示例#1
0
    def expressions():
        # Matching
        #   o  o
        #   |  |
        # /======\

        g = SDFGState()
        g.add_node(MergeArrays._array1)
        g.add_node(MergeArrays._array2)
        g.add_node(MergeArrays._map_entry)
        g.add_edge(MergeArrays._array1, None, MergeArrays._map_entry, None,
                   memlet.EmptyMemlet())
        g.add_edge(MergeArrays._array2, None, MergeArrays._map_entry, None,
                   memlet.EmptyMemlet())
        return [g]
示例#2
0
    def apply(self, sdfg: sd.SDFG):

        #######################################################
        # Step 0: SDFG metadata

        # Find all input and output data descriptors
        input_nodes = []
        output_nodes = []
        global_code_nodes = [[] for _ in sdfg.nodes()]

        for i, state in enumerate(sdfg.nodes()):
            sdict = state.scope_dict()
            for node in state.nodes():
                if (isinstance(node, nodes.AccessNode)
                        and node.desc(sdfg).transient == False):
                    if (state.out_degree(node) > 0
                            and node.data not in input_nodes):
                        # Special case: nodes that lead to top-level dynamic
                        # map ranges must stay on host
                        for e in state.out_edges(node):
                            last_edge = state.memlet_path(e)[-1]
                            if (isinstance(last_edge.dst, nodes.EntryNode)
                                    and last_edge.dst_conn and
                                    not last_edge.dst_conn.startswith('IN_')
                                    and sdict[last_edge.dst] is None):
                                break
                        else:
                            input_nodes.append((node.data, node.desc(sdfg)))
                    if (state.in_degree(node) > 0
                            and node.data not in output_nodes):
                        output_nodes.append((node.data, node.desc(sdfg)))
                elif isinstance(node, nodes.CodeNode) and sdict[node] is None:
                    if not isinstance(node,
                                      (nodes.LibraryNode, nodes.NestedSDFG)):
                        global_code_nodes[i].append(node)

            # Input nodes may also be nodes with WCR memlets and no identity
            for e in state.edges():
                if e.data.wcr is not None:
                    if (e.data.data not in input_nodes
                            and sdfg.arrays[e.data.data].transient == False):
                        input_nodes.append(
                            (e.data.data, sdfg.arrays[e.data.data]))

        start_state = sdfg.start_state
        end_states = sdfg.sink_nodes()

        #######################################################
        # Step 1: Create cloned GPU arrays and replace originals

        cloned_arrays = {}
        for inodename, inode in set(input_nodes):
            if isinstance(inode, data.Scalar):  # Scalars can remain on host
                continue
            newdesc = inode.clone()
            newdesc.storage = dtypes.StorageType.GPU_Global
            newdesc.transient = True
            name = sdfg.add_datadesc('gpu_' + inodename,
                                     newdesc,
                                     find_new_name=True)
            cloned_arrays[inodename] = name

        for onodename, onode in set(output_nodes):
            if onodename in cloned_arrays:
                continue
            newdesc = onode.clone()
            newdesc.storage = dtypes.StorageType.GPU_Global
            newdesc.transient = True
            name = sdfg.add_datadesc('gpu_' + onodename,
                                     newdesc,
                                     find_new_name=True)
            cloned_arrays[onodename] = name

        # Replace nodes
        for state in sdfg.nodes():
            for node in state.nodes():
                if (isinstance(node, nodes.AccessNode)
                        and node.data in cloned_arrays):
                    node.data = cloned_arrays[node.data]

        # Replace memlets
        for state in sdfg.nodes():
            for edge in state.edges():
                if edge.data.data in cloned_arrays:
                    edge.data.data = cloned_arrays[edge.data.data]

        #######################################################
        # Step 2: Create copy-in state
        excluded_copyin = self.exclude_copyin.split(',')

        copyin_state = sdfg.add_state(sdfg.label + '_copyin')
        sdfg.add_edge(copyin_state, start_state, sd.InterstateEdge())

        for nname, desc in dtypes.deduplicate(input_nodes):
            if nname in excluded_copyin or nname not in cloned_arrays:
                continue
            src_array = nodes.AccessNode(nname, debuginfo=desc.debuginfo)
            dst_array = nodes.AccessNode(cloned_arrays[nname],
                                         debuginfo=desc.debuginfo)
            copyin_state.add_node(src_array)
            copyin_state.add_node(dst_array)
            copyin_state.add_nedge(
                src_array, dst_array,
                memlet.Memlet.from_array(src_array.data, src_array.desc(sdfg)))

        #######################################################
        # Step 3: Create copy-out state
        excluded_copyout = self.exclude_copyout.split(',')

        copyout_state = sdfg.add_state(sdfg.label + '_copyout')
        for state in end_states:
            sdfg.add_edge(state, copyout_state, sd.InterstateEdge())

        for nname, desc in dtypes.deduplicate(output_nodes):
            if nname in excluded_copyout or nname not in cloned_arrays:
                continue
            src_array = nodes.AccessNode(cloned_arrays[nname],
                                         debuginfo=desc.debuginfo)
            dst_array = nodes.AccessNode(nname, debuginfo=desc.debuginfo)
            copyout_state.add_node(src_array)
            copyout_state.add_node(dst_array)
            copyout_state.add_nedge(
                src_array, dst_array,
                memlet.Memlet.from_array(dst_array.data, dst_array.desc(sdfg)))

        #######################################################
        # Step 4: Modify transient data storage

        for state in sdfg.nodes():
            sdict = state.scope_dict()
            for node in state.nodes():
                if isinstance(node,
                              nodes.AccessNode) and node.desc(sdfg).transient:
                    nodedesc = node.desc(sdfg)

                    # Special case: nodes that lead to dynamic map ranges must
                    # stay on host
                    if any(
                            isinstance(
                                state.memlet_path(e)[-1].dst, nodes.EntryNode)
                            for e in state.out_edges(node)):
                        continue

                    gpu_storage = [
                        dtypes.StorageType.GPU_Global,
                        dtypes.StorageType.GPU_Shared,
                        dtypes.StorageType.CPU_Pinned
                    ]
                    if sdict[
                            node] is None and nodedesc.storage not in gpu_storage:
                        # NOTE: the cloned arrays match too but it's the same
                        # storage so we don't care
                        nodedesc.storage = dtypes.StorageType.GPU_Global

                        # Try to move allocation/deallocation out of loops
                        if (self.toplevel_trans
                                and not isinstance(nodedesc, data.Stream)):
                            nodedesc.lifetime = dtypes.AllocationLifetime.SDFG
                    elif nodedesc.storage not in gpu_storage:
                        # Make internal transients registers
                        if self.register_trans:
                            nodedesc.storage = dtypes.StorageType.Register

        #######################################################
        # Step 5: Wrap free tasklets and nested SDFGs with a GPU map

        for state, gcodes in zip(sdfg.nodes(), global_code_nodes):
            for gcode in gcodes:
                if gcode.label in self.exclude_tasklets.split(','):
                    continue
                # Create map and connectors
                me, mx = state.add_map(gcode.label + '_gmap',
                                       {gcode.label + '__gmapi': '0:1'},
                                       schedule=dtypes.ScheduleType.GPU_Device)
                # Store in/out edges in lists so that they don't get corrupted
                # when they are removed from the graph
                in_edges = list(state.in_edges(gcode))
                out_edges = list(state.out_edges(gcode))
                me.in_connectors = set('IN_' + e.dst_conn for e in in_edges)
                me.out_connectors = set('OUT_' + e.dst_conn for e in in_edges)
                mx.in_connectors = set('IN_' + e.src_conn for e in out_edges)
                mx.out_connectors = set('OUT_' + e.src_conn for e in out_edges)

                # Create memlets through map
                for e in in_edges:
                    state.remove_edge(e)
                    state.add_edge(e.src, e.src_conn, me, 'IN_' + e.dst_conn,
                                   e.data)
                    state.add_edge(me, 'OUT_' + e.dst_conn, e.dst, e.dst_conn,
                                   e.data)
                for e in out_edges:
                    state.remove_edge(e)
                    state.add_edge(e.src, e.src_conn, mx, 'IN_' + e.src_conn,
                                   e.data)
                    state.add_edge(mx, 'OUT_' + e.src_conn, e.dst, e.dst_conn,
                                   e.data)

                # Map without inputs
                if len(in_edges) == 0:
                    state.add_nedge(me, gcode, memlet.EmptyMemlet())
        #######################################################
        # Step 6: Change all top-level maps and library nodes to GPU schedule

        for i, state in enumerate(sdfg.nodes()):
            sdict = state.scope_dict()
            for node in state.nodes():
                if isinstance(node, (nodes.EntryNode, nodes.LibraryNode)):
                    if sdict[node] is None:
                        node.schedule = dtypes.ScheduleType.GPU_Device
                    elif (isinstance(node,
                                     (nodes.EntryNode, nodes.LibraryNode))
                          and self.sequential_innermaps):
                        node.schedule = dtypes.ScheduleType.Sequential

        #######################################################
        # Step 7: Introduce copy-out if data used in outgoing interstate edges

        for state in list(sdfg.nodes()):
            arrays_used = set()
            for e in sdfg.out_edges(state):
                # Used arrays = intersection between symbols and cloned arrays
                arrays_used.update(
                    set(e.data.free_symbols)
                    & set(cloned_arrays.keys()))

            # Create a state and copy out used arrays
            if len(arrays_used) > 0:
                co_state = sdfg.add_state(state.label + '_icopyout')

                # Reconnect outgoing edges to after interim copyout state
                for e in sdfg.out_edges(state):
                    sdutil.change_edge_src(sdfg, state, co_state)
                # Add unconditional edge to interim state
                sdfg.add_edge(state, co_state, sd.InterstateEdge())

                # Add copy-out nodes
                for nname in arrays_used:
                    desc = sdfg.arrays[nname]
                    src_array = nodes.AccessNode(cloned_arrays[nname],
                                                 debuginfo=desc.debuginfo)
                    dst_array = nodes.AccessNode(nname,
                                                 debuginfo=desc.debuginfo)
                    co_state.add_node(src_array)
                    co_state.add_node(dst_array)
                    co_state.add_nedge(
                        src_array, dst_array,
                        memlet.Memlet.from_array(dst_array.data,
                                                 dst_array.desc(sdfg)))

        #######################################################
        # Step 8: Strict transformations
        if not self.strict_transform:
            return

        # Apply strict state fusions greedily.
        sdfg.apply_strict_transformations()
示例#3
0
    def apply(self, sdfg: sd.SDFG):
        graph: sd.SDFGState = sdfg.nodes()[self.state_id]
        map_entry = graph.node(self.subgraph[MapFission._map_entry])
        map_exit = graph.exit_nodes(map_entry)[0]
        nsdfg_node: Optional[nodes.NestedSDFG] = None

        # Obtain subgraph to perform fission to
        if self.expr_index == 0:  # Map with subgraph
            subgraphs = [(graph,
                          graph.scope_subgraph(map_entry,
                                               include_entry=False,
                                               include_exit=False))]
            parent = sdfg
        else:  # Map with nested SDFG
            nsdfg_node = graph.node(self.subgraph[MapFission._nested_sdfg])
            subgraphs = [(state, state) for state in nsdfg_node.sdfg.nodes()]
            parent = nsdfg_node.sdfg
        modified_arrays = set()

        # Get map information
        outer_map: nodes.Map = map_entry.map
        mapsize = outer_map.range.size()

        # Add new symbols from outer map to nested SDFG
        if self.expr_index == 1:
            map_syms = outer_map.range.free_symbols
            for edge in graph.out_edges(map_entry):
                if edge.data.data:
                    map_syms.update(edge.data.subset.free_symbols)
            for edge in graph.in_edges(map_exit):
                if edge.data.data:
                    map_syms.update(edge.data.subset.free_symbols)
            for symname, sym in map_syms.items():
                if symname in outer_map.params:
                    continue
                if symname not in nsdfg_node.symbol_mapping.keys():
                    nsdfg_node.symbol_mapping[symname] = sym

        for state, subgraph in subgraphs:
            components = MapFission._components(subgraph)
            sources = subgraph.source_nodes()
            sinks = subgraph.sink_nodes()

            # Collect external edges
            if self.expr_index == 0:
                external_edges_entry = list(state.out_edges(map_entry))
                external_edges_exit = list(state.in_edges(map_exit))
            else:
                external_edges_entry = [
                    e for e in subgraph.edges()
                    if (isinstance(e.src, nodes.AccessNode)
                        and not nsdfg_node.sdfg.arrays[e.src.data].transient)
                ]
                external_edges_exit = [
                    e for e in subgraph.edges()
                    if (isinstance(e.dst, nodes.AccessNode)
                        and not nsdfg_node.sdfg.arrays[e.dst.data].transient)
                ]

            # Map external edges to outer memlets
            edge_to_outer = {}
            for edge in external_edges_entry:
                if self.expr_index == 0:
                    # Subgraphs use the corresponding outer map edges
                    path = state.memlet_path(edge)
                    eindex = path.index(edge)
                    edge_to_outer[edge] = path[eindex - 1]
                else:
                    # Nested SDFGs use the internal map edges of the node
                    outer_edge = next(e for e in graph.in_edges(nsdfg_node)
                                      if e.dst_conn == edge.src.data)
                    edge_to_outer[edge] = outer_edge

            for edge in external_edges_exit:
                if self.expr_index == 0:
                    path = state.memlet_path(edge)
                    eindex = path.index(edge)
                    edge_to_outer[edge] = path[eindex + 1]
                else:
                    # Nested SDFGs use the internal map edges of the node
                    outer_edge = next(e for e in graph.out_edges(nsdfg_node)
                                      if e.src_conn == edge.dst.data)
                    edge_to_outer[edge] = outer_edge

            # Collect all border arrays and code->code edges
            arrays = MapFission._border_arrays(
                nsdfg_node.sdfg if self.expr_index == 1 else sdfg, state,
                subgraph)
            scalars = defaultdict(list)
            for _, component_out in components:
                for e in subgraph.out_edges(component_out):
                    if isinstance(e.dst, nodes.CodeNode):
                        scalars[e.data.data].append(e)

            # Create new arrays for scalars
            for scalar, edges in scalars.items():
                desc = parent.arrays[scalar]
                name, newdesc = parent.add_temp_transient(
                    mapsize,
                    desc.dtype,
                    desc.storage,
                    toplevel=desc.toplevel,
                    debuginfo=desc.debuginfo,
                    allow_conflicts=desc.allow_conflicts)

                # Add extra nodes in component boundaries
                for edge in edges:
                    anode = state.add_access(name)
                    state.add_edge(
                        edge.src, edge.src_conn, anode, None,
                        mm.Memlet(
                            name, outer_map.range.num_elements(),
                            subsets.Range.from_string(','.join(
                                outer_map.params)), 1))
                    state.add_edge(
                        anode, None, edge.dst, edge.dst_conn,
                        mm.Memlet(
                            name, outer_map.range.num_elements(),
                            subsets.Range.from_string(','.join(
                                outer_map.params)), 1))
                    state.remove_edge(edge)

            # Add extra maps around components
            new_map_entries = []
            for component_in, component_out in components:
                me, mx = state.add_map(outer_map.label + '_fission',
                                       [(p, '0:1') for p in outer_map.params],
                                       outer_map.schedule,
                                       unroll=outer_map.unroll,
                                       debuginfo=outer_map.debuginfo)

                # Add dynamic input connectors
                for conn in map_entry.in_connectors:
                    if not conn.startswith('IN_'):
                        me.add_in_connector(conn)

                me.map.range = dcpy(outer_map.range)
                new_map_entries.append(me)

                # Reconnect edges through new map
                for e in state.in_edges(component_in):
                    state.add_edge(me, None, e.dst, e.dst_conn, dcpy(e.data))
                    # Reconnect inner edges at source directly to external nodes
                    if self.expr_index == 0 and e in external_edges_entry:
                        state.add_edge(edge_to_outer[e].src,
                                       edge_to_outer[e].src_conn, me, None,
                                       dcpy(edge_to_outer[e].data))
                    else:
                        state.add_edge(e.src, e.src_conn, me, None,
                                       dcpy(e.data))
                    state.remove_edge(e)
                # Empty memlet edge in nested SDFGs
                if state.in_degree(component_in) == 0:
                    state.add_edge(me, None, component_in, None,
                                   mm.EmptyMemlet())

                for e in state.out_edges(component_out):
                    state.add_edge(e.src, e.src_conn, mx, None, dcpy(e.data))
                    # Reconnect inner edges at sink directly to external nodes
                    if self.expr_index == 0 and e in external_edges_exit:
                        state.add_edge(mx, None, edge_to_outer[e].dst,
                                       edge_to_outer[e].dst_conn,
                                       dcpy(edge_to_outer[e].data))
                    else:
                        state.add_edge(mx, None, e.dst, e.dst_conn,
                                       dcpy(e.data))
                    state.remove_edge(e)
                # Empty memlet edge in nested SDFGs
                if state.out_degree(component_out) == 0:
                    state.add_edge(component_out, None, mx, None,
                                   mm.EmptyMemlet())
            # Connect other sources/sinks not in components (access nodes)
            # directly to external nodes
            if self.expr_index == 0:
                for node in sources:
                    if isinstance(node, nodes.AccessNode):
                        for edge in state.in_edges(node):
                            outer_edge = edge_to_outer[edge]
                            memlet = dcpy(edge.data)
                            memlet.subset = subsets.Range(
                                outer_map.range.ranges + memlet.subset.ranges)
                            state.add_edge(outer_edge.src, outer_edge.src_conn,
                                           edge.dst, edge.dst_conn, memlet)

                for node in sinks:
                    if isinstance(node, nodes.AccessNode):
                        for edge in state.out_edges(node):
                            outer_edge = edge_to_outer[edge]
                            state.add_edge(edge.src, edge.src_conn,
                                           outer_edge.dst, outer_edge.dst_conn,
                                           dcpy(outer_edge.data))

            # Augment arrays by prepending map dimensions
            for array in arrays:
                if array in modified_arrays:
                    continue
                desc = parent.arrays[array]
                for sz in reversed(mapsize):
                    desc.strides = [desc.total_size] + list(desc.strides)
                    desc.total_size = desc.total_size * sz

                desc.shape = mapsize + list(desc.shape)
                desc.offset = [0] * len(mapsize) + list(desc.offset)
                modified_arrays.add(array)

            # Fill scope connectors so that memlets can be tracked below
            state.fill_scope_connectors()

            # Correct connectors and memlets in nested SDFGs to account for
            # missing outside map
            if self.expr_index == 1:
                to_correct = ([(e, e.src) for e in external_edges_entry] +
                              [(e, e.dst) for e in external_edges_exit])
                corrected_nodes = set()
                for edge, node in to_correct:
                    if isinstance(node, nodes.AccessNode):
                        if node in corrected_nodes:
                            continue
                        corrected_nodes.add(node)

                        outer_edge = edge_to_outer[edge]
                        desc = parent.arrays[node.data]

                        # Modify shape of internal array to match outer one
                        outer_desc = sdfg.arrays[outer_edge.data.data]
                        if not isinstance(desc, dt.Scalar):
                            desc.shape = outer_desc.shape
                        if isinstance(desc, dt.Array):
                            desc.strides = outer_desc.strides
                            desc.total_size = outer_desc.total_size

                        # Inside the nested SDFG, offset all memlets to include
                        # the offsets from within the map.
                        # NOTE: Relies on propagation to fix outer memlets
                        for internal_edge in state.all_edges(node):
                            for e in state.memlet_tree(internal_edge):
                                e.data.subset.offset(desc.offset, False)
                                e.data.subset = helpers.unsqueeze_memlet(
                                    e.data, outer_edge.data).subset

                        # Only after offsetting memlets we can modify the
                        # overall offset
                        if isinstance(desc, dt.Array):
                            desc.offset = outer_desc.offset

            # Fill in memlet trees for border transients
            # NOTE: Memlet propagation should run to correct the outer edges
            for node in subgraph.nodes():
                if isinstance(node, nodes.AccessNode) and node.data in arrays:
                    for edge in state.all_edges(node):
                        for e in state.memlet_tree(edge):
                            # Prepend map dimensions to memlet
                            e.data.subset = subsets.Range(
                                [(d, d, 1) for d in outer_map.params] +
                                e.data.subset.ranges)

        # If nested SDFG, reconnect nodes around map and modify memlets
        if self.expr_index == 1:
            for edge in graph.in_edges(map_entry):
                if not edge.dst_conn or not edge.dst_conn.startswith('IN_'):
                    continue

                # Modify edge coming into nested SDFG to include entire array
                desc = sdfg.arrays[edge.data.data]
                edge.data.subset = subsets.Range.from_array(desc)
                edge.data.num_accesses = edge.data.subset.num_elements()

                # Find matching edge inside map
                inner_edge = next(
                    e for e in graph.out_edges(map_entry)
                    if e.src_conn and e.src_conn[4:] == edge.dst_conn[3:])
                graph.add_edge(edge.src, edge.src_conn, nsdfg_node,
                               inner_edge.dst_conn, dcpy(edge.data))

            for edge in graph.out_edges(map_exit):
                # Modify edge coming out of nested SDFG to include entire array
                desc = sdfg.arrays[edge.data.data]
                edge.data.subset = subsets.Range.from_array(desc)

                # Find matching edge inside map
                inner_edge = next(e for e in graph.in_edges(map_exit)
                                  if e.dst_conn[3:] == edge.src_conn[4:])
                graph.add_edge(nsdfg_node, inner_edge.src_conn, edge.dst,
                               edge.dst_conn, dcpy(edge.data))

        # Remove outer map
        graph.remove_nodes_from([map_entry, map_exit])
示例#4
0
    def apply(self, sdfg: sd.SDFG):

        #######################################################
        # Step 0: SDFG metadata

        # Find all input and output data descriptors
        input_nodes = []
        output_nodes = []
        global_code_nodes = [[] for _ in sdfg.nodes()]

        for i, state in enumerate(sdfg.nodes()):
            sdict = state.scope_dict()
            for node in state.nodes():
                if (isinstance(node, nodes.AccessNode)
                        and node.desc(sdfg).transient == False):
                    if (state.out_degree(node) > 0
                            and node.data not in input_nodes):
                        input_nodes.append((node.data, node.desc(sdfg)))
                    if (state.in_degree(node) > 0
                            and node.data not in output_nodes):
                        output_nodes.append((node.data, node.desc(sdfg)))
                elif isinstance(node, nodes.CodeNode) and sdict[node] is None:
                    if not isinstance(node, nodes.EmptyTasklet):
                        global_code_nodes[i].append(node)

            # Input nodes may also be nodes with WCR memlets and no identity
            for e in state.edges():
                if e.data.wcr is not None and e.data.wcr_identity is None:
                    if (e.data.data not in input_nodes
                            and sdfg.arrays[e.data.data].transient == False):
                        input_nodes.append(e.data.data)

        start_state = sdfg.start_state
        end_states = sdfg.sink_nodes()

        #######################################################
        # Step 1: Create cloned GPU arrays and replace originals

        cloned_arrays = {}
        for inodename, inode in input_nodes:
            newdesc = inode.clone()
            newdesc.storage = types.StorageType.GPU_Global
            newdesc.transient = True
            sdfg.add_datadesc('gpu_' + inodename, newdesc)
            cloned_arrays[inodename] = 'gpu_' + inodename

        for onodename, onode in output_nodes:
            if onodename in cloned_arrays:
                continue
            newdesc = onode.clone()
            newdesc.storage = types.StorageType.GPU_Global
            newdesc.transient = True
            sdfg.add_datadesc('gpu_' + onodename, newdesc)
            cloned_arrays[onodename] = 'gpu_' + onodename

        # Replace nodes
        for state in sdfg.nodes():
            for node in state.nodes():
                if (isinstance(node, nodes.AccessNode)
                        and node.data in cloned_arrays):
                    node.data = cloned_arrays[node.data]

        # Replace memlets
        for state in sdfg.nodes():
            for edge in state.edges():
                if edge.data.data in cloned_arrays:
                    edge.data.data = cloned_arrays[edge.data.data]

        #######################################################
        # Step 2: Create copy-in state

        copyin_state = sdfg.add_state(sdfg.label + '_copyin')
        sdfg.add_edge(copyin_state, start_state, ed.InterstateEdge())

        for nname, desc in input_nodes:
            src_array = nodes.AccessNode(nname, debuginfo=desc.debuginfo)
            dst_array = nodes.AccessNode(cloned_arrays[nname],
                                         debuginfo=desc.debuginfo)
            copyin_state.add_node(src_array)
            copyin_state.add_node(dst_array)
            copyin_state.add_nedge(
                src_array, dst_array,
                memlet.Memlet.from_array(src_array.data, src_array.desc(sdfg)))

        #######################################################
        # Step 3: Create copy-out state

        copyout_state = sdfg.add_state(sdfg.label + '_copyout')
        for state in end_states:
            sdfg.add_edge(state, copyout_state, ed.InterstateEdge())

        for nname, desc in output_nodes:
            src_array = nodes.AccessNode(cloned_arrays[nname],
                                         debuginfo=desc.debuginfo)
            dst_array = nodes.AccessNode(nname, debuginfo=desc.debuginfo)
            copyout_state.add_node(src_array)
            copyout_state.add_node(dst_array)
            copyout_state.add_nedge(
                src_array, dst_array,
                memlet.Memlet.from_array(dst_array.data, dst_array.desc(sdfg)))

        #######################################################
        # Step 4: Modify transient data storage

        for state in sdfg.nodes():
            sdict = state.scope_dict()
            for node in state.nodes():
                if isinstance(node,
                              nodes.AccessNode) and node.desc(sdfg).transient:
                    nodedesc = node.desc(sdfg)
                    if sdict[node] is None:
                        # NOTE: the cloned arrays match too but it's the same
                        # storage so we don't care
                        nodedesc.storage = types.StorageType.GPU_Global

                        # Try to move allocation/deallocation out of loops
                        if self.toplevel_trans:
                            nodedesc.toplevel = True
                    else:
                        # Make internal transients registers
                        if self.register_trans:
                            nodedesc.storage = types.StorageType.Register

        #######################################################
        # Step 5: Wrap free tasklets and nested SDFGs with a GPU map

        for state, gcodes in zip(sdfg.nodes(), global_code_nodes):
            for gcode in gcodes:
                # Create map and connectors
                me, mx = state.add_map(gcode.label + '_gmap',
                                       {gcode.label + '__gmapi': '0:1'},
                                       schedule=types.ScheduleType.GPU_Device)
                # Store in/out edges in lists so that they don't get corrupted
                # when they are removed from the graph
                in_edges = list(state.in_edges(gcode))
                out_edges = list(state.out_edges(gcode))
                me.in_connectors = set('IN_' + e.dst_conn for e in in_edges)
                me.out_connectors = set('OUT_' + e.dst_conn for e in in_edges)
                mx.in_connectors = set('IN_' + e.src_conn for e in out_edges)
                mx.out_connectors = set('OUT_' + e.src_conn for e in out_edges)

                # Create memlets through map
                for e in in_edges:
                    state.remove_edge(e)
                    state.add_edge(e.src, e.src_conn, me, 'IN_' + e.dst_conn,
                                   e.data)
                    state.add_edge(me, 'OUT_' + e.dst_conn, e.dst, e.dst_conn,
                                   e.data)
                for e in out_edges:
                    state.remove_edge(e)
                    state.add_edge(e.src, e.src_conn, mx, 'IN_' + e.src_conn,
                                   e.data)
                    state.add_edge(mx, 'OUT_' + e.src_conn, e.dst, e.dst_conn,
                                   e.data)

                # Map without inputs
                if len(in_edges) == 0:
                    state.add_nedge(me, gcode, memlet.EmptyMemlet())
        #######################################################
        # Step 6: Change all top-level maps to GPU maps

        for i, state in enumerate(sdfg.nodes()):
            sdict = state.scope_dict()
            for node in state.nodes():
                if isinstance(node, nodes.EntryNode):
                    if sdict[node] is None:
                        node.schedule = types.ScheduleType.GPU_Device
                    elif self.sequential_innermaps:
                        node.schedule = types.ScheduleType.Sequential

        #######################################################
        # Step 7: Strict transformations
        if not self.strict_transform:
            return

        # Apply strict state fusions greedily.
        opt = optimizer.SDFGOptimizer(sdfg, inplace=True)
        fusions = 0
        arrays = 0
        options = [
            match for match in opt.get_pattern_matches(strict=True)
            if isinstance(match, (StateFusion, RedundantArray))
        ]
        while options:
            ssdfg = sdfg.sdfg_list[options[0].sdfg_id]
            options[0].apply(ssdfg)
            ssdfg.validate()
            if isinstance(options[0], StateFusion):
                fusions += 1
            if isinstance(options[0], RedundantArray):
                arrays += 1

            options = [
                match for match in opt.get_pattern_matches(strict=True)
                if isinstance(match, (StateFusion, RedundantArray))
            ]

        if Config.get_bool('debugprint') and (fusions > 0 or arrays > 0):
            print('Automatically applied {} strict state fusions and removed'
                  ' {} redundant arrays.'.format(fusions, arrays))