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dfcc_spec_functions.cpp
Go to the documentation of this file.
1/*******************************************************************\
2
3Module: Dynamic frame condition checking
4
5Author: Remi Delmas, delmarsd@amazon.com
6
7\*******************************************************************/
8
11
12#include <util/format_expr.h>
13#include <util/namespace.h>
14
16
18
19#include "dfcc_library.h"
20
22 goto_modelt &goto_model,
23 message_handlert &message_handler,
24 dfcc_libraryt &library)
25 : goto_model(goto_model),
26 message_handler(message_handler),
27 log(message_handler),
28 library(library),
29 ns(goto_model.symbol_table)
30{
31}
32
34{
36 expr.id() == ID_typecast && expr.type().id() == ID_pointer &&
37 expr.operands().at(0).id() == ID_address_of,
38 "target expression must be of the form `cast(address_of(target), empty*)`");
39
40 return expr.operands().at(0).operands().at(0).type();
41}
42
44 const irep_idt &function_id,
45 const irep_idt &havoc_function_id,
46 std::size_t &nof_targets)
47{
49 !goto_model.symbol_table.has_symbol(havoc_function_id),
50 "DFCC: havoc function id '" + id2string(havoc_function_id) +
51 "' already exists");
52
53 const auto &function_symbol =
55
56 // create the code type that goes on the function symbol
57 const typet &write_set_param_type =
59 code_typet::parametert write_set_param{write_set_param_type};
60 code_typet havoc_code_type({std::move(write_set_param)}, empty_typet());
61
62 // create the havoc function symbol
63 symbolt havoc_function_symbol;
64 havoc_function_symbol.base_name = havoc_function_id;
65 havoc_function_symbol.name = havoc_function_id;
66 havoc_function_symbol.pretty_name = havoc_function_id;
67 havoc_function_symbol.type = havoc_code_type;
68 havoc_function_symbol.mode = function_symbol.mode;
69 havoc_function_symbol.module = function_symbol.module;
70 havoc_function_symbol.location = function_symbol.location;
71 havoc_function_symbol.set_compiled();
72 bool add_function_failed = goto_model.symbol_table.add(havoc_function_symbol);
74 !add_function_failed,
75 "DFCC: could not insert havoc function '" + id2string(havoc_function_id) +
76 "' in the symbol table");
77
78 // create the write_set symbol used as input by the havoc function
79 const auto &write_set_symbol = dfcc_utilst::create_new_parameter_symbol(
81 havoc_function_id,
82 "__write_set_to_havoc",
83 write_set_param_type);
86 .parameters()[0]
87 .set_identifier(write_set_symbol.name);
88
89 // create new goto_function
90 goto_functiont dummy_havoc_function;
91 dummy_havoc_function.parameter_identifiers = {write_set_symbol.name};
92 goto_model.goto_functions.function_map[havoc_function_id].copy_from(
93 dummy_havoc_function);
94
95 // body will be filled with instructions
96 auto &havoc_program =
97 goto_model.goto_functions.function_map.at(havoc_function_id).body;
98
99 const goto_programt &original_program =
100 goto_model.goto_functions.function_map.at(function_id).body;
101
103 havoc_function_id,
104 original_program,
105 write_set_symbol.symbol_expr(),
106 havoc_program,
107 nof_targets);
108
109 havoc_program.add(goto_programt::make_end_function());
110
112
113 std::set<irep_idt> no_body;
114 std::set<irep_idt> missing_function;
115 std::set<irep_idt> recursive_call;
116 std::set<irep_idt> not_enough_arguments;
119 havoc_function_id,
120 no_body,
121 recursive_call,
122 missing_function,
123 not_enough_arguments,
125 INVARIANT(
126 no_body.empty(),
127 "no body warnings when inlining " + id2string(havoc_function_id));
128 INVARIANT(
129 missing_function.empty(),
130 "missing function warnings when inlining " + id2string(havoc_function_id));
131 INVARIANT(
132 recursive_call.empty(),
133 "recursive calls when inlining " + id2string(havoc_function_id));
134 INVARIANT(
135 not_enough_arguments.empty(),
136 "not enough arguments when inlining " + id2string(havoc_function_id));
137
138 goto_model.goto_functions.function_map.at(havoc_function_id).make_hidden();
139
141}
142
144 const irep_idt &function_id,
145 const goto_programt &original_program,
146 const exprt &write_set_to_havoc,
147 goto_programt &havoc_program,
148 std::size_t &nof_targets)
149{
150 // index of the CAR to havoc in the write set
151 std::size_t next_idx = 0;
152
153 // iterate on the body of the original function and emit one havoc instruction
154 // per target
155 forall_goto_program_instructions(ins_it, original_program)
156 {
157 if(ins_it->is_function_call())
158 {
159 if(ins_it->call_function().id() != ID_symbol)
160 {
162 "Function pointer calls are not supported in assigns clauses: '" +
163 from_expr(ns, function_id, ins_it->call_function()) +
164 "' called in function '" + id2string(function_id) + "'",
165 ins_it->source_location());
166 }
167
168 const irep_idt &callee_id =
169 to_symbol_expr(ins_it->call_function()).get_identifier();
170
171 // Only process built-in functions that represent assigns clause targets,
172 // and error-out on any other function call
173
174 // Find the corresponding instrumentation hook
175 auto hook_opt = library.get_havoc_hook(callee_id);
176 INVARIANT(
177 hook_opt.has_value(),
178 "dfcc_spec_functionst::generate_havoc_instructions: function calls "
179 "must be inlined before calling this function");
180
181 // Use same source location as original call
182 source_locationt location(ins_it->source_location());
183 auto hook = hook_opt.value();
185 library.dfcc_fun_symbol.at(hook).symbol_expr(),
186 {write_set_to_havoc, from_integer(next_idx, size_type())});
187
189 {
190 // ```
191 // DECL __havoc_target;
192 // CALL __havoc_target = havoc_hook(set, next_idx);
193 // IF !__havoc_target GOTO label;
194 // ASSIGN *__havoc_target = nondet(target_type);
195 // label: DEAD __havoc_target;
196 // ```
197 // declare a local var to store targets havoced via nondet assignment
198 auto &target_type = get_target_type(ins_it->call_arguments().at(0));
199
200 const auto target_expr = dfcc_utilst::create_symbol(
202 pointer_type(target_type),
203 function_id,
204 "__havoc_target",
205 location);
206
207 havoc_program.add(goto_programt::make_decl(target_expr, location));
208
209 call.lhs() = target_expr;
210 havoc_program.add(goto_programt::make_function_call(call, location));
211
212 auto goto_instruction =
214 dfcc_utilst::make_null_check_expr(target_expr), location));
215
216 // create nondet assignment to the target
217 side_effect_expr_nondett nondet(target_type, location);
220 target_expr, pointer_type(target_type))},
221 nondet,
222 location));
223 auto label =
224 havoc_program.add(goto_programt::make_dead(target_expr, location));
225 goto_instruction->complete_goto(label);
226 }
227 else if(
230 {
231 // ```
232 // CALL havoc_hook(set, next_idx);
233 // ```
234 havoc_program.add(goto_programt::make_function_call(call, location));
235 }
236 else
237 {
239 }
240 ++next_idx;
241 }
242 }
243 nof_targets = next_idx;
244}
245
247 const irep_idt &function_id,
248 std::size_t &nof_targets)
249{
250 auto &goto_function = goto_model.goto_functions.function_map.at(function_id);
251
252 // add write_set parameter
253 const exprt write_set_to_fill =
256 function_id,
257 "__write_set_to_fill",
259 .symbol_expr();
260
262 write_set_to_fill,
264 goto_function.body,
265 nof_targets);
266
268
269 goto_model.goto_functions.function_map.at(function_id).make_hidden();
270}
271
273 const exprt &write_set_to_fill,
274 const irep_idt &language_mode,
275 goto_programt &program,
276 std::size_t &nof_targets)
277{
278 // counts the number of calls to built-ins to get an over approximation
279 // of the size of the set
280 std::size_t next_idx = 0;
281
282 // rewrite calls
283 Forall_goto_program_instructions(ins_it, program)
284 {
285 if(ins_it->is_function_call())
286 {
287 if(ins_it->call_function().id() != ID_symbol)
288 {
290 "Function pointer calls are not supported in assigns clauses '" +
291 from_expr_using_mode(ns, language_mode, ins_it->call_function()) +
292 "'",
293 ins_it->source_location());
294 }
295
296 const irep_idt &callee_id =
297 to_symbol_expr(ins_it->call_function()).get_identifier();
298
299 // Only process built-in functions that specify assignable targets
300 // and error-out on any other function call
301
302 // Find the corresponding instrumentation hook
303 INVARIANT(
304 library.is_front_end_builtin(callee_id),
305 "dfcc_spec_functionst::to_spec_assigns_function: function calls must "
306 "be inlined before calling this function");
307
308 auto hook = library.get_hook(callee_id);
309 // redirect the call to the hook
310 ins_it->call_function() = library.dfcc_fun_symbol.at(hook).symbol_expr();
311 // insert insertion index argument
312 ins_it->call_arguments().insert(
313 ins_it->call_arguments().begin(), from_integer(next_idx, size_type()));
314 // insert write set argument
315 ins_it->call_arguments().insert(
316 ins_it->call_arguments().begin(), write_set_to_fill);
317
318 // remove the is_pointer_to_pointer argument which is not used in the
319 // hook for insert assignable
321 ins_it->call_arguments().pop_back();
322
323 ++next_idx;
324 }
325 }
326 nof_targets = next_idx;
327}
328
330 const irep_idt &function_id,
331 std::size_t &nof_targets)
332{
333 auto &goto_function = goto_model.goto_functions.function_map.at(function_id);
334
335 // add __dfcc_set parameter
336 const exprt &write_set_to_fill =
339 function_id,
340 "__write_set_to_fill",
342 .symbol_expr();
343
345 write_set_to_fill,
347 goto_function.body,
348 nof_targets);
349
351
352 goto_model.goto_functions.function_map.at(function_id).make_hidden();
353}
354
356 const exprt &write_set_to_fill,
357 const irep_idt &language_mode,
358 goto_programt &program,
359 std::size_t &nof_targets)
360{
361 // counts the number of calls to the `freeable` builtin
362 std::size_t next_idx = 0;
363 Forall_goto_program_instructions(ins_it, program)
364 {
365 if(ins_it->is_function_call())
366 {
367 if(ins_it->call_function().id() != ID_symbol)
368 {
370 "Function pointer calls are not supported in frees clauses: '" +
371 from_expr_using_mode(ns, language_mode, ins_it->call_function()) +
372 "'",
373 ins_it->source_location());
374 }
375
376 const irep_idt &callee_id =
377 to_symbol_expr(ins_it->call_function()).get_identifier();
378
379 // only process the built-in `freeable` function
380 // error out on any other function call
381 INVARIANT(
382 callee_id == CPROVER_PREFIX "freeable",
383 "dfcc_spec_functionst::to_spec_frees_function: function calls must "
384 "be inlined before calling this function");
385
386 ins_it->call_function() =
388 .symbol_expr();
389 ins_it->call_arguments().insert(
390 ins_it->call_arguments().begin(), write_set_to_fill);
391 ++next_idx;
392 }
393 }
394
395 nof_targets = next_idx;
396}
constant_exprt from_integer(const mp_integer &int_value, const typet &type)
unsignedbv_typet size_type()
Definition c_types.cpp:50
pointer_typet pointer_type(const typet &subtype)
Definition c_types.cpp:235
goto_instruction_codet representation of a function call statement.
Base type of functions.
Definition std_types.h:583
const parameterst & parameters() const
Definition std_types.h:699
Operator to dereference a pointer.
Class interface to library types and functions defined in cprover_contracts.c.
bool is_front_end_builtin(const irep_idt &function_id) const
Returns true iff the given function_id is one of __CPROVER_assignable, __CPROVER_object_whole,...
dfcc_funt get_hook(const irep_idt &function_id) const
Returns the library instrumentation hook for the given front-end function.
std::map< dfcc_typet, typet > dfcc_type
Maps enum values to the actual types (dynamically loaded)
std::map< dfcc_funt, symbolt > dfcc_fun_symbol
Maps enum values to the actual function symbols (dynamically loaded)
std::optional< dfcc_funt > get_havoc_hook(const irep_idt &function_id) const
Returns the library instrumentation hook for the given built-in.
void to_spec_assigns_function(const irep_idt &function_id, std::size_t &nof_targets)
Transforms (in place) a function.
void to_spec_frees_instructions(const exprt &write_set_to_fill, const irep_idt &language_mode, goto_programt &program, std::size_t &nof_targets)
Rewrites in place program expressed in terms of built-ins specifying freeable targets declaratively u...
void generate_havoc_function(const irep_idt &function_id, const irep_idt &havoc_function_id, std::size_t &nof_targets)
From a function:
void generate_havoc_instructions(const irep_idt &function_id, const goto_programt &original_program, const exprt &write_set_to_havoc, goto_programt &havoc_program, std::size_t &nof_targets)
Translates original_program that specifies assignable targets into a program that havocs the targets.
message_handlert & message_handler
void to_spec_assigns_instructions(const exprt &write_set_to_fill, const irep_idt &language_mode, goto_programt &program, std::size_t &nof_targets)
Rewrites in place program expressed in terms of built-ins specifying assignable targets declaratively...
const typet & get_target_type(const exprt &expr)
Extracts the type of an assigns clause target expression The expression must be of the form: expr = c...
dfcc_spec_functionst(goto_modelt &goto_model, message_handlert &message_handler, dfcc_libraryt &library)
void to_spec_frees_function(const irep_idt &function_id, std::size_t &nof_targets)
Transforms (in place) a function.
dstringt has one field, an unsigned integer no which is an index into a static table of strings.
Definition dstring.h:38
The empty type.
Definition std_types.h:51
Base class for all expressions.
Definition expr.h:56
typet & type()
Return the type of the expression.
Definition expr.h:84
operandst & operands()
Definition expr.h:94
function_mapt function_map
A goto function, consisting of function body (see body) and parameter identifiers (see parameter_iden...
parameter_identifierst parameter_identifiers
The identifiers of the parameters of this function.
symbol_tablet symbol_table
Symbol table.
Definition goto_model.h:31
goto_functionst goto_functions
GOTO functions.
Definition goto_model.h:34
A generic container class for the GOTO intermediate representation of one function.
static instructiont make_dead(const symbol_exprt &symbol, const source_locationt &l=source_locationt::nil())
static instructiont make_end_function(const source_locationt &l=source_locationt::nil())
static instructiont make_assignment(const code_assignt &_code, const source_locationt &l=source_locationt::nil())
Create an assignment instruction.
static instructiont make_function_call(const code_function_callt &_code, const source_locationt &l=source_locationt::nil())
Create a function call instruction.
targett add(instructiont &&instruction)
Adds a given instruction at the end.
static instructiont make_decl(const symbol_exprt &symbol, const source_locationt &l=source_locationt::nil())
static instructiont make_incomplete_goto(const exprt &_cond, const source_locationt &l=source_locationt::nil())
Thrown when we can't handle something in an input source file.
const irep_idt & id() const
Definition irep.h:388
A side_effect_exprt that returns a non-deterministically chosen value.
Definition std_code.h:1520
const irep_idt & get_identifier() const
Definition std_expr.h:160
symbolt & get_writeable_ref(const irep_idt &name)
Find a symbol in the symbol table for read-write access.
bool has_symbol(const irep_idt &name) const
Check whether a symbol exists in the symbol table.
bool add(const symbolt &symbol)
Add a new symbol to the symbol table.
Symbol table entry.
Definition symbol.h:28
irep_idt base_name
Base (non-scoped) name.
Definition symbol.h:46
typet type
Type of symbol.
Definition symbol.h:31
irep_idt mode
Language mode.
Definition symbol.h:49
static exprt conditional_cast(const exprt &expr, const typet &type)
Definition std_expr.h:2076
The type of an expression, extends irept.
Definition type.h:29
#define CPROVER_PREFIX
Dynamic frame condition checking library loading.
@ WRITE_SET_INSERT_ASSIGNABLE
@ WRITE_SET_HAVOC_SLICE
@ WRITE_SET_HAVOC_GET_ASSIGNABLE_TARGET
@ WRITE_SET_ADD_FREEABLE
@ WRITE_SET_HAVOC_OBJECT_WHOLE
@ CAR_SET_PTR
type of pointers to sets of CAR
@ WRITE_SET_PTR
type of pointers to descriptors of assignable/freeable sets of locations
Translate functions that specify assignable and freeable targets declaratively into active functions ...
Program Transformation.
Symbol Table + CFG.
#define forall_goto_program_instructions(it, program)
#define Forall_goto_program_instructions(it, program)
const std::string & id2string(const irep_idt &d)
Definition irep.h:44
std::string from_expr(const namespacet &ns, const irep_idt &identifier, const exprt &expr)
std::string from_expr_using_mode(const namespacet &ns, const irep_idt &mode, const exprt &expr)
Formats an expression using the given namespace, using the given mode to retrieve the language printe...
#define UNREACHABLE
This should be used to mark dead code.
Definition invariant.h:525
#define INVARIANT(CONDITION, REASON)
This macro uses the wrapper function 'invariant_violated_string'.
Definition invariant.h:423
const symbol_exprt & to_symbol_expr(const exprt &expr)
Cast an exprt to a symbol_exprt.
Definition std_expr.h:272
const code_typet & to_code_type(const typet &type)
Cast a typet to a code_typet.
Definition std_types.h:788
static symbolt & get_function_symbol(symbol_table_baset &, const irep_idt &function_id)
Returns the symbolt for function_id.
static void inline_function(goto_modelt &goto_model, const irep_idt &function_id, message_handlert &message_handler)
Inlines the given function, aborts on recursive calls during inlining.
static const exprt make_null_check_expr(const exprt &ptr)
Returns the expression expr == NULL.
static const symbolt & create_new_parameter_symbol(symbol_table_baset &, const irep_idt &function_id, const std::string &base_name, const typet &type)
Creates a new parameter symbol for the given function_id.
static void add_parameter(goto_modelt &, const symbolt &symbol, const irep_idt &function_id)
Adds the given symbol as parameter to the function symbol's code_type.
static symbol_exprt create_symbol(symbol_table_baset &, const typet &type, const irep_idt &function_id, const std::string &base_name, const source_locationt &source_location)
Adds a new symbol named function_id::base_name of type type with given attributes in the symbol table...