335 lines
13 KiB
Python
335 lines
13 KiB
Python
# Copyright 2013-2014 Free Software Foundation, Inc.
|
|
#
|
|
# This is free software: you can redistribute it and/or modify it
|
|
# under the terms of the GNU General Public License as published by
|
|
# the Free Software Foundation, either version 3 of the License, or
|
|
# (at your option) any later version.
|
|
#
|
|
# This program is distributed in the hope that it will be useful, but
|
|
# WITHOUT ANY WARRANTY; without even the implied warranty of
|
|
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
|
|
# General Public License for more details.
|
|
#
|
|
# You should have received a copy of the GNU General Public License
|
|
# along with this program. If not, see
|
|
# <http://www.gnu.org/licenses/>.
|
|
|
|
import gcc
|
|
import gccutils
|
|
import sys
|
|
|
|
want_raii_info = False
|
|
|
|
logging = False
|
|
show_cfg = False
|
|
|
|
def log(msg, indent=0):
|
|
global logging
|
|
if logging:
|
|
sys.stderr.write('%s%s\n' % (' ' * indent, msg))
|
|
sys.stderr.flush()
|
|
|
|
def is_cleanup_type(return_type):
|
|
if not isinstance(return_type, gcc.PointerType):
|
|
return False
|
|
if not isinstance(return_type.dereference, gcc.RecordType):
|
|
return False
|
|
if str(return_type.dereference.name) == 'cleanup':
|
|
return True
|
|
return False
|
|
|
|
def is_constructor(decl):
|
|
"Return True if the function DECL is a cleanup constructor; False otherwise"
|
|
return is_cleanup_type(decl.type.type) and (not decl.name or str(decl.name) != 'make_final_cleanup')
|
|
|
|
destructor_names = set(['do_cleanups', 'discard_cleanups'])
|
|
|
|
def is_destructor(decl):
|
|
return decl.name in destructor_names
|
|
|
|
# This list is just much too long... we should probably have an
|
|
# attribute instead.
|
|
special_names = set(['do_final_cleanups', 'discard_final_cleanups',
|
|
'save_cleanups', 'save_final_cleanups',
|
|
'restore_cleanups', 'restore_final_cleanups',
|
|
'exceptions_state_mc_init',
|
|
'make_my_cleanup2', 'make_final_cleanup', 'all_cleanups',
|
|
'save_my_cleanups', 'quit_target'])
|
|
|
|
def needs_special_treatment(decl):
|
|
return decl.name in special_names
|
|
|
|
# Sometimes we need a new placeholder object that isn't the same as
|
|
# anything else.
|
|
class Dummy(object):
|
|
def __init__(self, location):
|
|
self.location = location
|
|
|
|
# A wrapper for a cleanup which has been assigned to a variable.
|
|
# This holds the variable and the location.
|
|
class Cleanup(object):
|
|
def __init__(self, var, location):
|
|
self.var = var
|
|
self.location = location
|
|
|
|
# A class representing a master cleanup. This holds a stack of
|
|
# cleanup objects and supports a merging operation.
|
|
class MasterCleanup(object):
|
|
# Create a new MasterCleanup object. OTHER, if given, is a
|
|
# MasterCleanup object to copy.
|
|
def __init__(self, other = None):
|
|
# 'cleanups' is a list of cleanups. Each element is either a
|
|
# Dummy, for an anonymous cleanup, or a Cleanup, for a cleanup
|
|
# which was assigned to a variable.
|
|
if other is None:
|
|
self.cleanups = []
|
|
self.aliases = {}
|
|
else:
|
|
self.cleanups = other.cleanups[:]
|
|
self.aliases = dict(other.aliases)
|
|
|
|
def compare_vars(self, definition, argument):
|
|
if definition == argument:
|
|
return True
|
|
if argument in self.aliases:
|
|
argument = self.aliases[argument]
|
|
if definition in self.aliases:
|
|
definition = self.aliases[definition]
|
|
return definition == argument
|
|
|
|
def note_assignment(self, lhs, rhs):
|
|
log('noting assignment %s = %s' % (lhs, rhs), 4)
|
|
self.aliases[lhs] = rhs
|
|
|
|
# Merge with another MasterCleanup.
|
|
# Returns True if this resulted in a change to our state.
|
|
def merge(self, other):
|
|
# We do explicit iteration like this so we can easily
|
|
# update the list after the loop.
|
|
counter = -1
|
|
found_named = False
|
|
for counter in range(len(self.cleanups) - 1, -1, -1):
|
|
var = self.cleanups[counter]
|
|
log('merge checking %s' % var, 4)
|
|
# Only interested in named cleanups.
|
|
if isinstance(var, Dummy):
|
|
log('=> merge dummy', 5)
|
|
continue
|
|
# Now see if VAR is found in OTHER.
|
|
if other._find_var(var.var) >= 0:
|
|
log ('=> merge found', 5)
|
|
break
|
|
log('=>merge not found', 5)
|
|
found_named = True
|
|
if found_named and counter < len(self.cleanups) - 1:
|
|
log ('merging to %d' % counter, 4)
|
|
if counter < 0:
|
|
self.cleanups = []
|
|
else:
|
|
self.cleanups = self.cleanups[0:counter]
|
|
return True
|
|
# If SELF is empty but OTHER has some cleanups, then consider
|
|
# that a change as well.
|
|
if len(self.cleanups) == 0 and len(other.cleanups) > 0:
|
|
log('merging non-empty other', 4)
|
|
self.cleanups = other.cleanups[:]
|
|
return True
|
|
return False
|
|
|
|
# Push a new constructor onto our stack. LHS is the
|
|
# left-hand-side of the GimpleCall statement. It may be None,
|
|
# meaning that this constructor's value wasn't used.
|
|
def push(self, location, lhs):
|
|
if lhs is None:
|
|
obj = Dummy(location)
|
|
else:
|
|
obj = Cleanup(lhs, location)
|
|
log('pushing %s' % lhs, 4)
|
|
idx = self._find_var(lhs)
|
|
if idx >= 0:
|
|
gcc.permerror(location, 'reassigning to known cleanup')
|
|
gcc.inform(self.cleanups[idx].location,
|
|
'previous assignment is here')
|
|
self.cleanups.append(obj)
|
|
|
|
# A helper for merge and pop that finds BACK_TO in self.cleanups,
|
|
# and returns the index, or -1 if not found.
|
|
def _find_var(self, back_to):
|
|
for i in range(len(self.cleanups) - 1, -1, -1):
|
|
if isinstance(self.cleanups[i], Dummy):
|
|
continue
|
|
if self.compare_vars(self.cleanups[i].var, back_to):
|
|
return i
|
|
return -1
|
|
|
|
# Pop constructors until we find one matching BACK_TO.
|
|
# This is invoked when we see a do_cleanups call.
|
|
def pop(self, location, back_to):
|
|
log('pop:', 4)
|
|
i = self._find_var(back_to)
|
|
if i >= 0:
|
|
self.cleanups = self.cleanups[0:i]
|
|
else:
|
|
gcc.permerror(location, 'destructor call with unknown argument')
|
|
|
|
# Check whether ARG is the current master cleanup. Return True if
|
|
# all is well.
|
|
def verify(self, location, arg):
|
|
log('verify %s' % arg, 4)
|
|
return (len(self.cleanups) > 0
|
|
and not isinstance(self.cleanups[0], Dummy)
|
|
and self.compare_vars(self.cleanups[0].var, arg))
|
|
|
|
# Check whether SELF is empty.
|
|
def isempty(self):
|
|
log('isempty: len = %d' % len(self.cleanups), 4)
|
|
return len(self.cleanups) == 0
|
|
|
|
# Emit informational warnings about the cleanup stack.
|
|
def inform(self):
|
|
for item in reversed(self.cleanups):
|
|
gcc.inform(item.location, 'leaked cleanup')
|
|
|
|
class CleanupChecker:
|
|
def __init__(self, fun):
|
|
self.fun = fun
|
|
self.seen_edges = set()
|
|
self.bad_returns = set()
|
|
|
|
# This maps BB indices to a list of master cleanups for the
|
|
# BB.
|
|
self.master_cleanups = {}
|
|
|
|
# Pick a reasonable location for the basic block BB.
|
|
def guess_bb_location(self, bb):
|
|
if isinstance(bb.gimple, list):
|
|
for stmt in bb.gimple:
|
|
if stmt.loc:
|
|
return stmt.loc
|
|
return self.fun.end
|
|
|
|
# Compute the master cleanup list for BB.
|
|
# Modifies MASTER_CLEANUP in place.
|
|
def compute_master(self, bb, bb_from, master_cleanup):
|
|
if not isinstance(bb.gimple, list):
|
|
return
|
|
curloc = self.fun.end
|
|
for stmt in bb.gimple:
|
|
if stmt.loc:
|
|
curloc = stmt.loc
|
|
if isinstance(stmt, gcc.GimpleCall) and stmt.fndecl:
|
|
if is_constructor(stmt.fndecl):
|
|
log('saw constructor %s in bb=%d' % (str(stmt.fndecl), bb.index), 2)
|
|
self.cleanup_aware = True
|
|
master_cleanup.push(curloc, stmt.lhs)
|
|
elif is_destructor(stmt.fndecl):
|
|
if str(stmt.fndecl.name) != 'do_cleanups':
|
|
self.only_do_cleanups_seen = False
|
|
log('saw destructor %s in bb=%d, bb_from=%d, argument=%s'
|
|
% (str(stmt.fndecl.name), bb.index, bb_from, str(stmt.args[0])),
|
|
2)
|
|
master_cleanup.pop(curloc, stmt.args[0])
|
|
elif needs_special_treatment(stmt.fndecl):
|
|
pass
|
|
# gcc.permerror(curloc, 'function needs special treatment')
|
|
elif isinstance(stmt, gcc.GimpleAssign):
|
|
if isinstance(stmt.lhs, gcc.VarDecl) and isinstance(stmt.rhs[0], gcc.VarDecl):
|
|
master_cleanup.note_assignment(stmt.lhs, stmt.rhs[0])
|
|
elif isinstance(stmt, gcc.GimpleReturn):
|
|
if self.is_constructor:
|
|
if not master_cleanup.verify(curloc, stmt.retval):
|
|
gcc.permerror(curloc,
|
|
'constructor does not return master cleanup')
|
|
elif not self.is_special_constructor:
|
|
if not master_cleanup.isempty():
|
|
if curloc not in self.bad_returns:
|
|
gcc.permerror(curloc, 'cleanup stack is not empty at return')
|
|
self.bad_returns.add(curloc)
|
|
master_cleanup.inform()
|
|
|
|
# Traverse a basic block, updating the master cleanup information
|
|
# and propagating to other blocks.
|
|
def traverse_bbs(self, edge, bb, bb_from, entry_master):
|
|
log('traverse_bbs %d from %d' % (bb.index, bb_from), 1)
|
|
|
|
# Propagate the entry MasterCleanup though this block.
|
|
master_cleanup = MasterCleanup(entry_master)
|
|
self.compute_master(bb, bb_from, master_cleanup)
|
|
|
|
modified = False
|
|
if bb.index in self.master_cleanups:
|
|
# Merge the newly-computed MasterCleanup into the one we
|
|
# have already computed. If this resulted in a
|
|
# significant change, then we need to re-propagate.
|
|
modified = self.master_cleanups[bb.index].merge(master_cleanup)
|
|
else:
|
|
self.master_cleanups[bb.index] = master_cleanup
|
|
modified = True
|
|
|
|
# EDGE is None for the entry BB.
|
|
if edge is not None:
|
|
# If merging cleanups caused a change, check to see if we
|
|
# have a bad loop.
|
|
if edge in self.seen_edges:
|
|
# This error doesn't really help.
|
|
# if modified:
|
|
# gcc.permerror(self.guess_bb_location(bb),
|
|
# 'invalid cleanup use in loop')
|
|
return
|
|
self.seen_edges.add(edge)
|
|
|
|
if not modified:
|
|
return
|
|
|
|
# Now propagate to successor nodes.
|
|
for edge in bb.succs:
|
|
self.traverse_bbs(edge, edge.dest, bb.index, master_cleanup)
|
|
|
|
def check_cleanups(self):
|
|
if not self.fun.cfg or not self.fun.decl:
|
|
return 'ignored'
|
|
if is_destructor(self.fun.decl):
|
|
return 'destructor'
|
|
if needs_special_treatment(self.fun.decl):
|
|
return 'special'
|
|
|
|
self.is_constructor = is_constructor(self.fun.decl)
|
|
self.is_special_constructor = not self.is_constructor and str(self.fun.decl.name).find('with_cleanup') > -1
|
|
# Yuck.
|
|
if str(self.fun.decl.name) == 'gdb_xml_create_parser_and_cleanup_1':
|
|
self.is_special_constructor = True
|
|
|
|
if self.is_special_constructor:
|
|
gcc.inform(self.fun.start, 'function %s is a special constructor' % (self.fun.decl.name))
|
|
|
|
# If we only see do_cleanups calls, and this function is not
|
|
# itself a constructor, then we can convert it easily to RAII.
|
|
self.only_do_cleanups_seen = not self.is_constructor
|
|
# If we ever call a constructor, then we are "cleanup-aware".
|
|
self.cleanup_aware = False
|
|
|
|
entry_bb = self.fun.cfg.entry
|
|
master_cleanup = MasterCleanup()
|
|
self.traverse_bbs(None, entry_bb, -1, master_cleanup)
|
|
if want_raii_info and self.only_do_cleanups_seen and self.cleanup_aware:
|
|
gcc.inform(self.fun.decl.location,
|
|
'function %s could be converted to RAII' % (self.fun.decl.name))
|
|
if self.is_constructor:
|
|
return 'constructor'
|
|
return 'OK'
|
|
|
|
class CheckerPass(gcc.GimplePass):
|
|
def execute(self, fun):
|
|
if fun.decl:
|
|
log("Starting " + fun.decl.name)
|
|
if show_cfg:
|
|
dot = gccutils.cfg_to_dot(fun.cfg, fun.decl.name)
|
|
gccutils.invoke_dot(dot, name=fun.decl.name)
|
|
checker = CleanupChecker(fun)
|
|
what = checker.check_cleanups()
|
|
if fun.decl:
|
|
log(fun.decl.name + ': ' + what, 2)
|
|
|
|
ps = CheckerPass(name = 'check-cleanups')
|
|
# We need the cfg, but we want a relatively high-level Gimple.
|
|
ps.register_after('cfg')
|