nondet_static.cpp

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/*******************************************************************\
 
Module: Nondeterministically initializes global scope variables, except for
 constants (such as string literals, final fields) and internal variables
 (such as CPROVER and symex variables, language specific internal
 variables).
 
Author: Daniel Kroening, Michael Tautschnig
 
Date: November 2011
 
\*******************************************************************/
 
 
#include "nondet_static.h"
 
#include <util/prefix.h>
#include <util/std_code.h>
 
#include <goto-programs/goto_model.h>
 
#include <linking/static_lifetime_init.h>
 
bool is_nondet_initializable_static(
  const symbol_exprt &symbol_expr,
  const namespacet &ns)
{
  const irep_idt &id = symbol_expr.get_identifier();
 
  // is it a __CPROVER_* variable?
  if(has_prefix(id2string(id), CPROVER_PREFIX))
    return false;
 
  // variable not in symbol table such as symex variable?
  if(!ns.get_symbol_table().has_symbol(id))
    return false;
 
  const symbolt &symbol = ns.lookup(id);
 
  // is the symbol explicitly marked as not to be nondet initialized?
  if(symbol.value.get_bool(ID_C_no_nondet_initialization))
  {
    return false;
  }
 
  // is the type explicitly marked as not to be nondet initialized?
  if(symbol.type.get_bool(ID_C_no_nondet_initialization))
    return false;
 
  // is the type explicitly marked as not to be initialized?
  if(symbol.type.get_bool(ID_C_no_initialization_required))
    return false;
 
  // static lifetime?
  if(!symbol.is_static_lifetime)
    return false;
 
  // constant?
  return !is_constant_or_has_constant_components(symbol_expr.type(), ns) &&
         !is_constant_or_has_constant_components(symbol.type, ns);
}
 
static void nondet_static(
  const namespacet &ns,
  goto_functionst &goto_functions,
  const irep_idt &fct_name)
{
  goto_functionst::function_mapt::iterator fct_entry =
    goto_functions.function_map.find(fct_name);
  CHECK_RETURN(fct_entry != goto_functions.function_map.end());
 
  goto_programt &init = fct_entry->second.body;
 
  for(auto &instruction : init.instructions)
  {
    if(instruction.is_assign())
    {
      const symbol_exprt sym =
        to_symbol_expr(as_const(instruction).assign_lhs());
 
      if(is_nondet_initializable_static(sym, ns))
      {
        const auto source_location = instruction.source_location();
        instruction = goto_programt::make_assignment(
          code_assignt(
            sym, side_effect_expr_nondett(sym.type(), source_location)),
          source_location);
      }
    }
    else if(instruction.is_function_call())
    {
      const symbol_exprt &fsym = to_symbol_expr(instruction.call_function());
 
      if(has_prefix(id2string(fsym.get_identifier()), "#ini#"))
        nondet_static(ns, goto_functions, fsym.get_identifier());
    }
  }
 
  // update counters etc.
  goto_functions.update();
}
 
void nondet_static(const namespacet &ns, goto_functionst &goto_functions)
{
  nondet_static(ns, goto_functions, INITIALIZE_FUNCTION);
}
 
void nondet_static(goto_modelt &goto_model)
{
  const namespacet ns(goto_model.symbol_table);
  nondet_static(ns, goto_model.goto_functions);
}
 
void nondet_static(
  goto_modelt &goto_model,
  const std::set<std::string> &except_values)
{
  const namespacet ns(goto_model.symbol_table);
  std::set<std::string> to_exclude;
 
  for(auto const &except : except_values)
  {
    const bool file_prefix_found = except.find(":") != std::string::npos;
 
    if(file_prefix_found)
    {
      to_exclude.insert(except);
      if(has_prefix(except, "./"))
      {
        to_exclude.insert(except.substr(2, except.length() - 2));
      }
      else
      {
        to_exclude.insert("./" + except);
      }
    }
    else
    {
      irep_idt symbol_name(except);
      symbolt lookup_results = ns.lookup(symbol_name);
      to_exclude.insert(
        id2string(lookup_results.location.get_file()) + ":" + except);
    }
  }
 
  symbol_tablet &symbol_table = goto_model.symbol_table;
 
  for(symbol_tablet::iteratort symbol_it = symbol_table.begin();
      symbol_it != symbol_table.end();
      symbol_it++)
  {
    symbolt &symbol = symbol_it.get_writeable_symbol();
    std::string qualified_name = id2string(symbol.location.get_file()) + ":" +
                                 id2string(symbol.display_name());
    if(to_exclude.find(qualified_name) != to_exclude.end())
    {
      symbol.value.set(ID_C_no_nondet_initialization, 1);
    }
    else if(is_nondet_initializable_static(symbol.symbol_expr(), ns))
    {
      symbol.value = side_effect_expr_nondett(symbol.type, symbol.location);
    }
  }
 
  nondet_static(ns, goto_model.goto_functions, INITIALIZE_FUNCTION);
}