def intervals(graph):
'''
Compute the intervals of the graph
Returns
interval_graph: a graph of the intervals of G
interv_heads: a dict of (header node, interval)
'''
interval_graph = Graph() # graph of intervals
heads = set([graph.get_entry()]) # set of header nodes
interv_heads = {} # interv_heads[i] = interval of header i
processed = dict([(i, False) for i in graph])
edges = {}
while heads:
head = heads.pop()
if not processed[head]:
processed[head] = True
interv_heads[head] = Interval(head)
# Check if if there is a node which has all its predecessor in the
# current interval. If there is, add that node to the interval and
# repeat until all the possible nodes have been added.
change = True
while change:
change = False
for node in graph.get_rpo()[1:]:
if all(p in interv_heads[head] for p in graph.preds(node)):
change |= interv_heads[head].add_node(node)
# At this stage, a node which is not in the interval, but has one
# of its predecessor in it, is the header of another interval. So
# we add all such nodes to the header list.
for node in graph:
if node not in interv_heads[head] and node not in heads:
if any(p in interv_heads[head] for p in graph.preds(node)):
edges.setdefault(interv_heads[head], []).append(node)
heads.add(node)
interval_graph.add_node(interv_heads[head])
interv_heads[head].compute_end(graph)
# Edges is a mapping of 'Interval -> [header nodes of interval successors]'
for interval, heads in edges.items():
for head in heads:
interval_graph.add_edge(interval, interv_heads[head])
interval_graph.set_entry(graph.get_entry().interval)
graph_exit = graph.get_exit()
if graph_exit:
interval_graph.set_exit(graph_exit.interval)
return interval_graph, interv_heads
def intervals(graph):
'''
Compute the intervals of the graph
Returns
interval_graph: a graph of the intervals of G
interv_heads: a dict of (header node, interval)
'''
interval_graph = Graph() # graph of intervals
heads = set([graph.get_entry()]) # set of header nodes
interv_heads = {} # interv_heads[i] = interval of header i
processed = dict([(i, False) for i in graph])
edges = {}
while heads:
head = heads.pop()
if not processed[head]:
processed[head] = True
interv_heads[head] = Interval(head)
# Check if if there is a node which has all its predecessor in the
# current interval. If there is, add that node to the interval and
# repeat until all the possible nodes have been added.
change = True
while change:
change = False
for node in graph.get_rpo()[1:]:
if all(p in interv_heads[head] for p in graph.preds(node)):
change |= interv_heads[head].add_node(node)
# At this stage, a node which is not in the interval, but has one
# of its predecessor in it, is the header of another interval. So
# we add all such nodes to the header list.
for node in graph:
if node not in interv_heads[head] and node not in heads:
if any(p in interv_heads[head] for p in graph.preds(node)):
edges.setdefault(interv_heads[head], []).append(node)
heads.add(node)
interval_graph.add_node(interv_heads[head])
interv_heads[head].compute_end(graph)
# Edges is a mapping of 'Interval -> [header nodes of interval successors]'
for interval, heads in edges.items():
for head in heads:
interval_graph.add_edge(interval, interv_heads[head])
interval_graph.set_entry(graph.get_entry().interval)
graph_exit = graph.get_exit()
if graph_exit:
interval_graph.set_exit(graph_exit.interval)
return interval_graph, interv_heads
