2 * Copyright 2010, INRIA, University of Copenhagen
3 * Julia Lawall, Rene Rydhof Hansen, Gilles Muller, Nicolas Palix
4 * Copyright 2005-2009, Ecole des Mines de Nantes, University of Copenhagen
5 * Yoann Padioleau, Julia Lawall, Rene Rydhof Hansen, Henrik Stuart, Gilles Muller, Nicolas Palix
6 * This file is part of Coccinelle.
8 * Coccinelle is free software: you can redistribute it and/or modify
9 * it under the terms of the GNU General Public License as published by
10 * the Free Software Foundation, according to version 2 of the License.
12 * Coccinelle is distributed in the hope that it will be useful,
13 * but WITHOUT ANY WARRANTY; without even the implied warranty of
14 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
15 * GNU General Public License for more details.
17 * You should have received a copy of the GNU General Public License
18 * along with Coccinelle. If not, see <http://www.gnu.org/licenses/>.
20 * The authors reserve the right to distribute this or future versions of
21 * Coccinelle under other licenses.
25 (* ---------------------------------------------------------------- *)
26 (* code to check for ambiguities *)
28 (* Idea: for each node that is said to be modified in any witness tree, we
29 check that all backward paths end up at the root of some witness tree
30 that says that the node should be modified. We then give a warning, if
31 the node itself appears more than once in such a path, because then there
32 could be some instances that are modified and some that are not. An
33 example is as follows:
35 f(); ... g(); ... - h();
37 with C code: f(); while(E) { h(); g(); } g(); h();
39 Then the h() in the while loop matches both the first ... and the - h();
41 Concretely, if a node 47 is in the witness tree rooted at 1 and the
42 witness tree rooted at 2, then we give an error if 47 is not in the set
43 of nodes satisfying AF[1v2] and give a warning if 47 is in the set of
44 nodes satisfying EXEF(47 & EXEF(1v2)). (Note that the root of a witness
45 tree here is the node causing the pattern to match; there might not be
46 any witnesses associated with this node.)
48 Another try on the exists formula:
49 !(1v2) & EXE[!(1v2) U 47]
50 The first !(1v2) is to discard immediately cases where the beginning and
51 end of the path are the same. Afterwards, it would only seem necessary to
52 serach up to the next occurrence of 47 (leaf), ensuring that there are not
53 1s or 2s (starting points) along the way. Then the second 47 would be in
54 the path, but possible not transformed.
57 module G
= Ograph_extended
60 (* Step 1: for each tree, make a mapping from the modified nodes to the root
63 let modified = (Hashtbl.create
(25) : (G.nodei
, G.nodei list
ref) Hashtbl.t
)
65 let build_modified (n
,_
,wits
) =
66 let rec loop = function
67 CTL.Wit
(st
,[CTL.Subst
(x
,Wrapper_ctl.PredVal
(CTL.Modif
(v
)))],anno
,wit
) ->
69 try Hashtbl.find
modified st
71 let cell = ref [] in Hashtbl.add
modified st
cell; cell in
74 | CTL.Wit
(st
,_
,anno
,wit
) -> List.iter
loop wit
75 | CTL.NegWit
(wit
) -> () in
78 (* Step 2: For each node in the hash table, create the error and warning
81 type 'a nodes
= Node
of 'a
| After
83 let create_formulas _
=
91 (Ast_ctl.BACKWARD,wrap(Ast_ctl.EF(Ast_ctl.BACKWARD,f)))) in*)
92 let match_node = Ast_ctl.Pred
(Node
(node
)) in
94 List.map
(function n
-> Ast_ctl.Pred
(Node
(n
)))
95 (List.sort compare
!roots
) in
98 (function prev
-> function cur
-> Ast_ctl.Or
(prev
,cur
))
99 (List.hd
match_roots) (List.tl
match_roots) in
100 (* no point to search if no path, and the presence of after
101 in the AF formula can make things slow *)
102 if List.mem node
!roots
106 Ast_ctl.AF
(Ast_ctl.BACKWARD
,Ast_ctl.NONSTRICT
,
107 Ast_ctl.Or
(or_roots,Ast_ctl.Pred
(After
))),
110 Ast_ctl.Not
(or_roots),
113 Ast_ctl.EU
(Ast_ctl.BACKWARD
,or_roots,match_node))))
115 (wrap(Ast_ctl.And(Ast_ctl.NONSTRICT,match_node,exef(roots))))*)
119 (* Step 3: check the formula on the control-flow graph *)
123 type t
= Ograph_extended.nodei nodes
124 let print_predicate = function
125 After
-> Format.print_string
"after"
126 | Node x
-> Format.print_string
(string_of_int x
)
133 let eq_mvar x x'
= failwith
"should not be invoked"
134 let eq_val v v'
= failwith
"should not be invoked"
135 let merge_val v v'
= failwith
"should not be invoked"
137 let print_mvar s
= failwith
"should not be invoked"
138 let print_value x
= failwith
"should not be invoked"
144 type node
= Ograph_extended.nodei
146 (Control_flow_c.node
, Control_flow_c.edge
)
147 Ograph_extended.ograph_mutable
148 let predecessors cfg n
= List.map fst
((cfg#
predecessors n
)#tolist
)
149 let successors cfg n
= List.map fst
((cfg#
successors n
)#tolist
)
150 let extract_is_loop cfg n
=
151 Control_flow_c.extract_is_loop (cfg#nodes#find n
)
152 let print_node i
= Format.print_string
(string_of_int i
)
153 let size cfg
= cfg#nodes#length
154 let print_graph cfg label border_nodes fill_nodes filename
= ()
157 module ENGINE
= Ctl_engine.CTL_ENGINE
(ENV
) (CFG
) (PRED
)
159 let test_formula state formula cfg
=
161 Node pred
-> [(pred
,[],[])]
165 (fun (nodei
, node
) ->
166 match Control_flow_c.unwrap node
with
167 Control_flow_c.AfterNode
-> [(nodei
,[],[])]
170 let verbose = !Flag_ctl.verbose_ctl_engine
in
171 let pm = !Flag_ctl.partial_match
in
172 (* let gt = !Flag_ctl.graphical_trace in *)
173 Flag_ctl.verbose_ctl_engine
:= false;
174 Flag_ctl.partial_match
:= false;
175 Flag_ctl.checking_reachability
:= true;
176 (* Flag_ctl.graphical_trace := ""; *)
178 ENGINE.sat
(cfg
,label,List.map fst cfg#nodes#tolist
)
179 (CTL.And
(CTL.NONSTRICT
,CTL.Pred
(Node
(state
)),formula
))
181 Flag_ctl.verbose_ctl_engine
:= verbose;
182 Flag_ctl.partial_match
:= pm;
183 Flag_ctl.checking_reachability
:= false;
184 (* Flag_ctl.graphical_trace := gt; *)
185 match res with [] -> false | _
-> true
187 (* ---------------------------------------------------------------- *)
190 (* The argument is a list of triples with a node name, an empty environment
191 and a witness tree *)
194 (Ograph_extended.nodei
, unit,
195 (Ograph_extended.nodei
, unit, unit) Ast_ctl.generic_ctl list
)
196 Ast_ctl.generic_witnesstree
198 type ('a
,'b
,'c
,'d
,'e
) triples
=
199 (Ograph_extended.nodei
* 'a
*
200 (Ograph_extended.nodei
,
201 ('b
, ('c
, 'd
) Wrapper_ctl.wrapped_binding
) CTL.generic_subst list
, 'e
)
202 CTL.generic_witnesstree list
) list
204 let check_reachability triples cfg
=
205 Hashtbl.clear
modified;
206 List.iter
build_modified triples
;
207 let formulas = create_formulas() in
209 (function (node
,af_formula
,ef_formula
) ->
210 if test_formula node af_formula cfg
212 if test_formula node ef_formula cfg
214 Printf.printf
"warning: node %d may be inconsistently modified\n"
220 "node %d reachable by inconsistent control-flow paths" node
))