def __init__(self, exprs, **kwargs):
# Check input legality
mapper = OrderedDict([(i.lhs, i) for i in exprs])
if len(set(mapper)) != len(mapper):
raise DSEException(
"Found redundant node, cannot build TemporariesGraph.")
# Construct Temporaries, tracking reads and readby
tensor_map = DefaultOrderedDict(list)
for i in mapper:
tensor_map[as_symbol(i)].append(i)
reads = DefaultOrderedDict(set)
readby = DefaultOrderedDict(set)
for k, v in mapper.items():
handle = retrieve_terminals(v.rhs)
for i in list(handle):
if i.is_Indexed:
for idx in i.indices:
handle |= retrieve_terminals(idx)
reads[k].update(
set(flatten([tensor_map.get(as_symbol(i), [])
for i in handle])))
for i in reads[k]:
readby[i].add(k)
# Make sure read-after-writes are honored for scalar temporaries
processed = [i for i in mapper if i.is_Indexed]
queue = [i for i in mapper if i not in processed]
while queue:
k = queue.pop(0)
if not readby[k]:
processed.insert(0, k)
elif all(i in processed for i in readby[k]):
index = min(processed.index(i) for i in readby[k])
processed.insert(index, k)
else:
queue.append(k)
# Build up the TemporariesGraph
temporaries = [(i,
Temporary(*mapper[i].args,
inc=q_inc(mapper[i]),
reads=reads[i],
readby=readby[i])) for i in processed]
super(TemporariesGraph, self).__init__(temporaries, **kwargs)
# Determine indices along the space and time dimensions
terms = [
v for k, v in self.items() if v.is_tensor and not q_indirect(k)
]
indices = filter_ordered(flatten([i.function.indices for i in terms]))
self.space_indices = tuple(i for i in indices if i.is_Space)
self.time_indices = tuple(i for i in indices if i.is_Time)
def __init__(self, exprs, **kwargs):
# Always convert to SSA
exprs = convert_to_SSA(exprs)
mapper = OrderedDict([(i.lhs, i) for i in exprs])
assert len(set(mapper)) == len(exprs), "not SSA Cluster?"
# Construct the Nodes, tracking reads and readby
tensor_map = DefaultOrderedDict(list)
for i in mapper:
tensor_map[as_symbol(i)].append(i)
reads = DefaultOrderedDict(set)
readby = DefaultOrderedDict(set)
for k, v in mapper.items():
handle = retrieve_terminals(v.rhs)
for i in list(handle):
if i.is_Indexed:
for idx in i.indices:
handle |= retrieve_terminals(idx)
reads[k].update(
set(flatten([tensor_map.get(as_symbol(i), [])
for i in handle])))
for i in reads[k]:
readby[i].add(k)
# Make sure read-after-writes are honored for scalar temporaries
processed = [i for i in mapper if i.is_Indexed]
queue = [i for i in mapper if i not in processed]
while queue:
k = queue.pop(0)
if not readby[k]:
processed.insert(0, k)
elif all(i in processed for i in readby[k]):
index = min(processed.index(i) for i in readby[k])
processed.insert(index, k)
else:
queue.append(k)
# Build up the FlowGraph
temporaries = [(i,
Node(*mapper[i].args,
inc=q_inc(mapper[i]),
reads=reads[i],
readby=readby[i])) for i in processed]
super(FlowGraph, self).__init__(temporaries, **kwargs)
# Determine indices along the space and time dimensions
terms = [
v for k, v in self.items() if v.is_tensor and not q_indirect(k)
]
indices = filter_ordered(flatten([i.function.indices for i in terms]))
self.space_indices = tuple(i for i in indices if i.is_Space)
self.time_indices = tuple(i for i in indices if i.is_Time)
def __init__(self, exprs, **kwargs):
# Always convert to SSA
exprs = makeit_ssa(exprs)
mapper = OrderedDict([(i.lhs, i) for i in exprs])
assert len(set(mapper)) == len(exprs), "not SSA Cluster?"
# Construct the Nodes, tracking reads and readby
tensor_map = DefaultOrderedDict(list)
for i in mapper:
tensor_map[as_symbol(i)].append(i)
reads = DefaultOrderedDict(set)
readby = DefaultOrderedDict(set)
for k, v in mapper.items():
handle = retrieve_terminals(v.rhs)
for i in list(handle):
if i.is_Indexed:
for idx in i.indices:
handle |= retrieve_terminals(idx)
reads[k].update(set(flatten([tensor_map.get(as_symbol(i), [])
for i in handle])))
for i in reads[k]:
readby[i].add(k)
# Make sure read-after-writes are honored for scalar nodes
processed = [i for i in mapper if i.is_Indexed]
queue = [i for i in mapper if i not in processed]
while queue:
k = queue.pop(0)
if not readby[k] or k in readby[k]:
processed.insert(0, k)
elif all(i in processed for i in readby[k]):
index = min(processed.index(i) for i in readby[k])
processed.insert(index, k)
else:
queue.append(k)
# Build up the FlowGraph
nodes = [(i, Node(mapper[i], reads=reads[i], readby=readby[i]))
for i in processed]
super(FlowGraph, self).__init__(nodes, **kwargs)
# Determine indices along the space and time dimensions
terms = [v for k, v in self.items() if v.is_Tensor and not q_indirect(k)]
indices = filter_ordered(flatten([i.function.indices for i in terms]))
self.space_indices = tuple(i for i in indices if i.is_Space)
self.time_indices = tuple(i for i in indices if i.is_Time)
def collect(exprs):
"""
Determine groups of aliasing expressions in ``exprs``.
An expression A aliases an expression B if both A and B apply the same
operations to the same input operands, with the possibility for indexed objects
to index into locations at a fixed constant offset in each dimension.
For example: ::
exprs = (a[i+1] + b[i+1], a[i+1] + b[j+1], a[i] + c[i],
a[i+2] - b[i+2], a[i+2] + b[i], a[i-1] + b[i-1])
The following expressions in ``exprs`` alias to ``a[i] + b[i]``: ::
a[i+1] + b[i+1] : same operands and operations, distance along i = 1
a[i-1] + b[i-1] : same operands and operations, distance along i = -1
Whereas the following do not: ::
a[i+1] + b[j+1] : because at least one index differs
a[i] + c[i] : because at least one of the operands differs
a[i+2] - b[i+2] : because at least one operation differs
a[i+2] + b[i] : because distance along ``i`` differ (+2 and +0)
"""
ExprData = namedtuple('ExprData', 'dimensions offsets')
# Discard expressions:
# - that surely won't alias to anything
# - that are non-scalar
candidates = OrderedDict()
for expr in exprs:
if expr.lhs.is_Indexed:
continue
indexeds = retrieve_indexed(expr.rhs, mode='all')
if indexeds and not any(q_indirect(i) for i in indexeds):
handle = calculate_offsets(indexeds)
if handle:
candidates[expr.rhs] = ExprData(*handle)
aliases = OrderedDict()
mapper = OrderedDict()
unseen = list(candidates)
while unseen:
# Find aliasing expressions
handle = unseen.pop(0)
group = [handle]
for e in list(unseen):
if compare(handle, e) and\
is_translated(candidates[handle].offsets, candidates[e].offsets):
group.append(e)
unseen.remove(e)
# Try creating a basis for the aliasing expressions' offsets
offsets = [tuple(candidates[e].offsets) for e in group]
try:
COM, distances = calculate_COM(offsets)
except DSEException:
# Ignore these potential aliases and move on
continue
alias = create_alias(handle, COM)
# An alias has been created, so I can now update the expression mapper
mapper.update([(i, group) for i in group])
# In circumstances in which an expression has repeated coefficients, e.g.
# ... + 0.025*a[...] + 0.025*b[...],
# We may have found a common basis (i.e., same COM, same alias) at this point
v = aliases.setdefault(alias,
Alias(alias, candidates[handle].dimensions))
v.extend(group, distances)
# Heuristically attempt to relax the aliases offsets
# to maximize the likelyhood of loop fusion
grouped = OrderedDict()
for i in aliases.values():
grouped.setdefault(i.dimensions, []).append(i)
for dimensions, group in grouped.items():
ideal_anti_stencil = Stencil.union(*[i.anti_stencil for i in group])
for i in group:
if i.anti_stencil.subtract(ideal_anti_stencil).empty:
aliases[i.alias] = i.relax(ideal_anti_stencil)
return mapper, aliases
def collect(exprs):
"""
Determine groups of aliasing expressions in ``exprs``.
An expression A aliases an expression B if both A and B apply the same
operations to the same input operands, with the possibility for indexed objects
to index into locations at a fixed constant offset in each dimension.
For example: ::
exprs = (a[i+1] + b[i+1], a[i+1] + b[j+1], a[i] + c[i],
a[i+2] - b[i+2], a[i+2] + b[i], a[i-1] + b[i-1])
The following expressions in ``exprs`` alias to ``a[i] + b[i]``: ::
a[i+1] + b[i+1] : same operands and operations, distance along i = 1
a[i-1] + b[i-1] : same operands and operations, distance along i = -1
Whereas the following do not: ::
a[i+1] + b[j+1] : because at least one index differs
a[i] + c[i] : because at least one of the operands differs
a[i+2] - b[i+2] : because at least one operation differs
a[i+2] + b[i] : because distance along ``i`` differ (+2 and +0)
"""
ExprData = namedtuple('ExprData', 'dimensions offsets')
# Discard expressions:
# - that surely won't alias to anything
# - that are non-scalar
candidates = OrderedDict()
for expr in exprs:
if expr.lhs.is_Indexed:
continue
indexeds = retrieve_indexed(expr.rhs, mode='all')
if indexeds and not any(q_indirect(i) for i in indexeds):
handle = calculate_offsets(indexeds)
if handle:
candidates[expr.rhs] = ExprData(*handle)
aliases = OrderedDict()
mapper = OrderedDict()
unseen = list(candidates)
while unseen:
# Find aliasing expressions
handle = unseen.pop(0)
group = [handle]
for e in list(unseen):
if compare(handle, e) and\
is_translated(candidates[handle].offsets, candidates[e].offsets):
group.append(e)
unseen.remove(e)
# Try creating a basis for the aliasing expressions' offsets
offsets = [tuple(candidates[e].offsets) for e in group]
try:
COM, distances = calculate_COM(offsets)
except DSEException:
# Ignore these potential aliases and move on
continue
alias = create_alias(handle, COM)
# An alias has been created, so I can now update the expression mapper
mapper.update([(i, group) for i in group])
# In circumstances in which an expression has repeated coefficients, e.g.
# ... + 0.025*a[...] + 0.025*b[...],
# We may have found a common basis (i.e., same COM, same alias) at this point
v = aliases.setdefault(alias, Alias(alias, candidates[handle].dimensions))
v.extend(group, distances)
# Heuristically attempt to relax the aliases offsets
# to maximize the likelyhood of loop fusion
groups = OrderedDict()
for i in aliases.values():
groups.setdefault(i.dimensions, []).append(i)
for group in groups.values():
ideal_anti_stencil = Stencil.union(*[i.anti_stencil for i in group])
for i in group:
if i.anti_stencil.subtract(ideal_anti_stencil).empty:
aliases[i.alias] = i.relax(ideal_anti_stencil)
return mapper, aliases