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preprocessing_util.cpp
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preprocessing_util.cpp
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/*******************************************************************\
Module: 2LS Command Line Options Processing
Author: Peter Schrammel
\*******************************************************************/
/// \file
/// 2LS Command Line Options Processing
#include <util/replace_expr.h>
#include <util/find_symbols.h>
#include <util/arith_tools.h>
#include <analyses/constant_propagator.h>
#include <goto-instrument/unwind.h>
#include <goto-instrument/function.h>
#include <ssa/dynobj_instance_analysis.h>
#include "2ls_parse_options.h"
void twols_parse_optionst::inline_main(goto_modelt &goto_model)
{
goto_programt &main=goto_model.goto_functions.function_map[ID__start].body;
goto_programt::targett target=main.instructions.begin();
while(target!=main.instructions.end())
{
if(target->is_function_call())
{
const code_function_callt &code_function_call=
to_code_function_call(target->code);
irep_idt fname=code_function_call.function().get(ID_identifier);
debug() << "Inlining " << fname << eom;
goto_programt tmp;
tmp.copy_from(goto_model.goto_functions.function_map[fname].body);
(--tmp.instructions.end())->make_skip();
goto_model.goto_functions.function_map.erase(fname);
goto_programt::targett next_target(target);
target->make_skip();
next_target++;
main.instructions.splice(next_target, tmp.instructions);
target=next_target;
}
else
target++;
}
goto_model.goto_functions.update();
goto_model.goto_functions.compute_loop_numbers();
}
void twols_parse_optionst::propagate_constants(goto_modelt &goto_model)
{
namespacet ns(goto_model.symbol_table);
Forall_goto_functions(f_it, goto_model.goto_functions)
{
constant_propagator_ait(f_it->second, ns);
}
}
/// explicitly assign a nondet_symbol to local variables this is required by the
/// unwinder, which would be unable to recognise in which scope variables have
/// been declared
void twols_parse_optionst::nondet_locals(goto_modelt &goto_model)
{
namespacet ns(goto_model.symbol_table);
Forall_goto_functions(f_it, goto_model.goto_functions)
{
Forall_goto_program_instructions(i_it, f_it->second.body)
{
if(i_it->is_decl())
{
const code_declt& decl=to_code_decl(i_it->code);
goto_programt::const_targett next=i_it; ++next;
if(next!=f_it->second.body.instructions.end() &&
next->is_assign() &&
to_code_assign(next->code).lhs().id()==ID_symbol &&
to_symbol_expr(to_code_assign(next->code).lhs())==decl.symbol())
continue;
side_effect_expr_nondett nondet(decl.symbol().type());
goto_programt::targett t=f_it->second.body.insert_after(i_it);
t->make_assignment();
code_assignt c(decl.symbol(), nondet);
t->code.swap(c);
t->source_location=i_it->source_location;
}
}
}
goto_model.goto_functions.update();
}
/// unwind all loops
bool twols_parse_optionst::unwind_goto_into_loop(
goto_modelt &goto_model,
unsigned k)
{
bool result=false;
typedef std::vector<std::pair<goto_programt::targett,
goto_programt::targett> > loopst;
Forall_goto_functions(f_it, goto_model.goto_functions)
{
goto_programt &body=f_it->second.body;
loopst loops;
Forall_goto_program_instructions(i_it, body)
{
if(i_it->is_backwards_goto())
{
goto_programt::targett loop_head=i_it->get_target();
goto_programt::targett loop_exit=i_it;
bool has_goto_into_loop=false;
goto_programt::targett it=loop_head;
if(it!=loop_exit)
it++;
for(; it!=loop_exit; it++)
{
for( std::set<goto_programt::targett>::iterator
s_it=it->incoming_edges.begin();
s_it!=it->incoming_edges.end(); ++s_it)
{
if((*s_it)->is_goto() &&
(*s_it)->location_number<loop_head->location_number)
{
has_goto_into_loop=true;
result=true;
break;
}
}
if(has_goto_into_loop)
break;
}
if(has_goto_into_loop)
{
status() << "Unwinding jump into loop" << eom;
loops.push_back(loopst::value_type(++loop_exit, loop_head));
}
}
}
for(loopst::iterator l_it=loops.begin(); l_it!=loops.end(); ++l_it)
{
std::vector<goto_programt::targett> iteration_points;
goto_unwindt goto_unwind;
goto_unwind.unwind(
body,
l_it->second,
l_it->first,
k,
goto_unwindt::PARTIAL, iteration_points);
assert(iteration_points.size()==2);
goto_programt::targett t=body.insert_before(l_it->first);
t->make_goto();
t->targets.push_back(iteration_points.front());
}
}
goto_model.goto_functions.update();
goto_model.goto_functions.compute_loop_numbers();
return result;
}
/// temporary fix to circumvent ssa_dereference problem
void twols_parse_optionst::remove_multiple_dereferences(
goto_modelt &goto_model,
goto_programt &body,
goto_programt::targett t,
exprt &expr,
unsigned &var_counter,
bool deref_seen)
{
if(expr.id()==ID_member)
{
member_exprt &member_expr=to_member_expr(expr);
if(member_expr.compound().id()==ID_dereference)
{
dereference_exprt &deref_expr=to_dereference_expr(member_expr.compound());
remove_multiple_dereferences(
goto_model, body, t, deref_expr.pointer(), var_counter, true);
if(deref_seen)
{
symbolt new_symbol;
new_symbol.type=member_expr.type();
new_symbol.name="$deref"+i2string(var_counter++);
new_symbol.base_name=new_symbol.name;
new_symbol.pretty_name=new_symbol.name;
goto_model.symbol_table.add(new_symbol);
goto_programt::targett t_new=body.insert_before(t);
t_new->make_assignment();
t_new->code=code_assignt(new_symbol.symbol_expr(), member_expr);
expr=new_symbol.symbol_expr();
for(std::set<goto_programt::targett>::iterator t_it=
t->incoming_edges.begin();
t_it!=t->incoming_edges.end(); ++t_it)
{
if((*t_it)->is_goto() && (*t_it)->get_target()==t)
{
(*t_it)->targets.clear();
(*t_it)->targets.push_back(t_new);
}
}
body.compute_location_numbers();
body.compute_target_numbers();
body.compute_incoming_edges();
}
}
else
Forall_operands(o_it, expr)
remove_multiple_dereferences(
goto_model, body, t, *o_it, var_counter, deref_seen);
}
else
Forall_operands(o_it, expr)
remove_multiple_dereferences(
goto_model, body, t, *o_it, var_counter, deref_seen);
}
/// temporary fix to circumvent ssa_dereference problem
void twols_parse_optionst::remove_multiple_dereferences(goto_modelt &goto_model)
{
unsigned var_counter=0;
namespacet ns(goto_model.symbol_table);
Forall_goto_functions(f_it, goto_model.goto_functions)
{
Forall_goto_program_instructions(i_it, f_it->second.body)
{
if(i_it->is_goto())
{
remove_multiple_dereferences(
goto_model,
f_it->second.body,
i_it,
i_it->guard,
var_counter,
false);
}
else if(i_it->is_assign())
{
remove_multiple_dereferences(
goto_model,
f_it->second.body,
i_it,
to_code_assign(i_it->code).lhs(),
var_counter, false);
remove_multiple_dereferences(
goto_model,
f_it->second.body,
i_it,
to_code_assign(i_it->code).rhs(),
var_counter, false);
}
}
}
}
/// assumes assertions after checking them
void twols_parse_optionst::add_assumptions_after_assertions(
goto_modelt &goto_model)
{
Forall_goto_functions(f_it, goto_model.goto_functions)
{
Forall_goto_program_instructions(i_it, f_it->second.body)
{
if(i_it->is_assert() && !i_it->guard.is_true())
{
goto_programt::targett t_new=f_it->second.body.insert_after(i_it);
t_new->make_assumption(i_it->guard);
f_it->second.body.compute_location_numbers();
f_it->second.body.compute_target_numbers();
f_it->second.body.compute_incoming_edges();
}
}
}
}
/// checks whether the program has threads
bool twols_parse_optionst::has_threads(const goto_modelt &goto_model)
{
namespacet ns(goto_model.symbol_table);
forall_goto_functions(f_it, goto_model.goto_functions)
{
const goto_programt& program=f_it->second.body;
forall_goto_program_instructions(i_it, program)
{
const goto_programt::instructiont &instruction=*i_it;
if(instruction.is_function_call())
{
const code_function_callt &fct=to_code_function_call(instruction.code);
if(fct.function().id()==ID_symbol)
{
const symbol_exprt &fsym=to_symbol_expr(fct.function());
if(ns.lookup(fsym.get_identifier()).base_name=="pthread_create")
return true;
}
}
}
}
return false;
}
/// filter certain assertions for SV-COMP
void twols_parse_optionst::filter_assertions(goto_modelt &goto_model)
{
Forall_goto_functions(f_it, goto_model.goto_functions)
{
goto_programt &program=f_it->second.body;
Forall_goto_program_instructions(i_it, program)
{
if(!i_it->is_assert())
continue;
if(i_it->source_location.get_comment()=="free argument is dynamic object")
i_it->make_skip();
}
}
}
/// insert skip at jump targets if they are goto, assume or assert instructions
void twols_parse_optionst::split_loopheads(goto_modelt &goto_model)
{
Forall_goto_functions(f_it, goto_model.goto_functions)
{
Forall_goto_program_instructions(i_it, f_it->second.body)
{
if(!i_it->is_backwards_goto())
continue;
goto_programt::targett loophead=i_it->get_target();
if(i_it->guard.is_true() && !loophead->is_assert())
continue;
// inserts the skip
goto_programt::targett new_loophead=
f_it->second.body.insert_before(loophead);
new_loophead->make_skip();
new_loophead->source_location=loophead->source_location;
new_loophead->function=i_it->function;
// update jumps to loophead
for(std::set<goto_programt::targett>::iterator j_it=
loophead->incoming_edges.begin();
j_it!=loophead->incoming_edges.end(); j_it++)
{
if(!(*j_it)->is_goto() || (*j_it)->get_target()!=loophead)
continue;
(*j_it)->targets.clear();
(*j_it)->targets.push_back(new_loophead);
}
}
}
}
/// Remove loop head from entry instruction of a function - causes problems with
/// input variables naming. If first instruction is target of back-jump, insert
/// SKIP instruction before.
void twols_parse_optionst::remove_loops_in_entry(goto_modelt &goto_model)
{
Forall_goto_functions(f_it, goto_model.goto_functions)
{
if(f_it->second.body_available() &&
f_it->second.body.instructions.begin()->is_target())
{
auto new_entry=
f_it->second.body.insert_before(f_it->second.body.instructions.begin());
new_entry->function=f_it->first;
new_entry->make_skip();
}
}
}
/// Create symbols for objects pointed by parameters of a function.
void twols_parse_optionst::create_dynamic_objects(goto_modelt &goto_model)
{
Forall_goto_functions(f_it, goto_model.goto_functions)
{
Forall_goto_program_instructions(i_it, f_it->second.body)
{
if(i_it->is_assign())
{
code_assignt &code_assign=to_code_assign(i_it->code);
add_dynamic_object_rec(code_assign.lhs(), goto_model.symbol_table);
add_dynamic_object_rec(code_assign.rhs(), goto_model.symbol_table);
}
}
}
}
/// For each pointer-typed symbol in an expression which is a parameter, create
/// symbol for pointed object in the symbol table.
void twols_parse_optionst::add_dynamic_object_rec(
exprt &expr, symbol_tablet &symbol_table)
{
if(expr.id()==ID_symbol)
{
const symbolt &symbol=
symbol_table.lookup(to_symbol_expr(expr).get_identifier());
if(symbol.is_parameter && symbol.type.id()==ID_pointer)
{
// New symbol
symbolt object_symbol;
object_symbol.base_name=id2string(symbol.base_name)+"'obj";
object_symbol.name=id2string(symbol.name)+"'obj";
const typet &pointed_type=symbol.type.subtype();
// Follow pointed type
if(pointed_type.id()==ID_symbol)
{
const symbolt type_symbol=symbol_table.lookup(
to_symbol_type(pointed_type).get_identifier());
object_symbol.type=type_symbol.type;
}
else
object_symbol.type=pointed_type;
object_symbol.mode=ID_C;
symbol_table.add(object_symbol);
}
}
else
{
Forall_operands(it, expr)
add_dynamic_object_rec(*it, symbol_table);
}
}
/// Split assignments that have same symbolic dereference object on both sides
/// into two separate assignments.
void twols_parse_optionst::split_same_symbolic_object_assignments(
goto_modelt &goto_model)
{
const namespacet ns(goto_model.symbol_table);
unsigned counter=0;
Forall_goto_functions(f_it, goto_model.goto_functions)
{
Forall_goto_program_instructions(i_it, f_it->second.body)
{
if(i_it->is_assign())
{
code_assignt &assign=to_code_assign(i_it->code);
auto lhs_sym_deref=symbolic_dereference(assign.lhs(), ns);
if((lhs_sym_deref.id()==ID_symbol || lhs_sym_deref.id()==ID_member)
&& has_symbolic_deref(lhs_sym_deref))
{
while(lhs_sym_deref.id()==ID_member)
lhs_sym_deref=to_member_expr(lhs_sym_deref).compound();
auto rhs_sym_deref=symbolic_dereference(assign.rhs(), ns);
std::set<symbol_exprt> rhs_symbols;
find_symbols(rhs_sym_deref, rhs_symbols);
if(rhs_symbols.find(to_symbol_expr(lhs_sym_deref))!=rhs_symbols.end())
{
symbolt tmp_symbol;
tmp_symbol.type=assign.lhs().type();
tmp_symbol.name="$symderef_tmp"+i2string(counter++);
tmp_symbol.base_name=tmp_symbol.name;
tmp_symbol.pretty_name=tmp_symbol.name;
goto_model.symbol_table.add(tmp_symbol);
auto new_assign=f_it->second.body.insert_after(i_it);
new_assign->make_assignment();
new_assign->code=code_assignt(
assign.lhs(), tmp_symbol.symbol_expr());
assign.lhs()=tmp_symbol.symbol_expr();
}
}
}
}
}
}
/// Remove dead backwards GOTO instructions (having false as guard)
void twols_parse_optionst::remove_dead_goto(goto_modelt &goto_model)
{
Forall_goto_functions(f_it, goto_model.goto_functions)
{
Forall_goto_program_instructions(i_it, f_it->second.body)
{
if(i_it->is_backwards_goto())
{
if(i_it->guard.is_false())
i_it->make_skip();
}
}
}
}
/// For each allocation site, compute the number of objects that must be used to
/// soundly represent all objects allocated at the given site.
void twols_parse_optionst::compute_dynobj_instances(
const goto_programt &goto_program,
const dynobj_instance_analysist &analysis,
std::map<symbol_exprt, size_t> &instance_counts,
const namespacet &ns)
{
forall_goto_program_instructions(it, goto_program)
{
auto &analysis_value=analysis[it];
for(auto &obj : analysis_value.live_pointers)
{
auto must_alias=analysis_value.must_alias_relations.find(obj.first);
if(must_alias==analysis_value.must_alias_relations.end())
continue;
std::set<size_t> alias_classes;
for(auto &expr : obj.second)
{
size_t n;
must_alias->second.get_number(expr, n);
alias_classes.insert(must_alias->second.find_number(n));
}
if(instance_counts.find(obj.first)==instance_counts.end() ||
instance_counts.at(obj.first)<alias_classes.size())
{
instance_counts[obj.first]=alias_classes.size();
}
}
}
}
/// For each allocation site, split the allocated abstract dynamic object into
/// multiple in order to preserve soundness of the analysis.
void twols_parse_optionst::create_dynobj_instances(
goto_programt &goto_program,
const std::map<symbol_exprt, size_t> &instance_counts,
symbol_tablet &symbol_table)
{
Forall_goto_program_instructions(it, goto_program)
{
if(it->is_assign())
{
auto &assign=to_code_assign(it->code);
if(assign.rhs().get_bool("#malloc_result"))
{
exprt &rhs=assign.rhs();
exprt &abstract_obj=rhs.id()==ID_if ? to_if_expr(rhs).false_case()
: rhs;
exprt &address=abstract_obj.id()==ID_typecast ?
to_typecast_expr(abstract_obj).op() : abstract_obj;
if(address.id()!=ID_address_of)
continue;
exprt &obj=to_address_of_expr(address).object();
if(obj.id()!=ID_symbol)
continue;
if(obj.get_bool("#concrete"))
continue;
if(instance_counts.find(to_symbol_expr(obj))==instance_counts.end())
continue;
size_t count=instance_counts.at(to_symbol_expr(obj));
if(count<=1)
continue;
symbolt obj_symbol=
symbol_table.lookup(to_symbol_expr(obj).get_identifier());
const std::string name=id2string(obj_symbol.name);
const std::string base_name=id2string(obj_symbol.base_name);
std::string suffix="$"+std::to_string(0);
obj_symbol.name=name+suffix;
obj_symbol.base_name=base_name+suffix;
symbol_table.add(obj_symbol);
exprt new_rhs=address_of_exprt(obj_symbol.symbol_expr());
if(abstract_obj.id()==ID_typecast)
new_rhs=typecast_exprt(new_rhs, rhs.type());
new_rhs.set("#malloc_result", true);
for(size_t i=1; i<count; ++i)
{
symbolt nondet;
nondet.type=bool_typet();
nondet.name="$guard#os"+std::to_string(it->location_number)+"#"+
std::to_string(i);
nondet.base_name=nondet.name;
nondet.pretty_name=nondet.name;
symbol_table.add(nondet);
suffix="$"+std::to_string(i);
obj_symbol.name=name+suffix;
obj_symbol.base_name=base_name+suffix;
exprt new_obj=address_of_exprt(obj_symbol.symbol_expr());
if(abstract_obj.id()==ID_typecast)
new_obj=typecast_exprt(new_obj, rhs.type());
new_rhs=if_exprt(
nondet.symbol_expr(), new_obj, new_rhs);
new_rhs.set("#malloc_result", true);
}
abstract_obj=new_rhs;
abstract_obj.set("#malloc_result", true);
}
}
}
}
std::map<symbol_exprt, size_t> twols_parse_optionst::split_dynamic_objects(
goto_modelt &goto_model,
const optionst &options)
{
std::map<symbol_exprt, size_t> dynobj_instances;
Forall_goto_functions(f_it, goto_model.goto_functions)
{
if(!f_it->second.body_available())
continue;
namespacet ns(goto_model.symbol_table);
ssa_value_ait value_analysis(f_it->second, ns, options);
dynobj_instance_analysist do_inst(
f_it->second, ns, options, value_analysis);
compute_dynobj_instances(
f_it->second.body, do_inst, dynobj_instances, ns);
create_dynobj_instances(
f_it->second.body, dynobj_instances, goto_model.symbol_table);
}
return dynobj_instances;
}
/// Assert size of static arrays to be max 50000.
void twols_parse_optionst::limit_array_bounds(goto_modelt &goto_model)
{
Forall_goto_functions(f_it, goto_model.goto_functions)
{
Forall_goto_program_instructions(i_it, f_it->second.body)
{
if(i_it->is_decl())
{
const exprt &symbol=to_code_decl(i_it->code).symbol();
if(symbol.type().id()==ID_array)
{
auto &size_expr=to_array_type(symbol.type()).size();
if(size_expr.id()==ID_constant)
{
int size=std::stoi(
id2string(to_constant_expr(size_expr).get_value()), nullptr, 2);
// @TODO temporary solution - there seems to be a bug in the solver
assert(size<=50000);
}
}
}
}
}
}
void twols_parse_optionst::memory_assert_info(goto_modelt &goto_model)
{
irep_idt file;
irep_idt line;
Forall_goto_functions(f_it, goto_model.goto_functions)
{
Forall_goto_program_instructions(i_it, f_it->second.body)
{
if(!i_it->source_location.get_file().empty())
{
file=i_it->source_location.get_file();
}
if(!i_it->source_location.get_line().empty())
{
line=i_it->source_location.get_line();
}
if(i_it->is_assert())
{
const auto &guard=i_it->guard;
if(guard.id()==ID_equal)
{
if(guard.op0().id()==ID_symbol)
{
const auto &id=id2string(
to_symbol_expr(guard.op0()).get_identifier());
if(id.find("__CPROVER_memory_leak")!=std::string::npos)
{
if(!file.empty())
i_it->source_location.set_file(file);
if(!line.empty())
i_it->source_location.set_line(line);
}
}
}
}
}
}
}
/// Transform comparison of pointers to be non-deterministic if the pointers
/// were freed.
/// This is done by transforming (x op y) into:
/// (x op y) XOR ((freed(x) || nondet) && (freed(y) && nondet))
void make_freed_ptr_comparison_nondet(
goto_modelt &goto_model,
goto_functionst::goto_functiont &fun,
goto_programt::instructionst::iterator loc,
exprt &cond,
const std::set<irep_idt> &typecasted_pointers)
{
if(cond.id()==ID_equal || cond.id()==ID_notequal || cond.id()==ID_le ||
cond.id()==ID_lt || cond.id()==ID_ge || cond.id()==ID_gt)
{
// Check if both operands are either pointers or type-casted pointers
if(cond.op0().id()==ID_symbol && cond.op1().id()==ID_symbol &&
!is_cprover_symbol(cond.op0()) && !is_cprover_symbol(cond.op1()) &&
(cond.op0().type().id()==ID_pointer ||
typecasted_pointers.find(to_symbol_expr(cond.op0()).get_identifier())!=
typecasted_pointers.end()) &&
(cond.op1().type().id()==ID_pointer ||
typecasted_pointers.find(to_symbol_expr(cond.op1()).get_identifier())!=
typecasted_pointers.end()))
{
const symbolt &freed=goto_model.symbol_table.lookup(
"__CPROVER_deallocated");
// LHS != __CPROVER_deallocated
auto lhs_not_freed_cond=notequal_exprt(
typecast_exprt(cond.op0(), freed.type), freed.symbol_expr());
// RHS != __CPROVER_deallocated
auto rhs_not_freed_cond=notequal_exprt(
typecast_exprt(cond.op1(), freed.type), freed.symbol_expr());
// XOR is implemented as ==
cond=equal_exprt(
cond,
and_exprt(
or_exprt(
lhs_not_freed_cond,
side_effect_expr_nondett(bool_typet())),
or_exprt(
rhs_not_freed_cond,
side_effect_expr_nondett(bool_typet()))));
}
}
else if(cond.id()==ID_not)
make_freed_ptr_comparison_nondet(
goto_model, fun, loc, to_not_expr(cond).op(), typecasted_pointers);
}
/// Transform each comparison of pointers so that it has a non-deterministic
/// result if the pointers were freed, since comparison of freed pointers is
/// an undefined behavior.
void twols_parse_optionst::handle_freed_ptr_compare(goto_modelt &goto_model)
{
std::set<irep_idt> typecasted_pointers;
Forall_goto_functions(f_it, goto_model.goto_functions)
{
Forall_goto_program_instructions(i_it, f_it->second.body)
{
if(i_it->is_goto() || i_it->is_assert())
{
auto &guard=i_it->guard;
make_freed_ptr_comparison_nondet(
goto_model, f_it->second, i_it, guard, typecasted_pointers);
}
else if(i_it->is_assign())
{
auto &assign=to_code_assign(i_it->code);
// If a pointer is casted to a non-pointer type (probably an integer),
// save the destination variable into typecasted_pointers
if(assign.lhs().id()==ID_symbol &&
((assign.rhs().id()==ID_typecast &&
to_typecast_expr(assign.rhs()).op().type().id()==ID_pointer &&
assign.lhs().type().id()!=ID_pointer) ||
typecasted_pointers.find(
to_symbol_expr(assign.lhs()).get_identifier())!=
typecasted_pointers.end()))
{
typecasted_pointers.insert(
to_symbol_expr(assign.lhs()).get_identifier());
}
}
}
}
}
/// Add assertions preventing analysis of programs using GCC builtin functions
/// that are not supported and can cause false results.
void twols_parse_optionst::assert_no_builtin_functions(goto_modelt &goto_model)
{
forall_goto_program_instructions(
i_it,
goto_model.goto_functions.function_map.find("_start")->second.body)
{
std::string name=id2string(i_it->source_location.get_function());
assert(
name.find("__builtin_")==std::string::npos &&
name.find("__CPROVER_overflow")==std::string::npos);
if(i_it->is_assign())
{
assert(i_it->code.op1().id()!=ID_popcount);
}
}
}
/// Prevents usage of atexit function which is not supported, yet
/// Must be called before inlining since it will lose the calls
void twols_parse_optionst::assert_no_atexit(goto_modelt &goto_model)
{
forall_goto_functions(f_it, goto_model.goto_functions)
{
forall_goto_program_instructions(i_it, f_it->second.body)
{
if(i_it->is_function_call())
{
auto &call=to_code_function_call(i_it->code);
if(!(call.function().id()==ID_symbol))
continue;
auto &name=id2string(to_symbol_expr(call.function()).get_identifier());
assert(name!="atexit");
}
}
}
}