link_to_library.cpp

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/*******************************************************************\
 
Module: Library Linking
 
Author: Daniel Kroening, kroening@kroening.com
 
\*******************************************************************/
 
 
#include "link_to_library.h"
 
#include <goto-programs/compute_called_functions.h>
#include <goto-programs/goto_model.h>
#include <goto-programs/link_goto_model.h>
 
#include <linking/static_lifetime_init.h>
 
#include "goto_convert_functions.h"
 
static std::pair<std::optional<replace_symbolt::expr_mapt>, bool>
add_one_function(
  goto_modelt &goto_model,
  message_handlert &message_handler,
  const std::function<void(
    const std::set<irep_idt> &,
    const symbol_tablet &,
    symbol_tablet &,
    message_handlert &)> &library,
  const irep_idt &missing_function)
{
  goto_modelt library_model;
  library(
    {missing_function},
    goto_model.symbol_table,
    library_model.symbol_table,
    message_handler);
 
  // convert to CFG
  if(
    library_model.symbol_table.symbols.find(missing_function) !=
      library_model.symbol_table.symbols.end() &&
    library_model.symbol_table.lookup_ref(missing_function).value.is_not_nil())
  {
    goto_convert(
      missing_function,
      library_model.symbol_table,
      library_model.goto_functions,
      message_handler);
    // this function is now included in goto_functions, no need to re-convert
    // should the goto binary be reloaded
    library_model.symbol_table.get_writeable_ref(missing_function)
      .set_compiled();
  }
  // We might need a function that's outside our own library, but brought in via
  // some header file included by the library. Those functions already exist in
  // goto_model.symbol_table, but haven't been converted just yet.
  else if(
    goto_model.symbol_table.symbols.find(missing_function) !=
      goto_model.symbol_table.symbols.end() &&
    goto_model.symbol_table.lookup_ref(missing_function).value.is_not_nil() &&
    !goto_model.symbol_table.lookup_ref(missing_function).is_compiled())
  {
    goto_convert(
      missing_function,
      goto_model.symbol_table,
      library_model.goto_functions,
      message_handler);
    // this function is now included in goto_functions, no need to re-convert
    // should the goto binary be reloaded
    goto_model.symbol_table.get_writeable_ref(missing_function).set_compiled();
  }
 
  // check whether additional initialization may be required
  bool init_required = false;
  if(
    goto_model.goto_functions.function_map.find(INITIALIZE_FUNCTION) !=
    goto_model.goto_functions.function_map.end())
  {
    for(const auto &entry : library_model.symbol_table)
    {
      if(
        entry.second.is_static_lifetime && !entry.second.is_type &&
        !entry.second.is_macro && entry.second.type.id() != ID_code &&
        !goto_model.symbol_table.has_symbol(entry.first))
      {
        init_required = true;
        break;
      }
    }
  }
 
  return {
    link_goto_model(goto_model, std::move(library_model), message_handler),
    init_required};
}
 
void link_to_library(
  goto_modelt &goto_model,
  message_handlert &message_handler,
  const std::function<void(
    const std::set<irep_idt> &,
    const symbol_tablet &,
    symbol_tablet &,
    message_handlert &)> &library)
{
  // this needs a fixedpoint, as library functions
  // may depend on other library functions
 
  std::set<irep_idt> added_functions;
  // Linking in library functions (now seeing full definitions rather than
  // forward declarations, or perhaps even cases of missing forward
  // declarations) may result in type changes to objects.
  replace_symbolt::expr_mapt object_type_updates;
  bool need_reinit = false;
 
  while(true)
  {
    std::unordered_set<irep_idt> called_functions =
      compute_called_functions(goto_model.goto_functions);
 
    bool changed = false;
    for(const auto &id : called_functions)
    {
      goto_functionst::function_mapt::const_iterator f_it =
        goto_model.goto_functions.function_map.find(id);
 
      if(
        f_it != goto_model.goto_functions.function_map.end() &&
        f_it->second.body_available())
      {
        // it's overridden!
      }
      else if(added_functions.find(id) != added_functions.end())
      {
        // already added
      }
      else
      {
        changed = true;
        added_functions.insert(id);
 
        auto one_result =
          add_one_function(goto_model, message_handler, library, id);
        auto updates_opt = one_result.first;
        need_reinit |= one_result.second;
        if(!updates_opt.has_value())
        {
          messaget log{message_handler};
          log.warning() << "Linking library function '" << id << "' failed"
                        << messaget::eom;
          continue;
        }
        object_type_updates.insert(updates_opt->begin(), updates_opt->end());
      }
    }
 
    // done?
    if(!changed)
      break;
  }
 
  if(need_reinit && goto_model.can_produce_function(INITIALIZE_FUNCTION))
    recreate_initialize_function(goto_model, message_handler);
 
  if(!object_type_updates.empty())
    finalize_linking(goto_model, object_type_updates);
}