def _extract_time_invariants(self,
cluster,
template,
with_cse=True,
costmodel=None,
**kwargs):
"""
Extract time-invariant subexpressions, and assign them to temporaries.
"""
# Extract time invariants
make = lambda i: ScalarFunction(name=template(i)).indexify()
rule = iq_timeinvariant(cluster.trace)
costmodel = costmodel or (lambda e: estimate_cost(e) > 0)
processed, found = xreplace_constrained(cluster.exprs, make, rule,
costmodel)
if with_cse:
leaves = [i for i in processed if i not in found]
# Search for common sub-expressions amongst them (and only them)
make = lambda i: ScalarFunction(name=template(i + len(found))
).indexify()
found = common_subexprs_elimination(found, make)
# Some temporaries may be droppable at this point
processed = compact_temporaries(found + leaves)
return cluster.reschedule(processed)
def _extract_sum_of_products(self, cluster, template, **kwargs):
"""
Extract sub-expressions in sum-of-product form, and assign them to temporaries.
"""
make = lambda i: ScalarFunction(name=template(i)).indexify()
rule = q_sum_of_product
costmodel = lambda e: not (q_leaf(e) or q_terminalop(e))
processed, _ = xreplace_constrained(cluster.exprs, make, rule,
costmodel)
return cluster.reschedule(processed)
def _extract_time_varying(self, cluster, template, **kwargs):
"""
Extract time-varying subexpressions, and assign them to temporaries.
Time varying subexpressions arise for example when approximating
derivatives through finite differences.
"""
make = lambda i: ScalarFunction(name=template(i)).indexify()
rule = iq_timevarying(cluster.trace)
costmodel = lambda i: estimate_cost(i) > 0
processed, _ = xreplace_constrained(cluster.exprs, make, rule,
costmodel)
return cluster.reschedule(processed)
def _extract_time_varying(self, cluster, **kwargs):
"""
Extract time-varying subexpressions, and assign them to temporaries.
Time varying subexpressions arise for example when approximating
derivatives through finite differences.
"""
template = self.conventions['time-dependent'] + "%d"
make = lambda i: ScalarFunction(name=template % i).indexify()
rule = iq_timevarying(cluster.trace)
cm = lambda i: estimate_cost(i) > 0
processed, _ = xreplace_constrained(cluster.exprs, make, rule, cm)
return cluster.rebuild(processed)
def _extract_time_invariants(self, cluster, **kwargs):
"""
Extract time-invariant subexpressions, and assign them to temporaries.
"""
# Extract time invariants
template = self.conventions['time-invariant'] + "%d"
make = lambda i: ScalarFunction(name=template % i).indexify()
rule = iq_timeinvariant(cluster.trace)
cm = lambda e: estimate_cost(e) > 0
processed, found = xreplace_constrained(cluster.exprs, make, rule, cm)
leaves = [i for i in processed if i not in found]
# Search for common sub-expressions amongst them (and only them)
template = "%s%s%s" % (self.conventions['redundancy'],
self.conventions['time-invariant'], '%d')
make = lambda i: ScalarFunction(name=template % i).indexify()
found = common_subexprs_elimination(found, make)
return cluster.rebuild(found + leaves)