorage(nsdfg.sdfg, nsdfg_id, nstate_id,
                                            local_storage_subgraph, 0)
            local_storage.array = array_out
            local_storage.apply(nsdfg.sdfg.node(0), nsdfg.sdfg)
            out_transient_node_inner = local_storage._data_node

            # push to register
            nsdfg.sdfg.data(out_transient_node_inner.data
                            ).storage = dtypes.StorageType.Register

            # remove WCRs from all edges where possible if there is no
            # prior occurrence
            if array_closest_ancestor is None:
                nstate.out_edges(outer_exit)[0].data.wcr = None
                nstate.out_edges(out_transient_node_inner)[0].data.wcr = None
                nstate.out_edges(out_transient_node_inner)[0].data.volume = 1
        else:

            # remove WCR from outer exit
            nstate.out_edges(outer_exit)[0].data.wcr = None

        if self.create_in_transient:
            # create an in-transient between inner and outer map entry
            array_in = nstate.in_edges(outer_entry)[0].data.data

            from dace.transformation.dataflow.local_storage import LocalStorage, InLocalStorage
            local_storage_subgraph = {
                LocalStorage.node_a:
                nsdfg.sdfg.nodes()[0].nodes().index(outer_entry),
                LocalStorage.node_b:
                nsdfg.sdfg.nodes()[0].nodes().index(inner_entry)
            }

            nsdfg_id = nsdfg.sdfg.sdfg_list.index(nsdfg.sdfg)
            nstate_id = 0
            local_storage = InLocalStorage(nsdfg.sdfg, nsdfg_id, nstate_id,
                                           local_storage_subgraph, 0)
            local_storage.array = array_in
            local_storage.apply(nsdfg.sdfg.node(0), nsdfg.sdfg)
            in_transient_node_inner = local_storage._data_node

            # push to register
            nsdfg.sdfg.data(in_transient_node_inner.data
                            ).storage = dtypes.StorageType.Register

        # inline fuse back our nested SDFG
        from dace.transformation.interstate import InlineSDFG
        inline_sdfg = InlineSDFG(
            sdfg, sdfg.sdfg_id, sdfg.node_id(graph),
            {InlineSDFG.nested_sdfg: graph.node_id(nsdfg)}, 0)
        inline_sdfg.apply(graph, sdfg)

        new_schedule = dtypes.ScheduleType.Default
        new_implementation = self.reduce_implementation \
                             if self.reduce_implementation is not None \
                             else implementation
        new_axes = dcpy(reduce_node.axes)

        reduce_node_new = graph.add_reduce(wcr=wcr,
                                           axes=new_axes,
                                           schedule=new_schedule,
                                           identity=identity)
        reduce_node_new.implementation = new_implementation
        # replace inner map with new reduction node
        edge_tmp = graph.in_edges(inner_entry)[0]
        memlet_src_reduce = dcpy(edge_tmp.data)
        graph.add_edge(edge_tmp.src, edge_tmp.src_conn, reduce_node_new, None,
                       memlet_src_reduce)

        edge_tmp = graph.out_edges(inner_exit)[0]
        memlet_reduce_dst = Memlet(data=edge_tmp.data.data,
                                   volume=1,
                                   subset=edge_tmp.data.subset)

        graph.add_edge(reduce_node_new, None, edge_tmp.dst, edge_tmp.dst_conn,
                       memlet_reduce_dst)

        identity_tasklet = graph.out_edges(inner_entry)[0].dst
        graph.remove_node(inner_entry)
        graph.remove_node(inner_exit)
        graph.remove_node(identity_tasklet)

        # propagate scope for correct volumes
        scope_tree = ScopeTree(outer_entry, outer_exit)
        scope_tree.parent = ScopeTree(None, None)
        propagate_memlets_scope(sdfg, graph, scope_tree)
        sdfg.validate()

        # create variables for outside access
        self._reduce = reduce_node_new
        self._outer_entry = outer_entry

        if identity is None and self.create_out_transient:
            if self.debug:
                print(
                    "ReduceExpansion::Trying to infer reduction WCR type due to out transient created"
                )
            # set the reduction identity accordingly so that the correct
            # blank result is written to the out_transient node
            # we use default values deducted from the reduction type
            reduction_type = detect_reduction_type(wcr)
            try:
                reduce_node_new.identity = self.reduction_type_identity[
                    reduction_type]
            except KeyError:

                if reduction_type == dtypes.ReductionType.Min:
                    reduce_node_new.identity = dtypes.max_value(
                        sdfg.arrays[out_storage_node.data].dtype)
                elif reduction_type == dtypes.ReductionType.Max:
                    reduce_node_new.identity = dtypes.min_value(
                        sdfg.arrays[out_storage_node.data].dtype)
                else:
                    raise ValueError(f"Cannot infer reduction identity."
                                     "Please specify the identity of node"
                                     "{reduce_node_new}")

        return