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#
# Copyright (C) 2016 The Android Open Source Project
#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
# http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.
#
class ArcSummary(object):
"""Summarizes an arc from a .gcno file.
Attributes:
src_block_index: integer index of the source basic block.
dstBlockIndex: integer index of the destination basic block.
on_tree: True iff arc has flag GCOV_ARC_ON_TREE.
fake: True iff arc has flag GCOV_ARC_FAKE.
fallthrough: True iff arc has flag GCOV_ARC_FALLTHROUGH.
resolved: True iff the arc's count has been resolved.
count: Integer number of times the arc was covered.
"""
GCOV_ARC_ON_TREE = 1
GCOV_ARC_FAKE = 1 << 1
GCOV_ARC_FALLTHROUGH = 1 << 2
def __init__(self, src_block, dst_block, flag):
"""Inits the arc summary with provided values.
Stores the source and destination block indices and parses
the arc flag.
Args:
src_block: BlockSummary of source block.
dst_block: BlockSummary of destination block.
flag: integer flag for the given arc.
"""
self.src_block = src_block
self.dst_block = dst_block
self.on_tree = bool(flag & self.GCOV_ARC_ON_TREE)
self.fake = bool(flag & self.GCOV_ARC_FAKE)
self.fallthrough = bool(flag & self.GCOV_ARC_FALLTHROUGH)
self.resolved = False
self.count = 0
def Resolve(self):
"""Resolves the arc count and returns True if successful.
Uses the property that the sum of counts of arcs entering a
node is equal to the sum of counts of arcs leaving a node. The
exception to this rule is fake non-fallthrough nodes, which have
no exit edges. In this case, remove the arc as an exit arc from
the source so that the source can be resolved.
Returns:
True if the arc could be resolved and False otherwise.
"""
if self.fake and not self.fallthrough:
try:
self.src_block.exit_arcs.remove(self)
except ValueError:
pass
elif (len(self.src_block.entry_arcs) > 0 and
all(a.resolved for a in self.src_block.entry_arcs) and
all(a.resolved for a in self.src_block.exit_arcs if a != self)):
in_flow = sum(a.count for a in self.src_block.entry_arcs)
out_flow = sum(a.count for a in self.src_block.exit_arcs
if a != self)
self.count = in_flow - out_flow
self.resolved = True
elif (len(self.dst_block.exit_arcs) > 0 and
all(a.resolved for a in self.dst_block.exit_arcs) and
all(a.resolved for a in self.dst_block.entry_arcs if a != self)):
out_flow = sum(a.count for a in self.dst_block.exit_arcs)
in_flow = sum(a.count for a in self.dst_block.entry_arcs
if a != self)
self.count = out_flow - in_flow
self.resolved = True
else:
return False
return True