def can_be_applied(self, graph, expr_index, sdfg, permissive=False):
map_entry = self.map_entry
transient = self.transient
# Only one dimensional maps are allowed
if len(map_entry.map.params) != 1:
return False
# Verify the map can be transformed to a for-loop
m2for = MapToForLoop()
m2for.setup_match(
sdfg, sdfg.sdfg_id, self.state_id,
{MapToForLoop.map_entry: self.subgraph[DoubleBuffering.map_entry]},
expr_index)
if not m2for.can_be_applied(graph, expr_index, sdfg, permissive):
return False
# Verify that all directly-connected internal access nodes point to
# transient arrays
first = True
for edge in graph.out_edges(map_entry):
if isinstance(edge.dst, nodes.AccessNode):
desc = sdfg.arrays[edge.dst.data]
if not isinstance(desc, data.Array) or not desc.transient:
return False
else:
# To avoid duplicate matches, only match the first transient
if first and edge.dst != transient:
return False
first = False
return True
def can_be_applied(graph, candidate, expr_index, sdfg, strict=False):
map_entry = graph.nodes()[candidate[DoubleBuffering._map_entry]]
transient = graph.nodes()[candidate[DoubleBuffering._transient]]
# Only one dimensional maps are allowed
if len(map_entry.map.params) != 1:
return False
# Verify the map can be transformed to a for-loop
if not MapToForLoop.can_be_applied(
graph,
{MapToForLoop._map_entry: candidate[DoubleBuffering._map_entry]},
expr_index, sdfg, strict):
return False
# Verify that all directly-connected internal access nodes point to
# transient arrays
first = True
for edge in graph.out_edges(map_entry):
if isinstance(edge.dst, nodes.AccessNode):
desc = sdfg.arrays[edge.dst.data]
if not isinstance(desc, data.Array) or not desc.transient:
return False
else:
# To avoid duplicate matches, only match the first transient
if first and edge.dst != transient:
return False
first = False
return True
def apply(self, graph: sd.SDFGState, sdfg: sd.SDFG):
map_entry = self.map_entry
map_param = map_entry.map.params[0] # Assuming one dimensional
##############################
# Change condition of loop to one fewer iteration (so that the
# final one reads from the last buffer)
map_rstart, map_rend, map_rstride = map_entry.map.range[0]
map_rend = symbolic.pystr_to_symbolic('(%s) - (%s)' %
(map_rend, map_rstride))
map_entry.map.range = subsets.Range([(map_rstart, map_rend,
map_rstride)])
##############################
# Gather transients to modify
transients_to_modify = set(edge.dst.data
for edge in graph.out_edges(map_entry)
if isinstance(edge.dst, nodes.AccessNode))
# Add dimension to transients and modify memlets
for transient in transients_to_modify:
desc: data.Array = sdfg.arrays[transient]
# Using non-python syntax to ensure properties change
desc.strides = [desc.total_size] + list(desc.strides)
desc.shape = [2] + list(desc.shape)
desc.offset = [0] + list(desc.offset)
desc.total_size = desc.total_size * 2
##############################
# Modify memlets to use map parameter as buffer index
modified_subsets = [] # Store modified memlets for final state
for edge in graph.scope_subgraph(map_entry).edges():
if edge.data.data in transients_to_modify:
edge.data.subset = self._modify_memlet(sdfg, edge.data.subset,
edge.data.data)
modified_subsets.append(edge.data.subset)
else: # Could be other_subset
path = graph.memlet_path(edge)
src_node = path[0].src
dst_node = path[-1].dst
# other_subset could be None. In that case, recreate from array
dataname = None
if (isinstance(src_node, nodes.AccessNode)
and src_node.data in transients_to_modify):
dataname = src_node.data
elif (isinstance(dst_node, nodes.AccessNode)
and dst_node.data in transients_to_modify):
dataname = dst_node.data
if dataname is not None:
subset = (edge.data.other_subset or
subsets.Range.from_array(sdfg.arrays[dataname]))
edge.data.other_subset = self._modify_memlet(
sdfg, subset, dataname)
modified_subsets.append(edge.data.other_subset)
##############################
# Turn map into for loop
map_to_for = MapToForLoop()
map_to_for.setup_match(
sdfg, self.sdfg_id, self.state_id,
{MapToForLoop.map_entry: graph.node_id(self.map_entry)},
self.expr_index)
nsdfg_node, nstate = map_to_for.apply(graph, sdfg)
##############################
# Gather node copies and remove memlets
edges_to_replace = []
for node in nstate.source_nodes():
for edge in nstate.out_edges(node):
if (isinstance(edge.dst, nodes.AccessNode)
and edge.dst.data in transients_to_modify):
edges_to_replace.append(edge)
nstate.remove_edge(edge)
if nstate.out_degree(node) == 0:
nstate.remove_node(node)
##############################
# Add initial reads to initial nested state
initial_state: sd.SDFGState = nsdfg_node.sdfg.start_state
initial_state.set_label('%s_init' % map_entry.map.label)
for edge in edges_to_replace:
initial_state.add_node(edge.src)
rnode = edge.src
wnode = initial_state.add_write(edge.dst.data)
initial_state.add_edge(rnode, edge.src_conn, wnode, edge.dst_conn,
copy.deepcopy(edge.data))
# All instances of the map parameter in this state become the loop start
sd.replace(initial_state, map_param, map_rstart)
# Initial writes go to the appropriate buffer
init_expr = symbolic.pystr_to_symbolic('(%s / %s) %% 2' %
(map_rstart, map_rstride))
sd.replace(initial_state, '__dace_db_param', init_expr)
##############################
# Modify main state's memlets
# Divide by loop stride
new_expr = symbolic.pystr_to_symbolic('(%s / %s) %% 2' %
(map_param, map_rstride))
sd.replace(nstate, '__dace_db_param', new_expr)
##############################
# Add the main state's contents to the last state, modifying
# memlets appropriately.
final_state: sd.SDFGState = nsdfg_node.sdfg.sink_nodes()[0]
final_state.set_label('%s_final_computation' % map_entry.map.label)
dup_nstate = copy.deepcopy(nstate)
final_state.add_nodes_from(dup_nstate.nodes())
for e in dup_nstate.edges():
final_state.add_edge(e.src, e.src_conn, e.dst, e.dst_conn, e.data)
# If there is a WCR output with transient, only output in last state
nstate: sd.SDFGState
for node in nstate.sink_nodes():
for e in list(nstate.in_edges(node)):
if e.data.wcr is not None:
path = nstate.memlet_path(e)
if isinstance(path[0].src, nodes.AccessNode):
nstate.remove_memlet_path(e)
##############################
# Add reads into next buffers to main state
for edge in edges_to_replace:
rnode = copy.deepcopy(edge.src)
nstate.add_node(rnode)
wnode = nstate.add_write(edge.dst.data)
new_memlet = copy.deepcopy(edge.data)
if new_memlet.data in transients_to_modify:
new_memlet.other_subset = self._replace_in_subset(
new_memlet.other_subset, map_param,
'(%s + %s)' % (map_param, map_rstride))
else:
new_memlet.subset = self._replace_in_subset(
new_memlet.subset, map_param,
'(%s + %s)' % (map_param, map_rstride))
nstate.add_edge(rnode, edge.src_conn, wnode, edge.dst_conn,
new_memlet)
nstate.set_label('%s_double_buffered' % map_entry.map.label)
# Divide by loop stride
new_expr = symbolic.pystr_to_symbolic('((%s / %s) + 1) %% 2' %
(map_param, map_rstride))
sd.replace(nstate, '__dace_db_param', new_expr)
# Remove symbol once done
del nsdfg_node.sdfg.symbols['__dace_db_param']
del nsdfg_node.symbol_mapping['__dace_db_param']
return nsdfg_node
def apply(self, sdfg):
graph = sdfg.nodes()[self.state_id]
subgraph = self.subgraph_view(sdfg)
map_entries = helpers.get_outermost_scope_maps(sdfg, graph, subgraph)
result = StencilTiling.topology(sdfg, graph, map_entries)
(children_dict, parent_dict, sink_maps) = result
# next up, calculate inferred ranges for each map
# for each map entry, this contains a tuple of dicts:
# each of those maps from data_name of the array to
# inferred outer ranges. An inferred outer range is created
# by taking the union of ranges of inner subsets corresponding
# to that data and substituting this subset by the min / max of the
# parametrized map boundaries
# finally, from these outer ranges we can easily calculate
# strides and tile sizes required for every map
inferred_ranges = defaultdict(dict)
# create array of reverse topologically sorted map entries
# to iterate over
topo_reversed = []
queue = set(sink_maps.copy())
while len(queue) > 0:
element = next(e for e in queue
if not children_dict[e] - set(topo_reversed))
topo_reversed.append(element)
queue.remove(element)
for parent in parent_dict[element]:
queue.add(parent)
# main loop
# first get coverage dicts for each map entry
# for each map, contains a tuple of two dicts
# each of those two maps from data name to outer range
coverage = {}
for map_entry in map_entries:
coverage[map_entry] = StencilTiling.coverage_dicts(
sdfg, graph, map_entry, outer_range=True)
# we have a mapping from data name to outer range
# however we want a mapping from map parameters to outer ranges
# for this we need to find out how all array dimensions map to
# outer ranges
variable_mapping = defaultdict(list)
for map_entry in topo_reversed:
map = map_entry.map
# first find out variable mapping
for e in itertools.chain(
graph.out_edges(map_entry),
graph.in_edges(graph.exit_node(map_entry))):
mapping = []
for dim in e.data.subset:
syms = set()
for d in dim:
syms |= symbolic.symlist(d).keys()
if len(syms) > 1:
raise NotImplementedError(
"One incoming or outgoing stencil subset is indexed "
"by multiple map parameters. "
"This is not supported yet.")
try:
mapping.append(syms.pop())
except KeyError:
# just append None if there is no map symbol in it.
# we don't care for now.
mapping.append(None)
if e.data in variable_mapping:
# assert that this is the same everywhere.
# else we might run into problems
assert variable_mapping[e.data.data] == mapping
else:
variable_mapping[e.data.data] = mapping
# now do mapping data name -> outer range
# and from that infer mapping variable -> outer range
local_ranges = {dn: None for dn in coverage[map_entry][1].keys()}
for data_name, cov in coverage[map_entry][1].items():
local_ranges[data_name] = subsets.union(
local_ranges[data_name], cov)
# now look at proceeding maps
# and union those subsets -> could be larger with stencil indent
for child_map in children_dict[map_entry]:
if data_name in coverage[child_map][0]:
local_ranges[data_name] = subsets.union(
local_ranges[data_name],
coverage[child_map][0][data_name])
# final assignent: combine local_ranges and variable_mapping
# together into inferred_ranges
inferred_ranges[map_entry] = {p: None for p in map.params}
for data_name, ranges in local_ranges.items():
for param, r in zip(variable_mapping[data_name], ranges):
# create new range from this subset and assign
rng = subsets.Range((r, ))
if param:
inferred_ranges[map_entry][param] = subsets.union(
inferred_ranges[map_entry][param], rng)
# get parameters -- should all be the same
params = next(iter(map_entries)).map.params.copy()
# define reference range as inferred range of one of the sink maps
self.reference_range = inferred_ranges[next(iter(sink_maps))]
if self.debug:
print("StencilTiling::Reference Range", self.reference_range)
# next up, search for the ranges that don't change
invariant_dims = []
for idx, p in enumerate(params):
different = False
if self.reference_range[p] is None:
invariant_dims.append(idx)
warnings.warn(
f"StencilTiling::No Stencil pattern detected for parameter {p}"
)
continue
for m in map_entries:
if inferred_ranges[m][p] != self.reference_range[p]:
different = True
break
if not different:
invariant_dims.append(idx)
warnings.warn(
f"StencilTiling::No Stencil pattern detected for parameter {p}"
)
# during stripmining, we will create new outer map entries
# for easy access
self._outer_entries = set()
# with inferred_ranges constructed, we can begin to strip mine
for map_entry in map_entries:
# Retrieve map entry and exit nodes.
map = map_entry.map
stripmine_subgraph = {
StripMining._map_entry: graph.nodes().index(map_entry)
}
sdfg_id = sdfg.sdfg_id
last_map_entry = None
original_schedule = map_entry.schedule
self.tile_sizes = []
self.tile_offset_lower = []
self.tile_offset_upper = []
# strip mining each dimension where necessary
removed_maps = 0
for dim_idx, param in enumerate(map_entry.map.params):
# get current_node tile size
if dim_idx >= len(self.strides):
tile_stride = symbolic.pystr_to_symbolic(self.strides[-1])
else:
tile_stride = symbolic.pystr_to_symbolic(
self.strides[dim_idx])
trivial = False
if dim_idx in invariant_dims:
self.tile_sizes.append(tile_stride)
self.tile_offset_lower.append(0)
self.tile_offset_upper.append(0)
else:
target_range_current = inferred_ranges[map_entry][param]
reference_range_current = self.reference_range[param]
min_diff = symbolic.SymExpr(reference_range_current.min_element()[0] \
- target_range_current.min_element()[0])
max_diff = symbolic.SymExpr(target_range_current.max_element()[0] \
- reference_range_current.max_element()[0])
try:
min_diff = symbolic.evaluate(min_diff, {})
max_diff = symbolic.evaluate(max_diff, {})
except TypeError:
raise RuntimeError("Symbolic evaluation of map "
"ranges failed. Please check "
"your parameters and match.")
self.tile_sizes.append(tile_stride + max_diff + min_diff)
self.tile_offset_lower.append(
symbolic.pystr_to_symbolic(str(min_diff)))
self.tile_offset_upper.append(
symbolic.pystr_to_symbolic(str(max_diff)))
# get calculated parameters
tile_size = self.tile_sizes[-1]
dim_idx -= removed_maps
# If map or tile sizes are trivial, skip strip-mining map dimension
# special cases:
# if tile size is trivial AND we have an invariant dimension, skip
if tile_size == map.range.size()[dim_idx] and (
dim_idx + removed_maps) in invariant_dims:
continue
# trivial map: we just continue
if map.range.size()[dim_idx] in [0, 1]:
continue
if tile_size == 1 and tile_stride == 1 and (
dim_idx + removed_maps) in invariant_dims:
trivial = True
removed_maps += 1
# indent all map ranges accordingly and then perform
# strip mining on these. Offset inner maps accordingly afterwards
range_tuple = (map.range[dim_idx][0] +
self.tile_offset_lower[-1],
map.range[dim_idx][1] -
self.tile_offset_upper[-1],
map.range[dim_idx][2])
map.range[dim_idx] = range_tuple
stripmine = StripMining(sdfg_id, self.state_id,
stripmine_subgraph, 0)
stripmine.tiling_type = 'ceilrange'
stripmine.dim_idx = dim_idx
stripmine.new_dim_prefix = self.prefix if not trivial else ''
# use tile_stride for both -- we will extend
# the inner tiles later
stripmine.tile_size = str(tile_stride)
stripmine.tile_stride = str(tile_stride)
outer_map = stripmine.apply(sdfg)
outer_map.schedule = original_schedule
# apply to the new map the schedule of the original one
map_entry.schedule = self.schedule
# if tile stride is 1, we can make a nice simplification by just
# taking the overapproximated inner range as inner range
# this eliminates the min/max in the range which
# enables loop unrolling
if tile_stride == 1:
map_entry.range[dim_idx] = tuple(
symbolic.SymExpr(el._approx_expr) if isinstance(
el, symbolic.SymExpr) else el
for el in map_entry.range[dim_idx])
# in map_entry: enlarge tiles by upper and lower offset
# doing it this way and not via stripmine strides ensures
# that the max gets changed as well
old_range = map_entry.range[dim_idx]
map_entry.range[dim_idx] = ((old_range[0] -
self.tile_offset_lower[-1]),
(old_range[1] +
self.tile_offset_upper[-1]),
old_range[2])
# We have to propagate here for correct outer volume and subset sizes
_propagate_node(graph, map_entry)
_propagate_node(graph, graph.exit_node(map_entry))
# usual tiling pipeline
if last_map_entry:
new_map_entry = graph.in_edges(map_entry)[0].src
mapcollapse_subgraph = {
MapCollapse._outer_map_entry:
graph.node_id(last_map_entry),
MapCollapse._inner_map_entry:
graph.node_id(new_map_entry)
}
mapcollapse = MapCollapse(sdfg_id, self.state_id,
mapcollapse_subgraph, 0)
mapcollapse.apply(sdfg)
last_map_entry = graph.in_edges(map_entry)[0].src
# add last instance of map entries to _outer_entries
if last_map_entry:
self._outer_entries.add(last_map_entry)
# Map Unroll Feature: only unroll if conditions are met:
# Only unroll if at least one of the inner map ranges is strictly larger than 1
# Only unroll if strides all are one
if self.unroll_loops and all(s == 1 for s in self.strides) and any(
s not in [0, 1] for s in map_entry.range.size()):
l = len(map_entry.params)
if l > 1:
subgraph = {
MapExpansion.map_entry: graph.nodes().index(map_entry)
}
trafo_expansion = MapExpansion(sdfg.sdfg_id,
sdfg.nodes().index(graph),
subgraph, 0)
trafo_expansion.apply(sdfg)
maps = [map_entry]
for _ in range(l - 1):
map_entry = graph.out_edges(map_entry)[0].dst
maps.append(map_entry)
for map in reversed(maps):
# MapToForLoop
subgraph = {
MapToForLoop._map_entry: graph.nodes().index(map)
}
trafo_for_loop = MapToForLoop(sdfg.sdfg_id,
sdfg.nodes().index(graph),
subgraph, 0)
trafo_for_loop.apply(sdfg)
nsdfg = trafo_for_loop.nsdfg
# LoopUnroll
guard = trafo_for_loop.guard
end = trafo_for_loop.after_state
begin = next(e.dst for e in nsdfg.out_edges(guard)
if e.dst != end)
subgraph = {
DetectLoop._loop_guard: nsdfg.nodes().index(guard),
DetectLoop._loop_begin: nsdfg.nodes().index(begin),
DetectLoop._exit_state: nsdfg.nodes().index(end)
}
transformation = LoopUnroll(0, 0, subgraph, 0)
transformation.apply(nsdfg)
elif self.unroll_loops:
warnings.warn(
"Did not unroll loops. Either all ranges are equal to "
"one or range difference is symbolic.")
self._outer_entries = list(self._outer_entries)