cprover
accelerate.cpp
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1 /*******************************************************************\
2 
3 Module: Loop Acceleration
4 
5 Author: Matt Lewis
6 
7 \*******************************************************************/
8 
11 
12 #include "accelerate.h"
13 
14 #include <analyses/natural_loops.h>
15 
17 
18 #include <util/arith_tools.h>
19 #include <util/find_symbols.h>
20 #include <util/std_code.h>
21 #include <util/std_expr.h>
22 
23 #include <iostream>
24 #include <list>
25 
26 #include "accelerator.h"
28 #include "overflow_instrumenter.h"
29 #include "path.h"
30 #include "scratch_program.h"
31 #include "util.h"
32 
34  goto_programt::targett loop_header)
35 {
37  natural_loops.loop_map.at(loop_header);
38  goto_programt::targett back_jump=loop_header;
39 
40  for(const auto &t : loop)
41  {
42  if(
43  t->is_goto() && t->get_condition().is_true() && t->targets.size() == 1 &&
44  t->targets.front() == loop_header &&
45  t->location_number > back_jump->location_number)
46  {
47  back_jump=t;
48  }
49  }
50 
51  return back_jump;
52 }
53 
55 {
57  natural_loops.loop_map.at(loop_header);
58 
59  for(const auto &t : loop)
60  {
61  if(t->is_backwards_goto())
62  {
63  if(t->targets.size()!=1 ||
64  t->get_target()!=loop_header)
65  {
66  return true;
67  }
68  }
69 
70  // Header of some other loop?
71  if(t != loop_header && natural_loops.is_loop_header(t))
72  {
73  return true;
74  }
75  }
76 
77  return false;
78 }
79 
81 {
82  pathst loop_paths, exit_paths;
83  goto_programt::targett back_jump=find_back_jump(loop_header);
84  int num_accelerated=0;
85  std::list<path_acceleratort> accelerators;
87  natural_loops.loop_map.at(loop_header);
88 
89  if(contains_nested_loops(loop_header))
90  {
91  // For now, only accelerate innermost loops.
92 #ifdef DEBUG
93  std::cout << "Not accelerating an outer loop\n";
94 #endif
95  return 0;
96  }
97 
98  goto_programt::targett overflow_loc;
99  make_overflow_loc(loop_header, back_jump, overflow_loc);
100  program.update();
101 
102 #if 1
103  enumerating_loop_accelerationt acceleration(
105  symbol_table,
107  program,
108  loop,
109  loop_header,
111  guard_manager);
112 #else
114  acceleration(symbol_table, goto_functions, program, loop, loop_header);
115 #endif
116 
117  path_acceleratort accelerator;
118 
119  while(acceleration.accelerate(accelerator) &&
120  (accelerate_limit < 0 ||
121  num_accelerated < accelerate_limit))
122  {
123  // set_dirty_vars(accelerator);
124 
125  if(is_underapproximate(accelerator))
126  {
127  // We have some underapproximated variables -- just punt for now.
128 #ifdef DEBUG
129  std::cout << "Not inserting accelerator because of underapproximation\n";
130 #endif
131 
132  continue;
133  }
134 
135  accelerators.push_back(accelerator);
136  num_accelerated++;
137 
138 #ifdef DEBUG
139  std::cout << "Accelerated path:\n";
140  output_path(accelerator.path, program, ns, std::cout);
141 
142  std::cout << "Accelerator has "
143  << accelerator.pure_accelerator.instructions.size()
144  << " instructions\n";
145 #endif
146  }
147 
149  program.insert_before_swap(loop_header, skip);
150 
151  goto_programt::targett new_inst=loop_header;
152  ++new_inst;
153 
154  loop.insert_instruction(new_inst);
155 
156  std::cout << "Overflow loc is " << overflow_loc->location_number << '\n';
157  std::cout << "Back jump is " << back_jump->location_number << '\n';
158 
159  for(std::list<path_acceleratort>::iterator it=accelerators.begin();
160  it!=accelerators.end();
161  ++it)
162  {
163  subsumed_patht inserted(it->path);
164 
165  insert_accelerator(loop_header, back_jump, *it, inserted);
166  subsumed.push_back(inserted);
167  num_accelerated++;
168  }
169 
170  return num_accelerated;
171 }
172 
174  goto_programt::targett &loop_header,
175  goto_programt::targett &back_jump,
176  path_acceleratort &accelerator,
177  subsumed_patht &subsumed_path)
178 {
180  loop_header,
181  back_jump,
182  accelerator.pure_accelerator,
183  subsumed_path.accelerator);
184 
185  if(!accelerator.overflow_path.instructions.empty())
186  {
188  loop_header, back_jump, accelerator.overflow_path, subsumed_path.residue);
189  }
190 }
191 
192 /*
193  * Insert a looping path (usually an accelerator) into a goto-program,
194  * beginning at loop_header and jumping back to loop_header via back_jump.
195  * Stores the locations at which the looping path was added in inserted_path.
196  *
197  * THIS DESTROYS looping_path!!
198  */
200  goto_programt::targett &loop_header,
201  goto_programt::targett &back_jump,
202  goto_programt &looping_path,
203  patht &inserted_path)
204 {
205  goto_programt::targett loop_body=loop_header;
206  ++loop_body;
207 
209  loop_body,
211  loop_body,
213  loop_body->source_location()));
214 
215  program.destructive_insert(loop_body, looping_path);
216 
217  jump = program.insert_before(
218  loop_body, goto_programt::make_goto(back_jump, true_exprt()));
219 
220  for(goto_programt::targett t=loop_header;
221  t!=loop_body;
222  ++t)
223  {
224  inserted_path.push_back(path_nodet(t));
225  }
226 
227  inserted_path.push_back(path_nodet(back_jump));
228 }
229 
231  goto_programt::targett loop_header,
232  goto_programt::targett &loop_end,
233  goto_programt::targett &overflow_loc)
234 {
235  symbolt overflow_sym=utils.fresh_symbol("accelerate::overflow", bool_typet());
236  const exprt &overflow_var=overflow_sym.symbol_expr();
238  natural_loops.loop_map.at(loop_header);
239  overflow_instrumentert instrumenter(program, overflow_var, symbol_table);
240 
241  for(const auto &loop_instruction : loop)
242  {
243  overflow_locs[loop_instruction] = goto_programt::targetst();
244  goto_programt::targetst &added = overflow_locs[loop_instruction];
245 
246  instrumenter.add_overflow_checks(loop_instruction, added);
247  for(const auto &new_instruction : added)
248  loop.insert_instruction(new_instruction);
249  }
250 
252  loop_header,
254  t->swap(*loop_header);
255  loop.insert_instruction(t);
256  overflow_locs[loop_header].push_back(t);
257 
258  overflow_loc = program.insert_after(loop_end, goto_programt::make_skip());
259  overflow_loc->swap(*loop_end);
260  loop.insert_instruction(overflow_loc);
261 
263  loop_end, goto_programt::make_goto(overflow_loc, not_exprt(overflow_var)));
264  t2->swap(*loop_end);
265  overflow_locs[overflow_loc].push_back(t2);
266  loop.insert_instruction(t2);
267 
268  goto_programt::targett tmp=overflow_loc;
269  overflow_loc=loop_end;
270  loop_end=tmp;
271 }
272 
274 {
275  trace_automatont automaton(program);
276 
277  for(subsumed_pathst::iterator it=subsumed.begin();
278  it!=subsumed.end();
279  ++it)
280  {
281  if(!it->subsumed.empty())
282  {
283 #ifdef DEBUG
285  std::cout << "Restricting path:\n";
286  output_path(it->subsumed, program, ns, std::cout);
287 #endif
288 
289  automaton.add_path(it->subsumed);
290  }
291 
292  patht double_accelerator;
293  patht::iterator jt=double_accelerator.begin();
294  double_accelerator.insert(
295  jt, it->accelerator.begin(), it->accelerator.end());
296  double_accelerator.insert(
297  jt, it->accelerator.begin(), it->accelerator.end());
298 
299 #ifdef DEBUG
301  std::cout << "Restricting path:\n";
302  output_path(double_accelerator, program, ns, std::cout);
303 #endif
304  automaton.add_path(double_accelerator);
305  }
306 
307  std::cout << "Building trace automaton...\n";
308 
309  automaton.build();
310  insert_automaton(automaton);
311 }
312 
314 {
315  for(std::set<exprt>::iterator it=accelerator.dirty_vars.begin();
316  it!=accelerator.dirty_vars.end();
317  ++it)
318  {
319  expr_mapt::iterator jt=dirty_vars_map.find(*it);
320  exprt dirty_var;
321 
322  if(jt==dirty_vars_map.end())
323  {
325  symbolt new_sym=utils.fresh_symbol("accelerate::dirty", bool_typet());
326  dirty_var=new_sym.symbol_expr();
327  dirty_vars_map[*it]=dirty_var;
328  }
329  else
330  {
331  dirty_var=jt->second;
332  }
333 
334 #ifdef DEBUG
335  std::cout << "Setting dirty flag " << expr2c(dirty_var, ns)
336  << " for " << expr2c(*it, ns) << '\n';
337 #endif
338 
339  accelerator.pure_accelerator.add(
341  }
342 }
343 
345 {
346  for(expr_mapt::iterator it=dirty_vars_map.begin();
347  it!=dirty_vars_map.end();
348  ++it)
349  {
353  }
354 
356 
358  it!=program.instructions.end();
359  it=next)
360  {
361  next=it;
362  ++next;
363 
364  // If this is an assign to a tracked variable, clear the dirty flag.
365  // Note: this order of insertions means that we assume each of the read
366  // variables is clean _before_ clearing any dirty flags.
367  if(it->is_assign())
368  {
369  const exprt &lhs = it->assign_lhs();
370  expr_mapt::iterator dirty_var=dirty_vars_map.find(lhs);
371 
372  if(dirty_var!=dirty_vars_map.end())
373  {
375  code_assignt(dirty_var->second, false_exprt()));
376  program.insert_before_swap(it, clear_flag);
377  }
378  }
379 
380  // Find which symbols are read, i.e. those appearing in a guard or on
381  // the right hand side of an assignment. Assume each is not dirty.
382  find_symbols_sett read;
383 
384  if(it->has_condition())
385  find_symbols_or_nexts(it->get_condition(), read);
386 
387  if(it->is_assign())
388  {
389  find_symbols_or_nexts(it->assign_rhs(), read);
390  }
391 
392  for(find_symbols_sett::iterator jt=read.begin();
393  jt!=read.end();
394  ++jt)
395  {
396  const exprt &var=ns.lookup(*jt).symbol_expr();
397  expr_mapt::iterator dirty_var=dirty_vars_map.find(var);
398 
399  if(dirty_var==dirty_vars_map.end())
400  {
401  continue;
402  }
403 
404  goto_programt::instructiont not_dirty =
405  goto_programt::make_assumption(not_exprt(dirty_var->second));
406  program.insert_before_swap(it, not_dirty);
407  }
408  }
409 }
410 
412 {
413  for(std::set<exprt>::iterator it=accelerator.dirty_vars.begin();
414  it!=accelerator.dirty_vars.end();
415  ++it)
416  {
417  if(it->id()==ID_symbol && it->type() == bool_typet())
418  {
419  const irep_idt &id=to_symbol_expr(*it).get_identifier();
420  const symbolt &sym = symbol_table.lookup_ref(id);
421 
422  if(sym.module=="scratch")
423  {
424  continue;
425  }
426  }
427 
428 #ifdef DEBUG
429  std::cout << "Underapproximate variable: " << expr2c(*it, ns) << '\n';
430 #endif
431  return true;
432  }
433 
434  return false;
435 }
436 
437 symbolt acceleratet::make_symbol(std::string name, typet type)
438 {
439  symbolt ret;
440  ret.module="accelerate";
441  ret.name=name;
442  ret.base_name=name;
443  ret.pretty_name=name;
444  ret.type=type;
445 
446  symbol_table.add(ret);
447 
448  return ret;
449 }
450 
452 {
453 #if 0
455  code_declt code(sym);
456 
457  decl->make_decl();
458  decl->code=code;
459 #endif
460 }
461 
463 {
464  decl(sym, t);
465 
468 }
469 
471 {
472  symbolt state_sym=make_symbol("trace_automaton::state",
474  symbolt next_state_sym=make_symbol("trace_automaton::next_state",
476  symbol_exprt state=state_sym.symbol_expr();
477  symbol_exprt next_state=next_state_sym.symbol_expr();
478 
479  trace_automatont::sym_mapt transitions;
480  state_sett accept_states;
481 
482  automaton.get_transitions(transitions);
483  automaton.accept_states(accept_states);
484 
485  std::cout
486  << "Inserting trace automaton with "
487  << automaton.num_states() << " states, "
488  << accept_states.size() << " accepting states and "
489  << transitions.size() << " transitions\n";
490 
491  // Declare the variables we'll use to encode the state machine.
493  decl(state, t, from_integer(automaton.init_state(), state.type()));
494  decl(next_state, t);
495 
496  // Now for each program location that appears as a symbol in the
497  // trace automaton, add the appropriate code to drive the state
498  // machine.
499  for(const auto &sym : automaton.alphabet)
500  {
501  scratch_programt state_machine{
503  trace_automatont::sym_range_pairt p=transitions.equal_range(sym);
504 
505  build_state_machine(p.first, p.second, accept_states, state, next_state,
506  state_machine);
507 
508  program.insert_before_swap(sym, state_machine);
509  }
510 }
511 
513  trace_automatont::sym_mapt::iterator begin,
514  trace_automatont::sym_mapt::iterator end,
515  state_sett &accept_states,
516  symbol_exprt state,
517  symbol_exprt next_state,
518  scratch_programt &state_machine)
519 {
520  std::map<unsigned int, unsigned int> successor_counts;
521  unsigned int max_count=0;
522  unsigned int likely_next=0;
523 
524  // Optimisation: find the most common successor state and initialise
525  // next_state to that value. This reduces the size of the state machine
526  // driver substantially.
527  for(trace_automatont::sym_mapt::iterator p=begin; p!=end; ++p)
528  {
529  trace_automatont::state_pairt state_pair=p->second;
530  unsigned int to=state_pair.second;
531  unsigned int count=0;
532 
533  if(successor_counts.find(to)==successor_counts.end())
534  {
535  count=1;
536  }
537  else
538  {
539  count=successor_counts[to] + 1;
540  }
541 
542  successor_counts[to]=count;
543 
544  if(count > max_count)
545  {
546  max_count=count;
547  likely_next=to;
548  }
549  }
550 
551  // Optimisation: if there is only one possible successor state, just
552  // jump straight to it instead of driving the whole machine.
553  if(successor_counts.size()==1)
554  {
555  if(accept_states.find(likely_next)!=accept_states.end())
556  {
557  // It's an accept state. Just assume(false).
558  state_machine.assume(false_exprt());
559  }
560  else
561  {
562  state_machine.assign(state,
563  from_integer(likely_next, next_state.type()));
564  }
565 
566  return;
567  }
568 
569  state_machine.assign(next_state,
570  from_integer(likely_next, next_state.type()));
571 
572  for(trace_automatont::sym_mapt::iterator p=begin; p!=end; ++p)
573  {
574  trace_automatont::state_pairt state_pair=p->second;
575  unsigned int from=state_pair.first;
576  unsigned int to=state_pair.second;
577 
578  if(to==likely_next)
579  {
580  continue;
581  }
582 
583  // We're encoding the transition
584  //
585  // from -loc-> to
586  //
587  // which we encode by inserting:
588  //
589  // next_state=(state==from) ? to : next_state;
590  //
591  // just before loc.
592  equal_exprt guard(state, from_integer(from, state.type()));
593  if_exprt rhs(guard, from_integer(to, next_state.type()), next_state);
594  state_machine.assign(next_state, rhs);
595  }
596 
597  // Update the state and assume(false) if we've hit an accept state.
598  state_machine.assign(state, next_state);
599 
600  for(state_sett::iterator it=accept_states.begin();
601  it!=accept_states.end();
602  ++it)
603  {
604  state_machine.assume(
605  not_exprt(equal_exprt(state, from_integer(*it, state.type()))));
606  }
607 }
608 
610 {
611  int num_accelerated=0;
612 
613  for(natural_loops_mutablet::loop_mapt::iterator it =
614  natural_loops.loop_map.begin();
615  it!=natural_loops.loop_map.end();
616  ++it)
617  {
618  goto_programt::targett t=it->first;
619  num_accelerated += accelerate_loop(t);
620  }
621 
622  program.update();
623 
624  if(num_accelerated > 0)
625  {
626  std::cout << "Engaging crush mode...\n";
627 
628  restrict_traces();
629  // add_dirty_checks();
630  program.update();
631 
632  std::cout << "Crush mode engaged.\n";
633  }
634 
635  return num_accelerated;
636 }
637 
639  goto_modelt &goto_model,
640  message_handlert &message_handler,
641  bool use_z3,
642  guard_managert &guard_manager)
643 {
644  for(auto &gf_entry : goto_model.goto_functions.function_map)
645  {
646  std::cout << "Accelerating function " << gf_entry.first << '\n';
647  acceleratet accelerate(
648  gf_entry.second.body, goto_model, message_handler, use_z3, guard_manager);
649 
650  int num_accelerated=accelerate.accelerate_loops();
651 
652  if(num_accelerated > 0)
653  {
654  std::cout << "Added " << num_accelerated
655  << " accelerator(s)\n";
656  }
657  }
658 }
void accelerate_functions(goto_modelt &goto_model, message_handlert &message_handler, bool use_z3, guard_managert &guard_manager)
Definition: accelerate.cpp:638
Loop Acceleration.
Loop Acceleration.
constant_exprt from_integer(const mp_integer &int_value, const typet &type)
Definition: arith_tools.cpp:99
void add_dirty_checks()
Definition: accelerate.cpp:344
void insert_accelerator(goto_programt::targett &loop_header, goto_programt::targett &back_jump, path_acceleratort &accelerator, subsumed_patht &subsumed_path)
Definition: accelerate.cpp:173
void insert_automaton(trace_automatont &automaton)
Definition: accelerate.cpp:470
acceleration_utilst utils
Definition: accelerate.h:118
goto_programt & program
Definition: accelerate.h:111
symbolt make_symbol(std::string name, typet type)
Definition: accelerate.cpp:437
natural_loops_mutablet natural_loops
Definition: accelerate.h:116
message_handlert & message_handler
Definition: accelerate.h:57
void decl(symbol_exprt &sym, goto_programt::targett t)
Definition: accelerate.cpp:451
symbol_tablet & symbol_table
Definition: accelerate.h:113
expr_mapt dirty_vars_map
Definition: accelerate.h:124
subsumed_pathst subsumed
Definition: accelerate.h:117
int accelerate_loops()
Definition: accelerate.cpp:609
bool contains_nested_loops(goto_programt::targett &loop_header)
Definition: accelerate.cpp:54
void build_state_machine(trace_automatont::sym_mapt::iterator p, trace_automatont::sym_mapt::iterator end, state_sett &accept_states, symbol_exprt state, symbol_exprt next_state, scratch_programt &state_machine)
Definition: accelerate.cpp:512
void make_overflow_loc(goto_programt::targett loop_header, goto_programt::targett &loop_end, goto_programt::targett &overflow_loc)
Definition: accelerate.cpp:230
void restrict_traces()
Definition: accelerate.cpp:273
overflow_mapt overflow_locs
Definition: accelerate.h:122
namespacet ns
Definition: accelerate.h:115
void set_dirty_vars(path_acceleratort &accelerator)
Definition: accelerate.cpp:313
goto_functionst & goto_functions
Definition: accelerate.h:112
bool is_underapproximate(path_acceleratort &accelerator)
Definition: accelerate.cpp:411
static const int accelerate_limit
Definition: accelerate.h:54
goto_programt::targett find_back_jump(goto_programt::targett loop_header)
Definition: accelerate.cpp:33
guard_managert & guard_manager
Definition: accelerate.h:114
void insert_looping_path(goto_programt::targett &loop_header, goto_programt::targett &back_jump, goto_programt &looping_path, patht &inserted_path)
Definition: accelerate.cpp:199
int accelerate_loop(goto_programt::targett &loop_header)
Definition: accelerate.cpp:80
symbolt fresh_symbol(std::string base, typet type)
The Boolean type.
Definition: std_types.h:36
A codet representing an assignment in the program.
A codet representing the declaration of a local variable.
dstringt has one field, an unsigned integer no which is an index into a static table of strings.
Definition: dstring.h:37
bool accelerate(path_acceleratort &accelerator)
Equality.
Definition: std_expr.h:1225
Base class for all expressions.
Definition: expr.h:54
const source_locationt & source_location() const
Definition: expr.h:230
typet & type()
Return the type of the expression.
Definition: expr.h:82
The Boolean constant false.
Definition: std_expr.h:2865
function_mapt function_map
goto_functionst goto_functions
GOTO functions.
Definition: goto_model.h:33
This class represents an instruction in the GOTO intermediate representation.
Definition: goto_program.h:180
A generic container class for the GOTO intermediate representation of one function.
Definition: goto_program.h:73
static instructiont make_assumption(const exprt &g, const source_locationt &l=source_locationt::nil())
Definition: goto_program.h:934
instructionst instructions
The list of instructions in the goto program.
Definition: goto_program.h:598
void update()
Update all indices.
void insert_before_swap(targett target)
Insertion that preserves jumps to "target".
Definition: goto_program.h:619
void destructive_insert(const_targett target, goto_programt &p)
Inserts the given program p before target.
Definition: goto_program.h:706
instructionst::iterator targett
Definition: goto_program.h:592
static instructiont make_assignment(const code_assignt &_code, const source_locationt &l=source_locationt::nil())
Create an assignment instruction.
static instructiont make_skip(const source_locationt &l=source_locationt::nil())
Definition: goto_program.h:880
targett insert_after(const_targett target)
Insertion after the instruction pointed-to by the given instruction iterator target.
Definition: goto_program.h:684
targett add(instructiont &&instruction)
Adds a given instruction at the end.
Definition: goto_program.h:715
static instructiont make_goto(targett _target, const source_locationt &l=source_locationt::nil())
targett insert_before(const_targett target)
Insertion before the instruction pointed-to by the given instruction iterator target.
Definition: goto_program.h:668
std::list< targett > targetst
Definition: goto_program.h:594
The trinary if-then-else operator.
Definition: std_expr.h:2226
bool is_loop_header(const T instruction) const
Returns true if instruction is the header of any loop.
Definition: loop_analysis.h:93
loop_mapt loop_map
Definition: loop_analysis.h:88
A loop, specified as a set of instructions.
Definition: loop_analysis.h:24
bool insert_instruction(const T instruction)
Adds instruction to this loop.
Definition: loop_analysis.h:74
A namespacet is essentially one or two symbol tables bound together, to allow for symbol lookups in t...
Definition: namespace.h:91
bool lookup(const irep_idt &name, const symbolt *&symbol) const override
See documentation for namespace_baset::lookup().
Definition: namespace.cpp:138
Boolean negation.
Definition: std_expr.h:2181
goto_programt overflow_path
Definition: accelerator.h:64
std::set< exprt > dirty_vars
Definition: accelerator.h:66
goto_programt pure_accelerator
Definition: accelerator.h:63
targett assume(const exprt &guard)
targett assign(const exprt &lhs, const exprt &rhs)
A side_effect_exprt that returns a non-deterministically chosen value.
Definition: std_code.h:1520
patht residue
Definition: subsumed.h:30
patht accelerator
Definition: subsumed.h:29
Expression to hold a symbol (variable)
Definition: std_expr.h:80
const irep_idt & get_identifier() const
Definition: std_expr.h:109
const symbolt & lookup_ref(const irep_idt &name) const
Find a symbol in the symbol table for read-only access.
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
irep_idt module
Name of module the symbol belongs to.
Definition: symbol.h:43
class symbol_exprt symbol_expr() const
Produces a symbol_exprt for a symbol.
Definition: symbol.cpp:121
typet type
Type of symbol.
Definition: symbol.h:31
irep_idt name
The unique identifier.
Definition: symbol.h:40
irep_idt pretty_name
Language-specific display name.
Definition: symbol.h:52
void get_transitions(sym_mapt &transitions)
void accept_states(state_sett &states)
std::multimap< goto_programt::targett, state_pairt > sym_mapt
std::pair< sym_mapt::iterator, sym_mapt::iterator > sym_range_pairt
std::pair< statet, statet > state_pairt
unsigned num_states()
void add_path(patht &path)
The Boolean constant true.
Definition: std_expr.h:2856
The type of an expression, extends irept.
Definition: type.h:29
const source_locationt & source_location() const
Definition: type.h:74
std::string expr2c(const exprt &expr, const namespacet &ns, const expr2c_configurationt &configuration)
Definition: expr2c.cpp:4011
void find_symbols_or_nexts(const exprt &src, find_symbols_sett &dest)
Add to the set dest the sub-expressions of src with id ID_symbol or ID_next_symbol.
std::unordered_set< irep_idt > find_symbols_sett
Definition: find_symbols.h:21
Goto Programs with Functions.
@ SKIP
Definition: goto_program.h:38
Compute natural loops in a goto_function.
Loop Acceleration.
void output_path(const patht &path, const goto_programt &program, const namespacet &ns, std::ostream &str)
Definition: path.cpp:16
Loop Acceleration.
std::list< patht > pathst
Definition: path.h:45
std::list< path_nodet > patht
Definition: path.h:44
Loop Acceleration.
API to expression classes.
const symbol_exprt & to_symbol_expr(const exprt &expr)
Cast an exprt to a symbol_exprt.
Definition: std_expr.h:189
This is unused by this implementation of guards, but can be used by other implementations of the same...
Definition: guard_expr.h:20
std::set< statet > state_sett
unsignedbv_typet unsigned_poly_type()
Definition: util.cpp:25
Loop Acceleration.