static_lifetime_init.cpp

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/*******************************************************************\
 
Module:
 
Author: Daniel Kroening, kroening@kroening.com
 
\*******************************************************************/
 
#include "static_lifetime_init.h"
 
#include <util/arith_tools.h>
#include <util/c_types.h>
#include <util/expr_initializer.h>
#include <util/namespace.h>
#include <util/prefix.h>
#include <util/std_code.h>
#include <util/symbol_table.h>
 
#include <set>
 
static optionalt<codet>
static_lifetime_init(const irep_idt &identifier, symbol_tablet &symbol_table)
{
  const namespacet ns(symbol_table);
  const symbolt &symbol = ns.lookup(identifier);
 
  if(!symbol.is_static_lifetime)
    return {};
 
  if(symbol.is_type || symbol.is_macro)
    return {};
 
  // special values
  if(
    identifier == CPROVER_PREFIX "constant_infinity_uint" ||
    identifier == CPROVER_PREFIX "memory" || identifier == "__func__" ||
    identifier == "__FUNCTION__" || identifier == "__PRETTY_FUNCTION__" ||
    identifier == "argc'" || identifier == "argv'" || identifier == "envp'" ||
    identifier == "envp_size'")
    return {};
 
  // just for linking
  if(has_prefix(id2string(identifier), CPROVER_PREFIX "architecture_"))
    return {};
 
  const typet &type = ns.follow(symbol.type);
 
  // check type
  if(type.id() == ID_code || type.id() == ID_empty)
    return {};
 
  if(type.id() == ID_array && to_array_type(type).size().is_nil())
  {
    // C standard 6.9.2, paragraph 5
    // adjust the type to an array of size 1
    symbolt &writable_symbol = symbol_table.get_writeable_ref(identifier);
    writable_symbol.type = type;
    writable_symbol.type.set(ID_size, from_integer(1, size_type()));
  }
 
  if(
    (type.id() == ID_struct || type.id() == ID_union) &&
    to_struct_union_type(type).is_incomplete())
  {
    return {}; // do not initialize
  }
 
  exprt rhs;
 
  if((symbol.value.is_nil() && symbol.is_extern) ||
     symbol.value.id() == ID_nondet)
  {
    if(symbol.value.get_bool(ID_C_no_nondet_initialization))
      return {};
 
    // Nondet initialise if not linked, or if explicitly requested.
    // Compilers would usually complain about the unlinked symbol case.
    const auto nondet = nondet_initializer(symbol.type, symbol.location, ns);
    CHECK_RETURN(nondet.has_value());
    rhs = *nondet;
  }
  else if(symbol.value.is_nil())
  {
    const auto zero = zero_initializer(symbol.type, symbol.location, ns);
    CHECK_RETURN(zero.has_value());
    rhs = *zero;
  }
  else
    rhs = symbol.value;
 
  return code_frontend_assignt{symbol.symbol_expr(), rhs, symbol.location};
}
 
void static_lifetime_init(
  symbol_tablet &symbol_table,
  const source_locationt &source_location)
{
  PRECONDITION(symbol_table.has_symbol(INITIALIZE_FUNCTION));
 
  const namespacet ns(symbol_table);
 
  symbolt &init_symbol = symbol_table.get_writeable_ref(INITIALIZE_FUNCTION);
 
  init_symbol.value=code_blockt();
  init_symbol.value.add_source_location()=source_location;
 
  code_blockt &dest=to_code_block(to_code(init_symbol.value));
 
  // add the magic label to hide
  dest.add(code_labelt(CPROVER_PREFIX "HIDE", code_skipt()));
 
  // do assignments based on "value"
 
  // sort alphabetically for reproducible results
  std::set<std::string> symbols;
 
  for(const auto &symbol_pair : symbol_table.symbols)
  {
    symbols.insert(id2string(symbol_pair.first));
  }
 
  // first do framework variables
  for(const std::string &id : symbols)
    if(has_prefix(id, CPROVER_PREFIX))
    {
      auto code = static_lifetime_init(id, symbol_table);
      if(code.has_value())
        dest.add(std::move(*code));
    }
 
  // now all other variables
  for(const std::string &id : symbols)
    if(!has_prefix(id, CPROVER_PREFIX))
    {
      auto code = static_lifetime_init(id, symbol_table);
      if(code.has_value())
        dest.add(std::move(*code));
    }
 
  // now call designated "initialization" functions
 
  for(const std::string &id : symbols)
  {
    const symbolt &symbol=ns.lookup(id);
 
    if(symbol.type.id() != ID_code)
      continue;
 
    const code_typet &code_type = to_code_type(symbol.type);
    if(
      code_type.return_type().id() == ID_constructor &&
      code_type.parameters().empty())
    {
      dest.add(code_expressiont{side_effect_expr_function_callt{
        symbol.symbol_expr(), {}, code_type.return_type(), source_location}});
    }
  }
}